RPM's????????????

[MAINEVENT]

I have a bbc with dual carb high rise manifold stock 454 forgot the cam specs and compression but the guy who built said top rpms was high 5k or if not 6k i maxxed out WOT 4750 WTF i dont get my impellar is a "ab cut impellar"
i am lost :confused:

[dmontzsta]

RPM????????????????
Sounds like the guy stretched the truth about the "RPM". :)
How long have you owned the boat?

[canuck1]

Originally posted by MAINEVENT
I have a bbc with dual carb high rise manifold stock 454 forgot the cam specs and compression but the guy who built said top rpms was high 5k or if not 6k i maxxed out WOT 4750 WTF i dont get my impellar is a "ab cut impellar"
i am lost :confused:
Stock 454
dual carbs
Unknown cam
400 horses maybe = 4750 with AB imp

[MAINEVENT]

Thanks guys i have owned the boat a year but first time out it blew along with the pump complete rebuilt on everything pump done by Jack over at MPD (very happy with his service:D ) and the motor i went to this J-O Ace Motor Co. in santa paula :mad: hey promised a 462 for about $2300 for a short block plus R+R when it came down to it he wanted another grand so he said i can build you a stock 454 that will run close to 550hp and 6k rpm i should have known would a new cam make a difference?????
MAIN(I REALLY WANT TO KICK THAT GUYS ASS)EVENT

[MudPumper]

I'm turning 5100rpm A/B imp 500hp

[HBjet]

I was turning 5100-5150rpm with a B impeller. Stock 454 .030 over, a little better cam, dual Holley 450's on a Weiand tunnel ram, and stock 990 heads.
Pump also done at MPD.
HBjet

[LVjetboy]

MainEvent,
First know (and state) your impeller mfg. Makes a difference. For example, a Berkeley A/B not the same as an Agressor A/B...or a Legend. Then know your true impeller cut...have you verified A/B cut? Then realize engine builders typically quote calibrated power and NOT lake power. Lake power is what turns an impeller. Most of us don't boat at calibrated conditions. Finally, engine builders may quote max hp or valve float rpm not what your engine-impeller combo at lake conditions will turn.
BTW, Berkeley A/B at 4750 rpm = 313 hp.
jer

[MAINEVENT]

Originally posted by HBjet
I was turning 5100-5150rpm with a B impeller. Stock 454 .030 over, a little better cam, dual Holley 450's on a Weiand tunnel ram, and stock 990 heads.
Pump also done at MPD.
HBjet
Hey HB i saw you at MPD when i was picking up my jet you were stripping your getting ready for paint you were talking to my wife... How are you doing ????

[MAINEVENT]

Originally posted by LVjetboy
MainEvent,
First know (and state) your impeller mfg. Makes a difference. For example, a Berkeley A/B not the same as an Agressor A/B...or a Legend. Then know your true impeller cut...have you verified A/B cut? Then realize engine builders typically quote calibrated power and NOT lake power. Lake power is what turns an impeller. Most of us don't boat at calibrated conditions. Finally, engine builders may quote max hp or valve float rpm not what your engine-impeller combo at lake conditions will turn.
BTW, Berkeley A/B at 4750 rpm = 313 hp.
jer
Soory it is a Dominator A/B impellar

[JET-O-VATOR]

mainevent i may be way off with this but it is what i found this weekend with my brendella... my rideplate was set downward so i had wat to much boat in the water even with the jet-o-vator up.. i didnt even know any better and squirtin thunder had stopped by and was whatching me make a pass and noticed it so we started playing with it and pulled the boat way out of the water.... before i could not pull more than 4200 rpm and after we did that i could pull 5000 rpm so go fiqure and thats with an a impeller......and i noticed the difference right away, every adjustment we made it kept getting better....so ya i dont know what your boat has but mine has 12-jg-a, back cut shoe (so im told) and a ride plate.
daniel

[Squirtcha?]

Originally posted by JET-O-VATOR
mainevent i may be way off with this but it is what i found this weekend with my brendella... my rideplate was set downward so i had wat to much boat in the water even with the jet-o-vator up.. i didnt even know any better and squirtin thunder had stopped by and was whatching me make a pass and noticed it so we started playing with it and pulled the boat way out of the water.... before i could not pull more than 4200 rpm and after we did that i could pull 5000 rpm so go fiqure and thats with an a impeller......and i noticed the difference right away, every adjustment we made it kept getting better....so ya i dont know what your boat has but mine has 12-jg-a, back cut shoe (so im told) and a ride plate.
daniel
That raises an interesting question......................
I always found that you could run your boat full of people, full tanks of gas, skis, coolers whatever, and you would turn the same rpm as when running with one person, empty tanks and (no non-essential equipment). Although it would affect your speed, rpm's would not change.
In other words you can adjust your ride all you like, and it may run faster but your rpm would remain the same.
I've done lots of ride tweaking on mine, including setting back the pump, rideplate/shoe combo (and lots of adjusting both good and bad), droop then snoot etc. etc. I got some mph gains and losses by adjusting/tweaking my ride, but my rpm remained the same no matter what I did.
Adding/subtracting horsepower and or changing impeller sizes/types should be the only way the rpm changes.
Anybody else care to chime in?
Not trying to be argumentative here. Just sharing what I've found with my boat by playing around with different stuff.

[JET-O-VATOR]

WELL SQUIRTCHA IM JUST SHARING WHAT I HAVE FOUND THIS WEEKEND WITH MY BOAT... MY RIDEPLATE WAS SET WAY TO FAR NEGATIVE(DOWN) AND I WAS ABLE TO FEEL THE DIFFERENCE EVERYTIME WE PULLED IT UP I WENT FASTER AND COULD PULL MORE RPM'S. ALL I KNOW IS THAT AFTER WE GOT THAT THING ALL THE WAY UP I WAS GOING THE SAME SPEED AT 3500 RPM AS IT WOULD AT 4200 BEFORE WE PLAYED WITH IT AND NOW I CAN PULL 5000 AND MOVING MUSH MUCH FASTER. IT ACCTUALLY SCARED ME A COUPLE OF TIMES.. BUT IVE NEVER DRIVEN A BOAT THAT FAST BEFORE AND NOW IM CRAVING MORE SPEED... I WANT IT FASTER.. IM SURE YOU ALL KNOW ABOUT THAT....

[Danhercules]

I know nothin, just thowin ideas.
If he has a loader, and the boat is too wet, could it be over loading the pump and slowing the RPM's down? Just a thought.

[JET-O-VATOR]

NO LOADER....YET...I THINK IM GUNNA TRY ONE.... AS WELL AS A DROOP

[Lightning]

How many RPM's shoud I be running with a stock 454mag (390hp). I think I am about 4500 - is that good?

[BrendellaJet]

Lightning, it depends on what impeller you have.

[Squirtin Thunder]

OK,
Tell me this if a shoe is use could a back cut shoe cause too much tail lift ? Which would cause the nose to be stuffed down ? And if this is happening would a regular flat shoe solve the stuffing problem ? The boat is a Brendela Jet (Jet-O-Vaders). The ride plate is all the way up.
Jim
Jet this is loooooosse but too tight.

[HBjet]

Originally posted by MAINEVENT
Hey HB i saw you at MPD when i was picking up my jet you were stripping your getting ready for paint you were talking to my wife... How are you doing ????
Yeah, that was me. Did you get my PM?
HBjet

[MAINEVENT]

Originally posted by HBjet
Yeah, that was me. Did you get my PM?
HBjet
Got it !!:D Nice boat.......:p

[Squirtcha?]

Originally posted by Squirtin Thunder
OK,
Tell me this if a shoe is use could a back cut shoe cause too much tail lift ? Which would cause the nose to be stuffed down ? And if this is happening would a regular flat shoe solve the stuffing problem ? The boat is a Brendela Jet (Jet-O-Vaders). The ride plate is all the way up.
Jim
Jet this is loooooosse but too tight.
Hmnnnn no takers except for Herc.
Lightening too many variables to say IMO. Need to know the impeller cut and what make it is etc.
Jim,
What do you mean when you say the rideplate is all the way up? Did you guys run it with different diverter positions? Did you get any pictures or video clips of it running wide open? Something that would show the boat's attitude, how wet it is would probably be real beneficial in determining what it needs. It would show where the spray is coming off the side and the bow's attitude and it's relationship to the rest of the boat.
If it is bow plowing some, the diverter can be adjusted to compensate for that and get it back on the back of the keel where it needs to be.
Just some thoughts.
I messed with mine for a while before I found the best rideplate angle, wedging for the snoot, type of shoe and how deep to run it. Now when I get the diverter adjusted to it's best position, it's like somebody took the parking break off. Real obvious (seat of the pants-wise) where it wants to be. You can feel the boat rise up and the speed pick up.
HB I see ya posting out there. You've done lots of ride stuff with your boat. What are your thoughts on this whole rpm vs. speed vs. load business? Have you ever gotten an rpm gain from making ride changes? Don't mean to put cha on the spot. I'm just trying to figure out if I'm crazy...............and the only one that ever noticed this deal.

[MAINEVENT]

Originally posted by JET-O-VATOR
mainevent i may be way off with this but it is what i found this weekend with my brendella... my rideplate was set downward so i had wat to much boat in the water even with the jet-o-vator up.. i didnt even know any better and squirtin thunder had stopped by and was whatching me make a pass and noticed it so we started playing with it and pulled the boat way out of the water.... before i could not pull more than 4200 rpm and after we did that i could pull 5000 rpm so go fiqure and thats with an a impeller......and i noticed the difference right away, every adjustment we made it kept getting better....so ya i dont know what your boat has but mine has 12-jg-a, back cut shoe (so im told) and a ride plate.
daniel
Hey man thanx for the .02 everything helps me
MAINEVENT

[Squirtin Thunder]

Squirtcha ???,
When he was cruising the boat looked very good. As soon as he opened that thing up it planted the nose, if it were a hydro it would have been fast. It was wet about a foot or two of the bow eye. All the way up about 12 degs. maybe more. Diverter same position portof hydrolic or electric he had no real idea where it was but he tried. same wieght in boat every run. I was able to loosen it up a bit. Not much but some.
Jim

[LVjetboy]

"Soory it is a Dominator A/B impellar"
Only reason I posted that argumentative comment was because cut size w/o mfg means little. Dominator A/B at 4750 rpm = 375 hp, significantly higher than a Berkeley A/B. Depending on where you boat MainEvent, and weather conditions when you spun that 4750, 375 hp lake power could be equivalent to an STP corrected 450 or more (engine builder terms) but not 550 hp...unless you boat Lake Tahoe :)
Sounds like you have a healthy 454 but I doubt it puts out what your builder claimed.
"Anybody else care to chime in?"
Sure. As long as tact or humor's not required :) just ideas.
I've also monkey'd with plate angle, wedges and shoes, had the pump setback...none of these changed maximum rpm noticeably. I've also added 260 lbs of weight with no max rpm change. And speed or intake (pump) loading seems to have little affect on my max rpm although if it changed by 100 rpms from launch load to max speed load I wouldn't notice. No QD yet. My experience similar to Dans.
So talking about how ride plate angle can change rpms. Engine only cares about impeller load for max rpm. Impeller load comes from mfg and cut size (constant), and how much cavitation (or ventilation if ingesting air) during operation (variable). A "fully loaded" impeller in my opinion has zero cavitation or ventilation going on within the blades.
Since water's incompressible, density doesn't change as pressure goes up, neither does fluid viscosity. So once the impeller's fully loaded, further increase in intake pressure in my opinion unlikely to affect impeller rpm. In other words, "overcharging the inlet" or "overloading the pump" unlikely to drag down rpm...certainly not to the tune of 800.
Accurately measured race data seems to back this up.
So how can 4200 jump to 5000? A mystery. Assuming your tach readings are accurate, it's possible the impeller's not fully loaded at 5000 rpm's due to cavitation or ventilation. A couple checks may solve this mystery. First, how much lake power does your 455 put out Herc? 5k on a Berk A's pretty healthy assuming the impeller's loaded. Second, you could chart speed vs rpms and see if there's a point where more rpm gives little change in speed...possible cavitation?
ps: Just my thoughts no doubt viewed negatively as controversial or argumentative by some.
jer

[Squirtin Thunder]

Jer,
On Jet-O-Vaders Brendela the rpm change came from tuning not plate. I tuned it I know. The darn thing was set so far retarded I moved the dist. counter clockwise 1 deg. and it died, I had to advance it about 10-12 to get it to run right. But I still think the cam is retarded. And the carb is screwed and it has vac leaks. With that all said no matter on the tune of the engine the nose is Still Planted . Will a back cut shoe creat too much transom lift or tail lift.
Jim

[Floored]

10-12 deg timing change is a large change in HP. my 455 runs 4700 day in and day out except on cool winter evenings it picks up 200 rpm in the cold air here at the river. will someday gps it to see what 4700 with a AA jacuzzi works out to. keep fine tuning your engine and your ride setup and you will probably gain some more. you can also use Jer's Hp info as a tuning tool to make informed changes to your engine to increase Hp that is useable at pump speeds to pick up rpm and boat speed.

[BrendellaJet]

I have the same hull. Jack has had experience with it- before I brought my boat to him I went to check his shop out and pick his brain. There was a hondo there with the same bottom as mine, and we came to the conclusion that the Brendella was a copy-given the fact that Irv owned both company's at one time... Jack said the Hondo(green and white-not sure whose it is) had about 600 hp and did over 80. Give him a call and he can explain why you need the back cut shoe. He put a back cut shoe on my intake, butI haven't got it wet yet...

[Squirtin Thunder]

Floored,
This is not my boat it is Jet-O-Vaders, I do understand what you are saying on the timing thats why I posted the facts. But the bottom line of this whole thing isThe gosh darn boat is stuck to the water like glue and no one is adressing my question "Does a back cut shoe give transom lift???". So everyone can through in what ever they want but the bottom line is the Nose is stuffed in the water. What I am looking for is the facts not BS. At this point I could careless what the RPMs are. The boat needs to set right at speed.
Thanks
Jim

[Danhercules]

Originally posted by LVjetboy
First, how much lake power does your 455 put out Herc?
jer
I think you got somone confused. I am a BBF, I am runnin bout 500HP. Not sure on the RPM yet, I have 2 diffrent numbers 5200 and 5500. Berk "B" imp. I am putting in an new tach today. So next weekend I will get RPM readings.
I think 5200 is right, I think the 5500 was a mistake.

[Floored]

squirtin thunder, sorry I was referring back to Mainevent's original post about engine and rpm's. just a quick ref to the olds engine picking up rpms with the timing change. :eek: does jet-o-vader have saddle or nose fuel tank, that affects the settings also?

[Squirtcha?]

Woah Jim!
I was kinda hoping someone with more knowledge woulda posted on your question, but I'll take a stab at it.
The backcut shoe is supposed to give the boat more lift in the back. I've run both flat and backcut on mine and to be perfectly honest, it didn't really make a whole hell of a lot of difference.
I'd have to wonder if his hull is straight or not. It almost sounds to me like he's got a hook and it's forcing the bow down, or he's got some hardware dragging. Is he running a shoe now? If he's running a shoe, what is it's relationship with the keelline? Is he running the old angle iron loader? Where are the ramps in relationship with the keelline? Hanging below it, or tucked up in the intake some? If you do a full speed pass, and get out of it..........can you feel hardware (shoe, loader) dragging? Or does it just glide along smoothly?
Each and every boat is a little different. Even the same hull by the same manufacturer can he different. I have a buddy of mine with a Kachina 18 just like mine. He's made the same exact changes that I have and didn't get the same results.
I think in order for anyone to help, you'll have to give more particulars.
I'd think the first thing to do would be to take some hardware measurements, then check to see if the bottom is straight.

[Cheap Thrills]

Originally posted by Squirtin Thunder
Floored,
The gosh darn boat is stuck to the water like glue
you mean like this ?
...///water buffalo\\\... (http://www.***boat.com/image_center/data/500/1127IMAG0020.JPG)
this is at 4,500 rpm on an A cut berkeley with a SBC :p I 've found a few hull deformities that needed some attention that may be causing it . if youve changed the ride plate angle & diverter angle and youre still glued to the water I would almost bet theres either too much weight in the bow
(Maybe even waterlogged floor flotation if it has any)
maybe the loader /grate/ pump hardware dragging.
or theres some hook in the hull.
C.T. :wink:

[Squirtin Thunder]

Cheep thrills,
Hell yes stuck like super glue.
I am betting on the back cut shoe.
I did ask Jet-O-Vader to check the floatation in the bow for water, I have a feeling it was totally set up wrong. And looking at the floor which has weather cracks in it. I do not say there is no water in the boat somewhere.
Jim
BTW this is too tight to go fast.

[LVjetboy]

Herc posted: "I think you got somone confused."
You're right. I meant, "how much lake power does your 455 put out JET-O-VATOR?"
My comment directed at Jet-o-vater's post on his experience with rpm change and 5k rpms. Your follow-up post seemed to credit his gain to a formerly overloaded pump drag'n down rpms...so I connected the two. But I have little knowledge in this just opinions.
Thunder, copy performance gain from timing not setup. That's a bit different from Jet-o-vators post on ride plate angle? Who's to know? Dan what do you think? I have little knowledge, but I post my thoughts on rpm change vs setup anyway.
jer

[Unchained]

Originally posted by Squirtin Thunder
Floored,
This is not my boat it is Jet-O-Vaders, The gosh darn boat is stuck to the water like glue
Thanks
Jim
I made this piece for my boat to give more hull lift without more shoe and to contain intake reversion on shutdown.
http://www.***boat.com/image_center/data/500/220Duct3-med.jpg
http://www.***boat.com/image_center/data/500/220Duct1-med.jpg
Ok, I know the bolt heads are ugly, I didn't put flat heads in yet.
I've run it for several weeks now and it has exceeded my expectations.
I picked up about 3 MPH at cruising speed as compared to engine RPM from what I had before. 3500 rpm = 45 mph
I also seems to keep the pump loaded going over rollers that would have had it sucking air before.
Still testing.
Mark

[Squirtcha?]

Thunder, copy performance gain from timing not setup. That's a bit different from Jet-o-vators post on ride plate angle? Who's to know? Dan what do you think? I have little knowledge, but I post my thoughts on rpm change vs setup anyway.
That makes more sense.

[LVjetboy]

Superdave's not gonna like those bolt heads :D
Wow! Good to see new ideas out there. I think we need more innovaters like you...let us know how it goes.
jer

[Squirtcha?]

Originally posted by LVjetboy
Superdave's not gonna like those bolt heads :D
Wow! Good to see new ideas out there. I think we need more innovaters like you...let us know how it goes.
jer
I believe those were my exact words to Mark when he emailed those pics to me a few weeks back.

[JET-O-VATOR]

NOW DONT I FEEL STUPID AS HELL I HAD FORGOTTEN THAT HE PLAYED WITH THE TIMMING.. BUT ANYWAYS IM STILL LEARNING ABOUT ALL OF THIS SH!T BUT I LEARNED ALOT OVER THE FOURTH OF JULY WEEKEND FROM JIM AND EVERY DAY ON THIS BOARD I LEARN MORE AND MORE..... OK A LITTLE MORE INFO ITS A 455 OLDS WITH RV cam 9:1 compression torker intake HEI ignition holley 750 vac secondaries. and squirtcha when i come off of the throttle it just glides along it doesnt try to throw me out of the boat or anything like that....

[pops1]

Originally posted by LVjetboy
MainEvent,
First know (and state) your impeller mfg. Makes a difference. For example, a Berkeley A/B not the same as an Agressor A/B...or a Legend. Then know your true impeller cut...have you verified A/B cut? Then realize engine builders typically quote calibrated power and NOT lake power. Lake power is what turns an impeller. Most of us don't boat at calibrated conditions. Finally, engine builders may quote max hp or valve float rpm not what your engine-impeller combo at lake conditions will turn.
BTW, Berkeley A/B at 4750 rpm = 313 hp.
jer Great Point- A/T Imp./legend/Dominator/
A/B Cut based on above 4750 sounds right on- Aggressor should hit @ 4400-4450
I think H.B.s Horse Power was up on his 5100 over the other stated boat, thats why he is was getting the 5100- on his Legend.

[Lightning]

Originally posted by BrendellaJet
Lightning, it depends on what impeller you have.
It's an A impeller in a dominator 12S

[BrendellaJet]

JETOVATOR/Squirtin Thunder-
Check the hull for some hook. Mine had it and has spent its life on a nice trailer. Both sides have nearly the same hook. When I had the hull blueprinted, we left it in there because Ill have the power to get through it.
Where to look. Check the outside strakes(theres only two sets on your hull). Inboard of that on both sides on my hull were laser straight. The strakes had a little hook in them though. That could be your problem.
The back cut shoe will help your boat. But it depends on the combination. Each boat is different. A performance minded boater with plenty of power is going to be able to use the back cut shoe. with the level of power you are currently making, you may not notice any changes.
To me it sounds as though the pump is cavitating. Makes sense, especially with all the ride plate adjustments. That thing was probably plowing through the water before, and now that you get it to air out a little, you may have uncovered another problem-perhaps your impeller clearances need to be checked?

[pops1]

Originally posted by Unchained
I made this piece for my boat to give more hull lift without more shoe and to contain intake reversion on shutdown.
Still testing.
Mark Mark good show- you will find height and configuration setting can also play a part in your test. Watch out for dead setting in big chop/ transom lift is changed on wave action as the transom will respond slower to waves. Dave-