Joe I am not trying to nit pick, but in the endless quest for more power we all like to be informed of what works and what does not. Buddy's numbers actually sound very accurate to me inline with a stage 4 which is where his car was when it arrived at GIAC. I currently am running GIAC software and am very happy with it, but I think there is a bunch of people on this board who are on the verge of buying a stage 5 and would like to see some hardcore numbers.

 

buddy,

If they used SAE J1349, there will not be any variable. If they used actual hp then there would be a variable. SAE J1469 takes actual numbers and converts then as if the run took place at an atmospheric pressure of 29.23 in./hg., temperature of 77 degrees F and the humidity of zero.

If you want to compare your power to most other cars on this board you need to make a run on a Dynojet 248 dynomometer using the SAE J1349 standard.

My SAE hp was 626 at the rear tires. If I was th use the 15 to 18 percent numbers dividing like you are doing I would be at 737 to 764 flywheel hp without nitrous. Of course the only real number is the 626 (It was verified with three back to back runs). Since it was done on a Dynojet 248, I really can't compare numbers. However, that is your baseline. You can gauge your progress from that and it is a good start. Good luck with your goal.

 

Duane,

That dyno is not a good comparison. First it is DIN hp. Same car would have a higher DIN then SAE number. It is about a 1+% difference. Second, you get higher power numbers in fifth gear than you do in fourth gear. Buddy had his car done it fourth gear. This is the same gear I use when testing.

Regarding 567 and 593 on an AWD dyno. The 567 hp would be believable on a 996tt without internal modifications or nitrous. It would be one of the strongest 996tt motors I have heard of. The 593 torque is not believable. I believe they need to re caliberate their dyno. Then again, I am open to someone teaching me something new.

 

Duane,
I just got off the phone with Andrew at GIAC and he confirmed that Matts car made 430HP on race gas at the wheels. I really hope that this thread can stay sane.

 

Wow... only off by 137hp at the wheels. Maybe with the proper SAE correction, and the Meridian BS variable, multiplied by the Matt BS correction factor somehow 567 equates to 430.

430hp at the wheels with 100 octane and 1.6 bar sure sounds impressive. Where do I sign up?

Once again, a very credible source we're dealing with...

 

Just one more comment and then I will wait for the tuned numbers. This was the FIRST RUN AND WE KNEW IT WOULD BE AROUND 600 HP FLYWHEEL. WE GOT 623, WE EXPECT TO BE OVER 700 HP FLYWHEEL WHEN WE ARE DONE!

REAR WHEEL HORSEPOWER SHOULD BE SOMEWHERE BETWEEN 525 AND 550 TO ACCOMPLISH OUR GOAL. THIS FIRST RUN WAS AT 467 SO WE NEED ANOTHER 60 RWHP MORE. LET THE TUNING AT GIAC BEGIN!! HOOK ER UP RIGHT BOYS!

STAY TUNED!

Now can we get back to planning our shootout so everybody can put up or shut up!!!

 

Tony,

I am trying to learn here. You state that the Stage 4GT made 423 HP to the wheels on GIAC's dyno on pump gas. The stage 4GT promotion materials state that it produces 640 HP...this is flywheel HP on, I imagine, pump gas. That means they are using a 34% correction between AWHP and FWHP????

How can this be right?

 

Hi John,
The GT that made 423 at GIAC made well over 500HP on a 2WD Dynojet (see EVO graph). The fact is that different dyno numbers vary widely. The shootout will tell alot when a stock car is baseline tested on a specific dyno to establish a correction factor for THAT dyno. Then all the cars will be compared fairly. We have dyno'd cars on Dynojets, Mustangs, Claytons, Dyno Dynamics, etc. The ONLY way to compare is same dyno, same day, same operator.

 

Hamann,
What did your car dyno at on what kind of dyno?

 

Tony@PES,

I believe people in the industry know what dyno(s) to use to get the best numbers. As for variance, the Dynojet 248 dynomometer based on SAE J1349 is repeatable accurate and comparable anywhere in the world. It also helps to use the same gear for comparisons.

The above is not intended to take anything from the Mustang 4wd dyno. I understand they are a very good dyno. I have never used one because there are so few around and therefore difficult to compare rwhp numbers with other cars.

 

Tony,

So there is roughly a 22% correction factor between the dyno used in the promo materials and the GIAC dyno?? I have long heard that there is a material correction factor between 2 and 4 wheel drive dynos...but I had not heard that it was that large. I recognise that there are other factors at work here, but that just seems very large.

 

I spoke to the company that made the dyno. Mustang Dynometer and they said you cannot accurately find flywheel horsepower by knowing the rear wheel horsepower. Too many variables exist and therefore you are just guessing. He said if you want to guess a 2 wheel dyno would be 15 to 18 percent and a 4 wheel dyno would be around 25 percent. You must take the RWHP number and DIVIDE it by in my case .75 that will give you a different number than if you just multiply the RWHP by 1.25.

In my case multiply 467 times 1.25 and you get 584 versus divide 467 by .75 and you get 623. Major difference.

 

This is really freaky! It is halloween and all but I just noticed my number of posts 467 equals the rear wheel horsepower that my car put down on the dyno today!!

Holy crap batman, that is freaky!!!!

 

buddy,

Flywheel hp is also elusive. I can take an engine dyno a vary the power simply by adding or subtracting such things as water pumps, alternators etc. Hmmmm!

The only only thing that really makes any difference is what gets to the road. Notice I didn't say rear tires. Suspension, width of tires, gearing, tire compound, weight, etc all add to the equation? Yea, I guess someone has already said, let's just line them up.

Dyno numbers are a rough indicator. Now, one hundred and thirty-seven hp might be stretching the word "rough" just a bit. On the other hand, who really cares. I can remember when the 427 Cobra was the fastest car out there. Not too long ago the GT1 won Le Mans with 600 flywheel hp. Alot of the cars on this board have 600+ hp on the street. All these cars are fast. Do we really derive satisfaction pointing out that someone may have embellished a bit. Let's just have fun a quit sweating how many fractions of a second one car is faster than the other. After all, these are street cars, not track cars. We all need to step back and take a reality check.

 

Well partner, if Sharky's shootout doesn't materialize we will just line em up on our own and see what happens!!