Re: [T3] Heads -- which, where to get?

["John Connolly" <john@aircooled.net>]

you want a quick CONTROLLED burn. The problem with slow combustion is that
pressure is slowly building. This means it's slowing the crank until you
reach TDC, then speeding it back up again after TDC. Nice for creating heat
and vibration, poor for efficient engine operation. You want peak pressure
at 15 ATDC.

John

----- Original Message -----
From: "Keith Park" <topnotch@nycap.rr.com>
To: <type3@vwtype3.org>
Sent: Thursday, October 17, 2002 5:28 PM
Subject: Re: [T3] Heads -- which, where to get?


>
> Wait... it just occured to me.. if the burn is significantly SLOWER with
> semi hemi... doesnt that put you in the opposite direction of detonation
> (which is too quick and too uncontrolled) of a burn??
>
> I have no temp or gas mileage complaints with my semi hemi 1641
>
> Keith
>
>
> Rule-of-thumb: the amount of time for fuel to burn is twice the amount of
> > the ideal amount of ignition advance.  The simplest proof of the slower
> burn
> > is the amount of advance needed: a good chamber with excellent quench
> > usually only needs 26-30 degrees of timing at WOT.  A Semi-hemi head
needs
> > 36-40 at WOT.
> >
> > Take care,
> > Shad Laws
> > LN Engineering - Aircooled Precision Performance
> > http://www.LNengineering.com
> >
> >
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>
>
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