>Hank
>The original reason for turbo charging the 465 was for emissions. It dosen't
>make that much more horsepower. The nonturbo trucks belch black smoke
>(unburned fuel) and the turbo just gives it more air to burn that excess
>fuel. The point Richard was trying to make, I think, was that you can't make
>a diesel run too lean- it will just make less power.
>
Quite so.
>The danger comes when
>you over fuel which you can't do by adding a turbo to a diesel because you're
>adding air only. You just may not be generating maximum possible horse power
>without adjusting the fuel pump.
>
The deduction is that the design of the head and pistons in the 465 was flawed,
black smoke is certainly over injection and/or poor combustion, huffing extra
air in would allow the excess fuel to fully burn and aid good cylinder
scavenging, a little extra power would be evident too.
Jeff's quite right, adding the exhaust windmill huffer doesn't do a great deal
unless the fuelling is commensurately increased to burn the extra air supplied
but this then needs auto coupling to the injection pump so the maximum injection
is controlled by inlet header boost pressure or you're back to the transient
black smoke scenario.
The supercharger/turbo effectively adds engine capacity, very roughly speaking
if you apply 15psi boost its like doubling the engine swept volume, sort of. A
useful spin-off though is the inherent self-compensating nature of a
turbo-supercharger with altitude, it just spins a little faster in thinner air
until reaching equilibrium again.
Perhaps is was a necessary expedient to just scrape up the specified power in
this engine by over fuelling and no one really cared in its early days until the
environmentalists got going.
Just a thought.
Richard
(Southampton UK)
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