STILLEN 370Z Supercharger System - Announcement!!!

RCZ

Umm, the difference can be higher than 2-4%. BOTH Stillen and GTM advertised STD numbers, not SAE. In my case there was around a 20hp difference between SAE and STD.

Some of you guys that are right around 400 or a little over SAE will end up around 420, which isnt as unacceptably far away from Stillen advertised results as it seemed before...

tomnavone

Umm, how can the differnece be higher than 2-4%? What math are u using? Stillen math?

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RCZ

The "SAE Air Correction Factor" which is used by all the dyno guys is:

SAE CF = 1.18[Ps/(Pm-Pv)][sqrt(Tm/Ts)]-0.18
(sqrt = square root)

This formula is right out of SAE Paper #J1349 (revision June 1990), and is the latest form of the air correction formula. SAE assumes 15% frictional loss within the engine, which is probably close for a piston engine. NOTE: this is NOT the losses from the crankshaft to the rear wheels, that is a different loss.

Ps = standard pressure
Pm = measured pressure (barometric pressure)
Pv = vapor pressure of water (relates to RH%)
Ts = standard temperature
Tm = measured temperature

The SAE baseline values are:
------------------------------------
Ps = 29.235 inHg
Ts = 77.0 deg F (534 deg R)
Pv = 0 inHg (dry air, no humidity)

Pv will not be 0 inHg during a dyno run, but will equate to the vapor pressure of water vapor in the air, which is a function of humidity.

P units = inHg
T units = deg R (deg F + 460). If not in deg R, you will get a wrong answer!

So, the CF will depend on where the actual air temperature, pressure and humidity is with respect the standard values listed above.

The CF can be less than, or more than 1.00. If you tested your Z06 on a dyno on a day when T = 77 deg F, P = 29.325 and the RH = 0% in the shop where the dyno was, then the CF would be exactly 1.00. As you can see, there are MANY combinations of T, P and RH that will give you the same CF.

Note, the Pv (vapor pressure of water) defines the RH% and is subtracted from the atmospheric pressure because the water vapor "displaces" that much pressure, and essentially makes it equivalent dry air (RH = 0%) at the resulting pressure of Pm - Pv.

BTW, the pressure values in the formula has more effect on HP than the temperature values (square root of a ratio)

Source: z06vette.com

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Yes Stillen Math. My correction was of 5.3% according to the dynojet.

You know, with an attitude like yours, I'm glad you're having so many problems.

tomnavone

Thanks



More bad news for stillen on the way wait for weiboys dyno results from today

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toner123

I don't understand why you would say that. I understand your car is running great but there are alot of people on here who are not happy with the product that was delievered. I also believe that they have givin stillen more time then really what I would have givin to correct the problem. Also to add more fuel to the fire the new tune isn't lving up to what he was expecting. SO I think he has every right to have a pissy atttude towards stillen just like everyone else in his stuation regardless of what company it is. Thats just my opinion RC and I can understand his frustration. I know stillen is tying to make it right and I respect that but if it was me they would be giving me my money back one way or the other and I would have went with the GTM kit.
Frank

Osiris

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stormcrow

I have bitten my tongue quite a bit as of late. But, these kinds of comments are just plain wrong, Raul. You know better than to let emotion flow from your fingertips into the keyboard. You are bigger than this.

toner123

I was waiting for this and knew it was coming. I hate to say this but Jeremy did call this out and a lot of people gave him **** for it.
Glade to see your still active in the threads bro and I hope everything is going well with you
Frank

rednek01

That is awesome I gotta use that now!

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