Tailpipe Probing of EGO

[Garfield Willis]

On Thu, 29 Jun 2000 08:26:12 -0400, Mike Rolica
<mrolica at meridian-mag.com> wrote:

>>We had occasion to tune an opposed 4-cyl experimental
>>aircraft engine (water-cooled) that was mounted in an auto for testing, and
>>were able to see a mixture imbalance from side-to-side at the conjunction of
>>the Y-pipe just prior to CAT, from the way the AFR jittered backNforth at
>>ALL rpms (it was worse under load; ick :).
>
>	Me thinks it may be a subaru engine No??... buit quite a few of
>them.....the induction system kinda sucks, as ds cyliners at front seem to
>run leaner than the rest......

Bingo, dood. It was indeed a Fuji engine, but this wasn't the fabled
Confucius saying,  "siamesed intakes and adjacent firing order cause
first cylinder to rob mixture from second". What was happening here is
that one SIDE was running leaner than the other. We use these engines a
LOT in XA, and I've never seen EVER any plugs that pointed to the fabled
"intake robbery". I've heard it's a problem on the Mini's with siamesed
intakes, but we don't see it much on the Fuji's. Course, we rarely use
the stock induction, but the heads on the smallest of the family do
indeed have siamesed intakes. The larger & later OHC engines from '90
on, the so-called EJ-22 & EG-33, aren't siamesed, and have very nice
induction and FI systems with absolutely no problems of mixture
imbalance. An all around nice family of boxers. There were some early
turkeys, but we just ignore em. :)

Gar


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