Re: [DML] Re: BAE Turbo Charger for the Delorean.

[William T Wilson <fluffy@xxxx>]

On Wed, 20 Nov 2002, David Teitelbaum wrote:

> pressures low you can get get by. On most applications with increased
> pressures (turbos and blowers) the compression ratio is reduced so you
> have less danger of predetonation which will destroy the pistons and
> rings. The camshaft is also usually replaced to change the valve timming

This is all true but I do not think it is important on the DeLorean. The
PRV already has a compression ratio of 8.8 (IIRC) which is lower than many
modern turbo cars. The camshaft on a turbo car is also usually different
but this is mostly for purposes of drivability, not performance. In fact
in the case of the Supra, for instance, the hot rod cam for the turbo
engine is actually the ordinary naturally aspirated cam for the same
engine!

That doesn't mean you can just increase the boost willy-nilly. The two
big problems with increasing boost are intercooling and fuel delivery. 
When air is compressed by a turbo (or a supercharger) it heats up and if
it gets too hot it will ignite the fuel simply by being hot rather than
waiting for the spark. This is very bad. Without an intercooler, 6 psi
of boost is about the limit. And the more air you blow into the engine,
the more fuel you need to add to burn. Not having enough fuel is even
worse than not having enough intercooling.

The DeLorean fuel system is only designed to deliver so much fuel. It's
plenty for the engine as-designed, but an engine running 10 psi of boost
needs twice as much fuel as a naturally aspirated engine. A good turbo
kit will increase the fuel delivery (and the Island kit, at least, does
this; I don't know about the BAE but I assume it also does), but there's
only so much that can be done without major system changes.

If a new fuel injection system were adapted and intercoolers added, along
with bigger turbo(s) than found in the BAE or Island kits, there'd be no
reason that 10 psi or more boost couldn't be used. It should be possible
to extract 250 or 300 HP from the PRV. But neither the BAE nor Island kit
could do this. Keep in mind both of these kits are 15 year old designs
and are designed for simplicity, not maximum performance.