Just thought I'd give everyone an update on the latest modded-95
comparison that Eric & I did. As a refresher, Eric's 95 has historically
had a lot more mods than mine, but his car hasn't been any quicker.
The
difference between this 3rd race and the prior one is that Eric replaced
his "late 95" ECU with an earlier, non-California ECU, and added a
front
mount intercooler. Here's the current list of mods on our cars-
My 95 GSX: K&N FIPK, Magnecor 8.5mm wires, RSR 3" Exhaust,
IM Intercooler pipe & BV upgrade, and a drilled wastegate solenoid
Eric's 95 GSX: K&N FIPK, Nology Hotwires, Trust 2.5" Exhaust,
custom Int pipe & BV upgrade, test pipe, Buschur 2.5" downpipe,
EVC (16 psi), secondary fuel pump, front mount intercooler,
ported exhaust manifold & O2 housing, turbo: Super60 compressor
(similar in size to a 16g), "T28" exhaust wheel w/ 10 degree clip,
ported turbo housings
We got together last night at our usual street-racing site. (Out of
town
& deserted). Eric brought a couple friends which was definitely
helpful
for flagging the start of each race. Temps were around 70 degrees.
Like usual we both maxxed our gas tanks at the same gas station.
We got in 4-5 good runs. The results? Well, it's a loss I can be
happy about- Eric's car has woken up and is finally starting to pull.
Every single run netted near-identical results. First gear and second
gear were relatively even, with Eric pulling maybe half a car or so
at the end of second. As soon as we shifted to third it was all over-
Eric's car quickly walked away. By the shift to 4th he was usually
5-6
car lengths ahead (but once we were both in 4th he usually maintained
but did not increase his lead). We took the cars up to between 100
&
110 (I was in the lower 100's, Eric the upper). (As a comparison,
by the way, the 600SL I raced did not pull away in 3rd gear even half
as quickly as Eric did.)
Thoughts on the results.. First, I like the fact that every run had
almost identical results with only a car length of variation at the
end of each run. I still think Eric's car should be pulling a little
more in 1st/2nd. While clearly I can no longer keep up with Eric
like I used to, we both think he still has problems to work out.
Running beyond 16psi is apparently leaning things out and causing
temps to rise, and I just don't see how that should be the case with
4550cc injectors, a secondary fuel pump, and a smaller-than-average
(compared to 1st gen's) performance turbo.
The changes since this race and last were the intercooler and ECU on
Eric's car. Eric installed the intercooler a few days before the ECU
and
noticed no difference. When he put the new ECU in, his car ran
nicer (I'll let him expand on this if he wants), and suddenly he's
beating me by 5 car lengths. Personally, I still don't buy into the
"major code changes" between the early & late ECU's. When we first
started modding these 95's, we all had problems with the boost falling
down to 10psi no matter what we did, and somewhere along the way the
ECU started getting blamed. Clearly the PSI drop is a result of the
small
Garrett turbo, not the ECU. I don't know of any cases that demonstrate
an actual performance difference between the 2 ECU's, we only know
that the earlier one is easier to modify due to having a standardized
chip with the spark/fuel data, and the later one having all that info
integrated on a single, custom Mitsubishi chip. Still, I'm hard
pressed to explain why the ECU change helped Eric out so much. Perhaps
his original ECU had something wrong with it, or somehow locked itself
into
one of those limp-modes due to his cat being bypassed. The latter
would be my best guess, perhaps the later ECU's or California ECU's
are more finicky about the 2nd O2 sensor. (I should like usual point
out
that this *whole* evaluation is of course strictly conjecture,
to be taken with a grain of salt. We still have yet to get to a real
race track).
Other variables.. Eric & I both have stock clutches. He's probably
losing a little of his power to a slipping clutch, which could explain
why we're so close in 1st/2nd gear. We're slowly killing these types
of variables though.
For our next meet, we plan to make the journey to a racetrack (Carlsbad)
and get some real numbers. We should both have performance clutches
installed by then. In addition, I plan on adding a few major mods-
a 3" downpipe, a 3" cat, and a 16G turbo. My hope is to kick Eric's
butt and still be running with a cat :). I'd really like to see
Eric do runs at the track with his current turbo, and then a TD05 16G
(with no other changes); at least we could find out what kind of difference
there really is.
On a final note, there's nothing more we can really "prove" regarding
early/late ECU's. While I had been under the impression that I had
a Jun 95 ("late") ECU, we checked and found that I in fact have a
Jan 95 ("early") ECU. (This car really must have been sitting around
considering I purchased it November 95). I'm sorry I can't bury the
myth when I go run decent numbers at the track in a couple months
(grin... thinking positive). Admittedly though, I am happy to know
my
ECU is more easily modified should I wish to re-program it at a later
date.
'nuff rambling.
Marc S.