Landjet

Race car 944 turbo running in GT3 with VR stage3 maf/turbo/chips, #72 injectors, WS setup running around 18psi boost. Just not wanting to buy a higher octane fuel than I need, but still want to be very safe. What do you think guys????? What we have around here is 101, 103, 105, 110, 116.
Thanks for the help

fast951

It depends which maps you are running, pump or race gas maps?
On the track use 100 octane or higher. I suggest you use the highest unleaded race fuel you can find. Higher octane will not hurt anything, so going up in the octane chart is fine.

Landjet

John
I finally got to the dyno and will post the results next week after I get back from the Hallett club race. I need to find a scanner so I can post the chart.

VRSTAGE2

Jhon what is more important when running higher boost, the Air/fuel ratio or how high the boost is? I'm running 18psi on pump gas but my A/F is fine. I know you reccommend 16 psi on pump gas with your Stage 2 but I do have some headwork done too. Should I turn the boost down a little? And if I do will I run richer if my car is tuned for 18 psi?

fast951

VRSTAGE2, you can run 16psi boost, the AFR will be fine. Make sure you are running the pump gas maps when using pump gas.

Landjet, drop me a note with the results.

Rogue_Ant

Not to hijack, but it sounds (to me) as if your not understanding intake pressure (boost) vs cylinder pressure (and overall flow in terms of volume).

If you have head-work (that was productive), then your increasing the flow for a given pressure. I.E. if to get X amount of air into a stock-head cylinder takes 15psi of boost. Then a worked-head might get that same amount of air at 13psi. This is the same concept as to why a better flowing turbo makes more power at the same psi then a smaller one.


Rogue