Tim Murphy

Hey, I like this chart better. You guys just forget about that other one.

Z, any way you can squeeze 3 more HP out of that chart for Louie's sake

Louie928

Just correct to SAE specs with an air temp of about 120F. Should do it.

mark kibort

I dont see how its possible for the curves you plot with a different software, but same data file to be that different in every way. first of all, the shape of the curves are totally different, having peak torque at 5500 and flat, going to 6000 with the newer curve and different in shape.

Usually the SAE is corrected for some type of atomospheric levels, while STD is actual (i think) i always use both, but both would have the same proportional shapes.

Pretty interested to see your automatic make that kind of hp with stock S4 cams. im sure the GT or 85 cams would bring some decent gains. what did you do with Dastek to make such great power? timing advance, mixture optimization, etc?? do tell. what levels did you have to change from stock to reach the better peak HP? (ie pullback timing, add fuel, change cam timing, etc)

thanks,

MK

mk

Tim Murphy

Z, get right on that would ya?


I'm glad this came up because there are alway a bunch of factors that guys like to argue about and this certainly puts it in perspective.

Louie, as you know driving a car in the HP arena that we (I guess Tom too) are experiencing you can give or take 10-20 HP and it's not going to make much of difference in the sphincter factor

Louie928

Ok, ok. Here is a file I found of the same run that Don sent me. It's a not very good picture of the crumpled up actual dyno sheet made from the WinPEP program using SAE correction. 573.3hp/478.7tq. Works out to about the same as the Dynojet Runviewer with STD correction and flat hp curve.

Tim Murphy

Mark, just in case you missed it (most will) my original chart showing the 556 rwhp has different scaling for the TQ and the HP. Look at the right and left sides of the chart, they are not the same. It's the way the dyno operator had it set when he printed the sheet.

EDIT: Mark, I think I miss understood your post but I am going to leave my statement here for future clarification on my original dyno chart.

Louie928

STD correction = Standard day correction = STP (Standard Temp & Pressure) is corrected to 15 deg C or 59 Deg F, at 29.92 in Hg pressure. SAE correction is to 77 deg F and 29.6 in Hg pressure. Since SAE correction is to a higher temp and lower pressure, it yields lower numbers than Standard day correction.

hacker-pschorr

I was chatting with a guy from superflow - he sent me some data on the changes to the SAE & STP "standard" over the years and how they react differently on different dynos (since not every dyno has the same base line). I'll be damned if I can find that e-mail now.

Louie928

I can't be sure I've had the engine wide open on the street at above 4000 rpm. By the time I get a goodly amount of throttle rolled in, it's like, "expletive deleted", and I back off. At this early level of experience with it, I'm a weenie.

shaaark89

yeah, that andrew olson is a troublemaker
interesting on the software. i wasn't aware of that. the sae i was aware of, but since i don't have the data file, i couldn't play with it. looks like louie had the corrected file at least. so maybe a bit more tweaking will get me there, but either way it's gonna be fun to drive

Tim Murphy

In my G-Tech Qtr mile run when I hit 132 mph it was not a comfortable feeling. Going 132 mph down the hwy is one thing but put your foot to the floor and wick it up there from a dead stop is a whole other experience.

hacker-pschorr

Now it's time you grow a pair and go 132mph into turn 5

Z

Not 3hp, but reducing the smoothing in that chart gets you an additional 1.61rwhp and 3.82rwft/lbs.

The Dastek was used to adjust the air/fuel curve and ignition timing. Fuel was removed at some points, and added at others to get the fuel curve you see in the chart. (Notice how it looks very similar to Louie's air fuel chart?) Timing was added in different amounts at different points. Chips are stock. Cam timing was changed a little bit, giving a little more top end at the expense of some bottom end. The only time the engine would see the bigger bottom end power would be at the bottom of first gear, where it couldn't be used anyway because of wheelspin. After the car shifts out of first, the RPMs never get low enough to where the increased bottom end power was. The change made the car easier to launch off the line without a lot of wheelspin, and gave a little more more top end power in first, second, third, and fourth gear at the expense of not really useable power at the bottom of only first gear. Seemed like a good trade to me.

Not everything I tried gave the results that might have been expected. Crankcase vacuum experiments showed a couple of horsepower gain at the very top end, but a reduction over most of the RPM range because of the pump drag. The overall result was a slower 0-60 time, even though there would have been a very slightly higher peak power number on a dyno chart. Because of those results, that crankcase vacuum pump configuration wasn't kept, even though it would have given slightly better maximum dyno numbers. Even if the engine were operated for longer periods at the higher RPMs than occur during 0-60 runs, the slight gain at just the very top end wouldn't have been worth the effort and complexity in my opinion.

PorKen

How many degrees retard did you put in?

Z

Three degrees from stock specs, done with a used timing belt to prevent any changes from occurring due to a new belt taking it's initial stretch.