v8 swap - your opinions?

Here's the goal - low budget horsepower.

I'm not crawling this rig at all. More like heavy track use. So I have been tossing around the idea of a v8 swap, and to keep things as simple as possible, a carb'd 360 (rules limit me to 389ci). Don't worry about fabrication, I've got that covered. And I'm using a 5sp tranny (I have an ax15 in there now, but considering a nv4500).

So what's everyone's thought on this? Is there a better option? I think that a stroked 6 wouldn't be as rev happy as I need, plus I can find aluminum block/heads for the v8. I've considered a newer 5.9 magnum, but the electronics of the mpfi introduce a whole bag of worms when considering simplicity and reliability (its a race car, it's going to break, I'd rather it be mechanical and not electrical).

What kind of track use?

It will most likely see use in various motorsports - stage rally, euro rallyx, random autox, a trip or two to the drag strip, maybe a time attack or track day for shits and giggles. Moral of the story - top end and acceleration are key. I'll be running small tires and minimal suspension travel.

and here i thought desert racing an xj was a bad idea!


i look forward to a build thread.

Sounds great. Post videos too!

Definitely go v8 over stroker. More power less/equal weight. Just build what you can afford and are comfortable with. Brand doesn't matter much. :farmer:

Brand does actually matter a bit - I have to run an AMC or Chrysler motor due to Rally America rules.

If you went the 5.9 Magnum, and you don't want to run EFI. Couldn't you just use a Carb and regular manifold?

I'm not much into the Mopar stuff, New into the Jeeps. Mainly Ford stuff before my jeep. I know even on the Ford 4.6 mod motor you can run a carb on them now.

Jet

Thats too bad.. an LSx swap would be amazing.
I am pretty sure there is carb manifold that bolts to the magnum motor. Dunno why you want to go carb tho.

Yeah, tell me about it. It actually has me entertaining the idea of running an s10 instead...

I was going to recommend you look up the guy that rallies a Commanche but I see that's you....Would a newer 5.7L Hemi be possible?

How about a 5.9 mopar, carb/conventional distributor ignition conversion(mopar performance sells a kit) NV 3500 5spd, NV242 full time Xfr. case?

No conversion/adapters needed. Just motor mounts.

I'd not use the AX15 or the NV4500. The AX15 won't last behind a hard driven V8. The NV4500 is a slow shifting truck tranny, with an extremely wide ratio between 1st and 2nd.
Plus, I'd never use a carb for the application you're contemplating; EFI is extremely reliable, with much better throttle response than a carb. IMHO.

do a 5.9 magnum. that would be awesome. i have often thougth of doing the same thing to my 85 2.5.

as fora carb manifold the diff between the magnum and non magnum intakes is the angle the bolts. the older la blocks the bolts go in at a angle and the magnums the bolts go in vertical. the la intake can be drilled to accept the vertical bolts.

xjbubba said:

I'd not use the AX15 or the NV4500. The AX15 won't last behind a hard driven V8. The NV4500 is a slow shifting truck tranny, with an extremely wide ratio between 1st and 2nd.
Plus, I'd never use a carb for the application you're contemplating; EFI is extremely reliable, with much better throttle response than a carb. IMHO.

Click to expand...

I appreciate your opinion of the trannys, but you didn't give a suggestion on what TO use. Any ideas?

And as for carb vs efi - the "reliability" I'm looking for has everything to do with the electrical nightmare that is jeep. I realize that there may be slightly better performance from efi, but at the same time, the idea of only having a throttle cable to worry about snapping is very appealing.

The goal is reliability through simplicity (which hopefully translates into cost as well). At an even this weekend, I was discussing with my codriver about some options, and we have kind of settled on this:
We drop a 318 in, iron out the bugs, run it for a few events, and when I get a feel for how it performs, swap in a built 360. This plan makes me think that I can retain the AX15 for the testing phase, and keep the stock axles and such because I won't be putting out tons of power.

Now, let's talk about the 360 in terms of a good transmission. What are my best options when talking about something easy to find, reliable, and realistic drive ratios? I have heard rumor that the Rubicon 6sp is the same tranny that comes in the Crossfire - is this true?

Also, we are thinking about running a full time awd system. I know that jeep has made a bunch, but which ones are better than others? Ideally, I'd like to have LSD's front/rear with a lockable center.

Keep your 318 and stroke it. Hughes Racing makes a 390ci stroker kit for the 318 at a reasonable price. I know its one cube over the limit, but close enough.
http://www.hughesengines.com/Index/...aW5lcw==&level1=U3Ryb2tlciBLaXRz&partid=25284

Close enough doesn't work once you get protested and they tear your engine apart.

Maybe they could build a kit with a little less overbore or a shorter stroke. Just an idea.

That thought had already gone through my mind

For a transmission, look and see what trans went into the Grand Cherokee, Dodge Dakota 4wd, or full size V-8 Ram 1/2ton.(pretty much the same place you source your motor from)
I know dodge used a NV3500 in some of their V-6 and V-8 trucks. The 3500 is the same transmission as the 3550. The only difference is the 3550 has a removable bell housing. The 3500 is a 1-piece front case/bellhousing.

You could use an old chrysler slant 6. Those were high revving motors and were used extensively for racing.