Diesel Torque Converter(1200 stall) in a gasoline car

[Coyote X]

My Astro had it's transmission die in the fall. I slapped together some junkyard parts to get me through the winter. The junkyard trans had no lockup on the torque converter. So my mileage went down to 12-19mpg driving normal. I rarely used it and mostly it just sat around all winter unless I needed to haul something.

So a few weeks ago I put a well built transmission in it and a Diesel torque converter that has a 1000-1200rpm stall speed. The stocker was 1400-1600rpm. Right away it was obvious it was going to be better at anything below the 45mph lockup speed, the motor would only slip about 100-200rpm when unlocked. So I got this thing put together and all the bugs out of it. I went and filled up so I could get a good mileage number. I ran the tank out and only got 21mpg. I figured something had to be wrong but it was only getting around 21mpg consistently. I had to go fill up my mom's car for her the other day and I checked the mileage in it. It was down by about 25% from usual. I checked the receipts for her car that I usually wrote the odometer reading on. After trying to figure it out, it turns out the last gas station here that sold gas without ethanol in it just started selling E10 a month or two ago.

So that pretty much kills any chance of getting a good number out of this experiment. Unless Nerys can come up with a good solution for washing gas, I will just have to say ethanol typically drops mileage by 25%-30% the converter gave me my 25% back so I am back where I started

I really would love to find a reliable place to get some E0 for a few tanks to see what it would have been capable of with the setup it currently has. I bet it would have been within range of getting a 30mpg tank this summer with just a few more minor mods.

But I can say for sure that if you are ever taking an automatic transmission out and there is a lower stall converter available you should get it. The increase in mileage should be pretty substantial. It would be a lot of work swapping converters by itself but if the engine or trans has to come out it is a no brainer.

[MadisonMPG]

Seriously, ethanol sucks.

[Christ]

Agreed. On both accounts.

With Cara, since the 5 speed swap was short in coming, I had thought about putting a manual valve body, manual lockup control, and having a new custom converter put in, with a stall speed basically just off idle. The 2.4 had enough torque in low gear to get the van moving without having to rev it up, so that setup would have worked out nicely.

Manual valve body is still something I'd like to see someone else try, though. Once you get used to it, it should help get rid of some of the inefficiency of driving an auto-equipped vehicle, since you can short shift when you want, and have better control over engine load.

[Coyote X]

I put the Transgo HD kit in with all the other heavy duty racing parts so it will override any of the transmission defaults that are not controlled by the computer. It will pretty much let me shift it into any gear that wont blow the engine or trans. I don't think manually shifting is going to help this one though. The shift points are pretty low already and other than the lockup being a bit higher than it needs to be it seems fine as is. I will probably change the computer's programming and set it to lock up at 40 instead of 45 in 4th and set it to lock up at 30-35 in 3rd gear.

The low stall converter has probably added at least a second to 0-60. It can pull itself over a speed bump if you stop against it. You won't sit anywhere in gear without holding the brakes pretty good. It wants to take off as soon as it is in gear. I like the feel of it in that van it suits the way it drives and the fact that it keeps the transmission much cooler is always a plus. Less heat generated is less fuel used.

A manual lockup switch would probably get a pretty good gain in mileage if you could keep track of using it and not killing the motor all the time by forgetting it is on

[Frank Lee]

Wow. Imagine what the Sport Coupe would get with E0.

Maybe your blend of E10 is different from mine somehow.

[Milwaukee]

update on that astro with diesel transmission?


My experience with gas V6+ low stall torque converter= you be lucky if it improve mileage.

Do you have vacuum gauge on that one?

[Coyote X]

I ran it for a while and other than it being pretty slow pulling out when loaded it was a pretty good swap. I never did get to say what kind of improvement it got. A nearby station started getting E0 again last month so my bike and Metro both are running E0 again but the Astro is no longer a gas engine car. I put a 6.5 diesel in it a few months ago. So now it has no problem getting 25mpg and will probably easily get 30mpg this summer.

I still think for someone doing lots of driving under 45mph it is a good swap. But if you want the car to accelerate fast it is going to probably get worse mileage. Just normal easy driving on the thing really was nice though with the engine never having to rev up. I really think it could have given me around 20% better mileage while driving under 45 with the converter unlocked.

http://www.youtube.com/watch?v=HnEJJGLhVLs

[Christ]

Excellent work, sir!