Yeah, beleive it or not, I'm looking for the lowest stall speed convertor on the market for an 88 700/4l60.... it's for my daily driver, 15MPG is killing me, and I've "Heard" a good low stall unit can provide .5-1.5 MPG increase depending on usage and all other associated elements.

Any suggestions on finding a good low stall/lockup unit? Most companies specialize in the logical choice for most shoppers... I'm jsut the black sheep in the pack.

 

It's not the stall speed of the converter that matters, it's the powerband of the engine. If you use a low stall converter on an engine that makes torque at high RPM, your mileage will decrease.

 

I think the low stall/better mileage thinking is more for non-lock converters. If yours if locking properly you won't save anything and very possibly be worse.

 

have you ever considered fine tuning the engine to increase mileage. you might be hard pressed to find a lower than stock stall, but as "Apeiron" said its not the stall that matters. trick shift fluid might help but i dont know. make sure your conv is locking up when its supposed to if at all.

 

It's an LO5, so I don't think I'll have much to worry about as far as high RPM torque...

Higher stall = greater slippage before lockup. Lockup only occurs between shifts (last I checked), therefore reducing stall between periods of lockup should improve economy. This is the line of reason that was explained to me, and I buy into it because it simply makes sense. Especially for my vehicle at 45-50 MPH. Got into 4th at 38 MPH, but don't get T/C lockup until 49MPH.... so in a 45 MPH zone I'm just throwing away good gas with a slipping convertor. Also, in those conditions, if vehicle speed varies, I'm constantly going in and out of lockup with speed, and that can't be good for the lockup clutch.

Prom tuning is coming slowly, but mechanical concerns are always first in my mind. They go hand in hand, but no amount of tuning will correct a mechanical issue/problem.


Thanks anyways guys... I'll keep looking

 

Lockup occurs while you're cruising. If you're that worried about it all, installing a manual lockup switch will be a lot cheaper and easier than chaing the torque converter.

In either case, you can easily make your mileage worse.

 

Maybe with a big block swap

15 MPG at best is nothing to be proud of with an overdrive trans and 2.73 gears driving only 2 tires (not 4x4).....

Maybe only if it was lifted 11 inches, and had 38 inch tires, 15 MPG might be just great then..... Some of the 73-87 guys simply laugh at the 88-95 trucks, one of the reasons being economy. (Carb applications getting better fuel economy than EFI, you bet it!) Yup, TBI has to be thrown out the window ASAP if you guys really think there is no mechanical driveline improvement to be had.

 

Unless your car has the 4th gear lockup only kit it should lock up in all gears. If you think your converter maybe bad I just put a stall in mine and I have a remanufactured converter with very low miles I would part with. I do not know beyond that.

 

http://transmissionhead.com/
They have the lockup converter for the 700R4 in 200 rpm increments down to 1200 rpm for diesels.
Somewhere between 2000 and 1200 should suit you. If your engine is stock, you do alot of city driving, don't care about taking off fast, then keeping your rpm below 2000 will get you better city mileage. My 93 GMC with a V6 has such a low stall it will take off at idle (600) pulling a trailer. You may want to look at changing the weights heavier($29) in your trans governor if it shifts above 1700 at light throttle.

 

Let me get this straight, you want to buy a converter, $100-700 depending on how good of a unit you get, remove your trans, install said converter, reinstall your transmission..... in an attempt to gain a possible 1.5 mpg ? You do realize that at the average 1000 miles a month you'd only save $15 per month @ 2.50$ / gal. And thats IF you managed that 1.5 mpg increase across the board, which probably wont even be helped by it for "city" driving, and may even make mileage worth with lugging the engine .....

 

Rather than change the converter. Get a prom burner and change the chip so that lockup occurs at a slower speed. Mine locks in 3rd at 35 mph and in 4th at 38 mph. It drops to just under 1,000 rpm around town doing 45 mph. I am also keeping the converter clutch locked under deceleration so that the delay is not there when you let off, then get back on the gas. I got sick of let off-unlock, step on the gas-lock.

Tweak on the fuel and the timing, setup highway mode, delay the PE, use a heated O2, get the engine into closed loop as soon as possible, etc and you could probably get around 1.5-2 mpg better without getting your hands dirty.

My 2,000 rpm stall actually helped my city mileage by letting me use less throttle to get off the line.