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Outdoor Adventure Bus Rig

If your not afraid to do a new engine if this one ever lets loose, then brand new optimizers will be available for years to come. GEP builds them for hmmwvs and they are set into production for the next 15 years we know of. That is an advantage imo over cummins or dmax.
 
I'm with Will. If ya can keep her rolling go for it. until covid hit I had been doing a lot of hot shot work which is basically hauling fifth wheel style trailer with your dually and delivering stuff for people.. basically you're a trucker with a smaller rig... A lot of people told me a 6.5 would never hold up to it.. I'm not going to say I can get through the mountains with a trailer loaded at breakneck speed, but I've always gotten over them.. my personal opinion, they might not be a powerhouse but they will do the job 90% of the time..I think you're going to notice a big difference once you get that turbo working. When I bought my truck my turbo was not working correctly and I was about ready to scrap it then the guys on here gave me some advice and I got it spooling properly... As far as the vac pump I d delete the b****.. put a manual wastegate on the turbo and call it good, makes a hell of a difference in my opinion. Unless it is needed for something else, a vacuum pump is just something to go wrong and give you a headache.. if you can put the DS2 injectior pump on it, you don't have to worry about pmd's going bad all the time or harness going bad. Somebody else mentioned this but I'll reiterate it ..don't let a Cummins mechanic touch that engine.. 6.5 engines might be a diesel but they are not like any other diesel..they are not set up the same they do not operate the same. A mechanic that's used to working on a Cummins it's almost definitely going to try to apply knowledge of those engines to a 6.5 and it don't work that way I learned it the hard way.. and while I'm on it yes commins is a good engine and it's strong but one thing you do have to pay attention to is cost of repairing a Cummins or a dirty Max compared to fixing a 6.5... a set of injectors on a 6.5 is under 500 bucks and changing them is about the same as changing spark plugs..try and change the injectors on a Cummins or a dirty Max and see how long it takes you or how much it costs you.. a lot of my friends put down a 6.5 but mine's been pretty loyal to me even if she has had some mechanical problems lately... Don't know if anybody has told you this but do not by any electronic part for it that does not say AC Delco on it..you will play chase the ghost trying to figure out what's wrong when you just put a new part in and it doesn't fix the problem so you think,that must not have been the problem let me try something else when that new part you put in wasn't any good. I'm sure some of us are probably beating a dead horse telling you some of the same things but trust me listen to the guys on here. you ain't going to find any place that knows more about 6.5 engines.
 
My .02...

If you're committed to the bus, stick with the 6.5 platform. The engine has a bad rap, yes, and most shops are clueless. This website is your best resource for honest and experienced information. While a cummins or dmax will give you more power right off the bat, the 6.5 is extremely cheap to work on and can be turned up to give you respectable power to go up hills at a respectable speed

How many miles are on the engine?

Get the turbo working. Given the center mount setup I don't know what options are out there that are reasonable drop-ins in terms of little to no fabrication work. @WillL, if you don't recommend a holset 35, 40, hybrid, or ATT, what do you recommend?

In terms of turbo, best thing you can do is convert to a mechanical wastegate and get rid of the vacuum pump if nothing else in the bus uses the vac system. One less thing to go wrong and leave you stranded on the side of the road

A tuned ECM will also help with power and making an upgraded turbo work. Best IP insurance is to go mechanical with a DB2. For what it's worth I've never had a PMD go bad in 5 years of being a 6.5 owner, so you may have similar luck.

Cold air intake system will help with the engine running cold too. Don't know where the bus originally pulled air, but anywhere is better than hot engine bay air.

An charge air cooler (intercooler) will also help with power and cold intake temps.

If you have the money and want this to be a reliable motor and vehicle/ home, and can rest well staying with the 6.5 platform. I strongly recommend considering a new Optimizer and sending it to @Twisted Steel Performance for ceramic coatings, head work, studs, lower compression ratio, etc. Might be less work overall in the long run being able to drop in a new cleaned up motor as opposed to spending so much time chasing problems as they arise. Given what you plan on doing with your rig you want peace of mind and a fresh build will give you just that.

As mentioned by others, there's some of us in Upstate NY that would be willing to look at your rig if you were in the area. I'm in the finger lakes near Bath/ Hammondsport. Also a permaculturist myself, I apprenticed at the Finger Lakes Permaculture Institute in 2010. Lots of cool stuff going on out this way if you wanted to fold some permie connections into an upstate 6.5 trip.
 
DieselAmateur said:
My .02...

... @WillL, if you don't recommend a holset 35, 40, hybrid, or ATT, what do you recommend?...
Click to expand...
(I edited quote for space/ relevant to question)

The OP mentioned specifically the hx35. Imo that turbo is too small still for his application. He doesn’t need mega torque like an off roading truck in the first few hundred rpm. He is going to need the power from 1400 rpm lowest up to maybe 3700 rpm. Mostly hiway use. So a set up like what WarWagon did with the stall converter and the ATT, Or an hx40, both would be good answers. I believe Quadstar had a turbo bigger than the 40 with a wastegate- another possibility. I am only ruling out the hx35 -and of course the GM chokester.

On the 5.9 liter or 360 cid cummins which only designed to hit rpm of 2850 iirc. 3,000 was in the red. That was a proper fit for hx35.
The 6.5 or 396 cid doing another thousand rpm...

4 stroke math
CFM= CID x RPM x VE / 3456
VE = Volumetric Efficiency
0.9 for naturally aspirated diesel engine
1.60-3.0 for turbo charged diesel engine depends on turbo size and if inner cooler and how well.

Look at the engine cfm without a turbo to compare what turbo ought be considered:
360x3000=1,080,000x.9 =972,000 / 3456= 281.25 CFM for the cummins
396x4000=1,584,000x.9 =1,425,000 / 3456 =412.326 CFM for the GM.
The GM is moving 1.466 times more air than the cummins. Almost one and a half! And people think the hx35 is maybe too big for a 6.5? Haha. No it doesn’t translate exactly like that to sizing the turbo, but when you are dealing with a rig that is going to focus on hiway use- letting that sucker breathe is huge.

Thats why imo to save this guy money long term, and to make it more useable, and with less overheating possibilities- I wouldn’t spend over $100 trying to get the gm6 to work. Why? It ought to be mounted on a honda ricer racer where it belongs. Why do I push this so strongly? Because I did it to my hummer KNOWING it was too small but justified it by cost at the moment. Money wasted. Time wasted. Worked the engine harder than it should have been. My hummer is at 10,000 lbs, but I would put a dollar to a donut his weighs more. Mine is like a brick wall going down the road, but his is like the whole brick house. To compare it to a pickup towing a trailer it would have to be a monster load to have the weight and the wind resistance.

I took it from the beginning he had some kind of accepable budget to work with. $20,000 should do it no problem. I wouldn’t push him to a new radiator- his could be fine. Get the proper cooling system in there- most likely the AK Diesel Driver mod of elecectro-viscous fan and clutch- and depending on turbo MAYBE a water to air cooler. Big non wastegated ATT shouldn’t need it. Stuffing the turbo in there, running all the pipes and oil lines is gonna cost some labor. A customized dog house is probably in the future too. But well worth it for the difference. Stuffing a tall and long cummins in there would do the same. And btw, dmax- yeah, big centermount turbo also, so same dilemma. Suck it up buttercup. Doing a custom bus means custom. So getting it to go from gubmint paid for tow truck on demand to self sufficient and more reliable means make changes.
 
DieselAmateur said:
The engine has a bad rap, yes, and most shops are clueless.
Click to expand...

Simply set expectations accordingly.

The GM Light Duty engine runs great until the main webs give way, the head gaskets let loose generally around 200K miles, the damper fails and snaps the "Detroit Diesel we told you so just doesn't cut it: don't use a cast crank!" crankshaft, you get it hot and instant blowby from rings loosing their temper (even Ford IDI's did this)... The damn thing earned it's bad rap and along with the Olds 5.7 Diesel that put Lemon Laws on the books ... GM beancounters ruined the American Diesel Market for 20 years.

Working this engine hard, or any engine, shortens it's life. Without gapless rings you are looking at 2500 mile oil changes. Used Oil Analysis confirmed 2500 miles as 3000 miles towing grades was too many. I changed the oil every week: sometimes twice a week doing 550 miles a weekday towing. Gapless rings doubled the oil change intervals for me.

A bigger turbo reduces the work the engine does by less heat trapped in the engine and less back pressure. Lower IAT as well.

At the end of the day price out dropping an Industrial Cummins in that has a B50 of 1/2 million miles vs. a light duty Optimizer 6.5 engine. Then price an engine from @Twisted Steel Performance who has done a lot to increase life by reducing strain etc. on the engine. Coatings, lower compression, etc. You may not go 1/2 million miles and the price for a conversion may be 2x that of a Optimizer 6.5.

We are not saying his engine is DOA: However before going "all in" on the mods to the bus it's best to know what a engine failure can cost. Just because of this engine's reputation and it looks tired and abused. Then he can set the funds aside and see what life is left in the existing engine. Start with a blowby test etc.

Another option is simply drop in a gas engine like a GM 6.0L. F'K MPG as the stock 6.5TD is miserable for MPG working hard. Only a 4.7 RAM V8 sucks fuel as fast as a 6.5TD in the 7MPG range.
 
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