The flaw with Car Craft's logic is that pinging (pre-ignition) due to
advancing the timing is a different effect than pre-ignition due to higher
compression ratios, and advancing the ignition timing will not produce the
kind of HP increses that higher (effective) compression will.
--- On Sat, 6/14/08, Sandy Ganz <sganz@pacbell.net> wrote:
> From: Sandy Ganz <sganz@pacbell.net>
> Subject: Re: [Tigers] engine ancillaries
> To: gswaybright@yahoo.com, tigers@autox.team.net
> Date: Saturday, June 14, 2008, 10:55 AM
> Yes car craft used same bottom ends, just swapped the heads,
> but the interesting thing was their idea that they might be
> able to try to advance the timing more on an Aluminum head
> vs Iron thus proving once and for all that it does do
> better at reducing hot spots, etc. I think the test and
> assumption might have been a bit loose at that point but
> they made the motor rattle at the same timing with either
> aluminum or iron. Still a 'fair' indicator that
> not much difference at that compression. I would have loved
> them to do a 12+:1 motor and see if that might have made
> something different. One thing I would question is the
> aluminum head just reducing the hot spots or actually
> costing some thermal efficiency as mentioned, in which case
> hp loss. But again, how much? I'll always give some
> small HP back to get rid of weight ;-)
>
> One other thought that I had, since the headers are close
> to the most exposed outer surface of the cylinder heads how
> much heat might be absorbed from that? If I'm trying to
> get rid of heat from convection would seem headers are
> going to mess with that whole idea. But like I said in the
> grand scheme of things my vote (IMO) goes with won't be
> a measurable difference if painted, polished or raw.
> Sandy
> P.S. The Galpin event with Dan Gurney was pretty quiet,
> about as many Saleen folks as Mustang'er. Still nice,
> and he was very acomadating with the people that did show
> up.
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