Bazman

Over 500rwhp and 500ft/lb at the wheels - you can't IMHO. If anyone has proven otherwise I need to know your secrets after going through 3 transmissions, 2 converters. The last 2 have been as follows:

1 - A stage 6 RPM - built to take 800hp, with my old 2800 rpm Converter. Lasted less than 500 miles, didn't even finish stage 1 of a 21 stage event.

2 - RPM admitted fault and built me a new trans under warranty (good on them) plus I paid for a billet input shaft, core charge, and a new Precision 2600 converter with twin lock up clutches good to hold 800rwhp. Worked brilliantly and ran for maybe 1000 miles, endured a track day and performed well though started to get hot towards last couple of laps when I warmed her down and retired. Then in a Targa event it lasted 12 stages of a 21 stage event before the lock up clutches burned out and that toasted the trans I'm sure. I can drive around lightly but any power it slips and is like a CVT trans lol.

I have the largest oil cooler on it I can get. It operated at 180 or less when fresh, that got to 200 after a few laps, then 220-230F once the lock up started to fatigue.

Lesson, get a manual if you want to do any real closed twisty road or circuit work. Auto is fine for street and drag racing.

After spending about $15k in total trying to make an auto work (and yes we checked everything and ran high temp synthetic oil, and had lock up come in early to stop slip which creates heat etc) this is my conclusion:

1 - The lock up clutches cannot be made big enough to handle the on and off constant demands of road racing, there is not enough room. They'll hold big power for drag racing, but not constant on and off throttle.

2 - Once the lock up fatigues - it burns up and that contaminates the oil so...

3 - the trans goes next and the oil smells like burned toast

4 - If you run a tight converter without lock up you might last longer, but you have nothing down low on tall gears, and you'll still be slipping some, which will eventually heat soak if enough power is going through on and off for long enough

5 - If you run a high stall it'll die in a single day regardless of converter type if you road race it more than a handful of laps due to the heat from slip

6 - therefore no combo I know of works with the 4L60/4l65

AMG, Porsche etc trans last raod racing because they ditched converters and run clutches

Reasons I didn't go manual to start with is with 630hp up front:

A - things happen real quick when racing in twisty mountain roads and stirring an H pattern box just complicates a busy enough situation with arms flailing from lock to lock.
B - the auto and a turbo combine perfectly to sling shot out of turns like jack the bear, no manual can get so much torque down as quickly without breaking traction (too harsh when it hits)
C - a manual has more turbo lag, and you can miss shifts

Sigh, I guess that means coughing up for a sequential

Comments? (other than I was a ******** for trying lol)

mrvedit

Interesting hypothesis, experiences and conclusion.
I don't doubt you; I only wonder if a triple clutch converter with a very low stall speed would hold up better.
I tried to turn my '81 Camaro into a road (course) racer but found the handling sloppy even with lots of aftermarket suspension pieces. (So I bought a BMW for that.)
I was alarmed by how much all temps rise from just a few hot laps at the drag strip; this also made me doubt the car would survive a road course.

Bazman

A triple will hold enormous power for drag racing, but you still have the physical space limitation inside the converter. It's just not big enough to allow clutches BIG enough to absorb high power on and off continuously. They might hold 1200rwhp for a 1/4 mile or even in a standing mile, but try doing it out of 100 corners, on/off....on/off etc. The clutches just burn up, then you have no lock up, then you have burned toast.

lol

Yeah - BMW's are the best value race cars around. No doubt. You could make an 81 handle, but you could buy 2 older BMW's for the cost of getting one right.