Impeller sizes?? [Archive]

Ranz1

10-06-2003, 04:40 PM

A little understanding please on impellers.... I thought all impellers started as an "A" and then they were cut to a "B" or "C". But i see from Berkeley (Click Here) (http://www.berkeleyjet.com/products/impellers.asp) there are A-4, A-3 , and A-2 (AA?) So if understand right a "A-4" will flow more volume of water at a givin RPM than a "A" and a "B" will flow more than a "C". Right :rolleyes: ??
So if ran a "C" and wanted to lower my RPM but run close to the same top speed i would want to run a "B" or "A" if i have the horsepower.....?? Is there a way to figure if i run X-MPH And X-RPM with a givin impeller, what would a other impeller give?
Does anyone ever run a "C"?
Im getting a headache smile_sp smile_sp Anthony
[ October 06, 2003, 05:42 PM: Message edited by: Ranz1 ]

Squirtcha?

10-06-2003, 05:26 PM

Never mind all that Ranz. Just send that stainless impeller my way. I know just what to do with it.
What impeller did you have in the boat originally? What rpm and speed were you running? Is the motor built up or stock?

Ranz1

10-07-2003, 05:22 AM

How do you know i just aquared a "AA" Sainless impeller :rolleyes: :) ?
A slopy pump with a "A" impeller, Badly adjusted ride plate, a stock 460 out of a 70' Lincoln w/ a Torquer II intake and a HOlley 650cfm carb. It would spin about 4200 or 4300 (i forget)with a GPS of 50 mph.
This winter the jet is being rebult ("Take a Look at my Impeller" thread), I think i got the ride plate adjust figured out, and going to either a 750 or a 800 cfm carb. Eventualy i hope to have a 400+ hp motor.
[ October 07, 2003, 06:29 AM: Message edited by: Ranz1 ]

pops1

10-07-2003, 08:02 AM

Ranz1:
A little understanding please on impellers.... I thought all impellers started as an "A" and then they were cut to a "B" or "C". But i see from Berkeley (Click Here) (http://www.berkeleyjet.com/products/impellers.asp) there are A-4, A-3 , and A-2 (AA?) So if understand right a "A-4" will flow more volume of water at a givin RPM than a "A" and a "B" will flow more than a "C". Right :rolleyes: ?? GENERALRULE IS 400 RPMS PER FULL CUT I.E.- "A"TO "B" WILL INCREASE OR LOWER YOUR RPMs 400 BASED ON UP OR DOWN, AS A HALF CUT OR 1/4 CUT WILL ACT MUCH THE SAME WAY. DAVE
So if ran a "C" and wanted to lower my RPM but run close to the same top speed i would want to run a "B" or "A" if i have the horsepower.....?? Is there a way to figure if i run X-MPH And X-RPM with a givin impeller, what would a other impeller give?
Does anyone ever run a "C"?
Im getting a headache smile_sp smile_sp Anthony

565edge

10-07-2003, 10:40 AM

Ranz1,i seen you win that auction on ebay or i think it was you.

Squirtcha?

10-07-2003, 11:48 AM

Ditto what 565 said Ranz. What can I say..............I'm a jetboat junkie.

Ranz1

10-07-2003, 04:52 PM

Yea it was me, Had to get it :) :) .....
So am i right on the understanding of the impellers?

LVjetboy

10-09-2003, 11:56 PM

at a given rpm...a "B" will flow more than a "C". Right??"?Right.
So if ran a "C" and wanted to lower my RPM but run close to the same top speed i would want to run a "B" or "A" if i have the horsepower.....?? Speeds all about power to the impeller. Upsizing will lower rpms, and if you're on a somewhat level part of your engine's power curve, won't hurt speed as much.
Is there a way to figure if i run X-MPH And X-RPM with a givin impeller, what would a other impeller give?Yep. A combination of drag reference point, impeller curves and engine power curve will get you very close to the right answer. With a custom drag curve for your hull even closer.
Does anyone ever run a "C"?Nobody I know. My thought once you cut to C or D you may be taking a significant hit in impeller efficiency and/or launch loading. But no hard data yet to prove one way or other.
jer

Ranz1

10-10-2003, 09:42 AM

Thanks LVjetboy, Just want to make sure im talking the right talk.
But whats up with the A4, A3, & A2? If all impellers start as an "A" are the others a custom cut/make? Who runs a A4?? At what HP sould you consider an A2? Ant
[ October 10, 2003, 10:50 AM: Message edited by: Ranz1 ]

LVjetboy

10-10-2003, 11:58 AM

According to Berkeley, the A3 and A4 are for use in "larger boats or barges, and in diesel applications" They told me they don't have impeller charts for them.
At what HP sould you consider an A2? Choosing an A2, or another size depends more on the shape of your engine power curve than any set power level. For example, my engine puts out over 600 true (not corrected) hp at 5700 rpm on a typical lake Mead day, and I'm running a Berk B. If I up-sized to an A2 I'd be significantly short of my engine's power peak, loosing 80 hp and about 5 mph off my top end. Not gonna happen.
So how about downsizing?
My engine's peaked at 6200, but is relatively flat from 5700 to 6200. If I cut to a C I'd only gain about 10 hp from downsizing at the cost of 350 rpm more stress on engine parts and impeller efficiency hit...those extra 10 hp's not worth it.
So to make these choices you need to know the shape of your engine power curve from a dyno, or at least have a good idea of the shape from an engine modeler or past experience. Not knowing that, I suppose if you build an engine with a peak in the low 6's putting out about 1000 hp at 6k, like maybe a blower engine, then the A2's a good choice. Just a guess.
jer
[ October 10, 2003, 01:09 PM: Message edited by: LVjetboy ]

Ranz1

10-11-2003, 06:28 AM

What does that mean when they say "Corrected Horsepower"??

TIMINATOR

10-11-2003, 07:19 AM

Corrected H.P. is a way to say that we were disappointed with the actual H.P. the motor makes with REAL AIR(thats the air that it will be breathing at the lake!). So we "correct" what we saw on the dyno to an ARBITRARY STANDARD of what the engine will never see in real life to make the numbers look better when your bragging about your sled AFTER YOU GOT WAXED! Correction factors are in major dispute and different dyno operators USE DIFFERENT CORRECTION FACTORS! When was the last time that you ran your boat at sea level,68 degrees,and 29.92"barometric pressure with 0% humidity? In Phoenix the lakes are at 2200-2800ft,100-118 degrees,29.6(avg),and 30% humidity. Your impeller only cares about the H.P. it has to work with where it is,(THE LAKE).When racing at the lake,we all are using the same air at the same time so corrections are irrelevant in the real world.The major point I am trying to make is if you want to select an impeller based on dyno info,DO NOT USE THE CORRECTED H.P.NUMBERS! To be accurate in your selection use the raw H.P.numbers,thats what the engine makes in the REAL WORLD. The dyno is useful as a tuning tool for A-B comparisons using real air. Also,don't dyno the motor in California if you are running in Colorado or Phoenix! Use a local dyno so you tune with local air,the results will be much closer.Let the arguements begin! TIMINATOR argue argue argue

screamdreambrad

10-11-2003, 09:47 PM

terminator, you are absolutly right! no argument from me.

565edge

10-11-2003, 09:53 PM

screamdreambrad:
terminator, you are absolutly right! no argument from me. I agree completely too!So screamdream are you going to get a new stealth for next year?I might be selling my dad my boat after this season and get a new one made.

LVjetboy

10-11-2003, 11:52 PM

My view of correcting to a standard more positive.
Sure STP (and other standards) make an engine look stronger except sea level cool air. But a common standard still makes sense for comparing engines and runs. And conditions of sea level air density with fairly low temperatures have a history of being used as standards for more applications than just engine dyno's. Some of those applications have nothing to do with bragging rights btw. STP's a common standard for performance engines, but I could care less what standard is used, as long as it's a "standard" and those conditions are well-defined.
Conditions at the lake for impeller matching can be calculated from a corrected power curve, or from actual dyno run conditions if there was no such thing as corrected power or standards. Either way, you'd need to account for actual lake conditions.
If someone wants to use corrected to brag that's their choice. Ask them if they're talking corrected and to what standard? If they say, "gee, I donno" then maybe that gives you a clue? But to conclude the STP standard is purely for bragging rights because some (who may not understand the purpose of a standard) use it for bragging I think is a bit off-base.
jer
[ October 12, 2003, 01:22 AM: Message edited by: LVjetboy ]

TexasJet

10-12-2003, 08:01 AM

I have been told by the guy that does my pump work that I have a C impeller. I have a 19' Baja with a 550 HP big block chevy. My boat is fairly heavy. The boat is very strong out of the hole and just as strong in the mid range. Top speed is 68 on GPS. I have some pics in the image center under TexasJet if your interested. Mike, the guy etc, said that you need to use whatever impeller that will get your motor up to peak H.P.

TIMINATOR

10-13-2003, 06:47 AM

WOW!!! two guys agree with me! I thought that I wouldn't get 2 to agree out of 20 or so.... What I forgot to add to the original post was that corrections are fine to get some baseline ON THE SAME DYNO on different days of testing, if you change dynos all bets are off. If you want I will look up the ENGINE MASTERS CHALLENGE series and post the difference in dyno readings ON THE SAME ENGINES that were all calibrated prior to the engines being run. As I remember there was about 50-70 H.P. difference. Its kinda like EPA gasmileage figures,"your results may vary". TIMINATOR

OMEGA_BUBBLE_JET

10-13-2003, 08:29 AM

I fully agree with TIMINATOR also, but then again I think everyone knows how I feel about dynos and measured vs. corrected HP. no need to go there again. wink I think that 600hp(measured) is very respectable LV. what kind of top speeds are you getting? Have you hit the magic number yet??? :cool:
Omega

pops1

10-13-2003, 08:35 AM

TIMINATOR:
WOW!!! two guys agree with me! I thought that I wouldn't get 2 to agree out of 20 or so.... What I forgot to add to the original post was that corrections are fine to get some baseline Its kinda like EPA gasmileage figures,"your results may vary". TIMINATOR Baseline is the Key. I and most others get the Baseline Dyno data, Only to find the guy was given A hot sheet, meaning the motor will not even begin to carry what it should in Impeller.
Start at the Baseline projected dyno sheet, and persue the real world as you set it up. Remember you will not be the first guy to get your feelings crushed, finding out you can not pull what is projected for the Impeller. :o

Blown 472

10-13-2003, 08:39 AM

TIMINATOR:
Corrected H.P. is a way to say that we were disappointed with the actual H.P. the motor makes with REAL AIR(thats the air that it will be breathing at the lake!). So we "correct" what we saw on the dyno to an ARBITRARY STANDARD of what the engine will never see in real life to make the numbers look better when your bragging about your sled AFTER YOU GOT WAXED! Correction factors are in major dispute and different dyno operators USE DIFFERENT CORRECTION FACTORS! When was the last time that you ran your boat at sea level,68 degrees,and 29.92"barometric pressure with 0% humidity? In Phoenix the lakes are at 2200-2800ft,100-118 degrees,29.6(avg),and 30% humidity. Your impeller only cares about the H.P. it has to work with where it is,(THE LAKE).When racing at the lake,we all are using the same air at the same time so corrections are irrelevant in the real world.The major point I am trying to make is if you want to select an impeller based on dyno info,DO NOT USE THE CORRECTED H.P.NUMBERS! To be accurate in your selection use the raw H.P.numbers,thats what the engine makes in the REAL WORLD. The dyno is useful as a tuning tool for A-B comparisons using real air. Also,don't dyno the motor in California if you are running in Colorado or Phoenix! Use a local dyno so you tune with local air,the results will be much closer.Let the arguements begin! TIMINATOR argue argue argue In a word "ding" we have a winner.

LVjetboy

10-13-2003, 11:27 AM

Omega, best so far 93.7 GPS (94 +/- 1 on speedo) last week...my first full day at the lake. Only one full speed pass.
But check this out...
Air temp: 95 F
Me and Karen plus full fuel, mufflers, two coolers, anchor, lots of tools, 1/2 of a stereo, neon lights, etc. i.e. 100 % lake boat.
With just me I'm guessing close to 98. For a stunt I could ditch the mufflers, run a light fuel load on a cool day...see the magic century. But it'd be a stunt since I never run that way. You know...for braggin rights.
:)
jer

Blown 472

10-13-2003, 11:31 AM

LVjetboy:
Omega, best so far 93.7 GPS (94 +/- 1 on speedo) last week...my first full day at the lake. Only one full speed pass.
But check this out...
Air temp: 95 F
Me and Karen plus full fuel, mufflers, two coolers, anchor, lots of tools, 1/2 of a stereo, neon lights, etc. i.e. 100 % lake boat.
With just me I'm guessing close to 98. For a stunt I could ditch the mufflers, run a light fuel load on a cool day...see the magic century. But it'd be a stunt since I never run that way. You know...for braggin rights.
:)
jer Wasn't this going to be the v drive ass hander boat??

LVjetboy

10-13-2003, 09:48 PM

Nope. Never claimed that. After all, they all go over 100 mph so jets got no chance :) But I may surprise a few lake v's here and there...you think? As long as they don't read this forum. And I do remember posting (a long time ago) in the v-drive forum that I could do 100 mph with 650 hp. Pretty close considering I'll be high 90's with 600 hp...with mufflers.
:)
Check this out. I calibrated the Berkeley B curve to dyno data and put in my old drag reference point (454, lake trim, 2 pax, 78 mph) Here's what JPC predicts for DNE speed...
http://users.lvcm.com/lvjetboy/SpeedPredictor.gif
94 mph. Is that close or what?
jer
[ October 13, 2003, 11:05 PM: Message edited by: LVjetboy ]

screamdreambrad

10-13-2003, 10:14 PM

565edge:
screamdreambrad:
terminator, you are absolutly right! no argument from me. I agree completely too!So screamdream are you going to get a new stealth for next year?I might be selling my dad my boat after this season and get a new one made. 565 edge, i will if i can sell this one. if i can't i'll be happy to keep this one.

screamdreambrad

10-13-2003, 10:26 PM

lvjetboy, why don't you bring that boat to bakersfield this weekend? i'd like to race ya. at least see a gullwing? with 600 run that good. not doubting you just like to see it for myself. brad

OMEGA_BUBBLE_JET

10-14-2003, 04:04 AM

LVjetboy:
Nope. Never claimed that. After all, they all go over 100 mph so jets got no chance :) But I may surprise a few lake v's here and there...you think? As long as they don't read this forum. And I do remember posting (a long time ago) in the v-drive forum that I could do 100 mph with 650 hp. Pretty close considering I'll be high 90's with 600 hp...with mufflers.
:)
Check this out. I calibrated the Berkeley B curve to dyno data and put in my old drag reference point (454, lake trim, 2 pax, 78 mph) Here's what JPC predicts for DNE speed...
http://users.lvcm.com/lvjetboy/SpeedPredictor.gif
94 mph. Is that close or what?
jer Now I take it when you are using the 618hp you are talking measured hp not corrected right? In any event I can't believe you're not gonna strip it down and see triple digits at least once... :confused: at least it would give you something to ruffle the v-drive feathers with. Not to mention you could be the first of the 'DNE lake boats' to hit the magic number. devil that has to be worth something wink , especially since you were the last one to get your engine built and your setup together.
Omega

572Daytona

10-14-2003, 04:40 AM

LVjetboy:
I calibrated the Berkeley B curve to dyno data and put in my old drag reference point (454, lake trim, 2 pax, 78 mph) Here's what JPC predicts for DNE speed...
hmm....how different is the "calibrated" curve from the standard berkeley B curve? And what speed would the new calibrated curve predict for your old 380hp motor? Your JPC is going to get pretty complicated if you need to create custom impeller curves for every dyno out there :)

LVjetboy

10-16-2003, 03:19 PM

All good questions. So how about this? My first top speed run...semi-lake trim...
http://users.lvcm.com/lvjetboy/CenturyGPS.gif
Stripping down? Not really. Just dropped Karen on the beach with the coolers and blankets. Kept 1/2 stereo, seats, tools and mufflers. Or how about this?
http://users.lvcm.com/lvjetboy/CenturyJet.gif
Check rpm's not speed...I cut throttle short of top speed after I snapped this shot. Holding a camera in one hand and steering in another, looking out front with one eye and focusing on the little green light with the other, not the best thing. Especially with a light porpoise. Trust me...during the first pass the speedo hovered over 100 mph, which was also backed up by the GPS. That tach verified during a dyno run. Or this?
http://users.lvcm.com/lvjetboy/CenturyDyno.gif
So I'm thinking 6200 rpm's at least 630 hp? Any guesses?
jer

572Daytona

10-16-2003, 03:39 PM

Congrats Jer! Tell RD he can add another 100mph fiberglass jet to his list :) Are the rpms fluctuating while you are porpoising or is the pump staying loaded? You may want to think about stepping up a size on the impeller as it looks like your are approaching the top of your power band for that motor.

LVjetboy

10-16-2003, 06:44 PM

Thanks Daytona.
Even with an "uncalibrated" curve, JPC predicts close to actual mph. That because speed curves are somewhat independent of pump curves...though not totally. I think some uncertainty comes with knowing true rpm's.
I've always heard a blueprinted pump absorbs more hp than a stock pump. I believe that true but how much more? No one knows for sure? So here's my take.
Pump curves are actually quit close. A flowed pump will absorb more hp, but not that much more...maybe 50 hp or less? I just turned an MPD pump to 6100 maybe 6200 rpm. Let's take the average and call that 6150 rpm. According to mfg pump curves that's 628 hp.
Now dyno conditions for my engine at 95 F. (Muffler run) That's higher than 80 and a factor, but not far off. Dyno runs show 634 hp at 6200 rpm. How much different than pump curves predicting 628 hp? Not much I'm guessing. Though temp, pressure and humidity all play. We're talking ballpark here.
jer

SPECTRABRENT

10-16-2003, 06:57 PM

LVjetboy,
What hull are you running, Advantage 21 foot?
Brent

572Daytona

10-16-2003, 09:37 PM

SpectraBrent, LV has a Placecraft tunnel, 19ft I think.
LV, it looks like your dyno numbers match up pretty good with the impeller curve. Did you say you dyno'ed both with the mufflers in and out? If so how much of a difference did it make? I'm running baffles right now since I got caught running without them but I'm dying to take them out just to compare but I don't want to chance the $100 ticket again :( I think you mentioned at one point that you had cut your baffles down somewhat, are these what you are running with? I'm considering doing something similar with mine.
[ October 16, 2003, 10:38 PM: Message edited by: 572Daytona ]

SPECTRABRENT

10-16-2003, 09:44 PM

I did not know that a 19 foot PLacecraft Tunnel came with a bow light.
Brent

screamdreambrad

10-16-2003, 09:55 PM

lv, i stand humbley corrected! i would still like to see you run at njba. to see what she'll do in the quarter. brad

HammerDown

10-17-2003, 05:08 AM

SPECTRABRENT:
I did not know that a 19 foot PLacecraft Tunnel came with a bow light.
Brent Thats a Bottle opener :D ...and Jer, congrats on the 100 mark.

LVjetboy

10-17-2003, 12:32 PM

Thanks Hammer.
Spectra, Daytona's right. It's a 1991 (19')PlaceCraft "Jetstar" built as a lake boat. I ask Ron Hamilton to put lights on it, so I don't know how many normally came like that.
Daytona, a 40-60 hp difference depending
on rpm. Those runs comparing Dave's headers (no mufflers) and my headers with mufflers. So the exact muffler loss not sure. Probably most of it though. Another note. The mufflers I ran on the dyno were Rex's spiral design that I'd cut in half (down to one spiral) But the mufflers I ran for the top speed test were Bassett High Performance...a straight through design with louvers. According to Rex, these are half as restrictive as uncut spirals.
On the impeller size, I think you're right. An A or at least A/B would be a better choice now than my B. But not sure the cost is worth swapping.
I'm not sure about the rpm flux. I noticed it both by myself and with Karen when we were at 94 with no porpoise. There's no hull vibrating going on or noticeable change in engine sound, so I figured it was electrical...not sure. My loader's way deep so I'm probably getting plenty of water.
jer