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      09-28-2013, 03:08 PM   #98
NISFAN
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Quote:
Originally Posted by mkoesel View Post
Oh, sure, but I am just wondering how much torque we could get from a naturally aspirated 4.5L V8 with a longer stroke. I guess I am wondering if we can calculate that, or is this discussion becoming religion instead of science now?

Regarding, the S55, probably it could never be pushed to 443 ft-lb, right?
The internal combustion engine is a complex beast. Peak torque value and where it occurs in the rev range is controlled by so many different parameters.

For example there must be hundreds of engine designs out there where the bore stroke, rod ratio dictates peak torque of X is possible at Y revs. However the cams or head design favour a different rev range, which ultimately limit the amount of torque achieved (but may allow increased torque elsewhere in the rev range).

The thing about the 458 engine, is it is highly tuned and fettled, which helps almost every performance characteristic. I would put money on the 458 engine achieving over 100% VE at specific revs, which outside of F1 engines, is remarkable.

Regarding maximum torque achievable for the S55, yes, no question it could reach 443ft.lbs, it would require increased boost pressure, which I would imagine a road tuned car would allow due to a safety margin.

Increasing boost pressure is not as simple as most seem to think. But as long as you keep intake charge temps under control (inter cooler capacity), perhaps go extra rich under boost (sort of fuel excess charge cooling), all to steer clear of detonation, it can be done.
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