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Old 06-06-2018, 04:28 PM
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Cummins R2.8 Repower

Ok, I am starting a new thread, I was going to do a 4BT but I have decided a R2.8 is the way to go. So I am trying to source parts and figure this out, never had much to do with these tiny diesels. WHat I have now is a 1993 Jeep YJ 2.5 4 cyl with an automatic behind it. I have 31" tires on it with a 3" BDS lift. The rear axle will be swapped out to a Ford 8.8 with disk brakes and front and rear diffs will both have either 3.73 or 4.10 gears installed (depends on if I stay with the 31" tires or go to a set of 35"tires) with air lockers front and rear. I am also going to instal aftermarket air conditioning in it because I am an old fart and I can LOL.

1) Should I run an air to air intercooler? Is there any benefit?
2) Where can I source motor mounts or should I just build them?
3) Should I buy a used AX15 transmission and rebuild it or buy a new AX15 transmission and from where?
4) What clutch assembly should I run with this build?
5) What mods should I do to my NP231 transfer case?
6) WHat is the best aftermarket air conditioning for these units?

I am sure I will be asking more questions. I will post a build thread once I get the parts all together and actually get rolling with this build.

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Old 06-06-2018, 04:38 PM   #2
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http://www.fourwheeler.com/how-to/en...-ugliest-jeep/ This will give you some guidance at least. Also Fred Williams on Dirt Every Day did a TJ conversion that goes over some details as well. Heck contact Cummins they may have some info for you too.

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Old 06-06-2018, 06:12 PM
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Well, I think I found an intercooler.....but it is pricey. Any other suggestions before I do something silly like break out the credit card

YJ R2.8 Intercooler Kit - Axis Industries USA
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Old 06-06-2018, 06:23 PM   #4
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Well, I think I found an intercooler.....but it is pricey. Any other suggestions before I do something silly like break out the credit card

YJ R2.8 Intercooler Kit - Axis Industries USA
You are already looking at around 10k for the swap whats a few more dollars?
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Old 06-06-2018, 06:52 PM
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By the time I am done with the repower, transmission, Tcase, diffs, ect,ect i think 22K USD or $28.5K Canadian. The cheaper you can do a build and still have a quality build is what I am striving for. The last engine I had in my race car was $96K USD, so to do all of this for $20K, and not keep dumping money into broken parts and tearing the engine and transmission down and freshening it up after every race weekend seems pretty reasonable to me.....but that is just me.
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Old 06-06-2018, 08:36 PM   #6
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Personally I wouldn't even consider a 4bt or an r2.8

These guys are toyota people but have some points worth considering...
Cummins R2.8 & 4BT | Diesel Toys® |TOYOTA DIESEL CONVERSION EXPERTS
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Old 06-06-2018, 08:49 PM
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Personally I wouldn't even consider a 4bt or an r2.8

These guys are toyota people but have some points worth considering...
Cummins R2.8 & 4BT | Diesel Toys® |TOYOTA DIESEL CONVERSION EXPERTS
Interesting read
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Old 06-06-2018, 09:21 PM   #8
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Personally I wouldn't even consider a 4bt or an r2.8

These guys are toyota people but have some points worth considering...
Cummins R2.8 & 4BT | Diesel Toys® |TOYOTA DIESEL CONVERSION EXPERTS



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Old 06-07-2018, 02:05 AM   #9
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Old 06-07-2018, 02:06 AM   #10
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Like I mentioned in the last thread, the OM617 is the "king" of street diesel swaps in a YJ/TJ/FJ for many reasons...

Not much compares to a modern LS swapped 2-door either
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Old 06-07-2018, 10:49 AM   #11
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I have struggled w what diesel to put in a wrangler for years.... om 617 looks great except not enough power for my liking... vw tdi looks good too but even smaller and still not enough power for me... both can be cranked up but I worry about longevity if a person actually uses the power for extended time like highway driving 80 mph w a headwind or climbing a grade....

I have decided to try a build w a gm 6.2 when I get around to it but gonna be a tight fit since cruise, a/c, a turbo, enclosed air cleaner, and 'as stock' fit and finish are requirements of mine.... I actually have a test bed jeep to try out and then would be swapping the build into a much nicer jeep if I'm satisfied w it.
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Currently in the stable: ... 97 tj 4.0 5 speed stock....04 tj 4.0 auto 4" and 33's... 98 tj roller for future build... 94 yj sahara 4.5" RE and 33's... 92 yj sbc 3/4 ton axles and 38's... Cj5,7,yj,xj,ex mud dragster project

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Old 06-07-2018, 12:44 PM
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Like I mentioned in the last thread, the OM617 is the "king" of street diesel swaps in a YJ/TJ/FJ for many reasons...

Not much compares to a modern LS swapped 2-door either
I am just not a fan of Mercedes. On their big engines they over rate their power. A buddy of mine has basically the same Motorhome as mine, but he has a 500hp Mercedes engine, and I have a 435 hp Cat motor in mine. Both loaded up with cars and racing gear in our trailers (going racing) weighing close to 60 thousand lbs and I can run circles around him with my little Cat motor and kick his butt with fuel economy as well. I have always been a Cummins fan, the only motor they have produced that I didn't like was the 444 Cummins, and it was junk. Hell I used to run the old Cummins mechanical 350 and Big Cam 400's.

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Originally Posted by Gottagofast View Post
I have struggled w what diesel to put in a wrangler for years.... om 617 looks great except not enough power for my liking... vw tdi looks good too but even smaller and still not enough power for me... both can be cranked up but I worry about longevity if a person actually uses the power for extended time like highway driving 80 mph w a headwind or climbing a grade....

I have decided to try a build w a gm 6.2 when I get around to it but gonna be a tight fit since cruise, a/c, a turbo, enclosed air cleaner, and 'as stock' fit and finish are requirements of mine.... I actually have a test bed jeep to try out and then would be swapping the build into a much nicer jeep if I'm satisfied w it.
That will be a cool build, I look forward to reading about it. I have my son in law checking out the Cummins R2.8, he is a Cummins certified tech and he will find the dirt on them
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Old 06-10-2018, 11:12 PM
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I have a question about transmissions for this repower. Could a person use a NSG370 6 speed transmission in a CJ? Would it even fit in the tunnel of a CJ? will it marry up to a NP231 transfer case? I like it for the gear ratios and the 1st gear if I run 4.30 gears and 35" tires. I was just going to go with an AX15 with the 3.83 1st gear, then I thought about a NVG3550 with the 4.01 1st gear, then I started looking at the NSG370 with the 4.46 1st gear. What are your thoughts? I guess the first thing is to see if I can find an adapter to ft an NSG370

NSG370: 4.46 2.61 1.72 1.25 1.00 0.84
NVG3550: 4.01 2.33 1.39 1.00 .78
AX15: 3.83, 2.33, 1.44, 1.00, 0.79
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Old 06-11-2018, 12:44 AM   #14
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I can't speak to the NSG370, but in regards to the NV3500 vs AX15, the slightly lower first gear is beneficial in the NV but the lack of factory support and OEM replacement parts is a deal breaker for me. I'm curious to see what you find out about the NSG370...
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Old 06-11-2018, 01:48 AM
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I I am overthinking this. I think my best bet is to go with the AX15, they are proven and they are a good transmission, go with a set of 4.30 gears and a set of 35' tires and I think that would be best. The KISS method works the best I think "Keep It Simple Stupid"
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Old 06-11-2018, 01:52 AM   #16
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The NSG370 is a junker almost as bad as the BA10 i wouldn't want one anywhere near a jeep i was building.
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Old 06-11-2018, 02:21 AM
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The NSG370 is a junker almost as bad as the BA10 i wouldn't want one anywhere near a jeep i was building.
I don't know much about them except for the good/bad reviews I have been reading,but I think the right one is the AX15.
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Old 06-11-2018, 04:38 PM
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I can`t seem to find any 4.30 gears. Does anyone know of a source for 4.30 gears for a D35 and a Ford 8.8
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Old 06-11-2018, 06:25 PM   #19
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My choice would be the VM diesel as used in the early Jeep Liberty 2.8 turbo plenty of power, easy conversion to your jeep, stock Liberty trans and "T"case + part time/ full time 4x4 .
If you could find a wrecked donor it would have most every thing you need.
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Old 06-13-2018, 12:53 AM   #20
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I can`t seem to find any 4.30 gears. Does anyone know of a source for 4.30 gears for a D35 and a Ford 8.8
That’s a bit of an odd ratio and not too common. I know it came stock on some D44’s (my Rodeo D44 came with them actually), but I’ve never seen a factory Ford with 4.30’s and never seen an aftermarket set of 4.30’s for a D35 (although I can’t say I was ever really looking).

With the diesel, I think you’d be good with 4.56 gears and 35” tires, assuming you’re sticking with a AX15 still. I’ve heard mixed reviews about the R2.8 so far (from local crowd who got to play with one and actually saw Tubesock from DED on the trails). While it is reliable (seemingly) and has good torque while providing exceptional gas mileage, it still lacks serious displacement (similar to what stifled the OM617 and 4BT to an extent). This means you’ll need to gear for the trails or gear for the highway and the general consensus now is to add more gear...

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