VW TDI Diesel Sahara

[BugoutJeep]

Just my perspective from dealing with previous modified diesels, I would not swap a TDI with the intention of gaining "much" power over the 4.2/4.0 engine. You will likely spend a ton of money on parts and chase down the next weak link of engine and drivetrain components and fixing forever. These engines are great for mileage, simplicity and long term reliability if you leave them relatively stock. People will argue with me about this, but you have to consider long term when going through the effort of swapping engines. How long is something going to last running at 100% load and demand. Just something to think about.

I'm not looking to gain HP, I'm just talking about the torque curves between the different TDI engines. In general most diesels will have much more low end torque vs the 4.0 and more often HP numbers come from high in the rpm band which makes higher hp often meaningless, especially because it's all about torque in the rpm range one drives in.

I use the 10% rule on increasing hp and will only consider a bump if it occurs in the usable rpm window.

Typically for turbo diesels, I put WAY more stock in displacement for all around functionality, but I'm interested in the tdi, due to availability rather than doing another R2.8 or something. Plus this will be a slow build rather than a fast build for me. If it takes a year or 2 then that's ok, especially if my money investment is fairly small. I will probably buy an adapter but I'm gonna copy and fabricate most stuff unless the price point is right. I do plan on doing some engine mods as deemed prudent, just due to a long service history that is known for typical issues.

 

[BugoutJeep]

I might add that I'm gonna be looking a lot at some different transmissions other than the ax15, but do prefer a manual for simplicity. I prefer the gearing of something like an nv4500, but at the same time it's twice as big as necessary IMO.

 

[TDI Sahara]

Have you had problems with the AX-15?

 

[BugoutJeep]

Have you had problems with the AX-15?

It's been fine, I just don't prefer the first 3 gears. I really want a first gear 5+:1 and then 2 or 3 gears to get me to 1:1 and then around .8:1 or so.

 

[Ephry73]

I'm not looking to gain HP, I'm just talking about the torque curves between the different TDI engines. In general most diesels will have much more low end torque vs the 4.0 and more often HP numbers come from high in the rpm band which makes higher hp often meaningless, especially because it's all about torque in the rpm range one drives in.

I use the 10% rule on increasing hp and will only consider a bump if it occurs in the usable rpm window.

Typically for turbo diesels, I put WAY more stock in displacement for all around functionality, but I'm interested in the tdi, due to availability rather than doing another R2.8 or something. Plus this will be a slow build rather than a fast build for me. If it takes a year or 2 then that's ok, especially if my money investment is fairly small. I will probably buy an adapter but I'm gonna copy and fabricate most stuff unless the price point is right. I do plan on doing some engine mods as deemed prudent, just due to a long service history that is known for typical issues.

TDI with a mild tune and EGR delete can gain close to 300FT/TQ from 1,900 RPM to about 4,300. That s perfect if you ask me. Couple that motor with a good regear of the axles.

 

[Ephry73]

What is making these TDI swaps more attractive, is the VW-gate issue. Now you can find a lot of these motors for pretty cheap. The Tuning is fairly easy, and can even use opensource software to tune(nefmoto, etc..) I was looking at something like this for a Willys project I had in mind a few years ago.

 

[BugoutJeep]

TDI with a mild tune and EGR delete can gain close to 300FT/TQ from 1,900 RPM to about 4,300. That s perfect if you ask me. Couple that motor with a good regear of the axles.

Is that the ALH?

TJs really like 300 ft lbs, I might add. But I'm not gonna complain if it's got 350 ft lbs at 1,900 RPMs either. I'm actually planning a build that will be a bit heavier. I was just gonna go YJ with just the 2 seater and small flat bed with a slightly extended frame, but more and more I'm leaning toward keeping the back seats and having ~4ft flat bed.

 

[Ephry73]

Is that the ALH?

TJs really like 300 ft lbs, I might add. But I'm not gonna complain if it's got 350 ft lbs at 1,900 RPMs either. I'm actually planning a build that will be a bit heavier. I was just gonna go YJ with just the 2 seater and small flat bed with a slightly extended frame, but more and more I'm leaning toward keeping the back seats and having ~4ft flat bed.

Correct. I wouldn't increase the turbo size too much and maybe just add those 520 nozzles. That combo I had in a Golf GLS and it was a great GTI killer indeed. Still was netting about 60mpg from regular driving.

 

[BugoutJeep]

If I can run a fairly reliable ~300 ft lb setup with 33" tires (might need to run 32s) and 4.10 gearing I'd be very happy. I still want the gearing of the NV4500 or similar transmission, but AX-15 will probably have to do coupled with a doubler of some sort to compensate for the gearing.

 

[TDI Sahara]

Correct. I wouldn't increase the turbo size too much and maybe just add those 520 nozzles. That combo I had in a Golf GLS and it was a great GTI killer indeed. Still was netting about 60mpg from regular driving.

What tune did you have, right now I am at Stage 1 Malone.

 

[Ephry73]

What tune did you have, right now I am at Stage 1 Malone.

Old Kerma tune, but I bought the nozzles and EGR delete pipe from his old store when I did

 

[gaabbee]

If I can run a fairly reliable ~300 ft lb setup with 33" tires (might need to run 32s) and 4.10 gearing I'd be very happy. I still want the gearing of the NV4500 or similar transmission, but AX-15 will probably have to do coupled with a doubler of some sort to compensate for the gearing.

Why not a nsg370? 4.46 1st and .84 6th. I know its rated for 270 ft lb but it should be ok for a tj/lj

 

[BugoutJeep]

Why not a nsg370? 4.46 1st and .84 6th. I know its rated for 270lb ft but it should be ok for a tj/lj

I certainly may go that direction. There is a way to convert the AX-15 to a 5.15 first gear, but the NV4500 are very abundant, though really heavy and not quite as smooth shifting.

To be honest I was thinking the first gear was 4.1 on the other TJ transmission or maybe I'm mixing up my transmissions.

 

[gaabbee]

I certainly may go that direction. There is a way to convert the AX-15 to a 5.15 first gear, but the NV4500 are very abundant, though really heavy and not quite as smooth shifting.

To be honest I was thinking the first gear was 4.1 on the other TJ transmission or maybe I'm mixing up my transmissions.

I had the nv4500 in my cj7. While it was nice having 5.6:1 1st the 2nd to 3rd ratio was like falling off a cliff. The 6 speed has way better ratios and is honestly a joy to shift comparatively.

nsg370 / nv4500
4.46 / 5.61 or 6.34 (gm)
2.61 / 3.04
1.72 / 1.67
1.25 / 1
1 / .75
.84

 

[BugoutJeep]

Yeah that is a big jump. I'm probably being a bit biased because I'm so used to the 5.9 Cummins I have bolted to my only NV 4500. That being said, I think I tend to have to get up pretty high in the RPMs before I shift to 3rd. Very good point.

Honestly, I probably should just go doubler and AX-15. That should give me plenty to choose from and the AX-15 is a very good transmission. I'm running what I believe to be 180k mi transmission with my R2.8. One of the syncros is probably a bit worn, but it's not bad at all.

 

[gaabbee]

Yeah that is a big jump. I'm probably being a bit biased because I'm so used to the 5.9 Cummins I have bolted to my only NV 4500. That being said, I think I tend to have to get up pretty high in the RPMs before I shift to 3rd. Very good point.

Honestly, I probably should just go doubler and AX-15. That should give me plenty to choose from and the AX-15 is a very good transmission. I'm running what I believe to be 180k mi transmission with my R2.8. One of the syncros is probably a bit worn, but it's not bad at all.

Yea I can see the ax-15 from a reliability stand point but I think the nsg gets a bad rep from a lot of people that don't know how to shift a manual properly. If you are thinking of upping the torque to 350 ft lb someday then yea ax-15 all the way.

 

[BugoutJeep]

Well if I could reliably get 350 ft lbs around 1,900 RPMs, I would do that mod. Though to be honest even with my current ~310 ft lbs, I'm very light on the throttle. I hate breaking stuff and I find not being hard on worn components, keeps me from replacing stuff and adds some mileage each fill up.

 

[TDI Sahara]

Yeah that is a big jump. I'm probably being a bit biased because I'm so used to the 5.9 Cummins I have bolted to my only NV 4500. That being said, I think I tend to have to get up pretty high in the RPMs before I shift to 3rd. Very good point.

Honestly, I probably should just go doubler and AX-15. That should give me plenty to choose from and the AX-15 is a very good transmission. I'm running what I believe to be 180k mi transmission with my R2.8. One of the syncros is probably a bit worn, but it's not bad at all.

Any problems with the 5th gear nut on the NV4500? In regards to the dodge Cummins.

 

[TDI Sahara]

Yea I can see the ax-15 from a reliability stand point but I think the nsg gets a bad rep from a lot of people that don't know how to shift a manual properly. If you are thinking of upping the torque to 350 ft lb someday then yea ax-15 all the way.

I had a nsg in a 2005 jeep liberty 2.4l and it seemed okay, however it had a rattle in neutral when warm that I could not explain.

 

[BugoutJeep]

Any problems with the 5th gear nut on the NV4500? In regards to the dodge Cummins.

I have had zero issues with the transmission, but I've only driven the truck about 30k mi, though the truck has 350k mi on it and engine and transmission seem to be solid. No noticeable blow-by or anything. Looks like there was some work in that area as some of the shifting stuff looks aftermarket. I can't think of the proper names at the moment for what's obviously replaced.