[torsen] re: Piston ruminations
auditude at neta.com
auditude at neta.com
Wed Oct 17 01:40:10 EDT 2001
Thanks for the feedback. Some of the stuff I don't understand,
such as the reference to 8.1, as far as prior unabused. Would this
be a custom motor, perhaps built out of a 7.8:1 MC-1 motor? Does
the knock table come into play only when there is detonation, or
pinging, or does it come into play when the effective c/r is too high
The part I guess I don't understand is if the MC-1 will be retarding
timing before and MC-2 would be, assuming they had the same
Quite a while back, I remember someone asking if there was a
problem running MC-2-boost levels in a MC-1 based motor. At the
time there was no response, but this post seems to be stating a
clear opinion on it.
How does EFI make it possible to run higher compression pistons
in a turbo motor? Dumping more fuel to prevent detonation?
Adjusting the timing much more faster and closer to the detonation
threshold? Well, I guess not that second part, since EFI doesn't
mean ignition mods, just fuel delivery.
On 16 Oct 2001, at 21:52, QSHIPQ at aol.com wrote:
> There is plenty of meat on the MC head to mill and cc as necessary to get any
> CR you so desire. For the MC1, I'd look at no more than 8.1 to avoid going
> to the lowest knock tables under boost. The MC1 running the MC2 cr of 8.4
> is too much. A properly done (and prior unabused) 8.1 should be able to use
> the stock timing belt.
> Personally, I find the audi pistons to be pretty darn good ones. Unless you
> are going overbore or lightening, I'd leave the turbo pistons alone on either
> the 10 or 20v motors
> I also am curious to know what other options there are.
> I would still like to get a higher compression piston than the MC-1's
> 7.8:1. I'm open to discussion about this. I do not have much
> technical knowledge about piston design either.
> I'm not crazy about the idea of additional piston slap than stock, or
> increased likelihood of detonation due to a less desireable dish
> design or location.
> My primary motivation for getting involved in this deal is to get a
> higher c/r for my 4kstq project, so that off-line performance isn't so
> bad, pre-boost.
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