80 MPh ...horsepower???

[lilrick]

So there are numerous variables to consider for my question , but approximately how many ponies does it take to get to 80. Those of you that are currently running 80, give me an idea. My boat runs 74 right now. I need to get to 80 to be competitive in the nost. comp jet class!!

[LAFD]

just throwind this out there but im gunna take a stab and say around 800 to 900 depending on size and weight on boat the lighter the boat the little less hp heavier the boat more hp. my buddy has around 956 hp and i beleive he sees 85. and hes in a 22 foot jet that kinda heavy.

[dmontzsta]

yup, it wont be long now. :)

[lilrick]

yup, it wont be long now. :)
.......for what?

[dmontzsta]

.......for what?
oh nothing.
:yuk: :rollside:

[superdave013]

If you want your boat to go faster try puting the fork down. :crossx:
I'll see you sunday

[lilrick]

If you want your boat to go faster try puting the fork down. :crossx:
I'll see you sunday
......goddamm!t..the truth hurts!:D

[77charger]

If you want your boat to go faster try puting the fork down. :crossx:
I'll see you sunday
you headed to ming?

[hack job]

my boat right now with full tanks and two fat guys in it runs 80 with 740 hp my guess is with the right setup ( a trip or two away ) ill be at 85 so .... hope this helps. also there is a small chance we might join you guys in nost. jet.

[LakesOnly]

My "station wagon motor" pushes my 18-ft Jet boat to 80+ on any given day. :D Seen 85+ more than once. It certainly don't have 950HP, not even 700HP, most likely less than 600HP. So yeah, lots more than HP to consider.
LO

[Squirtin Thunder]

Rick,
It really does not matter how fast you can run in/on glass, Set the boat up to run 75+ in shit water/ocean swells and you will do real good.

[canuck1]

420 will do it

[lilrick]

Rick,
It really does not matter how fast you can run in/on glass, Set the boat up to run 75+ in shit water/ocean swells and you will do real good.
well Jim I know but I'm wondering what the avg HP is on an 80 mph jet.

[Squirtin Thunder]

The only one that might actually have an idea of what it takes is Hackjob, being he has run circles at Parker. Most of these guys have loose set-ups and it takes far less power to run. But those are the boats that will be very wet at the end of the day. :cool: I figure if you add about 100hp you will be close !!!

[Squirtcha?]

My guess would be between 600 and 650, if your setup is tweaked. That oughta put you flush in the 80-85 range. You might be able to hit it with less, but I'd think this hp range oughta guarantee it for you.
If you can find someone with a plate nitrous setup that you could borrow, you could put it on for a few passes and know for sure. They're pretty easy to hookup and it would take the guess work out of things.
We could probably figure it out using LVjetboy's JPC. I've always found it to be very accurate on my boat/setup. All we need to know is your max speed, rpm, impeller make and cut.

[396_WAYS_TO_SPIT]

I am running over 80 and Im under 700hp.........

[IMPATIENT 1]

I Have @600hp On The Motor And Another 200hp On The Button. I'm Runnin 84mph Gps'd And Have Used To No2 Yet.giving The Mill Break In Time.heavy 18ft. Lake V.

[Danhercules]

My guess would be between 600 and 650, if your setup is tweaked. That oughta put you flush in the 80-85 range. You might be able to hit it with less, but I'd think this hp range oughta guarantee it for you.
If you can find someone with a plate nitrous setup that you could borrow, you could put it on for a few passes and know for sure. They're pretty easy to hookup and it would take the guess work out of things.
We could probably figure it out using LVjetboy's JPC. I've always found it to be very accurate on my boat/setup. All we need to know is your max speed, rpm, impeller make and cut.
You and your laughing gas!! LOL
I think Squirtcha is right. I am running about 500, and I am mid to upper 70's. A 100 shot of the silly gas would get me to 80+, I could work on set up too.

[Jeanyus]

My 10:1 standard bore 427 turns a B impeller 5500 RPMs for a speed of 78 MPH. Acording to this chart thats about 450 horsepower.
http://www.cpperformance.com/TechTips/images/pwr-curve-lg.jpg
I have the B impeller with the ultimate wear ring, and would consider letting you borrow it to see if it makes you any faster.
http://www.hotboatpics.com/pics/data/500/5859berkeley_B.jpg

[Rondane]

hey jeanyus,
what did you notice by changing impellers and wear rings?
rondane.

[Jeanyus]

I started out with this combination, I can say it has a good holeshot, no cavitation to speak of, it was simple to install, I was happy with the results.
I replaced the old impeller with this impeller, a performance preped B impeller.
http://www.hotboatpics.com/pics/data/500/5859new_impeller.jpg
I'll try this setup, and will have the old impeller turned down to a BC, and preped, and try a back cut shoe.

[LAFD]

My "station wagon motor" pushes my 18-ft Jet boat to 80+ on any given day. :D Seen 85+ more than once. It certainly don't have 950HP, not even 700HP, most likely less than 600HP. So yeah, lots more than HP to consider.
LO
i agree you dont have to have alot of hp to go that fast there alot to take into consideration weight, jet setup all that junk.

[lilrick]

I started out with this combination, I can say it has a good holeshot, no cavitation to speak of, it was simple to install, I was happy with the results.
I replaced the old impeller with this impeller, a performance preped B impeller.
http://www.hotboatpics.com/pics/data/500/5859new_impeller.jpg
I'll try this setup, and will have the old impeller turned down to a BC, and preped, and try a back cut shoe.
thanks Jeanyus! I'm turning a C right now at 5500...

[Brooski]

You and your laughing gas!! LOL
I think Squirtcha is right. I am running about 500, and I am mid to upper 70's. A 100 shot of the silly gas would get me to 80+, I could work on set up too.
ROFLMAO! I am running 425 and top out at 72, you were dead even with me!
If your pushing 500, your set up needs alot of work. :p
Mid to upper 70's......we are talking mph, not the year of your boat..... :skull:
I agree with an additional 100hp should work.

[78Southwind]

ROFLMAO! I am running 425 and top out at 72, you were dead even with me!
If your pushing 500, your set up needs alot of work. :p
Mid to upper 70's......we are talking mph, not the year of your boat..... :skull:
I agree with an additional 100hp should work.
I got both of you beat my Southwind is a 78.........1978 :)

[roostwear]

83... nanner nanner

[Squirtcha?]

I'm turning 74 mph with a C right now at 5500...
If that's a Berk C JPC shows you with 377 horsepower.
85 wants 500 hp and would be turning the C at just over 6000 rpm.
Too many rpm for an endurance situation?
I'm just guessing around here, but it seems like 600 hp coming in at around 5500 rpm and a bigger cut impeller (A or AB maybe) would be the ticket. Just figuring that it would do the 80-85 mph @ the 5500 rpm, but you wouldn't be keeping your foot in it for the duration..............would ya? With some luck she just might hold together.

[Liberator TJ1984]

My 10:1 standard bore 427 turns a B impeller 5500 RPMs for a speed of 78 MPH. Acording to this chart thats about 450 horsepower.
http://www.cpperformance.com/TechTips/images/pwr-curve-lg.jpg
I have the B impeller with the ultimate wear ring, and would consider letting you borrow it to see if it makes you any faster.
http://www.hotboatpics.com/pics/data/500/5859berkeley_B.jpg
Can't figure mine out........................
Your chart does not go High Enough !!!! :rolleyes: :yuk:
J/k :p

[cp028]

Hey guys, was reading all your variations of set ups and speeds, so i thought i would put in my .02. i have a 19.5 74 bubble deck hallet, with a 489 single carb. pumb gas making just under 700 hp. through transom headers. in race set up i have clocked in at 96 mph. at the river with all the seats and gas tanks full i get approx, 90 out of her, and yes this took alot of set up work on the track but i think it was well worth it.
tom b.

[Jeanyus]

Can't figure mine out........................
Your chart does not go High Enough !!!! :rolleyes: :yuk:
J/k :p
Pull a couple plug wires :rollside:

[lilrick]

I don't think that chart works for my numbers either, is it accurate?? I 'm sure I'm making over 450 HP!:cry::confused:

[dmontzsta]

You know there is an easy fix to this right?
Partner up with CBR and have him build you a Ford. :)

[hack job]

Hey guys, was reading all your variations of set ups and speeds, so i thought i would put in my .02. i have a 19.5 74 bubble deck hallet, with a 489 single carb. pumb gas making just under 700 hp. through transom headers. in race set up i have clocked in at 96 mph. at the river with all the seats and gas tanks full i get approx, 90 out of her, and yes this took alot of set up work on the track but i think it was well worth it.
tom b.
good to see you posting again tom!
toms boat is a perfect example of a properly set up boat . he has taken his time and put many pass's on this set up. some one you might want to talk to .;)

[Jeanyus]

I don't think that chart works for my numbers either, is it accurate?? I 'm sure I'm making over 450 HP!:cry::confused:
Its the berkeley chart. I got it off the CP website.
http://www.cpperformance.com/TechTips/images/pwr-curve-lg.jpg

[Schiada Time]

With 533 HP, a MPD prepped Berkeley 12JC converted to a 12 JG with a droop snoot, manual place diverter, AB blend aluminum impeller, ride plate and back cut shoe, MPD loader, stage 1.5 blueprint, bottom blueprinted by Bennett my old '77 19 bubble deck Hallett went 78 MPH on GPS. This is a fairly heavy hull considering most other 18-19 foot Jets in non-daycruiser form and it did that with just me (about 225) and full tanks. The key is all in set-up. I never pulled shims or played with the ride plate or re-jetted the carbs so I think she could have seen 80 no problem. I would say for your goal of 80 600 HP and the pump to match should do the trick.

[sanger rat]

525HP, Aggressor B 5500 RPM's. Got me to 79.5 on the GPS.

[canuck1]

You guys need to get better hulls to go with the power you run. A stock ZZ4 will out run most of your rides and it only is rated at 355HP. Damm at 550 you should be crackin 90

[bottom feeder]

Damn Canuck you are on fire tonight :rolleyes:

[572Daytona]

I cracked 90 with 608hp in a 3000lb 21' fiberglass boat, good enough for you canuck? Setup and hull efficiency has a lot to do with it.

[canuck1]

Damn Canuck you are on fire tonight :rolleyes:
Sorry....I'll be good from tommorow on......
PM me your #

[canuck1]

I cracked 90 with 608hp in a 3000lb 21' fiberglass boat, good enough for you canuck? Setup and hull efficiency has a lot to do with it.
Somebody knows what I was aimin for

[LVjetboy]

lilrick,
Power alone, you'll need about 70 hp more to get to your goal. If you truly are turning a Berk C to 5500 rpm then your power to the impeller is about 380 hp. Sorry. If you're topped out at 74 mph, then 80 mph will take about 70 hp more with the same setup.
As for accurate charts, they're the best we've got although they don't account for varibles like intake loading and impeller cavitation. I think most pump curve confusion comes from these curves showing actual power applied to the impeller not rated or reported engine power. You mentioned your engine is 450 hp. Do you know this for a fact from a dyno test adjusted for track density altitude and does your engine produce this peak power at 5500 rpm? If it's a guess, then your rpm, impeller cut and the pump curve may be more accurate for what you really are running.
As for setup, I don't know your hull, weight or pump setup so it's hard to say, but I can say that a 19' jet can run 74 mph with a bit less power. So you may have extra mphs to gain in setup, although 74 mph with 380 hp is not way off for many 19' jets.
jer

[canuck1]

lilrick,
Power alone, you'll need about 70 hp more to get to your goal. If you truly are turning a Berk C to 5500 rpm then your power to the impeller is about 380 hp. Sorry. If you're topped out at 74 mph, then 80 mph will take about 70 hp more with the same setup.
As for accurate charts, they're the best we've got although they don't account for varibles like intake loading and impeller cavitation. I think most pump curve confusion comes from these curves showing actual power applied to the impeller not rated or reported engine power. You mentioned your engine is 450 hp. Do you know this for a fact from a dyno test adjusted for track density altitude and does your engine produce this peak power at 5500 rpm?
As for setup, I don't know your hull, weight or pump setup so it's hard to say, but I can say that a 19' jet can run 74 mph with a bit less power. So you may have extra mphs to gain in setup, although 74 mph with 380 hp is not way off for many 19' jets.
jer
Flywheel power?

[TRG]

767HP, S.S. American Turbine "A" imp. spins 6200rpm flat cut shoe @ 1/8" above keel and the plate is @ 4 deg.
Oh! almost forgot,....an inducer!
96 Mph

[Cs19]

767HP, S.S. American Turbine "A" imp. spins 6200rpm
something doesnt seem right there, id get that tachometer looked at.

[LVjetboy]

Flywheel power?
Power to the impeller. Not much different than flywheel neglecting ujoint or thrust bearing losses. Consider these 19' shallow v's...
FOMOCO:
18.5' Kachina
Berk A/B @5300 = 82 mph
Power to impeller = 432 hp
Estimated speed at 377 hp = 77 mph
HBjet:
19' Liberty
Legend B @5800 = 95 mph
Power to impeller = 568 hp
Estimated speed at 377 hp = 79 mph
Squirt(Don):
18'4" Bahner Bubble deck
Berk A@4750 = 72 mph
Power to impeller = 340 hp
Estimated speed at 377 hp = 76 mph
Just to mention a few.
jer

[LVjetboy]

CS,
Todds reported power is close to what AT's curves say for 6200 rpm on an A cut.
jer

[QuickJet]

My Bahner before I sold it was equiped with litterally a stock 454 out of an 82 motor home. I installed a small .580 flat tappet cam, a set of stock square ports that some would swear were wrong for a motor making barely 9.1 compression, topped off with a tunnel ram and two 660's. The punp is a Berkley JC with a stock A impeller and an extreme loader grate. The pump was new and the motor was just a re-ring and bearing job. I can't imagine the thing made more tha 450 hp on a good day. The Bahner ran consistently 81 mph with a best of 81.7 porpoising like flipper. Yes it had MSD and no mufflers, however it was a heavy hull with 2 10 gallon tanks.
So point being, any 19' jet boat worth a shit should hit atleast 80. If it doesn't and you have more motor than I had, something is terribly wrong.
And for those of you keeping score, I picked up 20mph when I put that same junk motor in my Cole (don't even try arguing the point we already had a 24 page discussion on this last year) :argue: :argue: :)

[dmontzsta]

My Bahner before I sold it was equiped with litterally a stock 454 out of an 82 motor home. I installed a small .580 flat tappet cam, a set of stock square ports that some would swear were wrong for a motor making barely 9.1 compression, topped off with a tunnel ram and two 660's. The punp is a Berkley JC with a stock A impeller and an extreme loader grate. The pump was new and the motor was just a re-ring and bearing job. I can't imagine the thing made more tha 450 hp on a good day. The Bahner ran consistently 81 mph with a best of 81.7 porpoising like flipper. Yes it had MSD and no mufflers, however it was a heavy hull with 2 10 gallon tanks.
So point being, any 19' jet boat worth a shit should hit atleast 80. If it doesn't and you have more motor than I had, something is terribly wrong.
And for those of you keeping score, I picked up 20mph when I put that same junk motor in my Cole (don't even try arguing the point we already had a 24 page discussion on this last year) :argue: :argue: :)
20mph is a great gain.

[QuickJet]

20mph is a great gain.
I considered it a "Bolt On" :D

[TRG]

chris, you are one cat i would'nt bullsheit! :boxed:
The motor made the power on the dyno at 6200 and the boat max's out @6200

[dmontzsta]

I considered it a "Bolt On" :D
Well, I guess it is in some way. :)

[Squirtin Thunder]

767HP, S.S. American Turbine "A" imp. spins 6200rpm flat cut shoe @ 1/8" above keel and the plate is @ 4 deg.
Oh! almost forgot,....an inducer!
96 Mph
Are you going to bring that thing to Parker ???

[Cs19]

CS,
Todds reported power is close to what AT's curves say for 6200 rpm on an A cut.
jer
oh really? i didnt check a chart, 6200 on full A just seemed a little high for his HP.

[TRG]

Are you going to bring that thing to Parker ???
I would really enjoy using it this summer but the boss is a little hardnosed about me not working 7/10's LOL!

[lilrick]

I appreciate the input fellas. I may need to consider some set up changes. Maybe my pump is hurt.I know the motor runs good but now I,m thinking I may have a problem with my pump.It's possible it may have been set up wrong!

[Cs19]

CS,
Todds reported power is close to what AT's curves say for 6200 rpm on an A cut.
jer
I just looked at the chart, it doesnt go high enough for Todd's HP but if it did, 6100 would be in he ballpark according to AMT. It would be interesting to see what he could turn that at if it was all race prepped by someone that knew what they were doing.
when there are guys who can barely turn a fuly prepped and detailed BC that high with more HP than hes got it makes me wonder....

[steelcomp]

I just looked at the chart, it doesnt go high enough for Todd's HP but if it did, 6100 would be in he ballpark according to AMT. It would be interesting to see what he could turn that at if it was all race prepped by someone that knew what they were doing.
when there are guys who can barely turn a fuly prepped and detailed BC that high with more HP than hes got it makes me wonder....
I've been reading post after post about hp and impeller cut/rpm comparisons, and still don't find enough consistancies to base any estimates on. The above is a perfect example. Another one...(I've put this up many times) I spun a race prepped B to 5500, and it went 93.
Now, with my new set-up, at 6200 measured hp is 705 (da 2975'), and that's where I was "told" I'll spin my prepped BC. At 6500, tq starts falling faster than hp is climbing, and measured is 727. I'm thinking this is where it's going to run. I'm looking forward to seeing just where this motor will spin the BC. Power stops climbing at 7100, which measured is 741, corrected is 821. (Big difference between bragging rights and actual power)

[Squirtcha?]

Speculation is cool, but I for one always enjoy seeing the real deal vs. predicted results. Especially where the ol torque vs. Horsepower deal enters the picture. Can you spin your impeller/pump past where the torque numbers start falling off, but horsepower is still climbing?
Hoping you'll put up your info when done Scott?

[Oldsquirt]

. Can you spin your impeller/pump past where the torque numbers start falling off, but horsepower is still climbing?
Dan, typically, that is what we all are doing. This is unless you are spinning(or trying to spin) an impeller that is so big it limits you to the RPM (or lower) at which peak torque occurs. Peak torque in our type of engines occurs well before peak HP. Some quick examples of BBC and BBF curves from an Edelbrock catalog(just happened to be handy) show a trend of torque peak around 4500rpm and HP peak in the 6000-6500 rpm area. By no means an absolute, but rather a fair generalization. There are always exceptions......

[Squirtcha?]

While I suppose that's true in a lot of cases............it's not in mine. These are desktop dyno numbers so take it for what it's worth.
My torque peaks to 503 @ 5000 rpm then starts dropping off.
My hp peaks to 518 @ 6000 rpm.
I can only spin my pump to 5300 rpm with an Aggressor AB.
Since the hp actually peaks to 518 @ 6000 rpm but I can't get to it, that's kinda my point. If my hp is still climbing to 6000 rpm then why can't I continue to spin my pump to that rpm? In theory I should be able to if it's simply a function of hp and tq doesn't play as big a role?
These numbers are all strictly the motor and no nitrous.
http://www.jetheaven.us/photopost/data/500/19dd_numbers.jpg

[Oldsquirt]

While I suppose that's true in a lot of cases............it's not in mine.
Dan, how is it NOT the case? Your torque has peaked at 5000rpm and your HP peaks at 6000rpm. You are turning 5300, so you are indeed turning your impeller past the point where torque is falling off but HP is still climbing. Seems you are doing exactly what your question asked.
You can't turn any faster because the torque you have available at 5300rpm is insufficient to overcome the resistive torque of your pump combo at that rpm.
Remember, DeskTop Dyno is an "estimate". ;)
BTW, I find it easier to use the graphs. Makes visualising the data easier.

[Squirtcha?]

It's true to a point, but it still seems that I should be able to spin it to (or at least closer to) the 6000 rpm. I'm just barely able to spin it past the point where the torque is falling off. I never expected there to be a wall at the point where the tq fell off, so I'm not surprised to see it surpass that number by a bit.
So.............the question would be, what do you suppose would happen tq and hp both peaked at the 6000 rpm? All things the same other than that, would I then be able to spin it to the 6000 rpm?
This isn't meant to be argumentative. They're just some questions I've always had in the back of my feeble mind.
I've always been in the horsepower camp, but I guess not definitively.

[396_WAYS_TO_SPIT]

thanks Jeanyus! I'm turning a C right now at 5500...
Rick, do you have a stock motor? Whats all done to it? Something is definately wrong here. I spun a berk detailed ab to 5800 when I first ran my boat. My buddy jonathan spins a stock berk "A" to 5100. I would look at the motor to see if something might be wrong.
396

[Oldsquirt]

So.............the question would be, what do you suppose would happen both tq and hp both peaked at the 6000 rpm? Would I then be able to spin it to the 6000 rpm?
Would this hypothetical engine have enough torque to match/exceed your pump/impeller's resistive torque(which you can calculate from the HP absorption charts)? If so, then yes. Might be a tough engine combo to create.
Keep in mind, the engine's HP and Torque curves cross the impeller's respective HP and Torque curves at the same rpm.

[Squirtcha?]

Would this hypothetical engine have enough torque to match/exceed your pump/impeller's resistive torque(which you can calculate from the HP absorption charts)? If so, then yes.
Keep in mind, the engine's HP and Torque curves cross the impeller's respective HP and Torque curves at the same rpm.
You're funny Craig. It's obvious that you never sat next to me in any of my high school or college algebra classes. Let's rephrase this to say that "YOU can calculate it from the charts?"
Dan doesn't calculate things. Math makes his head hurt.

[Oldsquirt]

.....Dan doesn't calculate things. Math makes his head hurt.
Then I guess I probably shouldn't suggest that you calculate how fast torque in your hypothetical engine would have to fall off in order to keep HP from increasing past the 6000rpm point. :D
Liquidaddiction.net has a graph of an impeller's HP and Torque curves.

[Squirtcha?]

Then I guess I probably shouldn't suggest that you calculate how fast torque in your hypothetical engine would have to fall off in order to keep HP from increasing past the 6000rpm point. :D
No............. you shouldn't :boxed:
You said the "C" word again too. I thought we talked about that?

[LVjetboy]

I just looked at the chart, it doesnt go high enough for Todd's HP but if it did, 6100 would be in he ballpark according to AMT. It would be interesting to see what he could turn that and if it was all race prepped when there are guys who can barely turn a fuly prepped and detailed BC that high with more HP than hes got it makes me wonder....
Todd quoted 767 hp here's AT's extended chart...
http://members.cox.net/lvjetboy/ATChart.jpg
Red line a curve fit to AT's published A cut numbers. Dashed black extrapolated from those numbers. Mixed flow pumps follow a cubic relationship between rpm and power so mfgs base charts on that relationship. Of course it's easier to use JPC than eyeball or extrapolate a chart, see inset.
Big picture. 767 hp very close to 754 hp assuming the 767 Todd quoted is his lake power not corrected power to a standard no where near his lake DA. Wouldn't you agree? As for race-prepped vs. stock, tight wear ring clearances and blade detailing...in principle I'd agree. A race impeller cavitates less and a tight ring cuts recirculation. But my dyno tested engine turned a race detailed Berk B with new ring very close to Berkeley chart power numbers.
jer

[LVjetboy]

I've been reading post after post about hp and impeller cut/rpm comparisons, and still don't find enough consistancies to base any estimates on. With my new set-up, at 6200 measured hp is 705 (da 2975'), and that's where I was "told" I'll spin my prepped BC. At 6500, tq starts falling faster than hp is climbing, and measured is 727. I'm thinking this is where it's going to run. I'm looking forward to seeing just where this motor will spin the BC. Power stops climbing at 7100, which measured is 741, corrected is 821. (Big difference between bragging rights and actual power)
Steel, the difference between corrected and actual is one reason why many are confused and bragging rights rule. But this stuff's not rocket science. If you have a Berk B/C cut at 6600 it's absorbing 700 hp according to charts. I'm also sure you understand chart limitations...charts are a starting point, a standard to base further testing on, not an end-all proof of everything.
But also consider the limitations of tachs, reported cut size, and engine output at test DA. On the net, you filter BS and those claiming without really knowing. Many jetters report engine power based on software etc. not a dyno test. Many don't even understand the difference between corrected and tested engine power. While DTD may be a good ballpark, it's just a guess and no more accurate than what you put in. I've read many posts talking engine power and rpm when they don't even know impeller cut size or mfg for sure. Or power quoted was what they thought their engine was rated at based on a collection of parts or what someone told them or what they read in a magazine...etc.
If you're confused by reading inconsistent posts on hp vs cut size, consider the accuracy of the source before concluding charts are wrong or somehow torque falling faster than power is rising is a magic number.
jer

[LVjetboy]

Speculation is cool, but I for one always enjoy seeing the real deal vs. predicted results. Especially where the ol torque vs. Horsepower deal enters the picture. Can you spin your impeller/pump past where the torque numbers start falling off, but horsepower is still climbing? Hoping you'll put up your info when done Scott?
Yes I can give you the real deal. My measured torque peaks at 5200 rpm (587 lb-ft) but my measured power peaks at 6200 rpm (634 hp) that's 1000 rpms later. At full throttle 6200...
http://members.cox.net/lvjetboy/CenturyJet.jpg
Not top speed in that shot but you see the tach. That tach matched the dyno tach at Westech during the engine test run. The engine's topped out full throttle. The dragn's still accelerating when I snapped this shot with one hand on the camera, one hand on the wheel. If my engine was turning 5100 rpm I would be putting 581 hp to the impeller. Since my engine turns 6200 rpm with a Berk B impeller I'm putting 634 hp to the impeller...53 hp more. Yet 50 lb-ft less torque. Would a bigger impeller matched to peak torque get me over 100 mph? Not likely.
A bigger impeller may improve my hole-shot and cruise economy, but not top speed. The point is, jet performance no matter hole-shot, cruise economy or top speed is NOT a function of torque or how fast the torque curve drops.
Performance depends on power delivered to the impeller, rpm and pump performance curves. Performance curves are based on power not torque. I think the sooner we jetters understand that performance is based on power and pump efficiency (not torque), the sooner we can move on to understanding more. If you're looking at torque numbers or how big torque is or how fast it drops off...you're looking at the wrong thing.
jer

[lilrick]

Rick, do you have a stock motor? Whats all done to it? Something is definately wrong here. I spun a berk detailed ab to 5800 when I first ran my boat. My buddy jonathan spins a stock berk "A" to 5100. I would look at the motor to see if something might be wrong.
396
well the motor is .030 over 454 with a 2399 piston .I run a closed chamber head which yields about 10:1 Cr .The heads have big valves and port work done. I run a solid flat tappet cam, Isky Z-45. I have an 830 holley carb. I run a locked out mag at with 40* lead in the motor. I started mixing my fuel 50/50 to resolve any predetonation issues. I think that I have resolved to try a place diverter.

[Oldsquirt]

Performance depends on power delivered to the impeller, rpm and pump performance curves. Performance curves are based on power not torque. I think the sooner we jetters understand that performance is based on power and pump efficiency (not torque), the sooner we can move on to understanding more. If you're looking at torque numbers or how big torque is or how fast it drops off...you're looking at the wrong thing.
jer
So Isaac Newton was wrong with his First Law of Motion? It isn't FORCE that causes acceleration of an object? I might need to go back and inform my high school and college professors of this...
While I agree that looking at POWER(HP) makes sense when we are trying to optimize the WORK we are doing with the engine(spinning the pump and moving water and thus moving the boat), it is, according to my understanding of Newtonian physics, the force(torque) applied to the pump by the engine that sets it moving and is responsible for increasing RPM to the max RPM point, which comes when the torque curves intersect.
I think people have become accustomed to looking to HP more because we can easily visualize the peak HP in either a graph or chart which makes it far easier to compare to the pump HP curves. Finding the optimum impeller by comparing the torque curves is far less obvious. What doesn't change is that for a given combination, the engine's HP and Torque curves cross the pump's curves at the SAME rpm.

[LVjetboy]

Dan,
You posted spinning an Aggressor AB to 5300 rpm. That's 514 hp according to Aggressor charts*
Your DTD charts show about 493 hp for your engine at 5300 rpm. Ok, 514-493 = 21 hp. Now, do you think the accuracy of you tach reading with one eye closed and a bit of vibration plus a software generated DTD engine curve for your engine combined with the wag of an Aggressor impeller cut chart* are all so precise that the 21 hp differcence is something we can comment on? Or something you can conclude tq drives performance instead of hp? I'm thinking not.
jer

[Squirtcha?]

Dan,
You posted spinning an Aggressor AB to 5300 rpm. That's 514 hp according to Aggressor charts*
Your DTD charts show about 493 hp for your engine at 5300 rpm. Ok, 514-493 = 21 hp. Now, do you think the accuracy of you tach reading with one eye closed and a bit of vibration plus a software generated DTD engine curve for your engine combined with the wag of an Aggressor impeller cut chart* are all so precise that the 21 hp difference is something we can comment on? Or something you can conclude tq drives performance instead of hp? I'm thinking not.
jer
Maybe not, but I've never been a blind follower either. I reckon there will always be at least a small amount of doubt. Since it's impossible to have one without the other (tq and hp), it may be the unsolvable riddle.

[jweeks123]

I might need to go back and inform my high school and college professors of this...many of us could benefit from a visit to those guys :)
the engine output is coverted to thrust by the jet. thrust = mass x velocity. velocity = distance per unit time. (like ft/sec.) theres units of time in velocity and therefore there are units of time in thrust. where are the units of time gioing into the jet? torque has no units of time. add units of time to tq and it's not tq anymore. it's horsepower. hp = tq x rpm / 5252 (english system).
i'm sure lvjb can explain it better
jw

[Cas]

I'm really, really tired of this subject. And trust me, I don't want to see another post with the definition of power and torque.
jer
Well damn, I was just about to jump into the fray ;) :p
I kept the thread from way back when we all really got heavily into this tq v hp thing. Anytime I want a fix, I just go back and read it. And to think the thread I saved started out by me asking a simple question of which large oval port BBC head was better, the 049's or the 781's :D

[LVjetboy]

Ya well, some things never change Steve. But I'd like to see those who champion the significance of the torque vs power crossing rpm (and related increasing faster or slower slope theories) explain how a 5250 crossing point is significant when applied to the same engine on the same dyno yet measured in metrics.
jer

[Cas]

well, you pretty much know where I stand although I have been swayed somewhat. I am going to be doing a little test with my set-up by swapping a couple of parts out. When done, I'll post some numbers based on the findings of the different set-ups.
As far as how much HP to hit 80? There are just too many variables to base it only on one aspect as others have touched on.

[squirt]

Power to the impeller. Not much different than flywheel neglecting ujoint or thrust bearing losses. Consider these 19' shallow v's...
FOMOCO:
18.5' Kachina
Berk A/B @5300 = 82 mph
Power to impeller = 432 hp
Estimated speed at 377 hp = 77 mph
HBjet:
19' Liberty
Legend B @5800 = 95 mph
Power to impeller = 568 hp
Estimated speed at 377 hp = 79 mph
Squirt(Don):
18'4" Bahner Bubble deck
Berk A@4750 = 72 mph
Power to impeller = 340 hp
Estimated speed at 377 hp = 76 mph
Just to mention a few.
jer
Well things have changed, two years ago a mpd pump and impeller and a bennett bottom. Impeller is a B+ motor with out NOS 4800rpm at 80mph about 350 hp on the chart. with NOS (100 shot) 5,000rpm and 82.5 MPH and motor is wore out!

[Cs19]

Todd quoted 767 hp here's AT's extended chart...
http://members.cox.net/lvjetboy/ATChart.jpg
Red line a curve fit to AT's published A cut numbers. Dashed black extrapolated from those numbers. Mixed flow pumps follow a cubic relationship between rpm and power so mfgs base charts on that relationship. Of course it's easier to use JPC than eyeball or extrapolate a chart, see inset.
Big picture. 767 hp very close to 754 hp assuming the 767 Todd quoted is his lake power not corrected power to a standard no where near his lake DA.
jer
Todds numbers (767hp) are corrected HP numbers.

[MikeF]

Here's something else to gobble up. :crossx:
Why did it take only 5700 to 5800 RPM for Cyclones(TR) and HBjet's (Eliminator Liberty) hulls to go 95 mph w/B impellers.......
And it takes 6200 RPM for Todd's smaller/lighter Bonneville to go 96mph w/an A impeller.
And how does RCB19 go nearly as fast w/ much less engine than all the above.
That's what I want to know!....Really. :mix:

[Cs19]

Here's something else to gobble up. :crossx:
Why did it take only 5700 to 5800 RPM for Cyclones(TR) and HBjet's (Eliminator Liberty) hulls to go 95 mph w/B impellers.......
And it takes 6200 RPM for Todd's smaller/lighter Bonneville to go 96mph w/an A impeller.
And how does RCB19 go nearly as fast w/ much less engine than all the above.
That's what I want to know!....Really. :mix:
lmao.
:)

[Cs19]

how about this one ??
750 uncorrected hp turning a berk B/C @ 6100-6200 RPM, 115.2 mph.

[steelcomp]

how about this one ??
750 uncorrected hp turning a berk B/C @ 6100-6200 RPM, 115.2 mph.
...or a B turning 5500, and going 93.
So 767 hp is turning an A 6200, and 750 is turning a BC 6200, and the 767 is more like 700 actual (that's being generous).
I'm not buying the power/rpm with the A cut. There's something wrong there. The speeds can't be compared due to hull differences.

[Triton]

If you think about it you can have all the horsepower in the world your pump musted be matched to the horsepower you are runing.

[MikeF]

750 uncorrected hp turning a berk B/C @ 6100-6200 RPM, 115.2 mph.
Can't compare an "air trapper" to a "shallow V". :rollside:

[396_WAYS_TO_SPIT]

this is gettin' good fellas;)

[LVjetboy]

Even a bigger mystery. Why get sucked into these debates? :)
Chris, there's lots of reasons hp/rpms don't match I'm sure you know. If I remember Hbjet was turning a Heritage(?) impeller which may not compare to Legend curves. And for those of us w/o data recording...it's really hard to eyeball a tach and not be off by 100 rpm. And how accurate are cut sizes reported? Remember Cyclone's HB article, I think it was the AA that really wasn't an AA? But beyond that, I suppose it's possible two guys with the same impeller can run different loading and see a difference of up to 100 rpm from that alone. How much does your rpm change going down the track? Small things add up.
As for Todds numbers, you'll notice I qualified my answer with, "assuming 767 is his lake power not corrected power to a standard no where near his lake DA." :boxed:
That's another unknown we usually don't talk about. How many lake guys pay attention to DA? When I took that shot above, my DA was close to measured dyno conditions...1200' and 80 degF. But if I ran a cool dry day on the river? I may run 100 to maybe even 150 rpms more.
In the winter it's not impossible to run close to "corrected" power conditions instead of "measured" Of course, dyno engine configuration isn't always real world. My mufflers are a bit less restrictive than what I ran on the dyno.
When you start adding all these things up, you can easily see how hp/rpms don't always match...even if the pump curves were dead on...which like everything else, they're probably not. These things aren't a mystery, they just need to be accounted for. When someone reports hp/rpm, you usually don't know how accurate their information is or what they accounted for.
jer

[Triton]

If you have A Impeller and over 500HP and running low RPMS some things you can do is cut down the impeller to a "AB" cut.And bring up the rpms for top end, And play around with some pump set ups,& loader grates.There are tons of things that can get you the speed you want.It just takes money."BOAT" Bring Out Onother Thoundsand. :rollside:

[canuck1]

Power to the impeller. Not much different than flywheel neglecting ujoint or thrust bearing losses. Consider these 19' shallow v's...
FOMOCO:
18.5' Kachina
Berk A/B @5300 = 82 mph
Power to impeller = 432 hp
Estimated speed at 377 hp = 77 mph
HBjet:
19' Liberty
Legend B @5800 = 95 mph
Power to impeller = 568 hp
Estimated speed at 377 hp = 79 mph
Squirt(Don):
18'4" Bahner Bubble deck
Berk A@4750 = 72 mph
Power to impeller = 340 hp
Estimated speed at 377 hp = 76 mph
Just to mention a few.
jer
I remember HB dyno #'s, they were alot higher than that....
Using HB dyno #'s at 4500 of 622# and the ZZ4 at 3500 and 405# the comparison seems not to match very well
So would these boats run close to 80 with a ZZ4 crate motor?

[Tom Brown]

Even a bigger mystery. Why get sucked into these debates? :)
I guess we don't all have the kind of willpower you do to stay out of these debates. :D :D :D
Sorry Jer. :D

[Oldsquirt]

Oldsquirt,
Not about Newton although the principles he established hold true. The fact that an engine's power and torque curves cross at the same rpm is a function of the power vs torque equation alone and units not some magical combination of engine or pump parts or best impeller cut performance based some mystical combination of power and torque. Or a contradiction of Newtons laws. Power and torque cross at an rpm depending on what units you choose.
The physical rpm where power and torque cross is not important to jet performance and never will be. Jet performance as well as any other drive performance based on power the the drive, losses w/in that drive and physics guys like Newton discovered. In metric units power and torque cross somewhere else at a bit higher rpm you think? So you think guys running metric jets with engine torque and power crossing at 9+k perform better than us for the same engine and drive? Whatever. The whole power vs torque confusion is a result of those who don't really understand power, torque and drive efficiency.
I'm really, really tired of this subject. And trust me, I don't want to see another post with the definition of power and torque.
jer
Jer, you TOTALLY misunderstood my comment about the crossing of the curves......I was NOT referring to the old "crosses at 5252rpm" issue. You might reread my post. Instead, I was pointing out that if you take an engine and impeller combination, turn it to its max rpm(let's say 6000rpm) and say that that is the max BECAUSE that is where the HP curves cross, if one were to take the time to look, you would find it is ALSO the rpm at which the two torque curves cross. Actually, no calculations are needed as long as one understands that this formula. HP=Tq x RPM /5252. applies to both the engine and the pump. If at any given RPM, pump HP = engine HP,then the third variable, Torque, must also be equal in both the engine and the pump.
Final thought. I was not referring to BOAT performance as a function of engine torque. I was simply referring to accelerating the PUMP as a function of torque.
EDIT: Jer, have you forgotten the summer of '02 when BOTH of us spent time trying to explain on this board that the 5252 crossing point of the Tq and HP curves was just a mathematical anomaly?

[Oldsquirt]

well the motor is .030 over 454 with a 2399 piston .I run a closed chamber head which yields about 10:1 Cr .The heads have big valves and port work done. I run a solid flat tappet cam, Isky Z-45. I have an 830 holley carb. I run a locked out mag at with 40* lead in the motor. I started mixing my fuel 50/50 to resolve any predetonation issues. I think that I have resolved to try a place diverter.
Rick, why so much spark advance? Seems about every BBC dyno test I've ever read finds optimum spark advance to be 36* or less.

[Oldsquirt]

To add my data to the list:
19.5 Eliminator Sprint
Single carb BBC 461
85.6mph @ 5400 on a Legend "B"

[cyclone]

Here's something else to gobble up. :crossx:
Why did it take only 5700 to 5800 RPM for Cyclones(TR) and HBjet's (Eliminator Liberty) hulls to go 95 mph w/B impellers.......
And it takes 6200 RPM for Todd's smaller/lighter Bonneville to go 96mph w/an A impeller.
And how does RCB19 go nearly as fast w/ much less engine than all the above.
That's what I want to know!....Really. :mix:
After driving his boat i think todd has more left with a few hours spent on some set up work and hardware.
Beyond that, they are different hulls and his 18 Bonneville is quite different than my 19 Bonneville TR. And as far was v bottoms go, i dont think it gets better than the Liberty bottom.

[JLB440Stroked]

While I suppose that's true in a lot of cases............it's not in mine. These are desktop dyno numbers so take it for what it's worth.
My torque peaks to 503 @ 5000 rpm then starts dropping off.
My hp peaks to 518 @ 6000 rpm.
I can only spin my pump to 5300 rpm with an Aggressor AB.
Since the hp actually peaks to 518 @ 6000 rpm but I can't get to it, that's kinda my point. If my hp is still climbing to 6000 rpm then why can't I continue to spin my pump to that rpm? In theory I should be able to if it's simply a function of hp and tq doesn't play as big a role?
These numbers are all strictly the motor and no nitrous.
http://www.jetheaven.us/photopost/data/500/19dd_numbers.jpg
Looking strictly at the DTD, you can see why you spin at 5300 RPM +/- and not your peek power of 518 @ 6000 RPM. There simply isn't a big enough difference in power. Assuming 20-25HP usually yields 100 RPM. Since the chart shows increments of 500 RPM, we will have to average for power @ 5300r's. From 5000 to 5500 the avg. 5.8HP per 100 RPM. So 5300 RPM is 497 HP. The difference from 5300r's to 6000r's = 21 HP. This is not enough to carry the impeller past it's HP absorption level. Just my thinking...could be wrong.
As for Torque vs. HP debate, I'm still learning.

[bigblockbill]

Here is my data
21 ft Daytona (Heavy Layup)
4500 ft elevation (No air to trap)
Berk AB cut 5500 rpm @ 74 mph GPS (1 person, light fuel, head wind)
Aggessor AA cut 4800-4900 rpm @ 71 mph GPS (2 people, heavy fuel, no wind)

[MikeF]

And as far was v bottoms go, i dont think it gets better than the Liberty bottom.
Maybe the 18' and 19' California Performance!?! :mix:

[lilrick]

[QUOTE=cyclone]After driving his boat i think todd has more left with a few hours spent on some set up work and hardware.
Beyond that, they are different hulls and his 18 Bonneville is quite different than my 19 Bonneville TR.
there aren't too many people around anymore that are familiar with the Liberty or Hornet bottom anymore. Now I know you know your stuff! :D Any suggestions on set up for this particular hull that sticks out in your mind Cyclone? thanks

[lilrick]

And as far was v bottoms go, i dont think it gets better than the Liberty bottom. Squirtin thunder is in big trouble now! All the prize money will be mine !!!!:D

[LVjetboy]

” Jer, have you forgotten the summer of ‘02….?”
Oldsquirt, I’m lucky to remember 4 days ago let alone 4 years. :smile: Was it good? I just re-read your post and maybe I missed your point. Just for context, here’s what Dan first posted:
Originally Posted by Squirtcha?
”Speculation is cool, but I for one always enjoy seeing the real deal vs. predicted results. Especially where the ol torque vs. Horsepower deal enters the picture. Can you spin your impeller/pump past where the torque numbers start falling off, but horsepower is still climbing? Hoping you'll put up your info when done Scott?”
To which I responded:
Originally Posted by LVjetboy
”Performance depends on power delivered to the impeller, rpm and pump performance curves. Performance curves are based on power not torque. I think the sooner we jetters understand that performance is based on power and pump efficiency (not torque), the sooner we can move on to understanding more. If you're looking at torque numbers or how big torque is or how fast it drops off...you're looking at the wrong thing.”
You then quoted me and talked about Newton, force, work and power. I guess I missed your point or how it applied to what I was telling Dan. But since you mentioned it :) I’ll try to talk to your points.
---
” So Isaac Newton was wrong with his First Law of Motion? It isn't FORCE that causes acceleration of an object?”
I’m pretty sure my posts about power and torque agree with Newton’s Laws and he'd be ok with that.
” While I agree that looking at POWER(HP) makes sense when we are trying to optimize the WORK we are doing with the engine(spinning the pump and moving water and thus moving the boat), it is, according to my understanding of Newtonian physics, the force(torque) applied to the pump by the engine that sets it moving and is responsible for increasing RPM to the max RPM point, which comes when the torque curves intersect.”
I try to not talk force or work unless it’s thrown out there. I'm sure a lot of jetters could care less. You probably won’t hear, “Jeeze Bp, you beat me by a nose, your engine’s really optimized for work huh? BTW, just how much force are you putting to that Berk impeller anyway?” :) But power and torque? People question, debate an wonder endlessly. That said...
Torque spins your impeller to the torque matching point, so also power spins it to the power matching point. And of course, that point’s the same rpm either way. Regardless of the fact that you can plot engine and pump torque curves instead of power curves and find the match point, pump performance is still driven by maximum power to the impeller and not maximum torque. So it makes more sense to look at power curves. Looking at the wrong variable and trying to explain performance can lead to bad conclusions. Like the magical 5250. Or theories about torque slope decreasing faster than power is increasing?
I’ll give an example. Say a mfg wants to measure gear box performance for spiral vs. hypoid bevel gears in a v-drive. Should they measure power out and divide by power in or measure torque out and compare to torque in? Based on a power ratio they calculate 3% loss. Yet if the boxes have different gear ratios, you can see how torque output divided by input has little to do with gearbox performance or efficiency, instead driven by gear ratio. A different ratio and power loss is still about 3%. Yet a different ratio and torque out over in is very different and really has nothing to do with gearbox performance. In this example, the difference between focusing on power or torque is clear. In our application, it may be a bit less clear but I think still worth understanding that there IS a difference. Low power, flat curves, you won’t see it. Bigger power, pushing the limits…maybe so. Either way, don’t we really want to know why?
”I think people have become accustomed to looking to HP more because we can easily visualize the peak HP in either a graph or chart which makes it far easier to compare to the pump HP curves. Finding the optimum impeller by comparing torque curves is far less obvious.”
I’d say there’s a good reason why pump designers use power curves to talk about pump performance. As for ease or visualization, curves are curves to me. If it made sense to compare engine and impeller torque for best performance, I’d be looking at torque instead. Beyond “less obvious” I’d suggest looking at torque curves to find the optimum impeller is the wrong thing to be looking at in the first place.
”Jer, you TOTALLY misunderstood my comment about the crossing of the curves......I was NOT referring to the old "crosses at 5252rpm" issue.”
Good. Maybe that myth is no more.
”Instead, I was pointing out…if pump HP = engine HP, then the third variable, Torque, must also be equal in both the engine and the pump.”
Yes it does. I’m just not sure if you’re saying because they cross at the same rpm, it makes no difference which quantity you look at, or what? Yes I know the Hp/Q equation well, I know why they cross and the same rpm, and I’ve looked at both torque and power curves for many dyno runs, some with later speed tests. The fact that engine output power or torque will equal impeller input power or torque at any given rpm doesn’t solve anything, or prove which of those quantities drives performance. But maybe that wasn’t your point.
[i]”Final thought. I was not referring to BOAT performance as a function of engine torque. I was simply referring to accelerating the PUMP as a function of torque.”[i]
Ok. But boat performance IS what we’re talking about. Or at least what Dan was talking about and my follow-up post you quoted was talking about. Typically, an engine will accelerate the impeller to max rpm in about a second or less. So if you say you need big torque (not power) on launch to accelerate the impeller, well I’m thinking you probably don’t.
jer

[Squirtin Thunder]

So there are numerous variables to consider for my question , but approximately how many ponies does it take to get to 80. Those of you that are currently running 80, give me an idea. My boat runs 74 right now. I need to get to 80 to be competitive in the nost. comp jet class!!
But to bring this back on track Rick is a Nostagia Comp Jet racer, he needs more than just power. He needs a boat set-up that will run 80mph wet holding the water in the worst conditions.