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Resident Ford Nut
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Discussion Starter #1 (Edited)
Your result's may vary ,but this chart has been very close over the year's for several engine/pump combo's that my brother and I have owned. The engines were a 710 HP 512" Ford our 780 HP 565 Ford and the re-done 565 that made 855 hp. All three ran nitrous 200 to 300 hp system's and the chart was accurate within 150-200 rpm's or so.

I also used this chart with three friends to dial in the boat's after they had dyno'd their engine's all three were within 200 rpm's. Two of them were 650 HP 502 Chevy's.

This chart will not work with an MPD fully blueprinted pump I learned that this past Summer. The MPD impeller will read a little over one size smaller than this chart shows. His "B" will perform like an "A" on the Chart
Please remember this chart is actual HP "Observed" not "Corrected" . If you dyno'd your engine on a 75 degree day and you have "corrected" numbers of 700 HP at 6,400 rpm's it won't (I'll repeat) it won't make 700 hp at the river on a 105 degree day. It will probalby be at least 15% off if not higher, which means it will be at least 105 HP less than the corrected dyno numbers.(Sorry that is more like 15% from the corrected numbers not observed. More like 7% off the observed numbers)

I'll reserve edit's:






Sleeper CP
Big Inch Ford Lover:)
 

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Resident Ford Nut
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Discussion Starter #2 (Edited)
Example of Overlay:



Just plot your dyno numbers on the chart, both observed and corrected and it will give you a good idea as to what you need.

On this one the blue hightlight I was correcting for the 115-118 degree day at Aha Quin vs the 84 degree dyno day. The engine was off an additional 7% in power. I think Shoe told me the corrected altitude was 4,700 plus (?) and that was at aprrox 105 degree's. Once I plotted it out it fell right on the chart where the power was that day. I called my dyno guy and asked him what he thought the power would be off on the 115 degree's vs the 84 degree dyno day, he said " 7-8% off). The power was off by approx 56 hp.

Sleeper CP
Big Inch Ford Lover:)
 

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Hmmmm

I dynoed at [email protected] 6200, Im turning a Heritage A impeller 5700-5800rpm. At that range Im making 775 hp. From the research I've done, thats spot on with others running this impeller. Appears that its slightly more than a berk AA on your chart.
 

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Resident Ford Nut
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Discussion Starter #5

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Resident Ford Nut
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Discussion Starter #7 (Edited)
I dynoed at [email protected] 6200, Im turning a Heritage A impeller 5700-5800rpm. At that range Im making 775 hp. From the research I've done, thats spot on with others running this impeller. Appears that its slightly more than a berk AA on your chart.
Are those numbers corrected or observed ? This chart was done by Jac Seastrom (sp) I can't tell you how much or if at all the impeller's and bowl's were detailed. That will make a dif.

I stated that an MPD an MPD "B" reads like an "A" on this chart. After the first trip to Aha Quin last year and the engine only pulled to 5,700 off the bottle(Very Bad air) 115* I pulled the pump out and sen the impeller to Jack to cut it back. After Jack and I lookied at the observed dyno #'s again I told him that my goal rpm was approx. 6,200 but I didn't want it to rev higher than 6,400 off the bottle. So he cut it back to his "B" to be conservative(you can alway's cut more, you can't weld it back on).

The next time out if turned 6,200 at 98 mph off the bottle (this was with only 28 psi intake pressure). The "A" cut on the chart above show's observed #'s of 826 HP. The impeller curve intersects the power at approx 6,300 - 6,400 rpm's.

Corrected or observed dyno number's ?

Your results will vary from either chart. They are just a bench mark.

Steel thank you for the post


Sleeper CP
 

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steelcomp was here
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Are those numbers corrected or observed ? This chart was done by Jac Seastrom (sp) I can't tell you how much or if at all the impeller's and bowl's were detailed. That will make a dif.

Corrected or observed dyno number's ?

Steel thank you for the post
Sleeper CP
No worries, sleeper.
It's hard to swallow sometimes, but corrected hp numbers in this application are about useless. Impellers don't absorb "corrected" hp, so you need to be sure you're using observed or actual hp numbers. If you're trying to analyze your RPM's with a given impeller, also take into consideration your conditions during the run. If your observed dyno numbers were taken at a density altitude of 3500', and you're at 5000' on a hot day at the river, you're not going to be making any where near the power you were on the dyno. Cold morning in the spring, cold be making more. It all needs to be factored in.
 

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steelcomp was here
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I dynoed at [email protected] 6200, Im turning a Heritage A impeller 5700-5800rpm. At that range Im making 775 hp. From the research I've done, thats spot on with others running this impeller. Appears that its slightly more than a berk AA on your chart.
Heritage A could be close to a AA berk, but according to the extended chrt above, that's about [email protected] 5700, not 775 if the Heritage pulls that much hp. If you dynoed at [email protected] 6200, and are only making [email protected] 5700, my guess is the 802 is a corrected number.

Edited to add...it's interesting to note that the difference between Duane's cahrt and Jack's for a straight A impeller at say, 6000 rpm is 78hp. (779 vs. 690 respectively). That's quite a difference. KNowing what my dyno numbers were and what I was turning my impeller, I'm thinking Duane's chart is a little high. Jack's chart is about dead on for my application.
 

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Boat Nut
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Now heres the complete Jack Seastrum chart, and yes use the uncorrected dyno numbers.

 

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Heritage A could be close to a AA berk, but according to the extended chrt above, that's about [email protected] 5700, not 775 if the Heritage pulls that much hp. If you dynoed at [email protected] 6200, and are only making [email protected] 5700, my guess is the 802 is a corrected number.
Yes the numbers I mentioned were corrected. Whats the point of having the corrected versus non corrected?
 

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Yes the numbers I mentioned were corrected. Whats the point of having the corrected versus non corrected?
uncorrected H.P. is what you tune to. Its the measured H.P. that will be constant. Corrected will change with air, At least thats how i understood it.
 

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So whats the correction factor? I dont see it on my dyno sheet...
 

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Resident Ford Nut
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Discussion Starter #15 (Edited)
So whats the correction factor? I dont see it on my dyno sheet...
Sleekcrafter cool thanks for the exented chart.


Brendellajet,

You should call who ever dyno'ed your engine, hopefully it wasn't to long ago and they have your pulls saved. Ask them to print you the observed sheet.
It shouldn't be a problem.

Depending on the day you dyno'ed the correction factor could be anywhere. I have dyno'ed on day's where it corrected 25 HP to day's where the dyno corrected 70 hp. Remember the computer corrects to the industry standard for temp,humidity and barometric pressure and altitude. With out the correction factor you could never compair two engine's power if one was run at sea level at 60 degree's and another was run at 2,500 feet at 85 degree's with 90% humdity.

We were on the dyno one cool March night at 6:30 pm and the dyno was correcting down, I thought that was pretty cool.
 

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steelcomp was here
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uncorrected H.P. is what you tune to. Its the measured H.P. that will be constant. Corrected will change with air, At least thats how i understood it.
Yes and no. You tune to uncorrected or measured power, but it will change with weather conditions. Power, corrected or uncorrected will always change with conditions. What changes with corrected power will be the correctioin factor to always bring the power number back to a sea level standard day measasurement. Like sleeper said, corrected power is an attampt to give each dyno session a common baseline in order to do comparisons. You couldn't compare an engine dynoed on an 85 degree day with the "weather" at 5000', to an engine dynoed at 65 degrees with the "weather" at 2500'. (On the same engine, there could be as much as 100hp difference between those two days). The correction factor brings both those sessions back to an equal test condition.
Hope that makes sense.
 

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Does anyone know where the AT hi-helix impellers fall into this? :confused:

Warp Speed :D

Duane @ Hi-Tech Performance, the principal designer of the 'Hi-Helix', is working on a description of the Hp vs. RPM characteristics for the impeller, but, as it is so new it's going to take some time to get enough data to put together a comprehensive description. All I can tell you is that we've run several different cuts and it bites much harder and moves considerably more water.

As far as equating the impeller's characteristics to the current AAA, AA, A, A-, B, B-, C, etc. system, I wouldn't even try at this point as I suspect it is so different in terms of the curves characteristics that it would be very missleading. To minimize possible future confusion, I have suggested to Duane that when he gets enough data and 'publishes' the info that he use the terminology Full HH, HH-AA, HH-A, HH-A-, HH-B and so on.

If you have questions about the cuts of the Hi-Helix, I suggest you contact Duane. At this point e-mailing him would be better than calling as Duane's granddaughter was in a serious car accident and is in a comma in the hospital where Duane and his wife, Barbara currently are. If your going to call Please Wait Until After the New Years when things have hopefully settled down.
 

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Prune-Picker
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Duane @ Hi-Tech Performance, the principal designer of the 'Hi-Helix', is working on a description of the Hp vs. RPM characteristics for the impeller, but, as it is so new it's going to take some time to get enough data to put together a comprehensive description.

As far as equating the impeller's characteristics to the current AAA, AA, A, A-, B, B-, C, etc. system, I wouldn't even try at this point as I suspect it is so different in terms of the curves characteristics that it would be very missleading.
Are you saying that this impeller was "designed" without knowing what it was going to do?? Isn't that totally backwards?? Doesn't a designer normally have design criteria in front of him before he starts dessigning something??

Cs
 
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