[s-cars] An EM upgrade question/poll

[Robert Pastore]

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Mike:

I had my rs2 EM  Jethot coated when new, and with the
turbo-ingests-stock-bypass valve incident, had occasion to take the turbo
off only a few months and a single track event later. Inside the manifold,
where the 5 runners come together, there were already cracks in all the webs
between the runners.  I did nothing about it, bolted on my rebuilt turbo,
and have pounded it for the last 4 or 5 years.  No problems at all, and the
cracks have not spread to the outside.

Maybe, just maybe, the redesign of the rs2 EM  from the AAN/3B 20v manifold
has more to do with clearance for the intake tube in the rs2 than it does
with exhaust flow.

Bob

-----Original Message-----
From: mlp qwest [mailto:mlped at qwest.net]
Sent: Thursday, July 10, 2003 11:59 AM
To: Dave Forgie; s-cars
Subject: RE: [s-cars] An EM upgrade question/poll


Dave - In my limited experience, the RS2 EM is no guarantee against
cracking.  BT,ST.  A pure guess on my part, and it is only a guess, is
either EM, stock or RS2, run about the same risk for cracking, unless
they've been spec'd for manufacture from different materials.  In a pinch
or,... OK crack I guess, one might take a look at
http://www.aremco.com/PDFs/A3.pdf

I don't know for sure about the EM's, but I was told in several conversation
with two different aftermarket turbo manufacturers, sometimes it isn't the
thing you can see that make the biggest differences in durability etc. of
the hotside turbo housings.  Apparently there can be some huge differences
in the quality & type of iron used in these types of castings. e.g.
http://www.mesacastings.com/product_4.htm  I've been told if you look
carefully on the OEM pieces, you should find a symbol indicating the factory
castings have a high nickel content.  Hopefully, any aftermarket type
castings can supply this info as well.

As far as the stock design vs. the RS2 we're all only guessing the its
"better" partly based on:

(1) I paid a bunch of dinero for it, so it must be an improvement;

(2) my eyeball tells me the exhaust path for 5&1 from head to turbo hotside
"looks" straighter, ergo it must be/run cooler; and

(3) it was in the RS2 package, therefore there must be some additional
engineering that went into this thing that makes it an improvement;

that the RS2 version helps cylinders #5 & maybe #1 run a bit cooler by
letting some of the exhaust gases out faster.  What we don't have is any
confirmation of (a) changing the one component is in fact good for an xxx
(you supply the number) power gain; or (b) a xx psi drop in exhaust manifold
pressure before the turbo; or (c) an xx drop in exhaust gas temp in cylinder
runner 1, or 2 or .... 5.

Anyone got a "It's good for xxx bhp number" AND an explanation for how the
gain was determined or established?

I suspect manifold durability may be more closely related to heat cycles and
engine shutdown events etc. after particularly hard drives, i.e. something
like a big splash of cold water at the wrong time would be of more
significance than RS2 vs. stock design and layout.

What the heck, Dave I guess we'll just go on living dangerously :-)

Mike "off to watch the submarine races" Pederson

~-----Original Message-----
~From: Dave Forgie

~
~S-gruppees: The recent post about the cracked Stock EM leads me to ask
~the question:  How many people have successfully gone beyond Stage 1
~(say 280 hp chip upgrade) to say 300 hp and above without changing the
~Stock EM and have not have problems with a) cracked stock EM,  b) burnt
~valves (say No. 1 and No. 5), c) cracked valves seats/head or d) all of
~the above?  Being cautiously  paranoid, I would always upgrade the EM to
~RS2 or Ned's improved RS2 clone before adding serious HP (> 280 say).
~For the same reason, I will always add more brakes before adding more
~HP. (to prevent the "OSS", i.e. the Oh, Sh*t!! syndrome that occurs when
~you have too much HP and overdrive the brakes.
~
~So what say ye?  EM upgrade or live dangerously?
~
~Dave F.
~


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