Pound for Pound... was Turbo Engine Life

[Alex Jenner <alexj@domain.elided>]

C M Smith writes.....

> A street engine properly turbocharged will produce more power and torque
> for far longer than any higher strung normally aspirated engine of similar
> power output. Pound for pound, lb ft for lb ft, a turbo engine is the best

Is there some theory behind this or just an observation? I'm sure it's a
cheaper way to get power than either a) designing a new engine, or b)
developing your engine to run high revs (e.g. Honda VTEC), so if we are
talking price, I'm sure turbo wins.

You might be right when it comes to torque (if the power is developed at
lower revs), but isn't torque for people who don't know how to change
gear ;-) and my question is about power.

It seems there are two main ways of getting a small engine to make more
power, i) supercharge (incuding turbo) to burn a larger fuel/air mixture
each cycle, or ii) carry out the modifications necessary for more cycles
per minute. Both methods put additional stress on the engine, which may
require stronger components, which may add more weight, but can you
explain why the forced induction method will be lighter.

When you say more power, pound for pound, are you including the weight
of the larger radiators, oil coolers, intercoolers, plumbing, exhaust
changes, extra oil and water capacity that go with the turbo?

> Now if you blow the bejeezus out of it (for example SAAB's stock 900 engine
> at 2.0 litres produces 205 hp and will do so for upwards of 200,000 miles
> no problem, that same block design can be persuaded to put out over 800 hp
> for most of an afternoon with headbolts that go right through from the head
> to the sump!).

Does that engine weigh less than the sub 100kg Formula 1 engines that
are now producing something like 850bhp? Possibly not fair to compare
with F1, but then I'm asking about weight, not price.

Best Regards
Lex Jenner
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