Since my car is finished with about 1000 miles, I thought it would be fun to show Pete Stout the finished project car and let him take it for a drive and get an objective opinion from the boss himself.

As we were flogging it down the local test road, I told Pete how happy I was with the car and it hadn't missed a beat since it got finished.....you got it, not 10 minutes later the car quit! We were stranded...... and I was embarrassed

As we waited for the tow truck, my stomach turned at the thought of scratching the new paint with an uncaring tow truck driver and we started to really hunt for the problem. We thought it was a fuel issue but Pete spotted a module under the seat that had melted clear through the carpet and had fallen apart!!!

Pete made a few phone calls giving the part # and it was determined that it was an ignition module and it was supposed to have a heat sink attached to it. When I bought the complete engine and harness the heat sink was not attached. (Nor did I know it should be)....damn!

A few more phone calls and one of Pete's friends brought us the needed part and we were back on the road! (the dude has connections)

For you 3.6 owners, make sure that heat sink is attached
and.....what you say may come back to haunt you....
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Not to butt in but if it has needs a heat sink, it also needs air moving around it. It probably shouldn't be under carpet.

Dave

Yup, those attach to the coil holder on my 1991 engine which is attached the the firewall...

-Steve

mhmmmm. is that the part that is closer to the brain? with the loop of other goodies?

mine has the heat sink attached, but it's just sitting (exposed) inside the cabin.

it has two mounting holes. should i attach it to bare metal (maybe using some computer heatsink paste) or just leave it sitting there?
Andy

with the computer parts thing. a couple of fans moving air would be a good thing. cooler is better.

Andy, it's a long ways from the coils and close the the DME. I don't know why the PET picture shows it with the coils except it's part of the ignition system.

Mine was just sitting on top of the carpet under the seat but got hot enough to burn through the carpet and to the floor pan. It is supposed to have a piece of aluminum bolted to the 2 holes (mine didn't).

I'm going to bolt a piece of aluminum to the bottom of the seat and attach it there so it's off the floor.

Cool,

Heated seat!





Glad to hear it was something SIMPLE.

John, although your humor isn't lost on me... Paul's car does in fact have heated seats!

Here are the first two pictures I found that show how mine mount.

-Steve

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Steve, thanks for the pic. The later engines only use one module at the DME. I had heard that the earlier ones used two and the pic confirms it. If that block a aluminum is stock, thats a bunch of heat sink......could probably fry an egg on it!

Yeah, lesson: don't drive project cars at lunch.

Paul (and Andy and other 3.6 guys): Talking with my "experts," you want to mount the ignition module to a sheetmetal wall or at least somewhere that has airflow. It (obviously) gets hot, and the heat sink was Porsche's solution for the problem in a better environment than where that device sits in your car now.

While it was no fun sitting on Lucas Valley Road, it woulda been a FAR longer day on our real test loop.

Paul's car sure was nice when it was running. Very little to critique in the driving, though I am not sure I like the diff setup and what it does to the steering on throttle. Also be curious to check it out with less fresh tires. That said, there's a TON of mechanical grip in that car, and the brakes are solid, and the (off throttle) steering is light and sweet, and it sure scoots, once you get your head around shifting into "first" on your way into a 30-mph corner...

Then there's the paint, which might be among the nicest black paint I've ever seen, at any price point. And we all know how black goes...

pete

Pete,
Paul is never going to be able to keep that car clean. The drool alone is going to take hours to wipe off He is going to have go rope the thing off if he doesn't want to follow guys around with a rag!

And here is the solution.....nothing a mill and a chunk of aluminum can't fix in a couple of minutes.....
It might take longer to train Pete to use that 52 mph first gear though.....

Pete is right on the diff. It is a Torque Biasing unit from Guard in a 915 and it locks pretty hard when you are on the gas with this engine. When you get off the gas and it releases it goes from understeer to more oversteer and it takes some getting used to and perhaps some more chassis tuning. I only notice it when you are really hard on it but Pete can explain the actual dynamics better than I can.

The good news is that when you stand on it you almost never get tire spin. But like all things you give up something somewhere else.
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My daughter has a Hello Kitty handheld fan you can pick-up tomorrow. (she'll want it back though... ) McPassenger can hold it on the heat sink.

What's the lock-up ratio on that diff?

pete

Varies by the torque applied but 80% on at full torque and 0 when off the throttle. It's easy to see why they like them for autocross and not track use.

And easy to see why I like it even less for road use.

Methinks you should bump that down to no more than 40-60% on throttle (the on-throttle lock-up Porsche uses on GT3s and GT2s). 80%, even if only at full throttle, is way too much judging by my time behind the wheel.

Not only will this make the steering sweeter (crucial in a street car for enjoyment), it will also probably help with your car's (subtle) tendency to drive itself over to the other side of the road on the way out of turns despite normal inputs.

Or you could just "get used to it," as I am sure you are loathe to spend another dime on that transmission...

I would be!

pete

Pete and Paul,
Interesting observations on the Guard TB unit... I have the same unit in mine and have about 50 street driven miles at this time. My commute is only 20 miles and I had only 10 non-commute miles on it before driving it this week.
I think perhaps what Paul could use is lots less power. My 2270 has about 170HP and I hardly notice the characteristics you describe.
I could be wrong but I don't think the unit is adjustable at all....

I have not noticed these tendencies in our Guard Transmission Torque Biased differential either (and ours is only track driven).

At the time, I didn't fully understand the differences between Limited slip and Torque biased differentials.

For those that don't know, Torque Biased are effectively locked under power and not while coasting (braking), while limited slip differentials are locked both under power and under braking (provides additional straight line stability under braking).

Here is a picture of the unit that is in our 915 box.

GT 930...

All I can say is that the difference on track between this differential and an open differential is like night and day. I would never desire to go back. That being said, I have never driven a car on track with a limited slip differential, so I assume there is some benefit, but I don't know what it would act like.

It doesn't lock fully all the time. It's based on the tires being on the ground and how much torque you apply.

I have asked Guard to supply a chart of the progressive lock and will post it when I receive it.

From Paul Guard:
"What does torque bias ratio mean?

Torque bias ratio (TBR) represents the "locking effect" of the differential. More specifically, it indicates how much more torque is sent to the high traction wheel (or axle) than is sent to the spinning wheel. For example, when a differential has a TBR of 3:1, 3 times the torque the spinning wheel can maintain (75% of the total torque) will go to the higher traction wheel. If a wheel is spinning and can support 100 lb-ft, the other wheel will get 300 lb-ft."
You can figure that most TBDs start with a TBR of around 3:1, and settle down to around 2.7-2.5:1 ... but this is theoretical, and probably not practical to attempt to scientifically measure.

John,

Love the looks of your GT 930.. I on the other hand love the ZF Limited slip @ 80% .
When I'm off the brakes or on the gas, I know it's locked - especially when I'm exiting a corner and on the gas. All I have to do is point and gas:)
There was an excellant article written in POC ( Porsche Owner Club ) a few years ago about to two styles.
In the end, it's all personnel.


PS Good info on the heat sink.

and here is my solution ...


thanks to Mike Zois for the aluminum velocity stacks. i put one of them to good use!

works very well, got handwarm on the ~800 mile trip to SLC. not too bad ...
Andy

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Paul,
Two points that may help. Andy mentioned the heat sink material ( dow dorning make a very good one - white in color) and I would drill some holes in the aluminum plate to allow more heat to dissapate from the plate. I have power supplies come back in that failed due to not having the dow corning heat sink paste applied. others with the paste applied seem to last and last. That stuff works.
Tom

Paul, it came out gorgeous
Nice headers too !
Marty