My Chevy Astro and a couple ideas.

[Isaac Zackary]

Great! So the diesel torque converter might work! I'll have to look into it.

[Isaac Zackary]

Ok. So I thought I'd get back about the hybrid idea. Doing some quick math (not as quick as before) I found that the van at full GVWR of 6,100lbs takes almost 1,000kW/s to accelerate or decelerate, not including air drag and rolling resistance and such. But to go from 30 mph it takes a quarter of that, almost 250kW/s. A 10gal accumulator that goes from 1250psi to 2,500 psi stores about 240kW/s of energy. As far as the 80hp 48gpm motor/pump goes I calculated it actually can't put out more than about 70hp theoretically meaning it probably takes about 80hp to turn as a pump and gives out about 60 HP when used a motor, which is actually right in line with the average 75% efficiency of such a system (much better than the 25% to 30% of an electric hybrid.) Since most of my driving is below 35mph one accumulator will do. But the question is the motor. I'd get a little less than 3mph per second (which is what I do anyway) but only if I gear it to go 30mph at max RPM. So I either need to have a way to disconnect it or two pumps geared to 60mph.

[ChopStix]

Originally Posted by Isaac Zackary

Ok. First of all I've been thinking about switching to a Hughes Fuel Miser torque converter. It's supposed to have a lower stall torque than stock (advertised at 1,000 to 1,200 RPM). Has anyone used one of these? Any opinions?

Stall ratings are mostly a scam. Any converter will have a broad range of stall based on engine torque. i.e. more torque = more stall, proof of this statement is listed in every Summit Racing catalog in the converter section. Where things like gearing, tire size, vehicle weight, etc affect the low end torque and thus the stall of the converter.

In my opinion I would doubt that there would be any notable difference (MPG gain) between the two converters in the real world when the claimed stall point is only 200 RPM difference. You would do better to simply put taller skinny tires on your van to reduce the RPM's at driving speeds further rather than gamble your cash and labor to install the converter on questionable advertising claims.

[Isaac Zackary]

Originally Posted by ChopStix

Stall ratings are mostly a scam. Any converter will have a broad range of stall based on engine torque. i.e. more torque = more stall, proof of this statement is listed in every Summit Racing catalog in the converter section. Where things like gearing, tire size, vehicle weight, etc affect the low end torque and thus the stall of the converter.

In my opinion I would doubt that there would be any notable difference (MPG gain) between the two converters in the real world when the claimed stall point is only 200 RPM difference. You would do better to simply put taller skinny tires on your van to reduce the RPM's at driving speeds further rather than gamble your cash and labor to install the converter on questionable advertising claims.

I do wonder what the stall speed actually is in my van. Maybe a previous owner put a higher stall converter in there. It seems to rev more than I like from at a stop when I step on the accelerator.

[ChopStix]

I don't know the stock claimed stall. But I do know a lockup converter is a weird thing compared to racing stall converters. Its truly got a mind of its own!

[ChopStix]

Btw since you have an Astro, here's my build thread which might help you.