moalaska

Was looking on wikipedia and read this

compared to the standard 944 Turbo the boost would decrease from 1.75 bar (175 kPa; 25.4 psi) at 3000 rpm to 1.52 bar (152 kPa; 22.0 psi) at 5800 rpm

I knew this was right except i noticed it said 25 psi. This cannot be 25 psi manifold pressure, i was thinking in stock form the turbo was pushing maybe 12 psi tops more like 9. I accidentally ran mine at 23psi once and my tires were spinning in 3rd gear.

mikey_audiogeek

Wikipedia is correct. Porsche state pressures as absolute, not gauge pressure. So 1.75bar absolute = 0.75bar gauge = 11-12 psi gauge.

Cheers,
Mike

Peedster

If the tyres we're spinning is just a sign of too narrow tyres. Change to wider and you can keep boosting 👍😎

moalaska

Haha then bigger clutch stronger axles. My porsche is expensive enough as it is I think ill keep it under 20psi for now

Jherriott

I found going to wider tires (from stock to 185s) made my tire spinning worse. Although the new tires were wider, I went from 16" to 18" and subsequently my sidewall profile dropped. Now I am losing traction way more than in stock form.

The "flex" in a higher profile tire may not be good for cornering, but it is better for acceleration. Most drag racers have high profile tires and even under-inflate their tires and let the centrifugal force do the inflating for them!

A side note: the area of your contact patch is always the same. Going from narrow to wide just changes the shape of the rectangle of rubber to road contact to suit your needs.

geno

^ +1 on what's in that side note. Always interesting to take a good hard look at how the shape and area of a contact patch changes when adjusting width, diameter, profile, and rubber compound and what that means for the car's table manners on the street/track.