Tuning 165 for SC - and ALUM Heads

[Knowlden and/or Eller]

Dave, if you are using alum head casting #10088113 there is a core shift
problem in these heads where the head gasket combustion chamber sealing
"ring" intrudes into the spark plug cooling chamber on cylinders 2 or 7
depending on which side the block it is on. It generally manifests itself
with minor cooling loss with a very slight dripping down the side of the
block. I have seen this on every head of this casting #, about eight. GM
denies the problem. I have pictures. Could be part of your problem.

I suspect you are also leaning out. You will need a higher capacity fuel
pump. I understand that the MAF "maxing out" problem can be accommodated by
adjusting the "percent acceleration enrichment vs. RPM" tables in the prom
but I have no hands on experience (yet) in this area. I have identified
these tables with an .ecu file for the APYP memcal. They are on the ftp.

Regards,

Bob Knowlden
-----Original Message-----
From: owner-gmecm at esl.eng.ohio-state.edu
[mailto:owner-gmecm at esl.eng.ohio-state.edu]On Behalf Of Dave Zug
Sent: Wednesday, July 07, 1999 9:49 AM
To: gmecm at efi332.eng.ohio-state.edu
Subject: Re: Tuning 165 for SC - and ALUM Heads


> Date:          Tue, 6 Jul 1999 16:54:58 -0500
> To:            gmecm at efi332.eng.ohio-state.edu
> From:          nacelp at jvlnet.com (CSH-HQ)
> Subject:       Re: Tuning 165 for SC - and ALUM Heads
> Reply-to:      gmecm at efi332.eng.ohio-state.edu

> Had you been reading the plugs?..

No

> Where did/how did the gasket fail?

Rad fluid into cyllinder, 3 consecutive hard WOT runs  on a 103 degre
day.

> If ARAP, are you doing something trick, or running MAF?

MAF, It is MAXXED out (255) at about 3200 rpm. O2 shows 0.89 - 0.91
thru the RPM's

> What are you doing for reading the addition Air Flow?

Not a thing at this point. Ideas? I can make a custom housing for the
MAF electronics section but I do not know what to bump on the ECM. 3"
or 3.5" MAF maybe... -OR- maybe a TWIN MAF setup.. I get the concept
of that but would need guidance for code changes.  - OR- should I go
1-bar MAP and scrap the MAF.  decisions.. I need help with all
avenues, whatever one I take. so far with no guidance, I'm scared to
strike ont and commit.

> What for addition fuel (pump+injectors)?

Syclone Pump, adj regulator at this point. nothing else. stock
injectors. If I have to run less boost I'll do that for now. The car
ran a 13.50 @ 103, I estimate the setup added 80-90HP to the stock
225. I don't know the limits of the stock injectors as far as HP
goes.

> I have a strong suspicion that the stock ESC might be kinda blind at oil
> enduced detonation, at higher RPM then when the ESC is tuned for.  A vary
> slight amount from the blower, might be the oil source, don't take much at
> higher rpm.

SC unit had a self contained resevoir and has not dropped level in 4k
miles. I DO get knock with anything other than sunoco 94.

> I'd think twice about running a syclone calibration.  That way you can go
> way retarded with the timing at any "over boost".

Okay.. I'll try to find out thru archives what I need to do to the
wiring etc to accomplish that... than back with more Q's..

THANKS!

> Bruce
> >Just an update - and any comments would be great.
> >
> >I had JUST gotten the knock outta the cal by tweaking some main spark
> >values, and was satisfied with the "base" changes I had made (spark
> >mods only) when POOF - a head gasket goes out. (125k miles). I had
> >not even the chance to start addressing the fuel changes for the SC
> >addition and now I gotta think about changes to help idle and changes
> >to accomodate/ take advantage of  the larger 200cc intake runners,
> >and the effect that the aluminum heads will have on the whole thing.
> >I am using GME (GREAT TOOL!) to tweak the thing and am open to being
> >taught what areas I should address first. tips, techniques etc..
> >anything. the car is an 89 IROC 5.7L, if you missed the last post a
> >month ago. ARAP bin, 165 ecm, (SC = Supercharger, 6 PSI max)
> >Dave Z. www.delanet.com/~tgp
> >
>
>
>
Dave Z. www.delanet.com/~tgp