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Supercharger Dynamics

To: 6pack@autox.team.net
Subject: Supercharger Dynamics
From: Jim Hurley <hurls@world.std.com>
Date: Sun, 24 Nov 2002 22:04:46 -0500
Hello,

This recent side discussion about superchargers is getting interesting.

"Robert M. Lang" wrote:
> > If I shave my TR250 head to 9.5:1 CR would I still be able to use an M62 
> > or similar supercharger? Your web site hints that the answer is no. 
> 
> WHoa! 
> 
> If you're going to add forced induction, you don't want to start with a 
> H.C. engine. Au contraire! The point of a blower is that _it_ increases 
> the cylinder pressure. If you start off with 9:1 or more, you will have to 
> worry about detonation. 

So late model TR6's will be easier to supercharge. Here is an interesting
question: Will a supercharged motor benefit from a cam change? Which cam?

And then Don Mailing wrote:

> Probably don't to spend a lot of money on head flow bench work 
> either... :-) 

I respectfully disagree with this, at least on the exhaust side of the
equation. Supercharging puts more combustible stuff into each cylinder,
which yields more power (that's what we are looking  for) but also produces
more exhaust gases that need as easy an exit pathway as possible.
Otherwise, you just lose some of the power pushing the gases down that long
exhaust tube. This is why I asked the question above. 

I also think that a cam might help get the combustible into the cylinders
too. An old racer I know, (who had a Ford 351 with Gurney/Westlake
heads!!!) told me to think of a motor as an air pump. To make it work
better, make  it easier for the pump to do its job - flow gases.

Ciao,




Jim Hurley                      "Life is too short for a backfire!"
'75 TR6
'83 F350 4 Door

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