H1 Hummer Cummins Swapped

[FellowTraveler]

I would be remix not to point out that the actual stall speed you will get from any converter always increases with modifications that raise peak torque and its rpm.

The converter was designed as a torque multiplier at speed which ceates lots of heat and increases your fuel consumption however; when dealing with the Cummins your peak torque comes in at lower rpm than say the 6.5td so it does not need much torque multiplication at the converter so a low stall makes for a much better DD diesel. Keep in mind if too low a stall it can overwhelm your breaks on stops.....so individuals who have the too low stall just put it in neutral at stops.

 

[Sand]

Still looking good. My midrange drone was solved by bolting an exhaust flange back together that had come loose a foot before my muffler....happens.
And my engine started pushing a lot of oil out of the crankcase on one 3 hr drive. I suspected vacuume leak and plugged the vac pump, disconnecting the pac brake (which I had not wired to a switch for use yet anyway). Seemed to stop the puking oil situation.
2 weeks go by and I suffer a lack of boost, skyrocketing EGTs and massive blowby out the crank breather and oil fill cap. It gets progressivly worse. Im reduced to no power above 1100 rpm and the slightest application of throttle brings egts to 1000 deg. I limp home at 30kph idling the whole 5km.Im thinking slipped timimg gear or hole in piston etc. As im ready to pull injector lines and check compression -someone suggests I may have an exhaust brake issue. Sure enough. Its jiggled shut slowly and then pegged itself closed under pressure. I plugged the Vac back in and the brake opens and all is well.
Ill send oil out for analysis in a few weeks and see if I blew a head gasket.... oil got dirty fast lol.
Still unsure why I had the inital oil out the crankcase condition. Seems fine for the moment.

 

[smokymtn65]

@Sand make sure you add the Cummins swap to signature. The 6.5 has a big enough black eye! LOL just messing..

 

[Sand]

Mmmmm. Got too focused. Missed that. Thanks! Done.

 

[Will L.]

Still looking good. My midrange drone was solved by bolting an exhaust flange back together that had come loose a foot before my muffler....happens.
And my engine started pushing a lot of oil out of the crankcase on one 3 hr drive. I suspected vacuume leak and plugged the vac pump, disconnecting the pac brake (which I had not wired to a switch for use yet anyway). Seemed to stop the puking oil situation.
2 weeks go by and I suffer a lack of boost, skyrocketing EGTs and massive blowby out the crank breather and oil fill cap. It gets progressivly worse. Im reduced to no power above 1100 rpm and the slightest application of throttle brings egts to 1000 deg. I limp home at 30kph idling the whole 5km.Im thinking slipped timimg gear or hole in piston etc. As im ready to pull injector lines and check compression -someone suggests I may have an exhaust brake issue. Sure enough. Its jiggled shut slowly and then pegged itself closed under pressure. I plugged the Vac back in and the brake opens and all is well.
Ill send oil out for analysis in a few weeks and see if I blew a head gasket.... oil got dirty fast lol.
Still unsure why I had the inital oil out the crankcase condition. Seems fine for the moment.

Could the closed exhaust brake have created excess pressure in the crankcase? Is there a pass through egr that ties with cranckcase venting?

 

[FellowTraveler]

Still looking good. My midrange drone was solved by bolting an exhaust flange back together that had come loose a foot before my muffler....happens.
And my engine started pushing a lot of oil out of the crankcase on one 3 hr drive. I suspected vacuume leak and plugged the vac pump, disconnecting the pac brake (which I had not wired to a switch for use yet anyway). Seemed to stop the puking oil situation.
2 weeks go by and I suffer a lack of boost, skyrocketing EGTs and massive blowby out the crank breather and oil fill cap. It gets progressivly worse. Im reduced to no power above 1100 rpm and the slightest application of throttle brings egts to 1000 deg. I limp home at 30kph idling the whole 5km.Im thinking slipped timimg gear or hole in piston etc. As im ready to pull injector lines and check compression -someone suggests I may have an exhaust brake issue. Sure enough. Its jiggled shut slowly and then pegged itself closed under pressure. I plugged the Vac back in and the brake opens and all is well.
Ill send oil out for analysis in a few weeks and see if I blew a head gasket.... oil got dirty fast lol.
Still unsure why I had the inital oil out the crankcase condition. Seems fine for the moment.

I forget what vac pump you are using. The 2nd Gen vac pump will pressurize the crankcase if there is any leak whatsoever. The Cummins is well known for excessive crankcase pressure so I went with extra venting "CASE tractor valve cover vent" it replaces two valve covers better yet two (2) valve cover vents for best results or go custom venting each valve cover to eliminate any future crankcase pressure period (on a good motor) "your oil should not get dirty fast."

You might figure a work around for that exhaust brake if it fails so you don't have a repeat of that issue.

 

[FellowTraveler]

Any late breaking news on your build, or?

 

[Sand]

Drive it daily. Its great. Keeps temp perfect. Tows what I need to. Still some relays and wiring to finish for my cold days intake heater etc. The pair of duramax intake heaters work great by the way below freezing. Trans controller feels settled. Oil analysis just came back clean and average.
Im looking at additional crank venting. Possibly through a CDR to the air cleaner from the oil filler neck.
I love the project. Might be time for z new one. Possibly superduty ford cummins...
My 05 duramax got rearended last week and they will write it off for sure.

 

[FellowTraveler]

Good to hear its working out for you.
You might want to look into the valve cover venting plumbed into the downpipe with a vortices tube and using a check valve the vacuum created will pull and incinerate whatever particles present.

 

[Sand]

A friend mentioned that style. Any good diagrams of the setup?

 

[Will L.]

I would include a catch can. The more vacuum -the better.

But why just shove oil out the exhaust? Recover it in a catch can. I got a provent 200, but it isn’t the best choice for going under water due to the regulator in it.

You just run vent line through catch can into draft tube in exhaust.

 

[FellowTraveler]

YES! Provent is perhaps the best way.......the dowpipe setup will because of high EGT's under boost incinerate whatever escapes the catch can.

 

[FellowTraveler]

On another note the valve cover vents on the Cummins separates the oil allowing it to drain back into the diesel through the valve cover. I have quite a few miles on my conversion and the hose from the valve cover vent is dry & w/o oily residue.

 

[Will L.]

I have worked on high mileage ones and noticed oil bypassed- but definitely did better than a 6.5 does.

 

[MRME4U]

Awesome Build.
I am thinking of doing a 12V swap in a Humvee do you sell swap kits. I want to go with the Dodge G56 Manual 6 Speed

In order not to jack another thread, a fellow member had asked to see the swap I'd done on a H1 Hummer.
Here is the results of that swap.
View attachment 51722 View attachment 51723 View attachment 51723 View attachment 51722 View attachment 51723 View attachment 51727 View attachment 51726 View attachment 51725 View attachment 51724

 

[Will L.]

@MRME4U
welcome to the forum. I have never seen a manual in a hmmwv yet. Thinking you’ll have to set up a cable system for shifting?
Doing that trans- I would promote the idea of an atlas transfer case.

Have you bought your hmmwv yet? When ya yank the 6.5 and trans out- list them here.