Quote:
Originally Posted by Levi
Even 300 PS on FA20 without FI is possible. But here were are takling about a car that should be road drivable. The torque cuvre is so flat, almost 200 Nm @ 3000-7000 RPM. Move that higher for worse daily drivability, you'd get about 230 Nm @ 5000-8.000 RPM with power about 250 PS @ 8.500 RPM. It should be doable on keeping 2.0l displacement. Increasing stroke would be better for torque and city driving, but the engine would be less rev friendly. I am not sure is there is place for increased bore.
Stroke 86 x Bore 86 = 1998 ccm
Stroke 86 x Bore 90 = 2188 ccm
Stroke 86 x Bore 92 = 2284 ccm
Stroke 86 x Bore 94 = 2387 ccm
Stroke 86 x Bore 96 = 2490 ccm
IMO 10 mm increase in bore is the max possible, but even this I doubt, is would mke the walls 5 mm thinner.
|
I think you're just about right.
Take the FA20 stroke out to 90mm and the bore to 94mm (which gives it the same dimensions as the FB25) and you get 2498cc.
Assume the same specific power output for this larger "FA25" motor and you have 250hp. Not really rocket science.
Cheap, easy to do, almost no increase in weight, no exotic forged internals, no screamingly high red-line and a nice fat torque curve.
Modify the valve-timing, fit a freer exhaust and tune it for a slightly higher red-line and you'd probably get another 10-12%, - 280hp!
That's a 40% increase in power without forced induction and all the accompanying weight/heat/cost issues. Sounds pretty good to me!