ChevyNo1

A response to the same topic on ls1.com from Doc99SS:

[quote]I have seen a max 39 to 41 lbm/min on my ATAP and I have been on the dyno at 389RWHP with no tuning. With some PCM tuning, I believe that I could hit about 400RWHP.<hr></blockquote>

Are you sure it's not RWHP?

- Dug

ChevyNo1

One more thing for thought . . . at a raceweight of 3700lbs and a trap speed of 118.34, HP calculators are saying I need 479rwhp to run that. My highest reported flow on that run was 47.29. Multiplied by 10, that comes out to 473, mysteriously close to the 479 I should need . . .

- Dug

really slow truck

i dont post much in here (yet.. heh), but i thought i would chime in on this one.

when i run autotap on my truck i see a max of a little over 31 lbs/min, since i only have a 4.8L having 310rwhp is nowhere near close for my mods, last time i dyno'd at 243, i know i have a little more power than that, but i was thinkin more along the lines of 255 now, sure as hell not 310 lol

bryan

[ February 28, 2002: Message edited by: really slow truck ]</p>

really slow truck

also, when i plug in my weight of 4850, and my mph of 89.27 (whoaa buddy watch out <img src="gr_grin.gif" border="0"> ), it says 269.28rwhp, not close to either of my guess

with a maf flow of 31.x that wouldnt work out...

would this way of guessing flywheel horsepower even work the same on a forced induction application as on a n/a application?

ChevyNo1

I thought I had seen somewhere that a basic rule of thumb is take your MAF rate, multiply by 10, and that gives you HP. If so, is it RWHP or FWHP?

- Dug

y2khawk

iTrader: (5)

Flyhweel power

~1 lb/min gives 10 HP at peak power

and

~1 lb/min give 9 ft*lb at peak torque

<img src="gr_stretch.gif" border="0">

ChevyNo1

Thanks Harlan. Hmmmm, that means that at 6.5psi and 100 octane, I am only putting out 475fwhp? Which is only slightly above 400rwhp?? That doesn't make sense. At 4.5psi and 100 octane, I'm showing 430fwhp, which is only about 365rwhp. Something is not adding up here . . .

- Dug

gwj

I don't think it's a real accurate parameter.
But, FWIW, my max rate usually falls in the upper 35.x range, which is probably pretty close FWHP for a stock motor.

y2khawk

iTrader: (5)

nope

it's flywheel

I see between 62 and 64 lb/min when dynoing in the 570RWHP range.

any changes to the MAF or using a MAFT will change the readings.

Unless you know how much you shifted the flow readings you can't use the reported value from a modified MAF.

ChevyNo1

Something's up then . . . I don't have either a MAFT or a modified MAF, it's bone-stock. I got it from the dealer just before the turbos went on. I'm WAYYYYY underpowered then!! Any ideas as to where all my power is going then??

- Dug