thegrid

what turbo would you guys recommend for autocross and track days on stock internal ap2 motor? i would like to keep it safe at maybe 5 or 6 psi and full boost around 4k.

is there a good kit for this?

CKit

Maybe pick up a used Greddy kit for cheap?

Personally, I'd get a used Comptech SC at those power goals.

Personally, personally, I'd think long and hard before going that route. If you're planning any kind of classed competition you're better off spending your money on good tires rather than boost.

murderedrsx

Yeah for that low amount of boost youll be way better off with sc. More linear. Less involved. More low end torque.

CKit

Wat? Only if you're comparing a Roots positive displacement SC vs. a humongous turbo at under 4k rpm.

murderedrsx

Rotrex! Yeah comptrch and vortech prob do little under 5k rpm.

CKit

Still no. Rotrex, to the best of my knowledge is still a centrifugal supercharger like the Comptech and Vortec. Just more efficient. A Roots or positive displacement SC like what Jason Collett has is different with "lobes" instead of a spinning turbine.

murderedrsx

I am well aware of the difference between centrifugal and roots blowers. And the rotrex has a much more quickly spinning turbine from their planetary drive setup hence you do start to make boost a bit earlier.

CKit

But still no. You will not make more torque with a Rotrex than a turbo below 5k unless you have a horribly oversized turbo.

CKit

murderedrsx

Not sure what that unlabeled random dyno graph is supposed to tell me.

But if you dont believe me, maybe you can do some additional reading.

Here <--plenty of links nestled in here.

and
here