3702 repower

[harry]

I need to repower a GM 3702 straight drive RH engine.
Would like to have automatic  transmission.
What do all of you think will work.

[Dallas]

Harry, Is that a PGA3702 or a PDA3702?

Are you wanting to keep it like it was or upgrade?

A little more info please.

Dallas

[harry]

Dallas:  it is a  1945 -  PDA 3702 and would like to upgrade. Mayby a school bus deisel with an automatic. What are your suggestions ?

[TomC]

From what I can see, this has the same power train as a 4104-a 6-71 with 4 speed manual V drive.  You don't have too many choices, and most require much in the way of modifying the present power train since the V drive is not made any more.  You could change it to a 6V-92TA with a Allison V730-would make a real hot rod out of it.  Good Luck, TomC

[Dallas]

Harry,
Consider swapping out your original 4-71 for something like a Cummins ISB or ISM with an Allison Auto. You'll get a lot more horsepower and  be able to top the hills like one of the big dogs.

Dave Lang put an ISM in his Flx Starliner and hasn't regretted it a bit.

You could also get rid of your 4-71 2Valve head with 123HP @ 2100 and build yourself a 4-71T with 202HP@2300
You could also probably stuff a 6V71 or a 6V92 in that hole, but you may run into cooling problems with that large a mill, especially the 6V92.

There are a lot of other options also, like a series 50 or a DT366 or a BT6, it all just depends on what you are looking for in a combination of reliability, power, ease of installation, type of transmission, economy, etc.
One that I thought might make a great swap was the Isuzu 4H 4 cyl 5.2L Turbo intercooled diesel with 205HP and 441Ft. lbs. of torque. Or if you want a real Power house, the Isuzu 6H with 250HP and 660 Ft.Lbs. of torque.

Congratulations on having a Real Classic there were only 600 PDA 3702's made and those were all in 1945. The PGA 3702 also had 600 made but those were made between 1944-1945. (By the way, the PGA 3702 had a 477CID gas engine originally).

Tom,
The 2903, 2904, 3302, 3702, 3703 and 3704 were longitudinal like a Flx Clipper. 

[TomC]

Thanks Dallas- If it is a T drive, then a multitude of engines come to mind.  The 4-71 and the 6V-71/6V-92 were just about the same length.  Since there are so many of them around, a 6V-92TA with 277 hp would be a giant step up.  Of course the Series 50 would really be the most modern, but it is close to a foot taller than the 4-71 and about 500lb heavier, but then you'd really have a performer.  With the correct engine mounts (read soft), the Series 50 makes a bit a vibration at idle, and is smooth enough when running.  With a light bus like that, you could get pushing 15mpg with the Series 50.  I believe most inline 6 cylinder Diesels will be too long. Good Luck, TomC

[harry]

Thanks everyone for all of the good suggestions.
The bus currently doesn't have an engine-it is missing.
I had been thinking of a 6V92 with an Allison 6 speed; if I can locate one at a reasonable cost.
Would a series 50 be about the same price.
Any ideas where I might be able to purchase one of the combinations.

Harry

[belfert]

If the Allison 6 speed tranny you're considering is a World transmission (B300/B400/B500), you'll be in for a fair bit of work interfacing with a non-electronic engine.  The World trannies have computer just like everything these days.  I'm not sure if a 6V92 with a DDEC III would work or not.

If you are going with a World tranny I would go with a newer four stroke motor so the electronics hook up easier.

[TomC]

The 6 spd Allison world transmission will interface with the latest DDEC for either a 6V or 8V-92TA-Don Fairchild has the 8V-92TA and world transmission on his newly bought motorhome.  It WILL interface with a mechanical engine-just need a throttle position sensor and your ready to go!  The mechanical HT740 is much cheaper though.  Good Luck, TomC