hello. I have a 750 drd Allison automatic that is currently behind a 6v92 Detroit. I have a 855 cummins that I want to put in place of the Detroit. I am trying to find out what I need as far as flex plate and mounting plate and so forth. thanks for any input and info
All you should need for the engine to trans mount is the proper flywheel housing, or if the bell housing on the tranny can be swapped, that would work too. My guess is your 855 prob has a no. 3 housing, and the Detroit a no. 2 if they're not the same. Have you measured anything yet? They could be the same size. If it was a 6-71 I'd probably be skeptical, but until you know, you don't know. As far as flex plate, you might need to call Allison and get a part number, then start calling wrecking yards.
You are going to create a mess of ratio troubles. The 6 71 spins at twice the cruising speed of the 855.
Agree to a point, but you should be able to get transmission pressures adjusted so it shifts at lower revs. You should try and determine the final drive ratio of the trans so you know what you'll have when done. I don't think that that trans is an overdrive, but you are going to lose more than a little top end. 10-15 mph for sure.
?? Am I missing something here?? All the 6-71's and 855 Cummins I have seen all run about the same RPM, most governed at around 2,100 or so. One may have a different torque curve from the other but to say one runs twice the speed of the others seems a stretch. If the 855 is cruising at 1,800 RPM are you saying the 6-71 would be set for 3,600 RPM? Not sure I want to be near a 6-71 at that speed!
Don't know this outfit but did a Google search and they seem to be big into the Allison transmissions. http://www.copelandintl.com/content/allison-ht-750-drd-wet-transmission Might be worth a call or eamil to them.
He has a 6V-92. It's been a good many years since I have driven one, but I do know that that engine is happier at 2100 than 1500, and that's where the Cummins is going to like it. I would still say the shift points are going to need calibrated, but the difference in top end might not be as bad as I thought.
Sorry my bad it's 92 not a 71. Different topend governed speeds. I would agree that the trans shift points would be at a different torque curve. The pump might be have to have different springs in it to change the torque curve for the auto also. I would be handy if the donor engine came out of the same make/model truck ie: motor mounts, radiator connections, wiring, fan placement. I have done a swap and had the same make/model donor to take what I needed. It would be a nightmare to try without. Im just saying do your homework.
The 6V-92 did have the "Fuel Pincher" that was goverened to 1,900 and the fastest 6-71 I know of was 2,250 rpm. I was just surprised at the " twice the cruising speed" comment. Not trying to dispute that there is a difference in the torque curves that might effect the best selection of gear ratios. Also agree that the simplest way to do a conversion is to have a doner that if not exactly the same at least be close. We repowered a 560 IH loader from the original DT817 to the then brand new KT1150 (now known as a KT19) Cummins. We actually were doing it for Cummins and they had factory engineers out to help us and they even messed up the coolant lines connections! At first start with radiator cap off it shot coolant probably 20 feet in the air!
Dont forget about the rearend ratios too. Most of the automatics that I have seen are usually running high 4's or even 5's for rear end ratios. Not sure what the 6v92 has for a ratio. You are going to need to do some homework to find out the auto's gear ratios and the truck that you want to put it in so they can be matched up.
Yep
I've done a few a few engine conversions in trucks and equipment . Don't see any trouble with gear ratio's as both Cummins 855 and Detroit 6-V92 are governed at same RPM , (around 2,100 ) . The in line 6 Cummins will be longer than the Detroit so that could be an issue ? Out of curiosity ............. What is the 6 - V 92's problem ? Is it the "Silver 92" with the turbo ?
thanks for the reply. the Detroit is just tired and I need more horsepower. do you know where I could find the flexplate and correct bellhousing adapter. thanks
I would give Adelman's a shout on the flex plate & bell housing . http://www.adelmans.com/ Does your 6-V 92 have a turbo on top of the blower ? What is the truck , mid 1980's GMC tandem strait truck possibly ?
thanks, I will give them a try. the 6v92 has a turbo on top of the blower. actually I have 2 of these engines. when I bought the truck it came with a spare engine. the truck is a gmc semi tractor that was set up as a heavy hauler in a steel mill
Any chance that Detroit might be for sale?
yes. both the 6v92s I have are for sale
I have a customer that runs a 6-92 turbo in one of his GMC's . I want to say they rated around 300 horse power depending on what injectors the engine had in it . I'm kind of on the fence I guess . If it was my truck I would probably just overhaul the Detroit & keep buzzing down the road But being you have the Cummins engine I can also understand wanting it installed in the truck . For myself it would depend on what the truck is used for & how often . Best of luck on the GMC project .
how did the swap turn out? I am considering the exact same swap.