New Twin Turbo Dyno Results

Herr-Kuhn · 04:25 PM

I put the Twin back onto the rollers this morning.

Here are the results on 8, 10 and 12 psi runs with straight 93 octane pump fuel, no water spray, no methanol, no nitrous, just air and 93 octane BP pump fuel. Same dyno as I used before with the same factors applied:

8 psig: 495 RWHP, 471 ft-lbs
10 psig: 523 RWHP, 559 ft-lbs
12 psig: 572 RWHP, 579 ft-lbs

The 10 lb run had the boost control set to "sharp", thus the reason you see it overshot a tad (see the drop-back). We softened up the control before the 12 psig run. While dialing in the boost control unit, the car shot to 16 psig mid range and we pulled throttle...at that pressure the midrange torque was 640 ft-lbs on the wheel. The potential here is enormous. I had the shop plot the boost curves for the skeptics out there.

I'm using all of the maps for fuel and ignition and given the compression ration of the stock engine I feel safe here at 12 psig. Think of it like a 12 psig teddy bear.

As always...this is on a FULLY stock (never rebuilt) 1988 928 S4 engine with 178,000 miles on the clock.

I have a video of the 570 RWHP pull that I should be able to load this week.

I'm very pleased with these results, specifically considering the car will get to just about 500 HP on the wheels at below 9 or so psig.

John Speake · 05-12-2008, 12:07 PM

Great numbers John !

Did you use the extended load maps and PEMs ?

Herr-Kuhn · 05-12-2008, 12:12 PM

Yes, extended load maps. I'm still popping them all the way to the bottom. It seems to be using the entire fuel and ignition map, except for the cells at the very lower right hand corner. I have a few light throttle issues to snip out before I call it done.

MrGST · 05-12-2008, 12:48 PM

Wow, very impressive. What would it take to make your kit California smog legal?

Herr-Kuhn · 05-12-2008, 04:16 PM

Usually to get CARB approval you have to have all of the factory emissions control equipment in place. It takes some investment to get something like this pulled off properly. The irony is the car would run exceptionally clean even by today's standards with all of this stuff. It runs closed loop and installing high-flow cats is very simple. The CARB is not something I am pursuing right now.

Herr-Kuhn · 05-12-2008, 04:25 PM

Thanks for the feedback on the pulls guys. I also wanted to add that these pulls were done back to back to back. We let the car run and idle for the time between runs. Temperature in the room was 78 F, relative humidity 17% and the barometric pressure was 29.30 in-Hg. I would expect slightly less on a 95F day and slightly more on a 50F day.

Red Baron · 05-12-2008, 04:46 PM

SWEET! Really looking forward to June!

Great Job!

rhjames · rhjames's Garage

Quote:

Originally Posted by Herr-Kuhn

Thanks for the feedback on the pulls guys. I also wanted to add that these pulls were done back to back to back. We let the car run and idle for the time between runs. Temperature in the room was 78 F, relative humidity 17% and the barometric pressure was 29.30 in-Hg. I would expect slightly less on a 95F day and slightly more on a 50F day.

(nothing like) detailed information on your project......

this is way to do this. it prevents most uninformed arguments over which dyno, what conditions, blah, blah, blah.....

great project John---keep after it.

--R

Herr-Kuhn · 05-13-2008, 03:06 AM

Good point RH. There is a reason I use the same machine every time I rerun these pulls. I've been given some grief for using Dynojet by some others as of late. The reasons I use Dynojet are as follows:

It's the most common dyno across the country therefore easy to compare to others.

Dynojets, unlike many other dynos do not allow you to set the correction factor, but rather only select between uncorrected, STD or SAE. Many other brands allow the operator to dial in the correction factor of the day. Trust me, I've seen this done time after time.

It's virtually impossible to get a true comparison between tests run on different machines. True story...when we built my brothers TT, I dynoed it on a Dyno Dynamics in 95F heat. The car made 400 WHP and 480 ft-lbs on 8 psi. Later he re-dynoed it with 2 psig more boost on a different dyno and got lower results. When I called the DD operator and asked him why that was he spilled his beans and told me that people were complaining about the numbers that day at the dyno showdown so he had "turned the correction factor up" that day.

I also heard that a supercharged car with a touted 596 HP on Dynacom dyno (when the "dynojet STD correction factor was applied") later was proven to have just north of 500 WHP when layed down on a Dynojet. It would take 4-5 extra psig to make 96 WHP.

One piece about all of this that bothers me is that people go and run their car on a certain machine, then state that "it would be at least 10% higher on a dynojet". If they are so concerned about the dynojet numbers, why not just find a dynojet machine and run the car on it? I thinks it's funny, because before there was competition out there people just used Dynojet and were flying their sheets. There's been a lot of dyno shopping as of late. I refuse to get into that.

Anyway, I'm done comparing numbers becasue there are too many variables at play with the dyno of the day being the largest variable. I believe my numbers are plausible given the setup on the car.

AOlson · 05-13-2008, 06:38 AM

Impressive numbers John. Congrats.

How was your AFR? You mentioned having fueling issues in your earlier fuel pump thread. Did you get that worked out?

Danglerb · 05-13-2008, 07:51 AM

Maybe at SITM some Gtech data could be gathered on several cars?

Herr-Kuhn · 05-13-2008, 08:28 AM

We managed to get into the 12:1 range upstairs. Fuel pressure was holding steady at just over 60 psig. I think the pump mods did their trick...now we have to see how long those mods hold out. I see no reason they won't go a long time as it can all be cleaned up and there is nothing to wear out. I still have to do some mapping down low...I have a spot on tip-in at light loads that seems to have me stumped right now, but I think I know how to get rid of it.

I think I have a G-Tech in the car somewhere... I think the better test is the "streak test". That's where each person gets a ride with a fresh pair on and we measure the size of the streak upon completion of the ride. No joke...I built this car and it STILL scares me sometimes when I drop the hammer on a back road. 600 HP will get you in deep very fast. When you drop the hammer at 50 MPH in 2nd and the back end comes out on you, it can get very interesting.

Olson...is it true you made a big streak after riding in the Murphy car last year?

AOlson · 05-13-2008, 11:22 AM

Quote:

Originally Posted by Herr-Kuhn

Olson...is it true you made a big streak after riding in the Murphy car last year?

By Murphy car, I suspect you mean his 5-speed (a.k.a. 650rwhp) Nope. Never felt out of control. My face did peel off of my skull however.

That's a wicked beast! The "wife's car" is also a quick ride but very similar to mine - very controlable.

Same goes for Todd's 700HP 7-speed wild ride. Always felt in control.

It makes me wonder... I've never felt out of control in a 928 - other cars, yes, but not so far in a properly setup 928. If you're feeling scared at these power levels, are you sure the car is up for the challenge? Or are you just not accustomed to controlling these power levels?

m21sniper · 05-13-2008, 11:25 AM

My 400hp Buick T-type turbo used to terrify my passengers even in a dead straight line.

Fabio421 · 05-13-2008, 11:34 AM

Andrew doesn't scare easily. Haven't you seen how he coldly dispatched that vicious wild skunk? Talking about streaks, I think that skunk left a nice one for Andrew to remember it by.