Diesel Comanche build

[Gaucho919]

I was looking online last night for a solution and I found this picture, the upper one is supposed to be found in early XJ's and work just right in my t-case

 

[88Xj]

The MJ has 4.10 gears stock, I want to put 31" tires on it, either a BFG AT or Goodyear MT/R. I think the 31's and 4.10's will work best with the OM617, from what I've read the OM617 has a similar powerband to the 4.0, just not as powerful. My 4.0 has 32" Rubi tires and 4.10's and I really like the combination. If I can get 25 mpg on 31's I'll be more than happy. Now I don't plan on making any huge gains in power with this motor, I'm gonna keep it stock at first. Then add the long runner intake, an intercooler, and crank up the fuel a bit. And neither am I going to make it as detailed as my '92 yet bc I just don't have the money right now. I may make my own long arms for it, flatbed, and a behind the cab stainless snorkel like the isuzu NPR trucks have. My point is this truck will be built on a tight budget, and most everything made at home.

Gearing: 4.10's and 31's would be about perfect for 65-68mph..32's will work better for 70-75mpg. Maybe you travel at 70-75mph..where revs will be higher..the 32's would work better in this case to lower them some, keeping them around 2400-2500rpm..if your a 65-68mpg guy like myself the 31's help you. Like I said the more you bring the torque to the left of the power band (lower) the better off you will be! But these sucks live in the 2400-2600rpm range for mileage in stock form. So if you can get the peak torque lower, then you can run bigger tires will less gear.

ax15/np231, 4.10's & 31's will get you around 2250+-rpm at 65mph, @ 75mph your around 2650+-.
With the same listed above & Rubicon 255/75's..at 65mph your at 2200+-rpm & 2500+-rpm @75mph.
If you want to compare check out this site here: http://www.grimmjeeper.com/gears.html

So if you can get the peak torque around 2300 or so you'd be golden for 32's at 65mpg. The W115 long runner intake & a Vnt/Vgt would be perfect for getting more down low! That 3" or 2.5" exhaust, which ever will help also. if you end up with a 2.5" exhaust try to do a 3" Dp still..it'll help it breath..also don't forget to add a piece of flex pipe on the DP somewhere..keep cracking at bay!
Gauhco the intercooler is a fabulous idea & an glad your going through with it! I've got tons of intercooler piping & couples in 2.25 & 2.5" size. I can donate to you buddy Pay shipping and you got it!
A air-air setup w/ a small fan to keep air moving through it at low speeds like when offroading would be sweet...actually while at low speeds the mechanical fan should lock up & pull enough air to keep the intercooler cool but hey its your rig & I'm just tossing ideas:coffeedrink:. I'm extremely excited over this build because I wanted the same thing..its just not possible legally! If you can get the air temp down a little the more power & the better the mileage, most Merc guys actually retro fitted some sort of intercooler to help with egts & mileage ect. Every 11* is 1hp so it'll help!
We also already talked about the slight port work..if you need details at all on that please pm me or ask publicly & I'll supply everything I can! It won't be 40 hours worth of work..maybe 3-5 at most! Your not pulling the head, so no head porting, just intake & exhaust & turbo! Its pretty much knocking out ridges, smoothing/blending & gasket matching.
The biggest upgrade in this swap is the fuel options & cost. Mileage will be slightly better..well for most people it will be 5-8mpg better so the mileage gain can be a plus for most as well. But we can't compare a 3"lift/31" tire jeep to a 4.5"/33-35" either..cause with lift & tire your probably looking at high teens..maybe 20 with the merc! With a semi low lift & 31-32's..Skinny tires! Those 32's won't hurt you anywhere but gearing my friend so don't be afraid to run em..if you do just do the few things to get the torque lower, they are actually skinnier than 31's & fit the expo rig theme better I think!
For those speculating mileage..we are pushing a brick through the wind here...the merc guys in their cars with the same motor & mods are getting about 28mpg MAX! And those guys are fighting for that much, low to the ground, small tires BUT again they have an auto trans...I think 25mpg is pretty darn good..remember he has a 5speed here, but also a transfer case he's got to spin. Plus worse areodynamics ect..25mpg should be a solid number to shoot for & with lower fuel cost if he runs a mix, then it will be a hell of a ExPo rig!

The OM617 is opposite of most diesels..with a 4bt swap you'd want 3.55's or 3.07s in some cases to get the revs down & mileage up! But with these old mercs they run like a gasser...Running to 5k stock isn't unheard of at all..The stock turbo will be out of breath but there are guys upgrading to 60mm wheels on the stock .45trim turbo which I believe is what Gaucho has. Some even go bigger turbos & so spinning them that high no issue! For a truck/offroad application that wouldn't be useful as that helps power up top & hurts spool times slightly..The 60trim upgrade or a VNT or VGT turbo would be extremely useful in this situation..the .45trim is a choke point & the 60trim upgrade or vnt/vgt would spool sooner & make more power everywhere! They lack low end stock but will rev to the moon, so the VNT or VGT will spool sooner & get you more power down low, but also will hold strong to the 5k redline! No problem no worries. People are upgrading the stock .45trim garret with a .60trim inducer wheel which is helping spool & power everywhere ..idk the price but alot of people are loving it!
As Gaucho stated, for anyone reading & wondering. These Merc om617's have a dead on rpm range match to our jeep 4.0s. So our rpm gauge is perfect in stock form..kinda a keep it stock looking type deal. The Merc om617 peak power is at 4500+-rpm. Peak torque at 2500rpm..they are highway cruisers if you can get the gearing on par! Best efficiency in stock form is around 2400-2600rpm, obviously which is where peak torque is at. These suckers have a fairly wide powerband..just like a gasser does, kinda starts out slow & the more revs the more power! So the more you can do to get the torque & power on faster, the lower you can keep the revs, the better the efficiency, the better the powerband for a every day driver & the more reliable. These old 5 cly tractor motors are called the million mile motor for a reason, but every little helps in terms of reliability.

I would seriously take a long hard look at filtering oil/atf/Veggie mixes..All can be done stupid cheap & as long as you aren't running 100% you won't have to do much other than running some good 1-2 micron filters!
To boot most guys at autoshops will give you oil or ATF for free since they pay to have it hauled off. Theres 2 little mexican food shops in town that a buddy of mine gets his Veggie oil from for free & they pump it for him! He running a early 90's 6bt 12v! He runs 100% veggie in the summer months cause the heat here in socal keeps it thin & flowing! And oil/atf & diesel mix in the winter because the veggie oil thickens & needs to be heated to run it, its also alot harder to pump because these places just place barrels or have a counter sitting outside..the oil then thickens or freezes & it a hender to pump..So veggie summer & oil/atf mix winter. He runs it 50/50 & I believe people call it 'black diesel' fuel..but I may be mistaken. It won't harm are darn thing at all..just needs to be filtered & dewatered! You can keep it stored in metal or plastic 55gallon drums..If it freezes then you can take a small propane torch and run it around the outside of the barrel to warm it up!
Ask around locally..small oil change shops, autozones, small or even large chain restraunts, donut shops which most don't think off lol, asian restraunts! Its there & most of the time its free! They have to PAY to get it removed, 90% of these places will let you take the oil for free! Now the key if finding a place that has decent oil so not much work is needed to clean it. Mcdonalds, BK, Carls ect, Have alot of crumbs/food particals & seem to have more water than most other places..you know frozen fries & patties leave water that gets mixed with the oil..donut shops are decent, so are asian shops..car oil & atf also work just fine & filtering is the same process! Like I said my bud Arron runs Veggie in the summer & car oil/atf in the winter. He says he would run the oil/atf year round but he would have to buy a pump that way as he has to pump his own oil/atf from the small shops. He currently uses a hand pump to get his oil/atf mix when at shops. Hydraulic & gear oil can also be ran but its thicker naturally so its kinda like veggie..needs to remain warm/heated.
If your running it mixed 50/50 you won't need to change anything to run it either..and you will see no difference mileage or performance wise! So say if you start a trip on 50/50, then refill 100% diesel, no worries brother. It won't make a difference! You can run it at whatever mixture you want, most say 70% oil is the MAX you should do. Just make sure your running good filters on the motor itself & have some fun! Bio/WVO/black diesel ect can be produced for around $.70 per gallon..diesels around $4.20.:drool: Can we say savings?

Also I know your tank is different..but your dropping it to clean it right? If not then you probably should. But while in there try to see if you can do something similar to this! Just mods the vent pipe in the tank..raises it up so it will hold more fuel! I did this on my XJ 25 gallons in the stock tank is a nice addition.
http://jeep-xj.info/HowtoFuelTank.htm




Honestly I wanted this swap so bad but commnifornia says its a big no no so I put it off my list for now! I did days..no weeks of research..in&outs, questions everywhere! I honestly thought of doing the swap anyway & just 'paying' my smog ref every 2 years to pass it on through..My better half talked me out of it though. So since I wasn't aloud to run this motor legally I decided for a efficient 4.0 build. Its actually a 4.2L mini stroker. I cruise at 65-68mph, no faster hardly ever! I use a hand throttle when on the highway cause I pulled my cruise control..way to unreliable lol. 31,s 3.55's, ax15 & a 3" lift. I'm pulling 22mpg consistantly at 2000+-rpm & even more if I can drafting the 18 wheelers safetly.. 18-19city when driven correctly! Which is pretty much stock figures, oh its an 88 original motor 342k on it & has perfect compression across the board! Thats all GPS verified on the mph & distance so its accurate! But I've also done every EXTERNAL bolt on mod availiable & replaced every single sensor for the motor..probably 500 bucks worth...and it will soon have my completed 4.2L mini stroker in it & a pacesetter header (longest runners of any header avaliable..should help keep more torque lower in the rpms. Think long tube headers.). Its 9.4:1 compression, quench height is .038", ported head with Ls1/Ls6 valvetrain, polished chambers & exhaust runners, exhaust valves & piston tops ect ect, alot of time in the head honestly. It will run a 7120 cast head! Its build for efficiency and will run on 87oct just fine & cost just over $1800 to build. Hoping to maybe get 25mpg with that..hopefully! Sorry to high jack you Gaucho.

 

[88Xj]

Please share your engine build up plans once you get it sorted out. I have heard/read that he OM617 is relatively easy to build into a 200 hp / 300 tq engine while being reliable. That's in the ball park of ~4.x stroker with twice the fuel economy. It would be great to see a good builder take it on to see if it lives up to expectations.

The om617 won't hold that kind of power reliably. You can get maybe 250ftlbs on the stock IP..big maybe..more likely around 200-210ftlbs. At that point you can add meth injection or a Myna pump which is $$$$..I wouldn't push much more than 250ftlbs or so because things tend to break! The Ip is the limiter here with its 5.5mm plungers..it can only supply enough fuel for about 200-210 ftlbs. You can upgrade it for a few thousand..around 2500 I think with a Myna pump..and then you will have all the fuel you need..but you still limited by the internals of the motor!
Reliably on the stock pump with very few mods, w115 long runner intake, nice 3" DP & exhaust, intake & intercooler & some form of turbo upgrade either to bigger or smaller to fit your powerband needs! You can get around 150hp/210-220ftlbs but thats gonna be max! And it will have plenty of boogy to move at that point!

These motors have a very short stroke when it comes to diesels..most diesels have a long stroke which gets the torque down low. The shorter stroke on the OM617 makes it run similar to a gasser. Think of the 4.0 strokers..stock crank stroke is 3.410", the stroker crank holds a 3.895" stroke..bigger stroke & it makes but loads more down low..similar here. The short stroke makes it run like a gasser & isn't helping the low end at all lol.



Gaucho, just to add you could clock your tcase while its out? Clock it so its flat..no mods really needed besides bolting it up in the correct position..Gain some free ground clearence whiles its out.
Also you turbo..its a Garret .45trim. Being you have a 78' you got the smaller before they upgraded to a .50 trim which spooled soooner & made more power everywhere. However idk your plans for the turbo yet..it could be bad, may be good..Either way you have a few options. A VNT or VGT turbo would be a huge upgrade and help down low ALOT I can start the search for one for you..usually they can be had fairly cheap! Or you can upgrade your current turbo to a 60trim & it'll be better still There's a shop out here thats been doing alot for the STD guys..started with Captain America who is actually a local jeep wheeler, hes got a Merc as well. Idk their price off hand but its been listed on STD at one point by him.
The stock .45trim is fairly small for the motor so thats gonna be your choke point.

Take a look at this thread here.
http://www.superturbodiesel.com/std/thread-2516.html

 

[Gaucho919]

Funny you mention pulling the tank, I just got done pulling all that off. Got 20 free gallons of gas from the PO going in the '92 haha. Here's what it's looking like









That's a lot of good info 88xj. This is my first time dealing with turbo's and I'm not very familiar with all those terms VNT or VGT, I guess I could try and find a newer style stock turbo and swap it in. The turbo on mine has very little play in the shaft. I plan on doing a snorkel on this one too and that should help with keeping the intake air nice and cool. That's good to hear on your jeep, mine has 94k original miles on the motor right now, and I can get 18 mpg if I'm easy on it, but I never am. Here is a pic of the wheel/tire combo i would like to use, with newer style MT/R's and this one being my spare.

 

[88Xj]

Those are just 255/75's right? If so they are 32.06" tall and about 9.5" wide. 31's will be more around 30.5" and 10 or 11" wide...pending which model/brand you get! I'd deffinetly go with the 255's. The 33x10.5's are actually 10.1 wide I believe and 32.6" tall..so either a 255/75 or a 33x10.5 would work out perfect!

On the tank pull off the pump and check inside..that link I posted has some pictures to give you an idea of what the basic idea is. Idk as I've never seen the inner of a MJ tank..but the basic goal is to raise the vent line so you can fit more gas. In my stock Xj tank I'm fitting 25 gallons..well the most ever was 26.2 but I had some spill over slightly, so I left it at 25gallons..Stock was like 18 or 19 I believe..basically like carrying 1 full jerry can all the time without taking up extra space lol.

What was your intercooler setup going to be? Just curious here..Cause with the turbo on the passenger side now I think you would need to run a passenger side snorkel...or a custom snorkle...like the hummer style intakes the people do. It goes through the cowl & its on the passenger side!
This is it..but its for a Tj. You could either use a small-ish cone filter or get a stock air box for a ford areostar/windstar or similar and just run their stock filter..The areostar/windstar is what I'm using..is round, fairly small but still a pretty large filter.
http://www.jeepforum.com/forum/f9/tj-hummer-intake-write-up-buick-airbox-473981/

I'd deffinetly like to see a simple air-air setup on here...you can pick up stock air-air intercooler for a small car or get a small aftermarket unit off ebay. I can supply you will all the couplers & piping & clamps..I've got enough here to do 2 setups I think lol.

Turbo wise, it will be a restriction in stock form. Its truely to small..you can upgrade the inducer wheel from a .45trim to a .60trim. That'll help spool & power across the board & is basically a stock rebuild on the turbo, with the upgrade .60trim wheel. Even though its bigger it helps spool & power everywhere cause the .45 is really really to small lol.

VNT - stands for Variable Nozzle Turbo
VGT - stands for Variable Gate Turbo

VNT is just a Garrett name for a otherwise known VGT turbo. Anyway heres a pretty simple video to show you how they work...
http://www.youtube.com/watch?v=Gc2awh0O0Bc

Because of the extra fins/vains whatever you want to call them, it can spool stupid fast with them closed because it acts as a smaller turbo! With them open it acts as a bigger turbo thus giving power all the way to 5k & an insane spool time for that grunt down low! I can do more research on it for you, but there will be some slight fab work needed!
'Such as an adapter/flange cause your exhaust manifold is a T3 while the VNT turbos are T4 I believe..no biggy there though. You swapped in a 8.8 in your old my so you can tackle this! The harder part seems to be controling the vanes...getting them open when you want, closed when you want, or open/closed while cruising to get the upmost fuel economy. But some reading and you should have it..I'll also track down some good reading on the subject for you.

Heres a thread where a fella installed a GT2256V which would be a damn good sized for what your doing! You can also see he has the W115 long runner intake. looking at post#6. Also look at post #7.
http://www.superturbodiesel.com/std/thread-188.html


After some reading I think it would be much easier to send your turbo out & upgrade it to a 60trim, vs trying to swap on a VNT. The VNT will be better overall in performance terms, but price wise, availiablity incase it breaks, to get it functioning ect ect. You haven't dealt too much with turbos..so it may be too much to take on. The 60trim upgrade would get you a completely stock rebuild with a bigger intake wheel. Spool will be better..well all claims are it gains in spool slightly 200+-rpm & it makes more power everywhere! It will get you the 150/210ftlbs without issue & incase something ever happened to the turbo, you can pick up a spare at almost any junkyard in the usa! The later models 82+ I think got a .50 trim t3 garrett..They just upgraded the intake wheel knowing the previous version was too small, so its a worthy upgrade!
The weaker turbos that you didnt get are the KKK24 & KKK26..most ditch them for the garrett model so its good you got a garrett from the start!

 

[FellowTraveler]

I suspect a GM8 turbo would be a great addition to that diesel motor.

 

[88Xj]

The Gm8 is actually a little big for what he's doing..however he could use a BW gm-x in the right size. Most tend to shy away from them as they aren't that great. Most upgrade to a similar size holset and are much happy with the performance & gains.

 

[Gaucho919]

Got the motor running today, I don't have provisions for a video at the moment but she purrs like a kitten! Diesel power! haha

 

[reece146]

Fun!

You've got the drivetrain all together already. What is the quality of the adapter peices like?

 

[Metcalf]

We put robots on mars and heaters in biodiesel tanks, maybe when people actually step foot on mars they'll have a monkey touch the monolith moment and figure out how to not make oils gel at cooler temperatures. While they're at it they might accidentally come up with a way to prevent water from freezing too.

The 'perma-flow' process can convert regular biodiesel in to VERY cold weather tolerant bio-diesel. I think in the original trials they ran it down into the -40-50F range....

I talk about it here more.....

http://www.expeditionportal.com/for...Instructions?highlight=cold+weather+biodiesel

Enjoy.

Cool build!

 

[Gaucho919]

thanks for the info on the biodiesel, the adapter kit is top notch and Nathan was great on the phone helping out with a few questions I had. I don't have the whole drivetrain together yet, it seems like it in the pic. I just put the flywheel and tranny on so I could start the engine, I had never seen it run so I just wanted to make sure before I sent it off to get balanced. I've called all the shops in my area and none of them can match balance a flywheel, might have to ship it to 4x4labs

 

[JWP58]

Looking forward to see the progress of this build!

 

[Gaucho919]

Thanks! Both flywheels are off to 4x4Labs in California. $50 to ship there alone. Gonna have to slow down on expenses haha. While the flywheel is off getting balanced I'm going to work on the motor mounts and other small stuff.

 

[jscusmcvet]

Fascinating build. Congrats on your work to date. I like the rims you are going to run. They look like an old stock type rim... mind sharing what they are?

Good luck to you on this project. I'll definitely stay tuned.

John

 

[Gaucho919]

Thanks John, looking at your user name I take you're a Marine veteran, I just finished my enlistment a few months ago. Those rims were the stock steelies in XJs/TJs in the 90's I think. They have a ton of backspacing so I'll need wheel spacers if i do run them.

I'm almost done! haha I wish. Just got the drivetrain in there to try and figure out the motor mount deal. The stock Mercedes motor mount brackets will not work. I'm thinking I'll fab some up and use a lower control arm bushing for a motor mount.





Not a lot of room to play with under that turbo



My helper decided he wanted to take a nap so I'm on my own.