It'* a long read, but well worth it. It captures the long road to unlocking the potential of this engine:
A long time ago, in a Galaxy far, far away, ok, back in Jan of 2003, I started to tinker
with the idea that temperatures were having a negative effect on performance far
more than we ever imagined. This topic was the result (locked, so my digging it up
won't start irrelavent replies):
I had already collected alot of heat data from the SC, engine bay, and engine. And
not long after, started the same for the trans temps in various locations.
To fully understand what'* going on here, you have to first (and I think everyone
does) understand what heat does to performance. Secondly, you have to
understand what CREATES the heat before you can kill the effects of it. OR you
have to find a way to get around it.
The biggest contributor to heat are obviously the combustion in the cylinders. That
heat travels up from the engine, through the LIM, and into the SC and TB. Cutting
off the coolant flow to the throttle body may only be a temporary measure good for
short track runs. This is why I haven't been after that yet. What I've done is used
the OTHER components around the engine bay to help me control heat, and try to keep
it from creeping into the LIM. This is where my hood vents, engine cover, ram-air
cooling duct, and other little ideas came from. Even the Trans has the effect of helping
to remove heat from the engine, so I went after that as well. Some of you are aware
of how long I've been working on this.
Two other sources of heat for the L67'* is the friction of the air movement over
rough surfaces, and the compression of the air. Heat is a natural by-product of both
of these effects. So the inlet of the SC right behind the TB and the outlet below the
rotors are also areas I knew I had to go after. The porting and polishing you've seen
on 2 of my superchargers was the result. I figured that if I was going to intercool (in
a sense) later, that it would be in my best interests to get the most out of everything
INTERCOOLER: Some of you have seen my idea. We are physically limited in the size
of pulley we can run. Particularly the 92/93 guys running Gen2 superchargers.
You can't go a whole lot smaller than 2.2" without machining grooves on the input
So what do we need for an intercooler? JUST enough cooling to allow us to drop
a pulley size or two. That was my goal all along.
So the intercooler was born, and it wasn't long after I got the concept down, and the
idea backed up with thermal analysis, that John Wikoff jumped on board with me to
help me finish it up. The results were a plate that insulated the SC from the LIM, and
a seperate cooling source for the SC/TB OEM ports.
Pretty neat idea, and I was confident it would allow most of us to run pulleys at least
0.2" smaller than before. Maybe even more. But that'* where you run into
problems. One of the goals all along was to make it far more affordable than a
Series 2 intercooler, because most of us with Series 1 cars have tighter budgets. By
the time we got around the alternator bracket, fuel rail, and fuel injector extensions, it
was far too expensive when added to the cost of the plate, pump, and heat
exchanger. Nearly the same cost as ZZP'* SS intercooler setup.
That'* the history up until recently, in a nutshell.
Now let'* jump to the very recent and future.
The intercooler isn't going to become a reality due to financial constraints of the kit
for most owners of Series 1 L67'*, so how do you go about improving
performance without one? I could probably piece together a kit for myself for less
than half the cost by machining the parts myself, but that doesn't help the rest. So
we put the idea on a shelf and move on.
Increasing flow in the top end of the engine THE key to moving on from here. The porting
I did last year while my beloved Zilla spent the summer in pieces was just the
beginning of this. The results in performance seemed at first to be lackluster, but
there were complicating factors.
Let'* start with the Throttle Body. Remember the idea of cutting out the MAF support
on one side? Worked great on Damemorder'* L27, but had negative effects on my
93 SSEi. Why? The L67 flows far more air. So I gained right up to the limits and
abilities of my MAF sensor, then the fuel fell short. Simply because the MAF was
limited in how much air it could detect, and didn't think there was more when there
really was. That left me lean on the top end. I could have used an AFC controller to get
it back, but you all know I feel they're no better than a bandaid. A custom PCM could
have been used as well, but I'm a firm believer in fixing all you can mechanically
before resorting to digital controls. I'm anal about that sometimes. I'm confident the
SC porting and polishing helped, as well as the LIM porting, but I was prevented
from really figuring it out by the extreme TB problems. It was so marginal in capability
at the top end that I would throw an O2 Lean code and light at WOT unless I had my
MAF screen installed to choke it back some. Was the car quicker? You bet. But
how much quicker could it be if I wasn't running lean? I don't know, and might not
ever, since I changed gears at that point.
Due to my anal-ness, and my ability to source extremely cheap parts off eBay with
great success, I had a spare supercharger for each car sitting under my bed. A gen2
for the 93 and a gen3 for the 95. If I ever needed one, I'd simply order the bearings
and seals, rebuild it, then swap in an afternoon with very little downtime. Great peace
of mind to sleep on every night.
Then I began looking lustfully at that Gen3.........and the next thing you know, I'd
concluded that the porting I did on my LIM and EM'* was doing just fine up until the point
I ran lean because of the over-porting of the TB (see, we can learn from goofs). So if
it'* doing well, maybe it just WANTS the conversion?
The last two (only other two) conversions I know of had problems idling and ran (one
still to this day) with the aid of an AFC controller. My goal was to convert, then use
the abilities of Sinister Performance to get it drivable without an AFC. So the tools
came out, the SC was stripped, ported, polished, and rebuilt, then one month ago,
was swapped onto my ported and polished top end with an optomistic 2.5" SC
pulley rather than the stock 2.85" that I should have started debug with. I had also
paid close attention to potential problem spots like EGR stovepipe diameter
differences (made a custom gasket) and completely confused many of us and myself
on the different fuel pressure regulators (more on that item later).
I turned the key and it idled better than the Gen2 setup.
So I went for a quick little conservative drive.
In my glee and adrenaline-fogged state of mind, I ran over some road debris. An
electric oil-filled space heater (it was dark).
No damage, thank god, but it
scared Bo and I to death.
The car ran GREAT. I could no longer hear detonation (pre-ignition or knock if you will)
at the top end like I could before. It pulled VERY hard. And due to my busy schedule,
I never put the scantool on it. I drive to work in the dark, and drive home in the dark.
Hard to scan in those circumstances while holding a cup of coffee, and the dog
only knows how to lick the display of the scantool, and doesn't understand the numbers
it spits out.
2 weekends later, I thought I might as well throw a smaller pulley on it and see if I
could hear the detonation again. I was so chicken about blowing up the motor, that
I never gave it full throttle, and removed it a week later. Back to the 2.5". Then in
a conversation a week later with Chadow427, the idea started eating at me again.
I decided in the interests of fully understanding the effects of all the work, I HAD to
find the limits of the setup. 5 minutes later, the 2.2" was on the car, scantool fired up,
and the dog in the back seat. This was the result:
I know now that the 4° of KR are caused by weak fueling at the top end. I have a
solution being shipped to me now. The 92/93 L67 stock FPR is a 3bar regulator, but
the 94/95 which naturally flows more air is a 2.7bar. Makes no sense. There
is conjecture that the bastard-child 94/95 PCM'* manage the duty cycle and pulsewidth
of the injectors differently, and therefore don't need as high of a fuel pressure. My
stock PCM coupled with my Jet Stage 2 PCM seem to do pretty well, so there must
be some changes programmed into the Jet to make this possible.
Nevertheless, when my fueling is fixed next week, I'll be running a 2.2" pulley with 0°
of KR on what is essentially a 1994/1995 top end. Far smaller than anything
ever attempted, and something that none of us would have ever thought possible. I
still have moments of disbelief myself, and I drive this sucker every day.
No KR with 2.2" pulley on a Gen3 setup? What the hell do I need an intercooler for? I
can POSSIBLY go to a 2.1" pulley now with no KR this time of year. Don't know
what summer will bring, but I personally think with my water injection running, I'll
possibly be able to go to a 2.0" pulley. I personally don't feel the 1.9" (smallest you
can possibly make and still be practical) is a good idea because of belt wrap.
I'm working on two solutions to that problem currently.
So that brings us up to the situation as of today.
Combining my efforts with those of another member, we're trying to sort out all the
LIM porting issues and thermal stuff. I've found someone that has been doing this
for almost as long as I have, and coincidentally came to many of the same conclusions
as myself. There'* still more potential to be gained for very little cost. Another idea
from him, as well as one design element of my old intercooler design will be built
into another LIM for my car very soon.
Some unanswered questions remain to be filled in:
1. What are the effects of the coolant in the TB? Helpful or hurtful on short runs and
2. How far can we go with pulleys and no KR without some form of cooling added?
3. Will other cars react the same since we already know many L67'* respond
differently to identical pulleys?
4. What effect do each of the available PCM'* have on the results?
5. How much difference is there in LIM porting for the Gen2 and Gen3?
So we have 2 other test cars working towards answering these questions now.
That will bring the total to 3, with slight PLANNED differences in each setup. They
are already moving in that direction, and some work/sourcing has already happened.
I'm moving forward with two more major changes to my LIM, but all other items
will remain the same (other than the fueling battle).
Many normal wear items MUST be in perfect condition to characterize this. Fuel
pumps, FPR'*, and all the normal tuneup items have to be at 100% when trying to
figure out extreme changes to these setups. Particularly due to the age of
the components in these cars.
If anyone is interested in moving forward with some of the ideas after we get
them sorted out, I can assure you that you MUST replace your fuel pump with at least
an OEM unit. My gut tells me the 94/95 cars will respond better to the changes, but
the 92/93 will still see an improvement. We'll know that soon, too. We'll also have a
test car trying ONLY a ported and polished Gen2 supercharger soon to see what
effects that change alone can have.
Many more details will follow in the weeks to come, but I knew there was alot of
interest in where this was going and felt the long history and conclusions were due
to be shared. As I have been doing recently, NO conclusions will be shared unless
I'm 100% sure they work. I don't want to see people jumping on un-tested or
un-proven ideas and wasting their hard-earned money on nothing.
I have no intention of keeping any of these ideas to myself. I gain nothing being the
only car doing this. The Zilla will be quite happy knowing she gave 'birth' to the ideas
that allowed other cars to achieve the same results.
:soapbox mode off: