[s-cars] EM type, chip upgrades and cracked heads

[Mihnea Cotet]

The most common problems I've seen with cylinder #3 were head gasket
related on older UrS-car models that had the paper headgasket. In some
cases (one of them was running the "racing" chipset I've mentioned about
this morning), the head gasket would burn right between the #2 and #3
cylinders, meaning indeed that those cylinders are running leaner than the
others in the AAN engine. I've personally NEVER heard of burnt exhaust
valves in an AAN engine, and additionally, stock and "generic" modified
chips run so rich (to ensure they can be run safely in every engine without
testing EGTs) that there's no issues with burning exhaust valves. But
legends are often never questioned and people often accept what reputable
tuners state as gospel, as Bob Pastore mentioned.

Once again, in my particular case, I have one s-car lister customer in
South Africa running my chips for an RS2 turbo/stock everything else at
about the limit for the stock AAN injectors (according to his own sayings
my chips run much stronger than an MTM 320HP chipset I've sent him for
testing purposes) and who hasn't experienced any issues yet from running an
RS2 turbo on a stock exhaust manifold.

Then, my chip tuning "teacher" has run an RS2 turbo at exactly 381 dyno HP
in his S2 on a stock ABY (thus AAN and 3B) exhaust manifold for years with
no troubles either and I can say that his car was among the fastest S2s
with an RS2 turbo around. He recently removed the head in order to have it
ported/polished by Lehmann and while pressure testing the head no leaks
have become apparent at all and he's still using it today with his
K26/27/29 turbocharger at about 435 HP.


Here's my 2 cents worth of 20vt tuning experience, if someone has more data
to add, please feel free to do so, but really, I haven't heard of anyone
yet stating that he has burnt exhaust valves due to a stock AAN EM or
something like that!


Cheers,

Mihnea

At 08:28 12/07/2003 -0600, mlp qwest wrote:
>One of my guesses I anyone were to be able to assemble the data, is the most
>likely candidate for a burnt valve/cracked cylinder etc. would by cylinder
>#3, and not because of anything in the exhaust manifold, but rather because
>of the layout of the intake manifold.  Assuming equal fuel delivery to all
>injectors, in a highly boosted motor, just on the basis of looks, #3 would
>be the most likely to run lean, which I guess would mean hotter, which I
>associated with "more likely than the rest" to experience a problem.  #1 and
>#5, if anything, would run slightly richer,... again nothing more than a
>pure guess based on the intake manifold layout.
>
>Dave, FWIW & notwithstanding Hap's recent paranoid :-) machinations with the
>intake, in no case have I heard of this rising to epidemic proportions, ....
>but then you never know.
>
>Bob the pics you asked for are attached.
>
>Mike
>
>~-----Original Message-----
>~From: Robert Pastore
>
>~Dave:
>~
>~Your assertion is precisely the story Hoppen gave everyone as they began
>~sellign rs2 upgrades.   It because accepted as gospel, and nobody
>~ever seems
>~to question or challenge it.   I don't have clear evidence one way or the
>~other, but have seen many 1+ chipsets run hard for 10's of thousands of
>~miles wthout any problems.  OTOH, I have also heard stories of
>~cracked heads
>~on moderately driven cars that ran stock chipsets.  I think we'd all like a
>~black and white answer, but the evidence I've seen suggests that there just
>~isn't one.
>~
>
>