Torque Talk on my 400

A week ago, I pulled the 400 tranny out of my '88 5.3. It is getting a full overhaul, a shift kit, and replacement of any weak parts. Thanks to e-bay, I now have my very own 12 pt. 7/16 swivel socket!
I am thinking about replacing the converter, and have found one that I think might work. It is a TCI Maximizer, P/n 241602. 12 inch diameter instead of 13, less mass, and a somewhat higher stall speed than stock, but not outrageous. Plus an anti-ballooning plate.
I put a similar converter in a 5200lb. Chevy wagon about 20 years ago, and the car woke up.
I would like to hear from other owners who have already been “converted.” Any thoughts?

Years ago I had TCI build a converter for my XJS. I was happy with the result although it wasn’t cheap. I specified 2500 stall speed; worked well. The original spec is 2000-2100 as I recall, so 2500 isn’t a huge jump but it helps!


To really wake it up, you could now fit a nice five speed manual in its place :wink:

As i get it, stall speed is the point that the spool is up and takes the load. Engine gets more 'time to rev and develop torque. Snappier take off…


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Isn’t there a problem, though, if the stall speed is close to the cruise RPM?

Hi Doug, without having a source for the OE converter stall speed, I had guessed that it would be around 1400-1800 RPM.I know that the 5.3 develops maximum torque around 2800 RPM. The converter I am looking at is supposed to be all-in at 2000. RPM. Your numbers suggest a different result. ??

Yeah, in a word- COSTLY!

Totally agree- just means more waste heat. I spend most of my time on the open road, or Interstates. Cruising RPM somewhere between 2200-2500.

Yes, and it was a concern for me in making the decision.

From memory, 80mph = 3000 rpm and 60mph = 2000 rpm.

In actual use, though nothing bad ever seem to happen. And I used the XJS very often for long, highway speed road trips, knocking off 600-700 miles in a weekend.



And the higher stall speed did help in letting the V12 engine get into power-making zone.


1400-1600 or so is ‘typical’, yes. The Jaguar spec is higher. I’ll verify in the ROM if I have time but I’m sure it’s higher than typical.


Mine was about $500 as I recall, and that was probably 15+ years ago. A huge plunge considering ordinary rebuilt converters were $159.95 all day long at the time

I told the guy I wanted something that would unquestionably stay together to 6500 rpm and he said “We can do it”.

It was furnace brazed, specially balanced, anti-balloon plate, special this, special that, blah blah. All the ‘trick’ stuff :slight_smile:


After searching through my ROM page after page, I finally found the OE spec for converter stall speed.
You were right- 2000RPM +_ 50.
Well, dagnabit- that changes everything!
Start again. (And thanks for your response.)

if your ordering an off the shelf converter, it may not lock up at the advertised rpm. they slip or lock up dependant on torque vs. load so a high torque engine would reach that point at a lower rpm. a lighter load would do the same so a 2500 stall converter may lock up at 2500 under spirited driving and still stall close to stock under more conservative driving. with peak torque at 2800, you could run 2700-2800 and still cruise at lower rpm’s without heat/slippage. the real question is if that is 2800 stall converter when used in your car.

Ready to handle 500 HP and similar numbers in torque at about 5500 RPM!!!

High stall + locx up, sounds like the ticket…

Wonder where the stock converter in my LT1 stalls at. it locks at about 45 mph… As it slows for a stop, the brake peal unlocks it…


Accidental PM posting…