RE: 10.4 pistons

["Jeff Greenfield" <alfaguy@xxxxxxxxxx>]

Richard and all -

The 10:1 compression pistons are the Motronic pistons.

I don't have anything 'real' to back this up, but the general consensus is
that the 10:1 compression pistons are a much better design, therefore the
performance is at least equal to or better than the 10.4:1 pistons.

I suppose the only real way to know for sure would be to dyno an engine with
one of them, then change them keeping everything else the same and repeat. I
don't really see that happening ...

Sorry I can't be of more help ... I've used the 10.4 pistons in some of my
own cars over the years with good success. More recently I've used the 10:1
pistons in 1 or 2 customers' cars and they seem to run pretty well. Nothing
quantifiable though.

Or I could be completely wrong about all this ...

Jeff

-----Original Message-----
From: owner-alfa@domain.elided [mailto:owner-alfa@domain.elided] On Behalf Of
Richard Welty
Sent: Thursday, June 05, 2003 10:05 AM
To: 'alfa-digest@domain.elided'
Subject: Re: 10.4 pistons

On Thu, 5 Jun 2003 09:31:10 -0400  "Watry, Andrew (LNG-SFR)"
<Andrew.Watry@domain.elided> wrote:

> If the 10.4:1 pistons are the "Motronic" late Bosch pistons, a guy here
> in
> Berkeley has been running a SPICA Berlina engine with those fitted for
> years
> without a problem on regular pump gas.

probably not the 10.4:1 pistons; the current IAP catalog shows the Motronic
pistons as 10:1

i'm quite interested in the tradeoffs of 10.4:1 and 10:1 pistons. i'm
preparing a request to the SCCA competition board for a limited preparation
F Production listing for the Alfetta GT and Alfetta Sedan, and there will
almost certainly be a cap on compression for the limited prep motor. the
question is should i just settle for 10:1 or try for 10.5:1 as the cap? the
bmws that are most similar in terms of size and era (2002/320/318) are
limited to 10:1 in limited prep FP.

another relevant question is what the cap on cam lift should be. all the
cams in the IAP catalog are 11mm tops. this fits under the 0.450" (11.43mm)
cap that, say, the BMW 2002/320/318 are subject to. are there any higher
lift cams of interest? (note that cam timing will be free.)

for fuel supply, i was planning to request OE FI (wes ingram race pumps
would be legal.) there is the possibility of dual sidedraft webers being
legal as well.

richard
--
Richard Welty                                         rwelty@domain.elided
Averill Park Networking                                         518-573-7592
              Unix, Linux, IP Network Engineering, Security
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