Have you read any of the other posts in this thread? They will answer a lot of your questions.
I am considering an engine swap and I think the magnum makes the most sense. I have a 1999 wrangler that a recently put 37 in tires on and I need more power but I don’t need a race jeep. I’m 49, I just want to get up the mountain to Flagstaff a bit easier. I know everyone says 37s are a recipe for disaster on a TJ but I have an 8.8 and dana 44 with 4.56 gears so I think I am fine, and I don’t think regearing is the answer either.
Regearing would be part of the answer. 5.13 or even better 5.38 gears would help out a LOT. Even with a V-8 you really need to have at least 5.13 gears for those tires.
So here are my questions:
Is there any advantage between the 5.2 and 5.9? I had a 93 Dakota with the 5.2 years ago and I loved it, but the larger displacement is attractive if I am going to do the swap. However, the rated power is not that much different and the 5.2 is much less expensive. I’m sure the 5.9 has a flatter torque curve, but other than that, are there advantages of one over the other? If there are any cheep and easy ways to boost power, I would be interested in that as well.
Yes you will notice a difference between a 5.2 & 5.9 but in a TJ I think the 5.2 is enough but if you don't want to regear then the 5.9 might be better.
As for power adders to the magnum engines the 2 main points are cam & heads. You can gain a lot just by fixing those.
I want to keep my AX15. I have read that with the Dakota bellhousing it will bolt to my trans and I don’t have to move the trans… but what about the other end? I know the ZJs came with a 4.0 and a magnum in some years. Am I hoping for too much when I hope I can bolt to the stock motor mount locations? I don’t weld so if I have to have new mounting locations I will have to have that done by a professional.
Yes the AX15 will bolt up to a magnum engine if you use a 92-98 Dakota bellhousing. But this isn't just bolt it up & you're done. If you put the new motor mounts in the prescribed location your transmission is moved forward about 2" so you have to modify your shifter. You'll also need to shorten your front driveshaft & lengthen your rear driveshaft.
No the stock motor mounts do not work. You need to get new mounts from Advance Adapter or Novak. They have to be welded on but if you don't weld you can hire a mobile wilding service to come and do the needed welding.
I have seen conflicting info about the wiring harness. In one video the guy said he used the magnum wiring harness for one of the three plugs into the ECU but the other two were the original wrangler harnesses. In other places, in fact in this thread I believe, it says the wiring harness has to be modified. But maybe this is just to accommodate an auto trans borrowed from the doner vehicle? Can I really just use the magnum motor harness and plug it into a magnum ecu? I also believe from what I have read that I need a 2000 or 1999 ecu. I understand I will need to have it flashed to work with a manual trans.
There isn't any conflicting information about the wiring.
You have to blend the two harnesses together no matter if you are doing a automatic or manual swap. What is different is the two ways of going about this.
Most people doing a manual swap will add the needed injector wires and other sensor wires to the TJ harness.
People doing an automatic swap will use the Dodge harness & add the TJ harness to make it work but either way you are blending the two harnesses together. If you aren't OK with doing this you can send both harnesses off to Hotwire & they will make you a harness for about $1300.
You need a 1998 to 2001 PCM (ECU) to make the engine run BUT if you have smog checks then you may need to use a 1999-2001 PCM. You won't have to have it flashed IF you get one from a manual truck. You can't use one from a Durango or Dakota as most of them have a SKIM or oter type of alarm that makes them not work. You need one from a Ram truck that was as bare boned as possible.
Does AC fit? I understand this can be difficult with some swaps, but I live in Phoenix. AC is a must! I know the ZJ brackets are preferred, but I want to know that the AC will fit before I decide to do this.
Yes you can have A/C but you have to have custom lines made & your accumulator has to be moved or use a different one as there isn't room where it's mounted stock.
Finally, will I have a check engine light? We have emissions testing here, so I have to be able to pass.
If you do the swap correctly NO you will not have any "check engine" lights. You can add the O2 sensors just like they were stock on the Dodge and everything else for the emissions system. The only time I have a check engine light is when I am having a issue.
Thank you in advance for any info you can provide.
Here was my Jeep with 38x12.5x16.5 TSL SX tires & I'm running 5.13 gears & a automatic transmission. This was with a 5.2 but I'm doing a 5.9 now.
This is a very informative thread over on Jeep Forum that you should read. It's a long thread but there is a wealth of information in it.
https://www.jeepforum.com/threads/wrangler-magnum-v8-discussion.1365878/
The short of all this is that the V-8 swap isn't the end all answer to your want for more power. Yes it will help a lot but will require other modifications.
