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4.0 vs. the GM 305

jeepman121

NAXJA Forum User
Location
Ohio
I love the Jeep 4.0, the low RPM power, the reliabilty, and the torque is descent as well. After some discussion with a friend we wondered how a 305 would suit in an XJ. We wondered if it would actually be a little better on gas due to the ease of load, and the power should be alot better right? But I didn't know if the weight would be alot greater or how much the adapter would cost. Just wondered if ya'll know how the two mesh together. I know alot of folks that ran the 5.0 ford and 5.0 GM motors in wranglers and CJ's but I've yet to see one in an XJ. Another thing I was thinking was since the 4.0 is an inline, would it be hard to stuff one of those old B series Jaguar V-12's in an XJ? Just food for thought I suppose. thanks- Josh
 
its a great idea. A later model 305 has a roller lifter/ cam.
it can loaf along with its torque and turn in 20 mpg. And yet put out 260 ft lbs of torque before any upgrades.

i tinkered with small block chevy before i got into 4.0 motors. they're a lot of fun, with the cheap parts everywhere.
 
Ugh, jaguar v-12s are garbage, trust me I'm a Jaguar Mechanic, you're way better off with a Jag I-6 if you want to go that way.

I don't know about a Chevy 305 either, theyre pretty gutless. They actually make LESS power than your 4.0 depending on the year! If you want to go with a sbc go with something with a 4 inch bore like a 327 or 350. Either can be tuned for power or economy, with a 305 its a lot harder to make power.

If it were me, I'd go with a sbf; smaller, lighter just as good as potential.
 
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stroke the 4.0 or be prepared to have to switch your transmission out as well. You can make as good or better power with one, and still have an engine bay that is easy to work in. Also be prepared to have a headache with running the exhaust.

I looked into a v8 swap, but most 305's only put out a little better than 200HP stock, so you would need to build that engine too. 350's were a little better on stock power output but not by much. And ford has never really made a small block motor that makes better power stock either. both are capable of good power gains, but neither is great stock. If you want to put a built v8 in, stroke a 350 to 383, grab a 700r4, np231 and be good to go, but that is about a $5k swap when you are done. for a sbf you are gonna have to go nitrous of FI to get to the same hp numbers.

the exception to this would be an LSx swap, stock they make very good power, but they are a pretty expensive motor, and you will probably not find one in a pickurpart.

these reasons are why I went with a 4.7l stroker. it cost me about $1500 total, makes outstanding torque, and runs pretty good economy. 18mpg or so w/ 33" tires.
 
http://www.novak-adapt.com/knowledge/xj_swap.htm

that is Novak's take on the situation. Read it. They make some great points about the whole "I want to stay MOPAR loyal" idea. As well as good general knowledge on what you need and what will fit. Fittign the motor in the bay is only half the battle. You still have to control it, run exhaust and intake routings, wiring, the rest of your drive train, get gauges to work, ect.

I want a stroker for my MJ, then I want to go CRD diesel on my cherokee.
 
If you are going to bother with a V8 swap I'd only consider the new Gen IV SBCs. Basically, the modern LSx and equivalent truck engines with iron blocks.

Small block anything will be lighter than a Jeep 4.0.
 
wolfpackjeeper said:
http://www.novak-adapt.com/knowledge/xj_swap.htm

that is Novak's take on the situation. Read it. They make some great points about the whole "I want to stay MOPAR loyal" idea. As well as good general knowledge on what you need and what will fit. Fittign the motor in the bay is only half the battle. You still have to control it, run exhaust and intake routings, wiring, the rest of your drive train, get gauges to work, ect.

I want a stroker for my MJ, then I want to go CRD diesel on my cherokee.

The 4.7L you plan for your MJ will be a PITA to fit! I would put the CRD in there and leave the XJ with the 4.7, MUCH easier job!

And to Root moose, do you mean the LT1? I've heard of some people just swapping for aluminum heads and reaching near-LS performance. And ditto to you about the 4.0, it's a good bit heavier than the SBC
 
we are all referring to it being a slouch stock, which it is. The motor you just showed has a set of $225 a piece heads($450) that were then custom milled. On top of that it has some other work done and was a custom rebuild. You would be better off stroking a 350 to 383 if you really want that v8.

You can rebuild a SBC and get great power. But the total swap will still cast far and above what a stroker will.
 
It would still be cheaper than the stroker kit for the Jeep right? and arent the 305's only like 100 bucks at a junkyard? I also know the 350 is the "king" of mod. But I'm looking for more fuel efficiency/power recipes.
 
Mr_Random said:
And to Root moose, do you mean the LT1? I've heard of some people just swapping for aluminum heads and reaching near-LS performance. And ditto to you about the 4.0, it's a good bit heavier than the SBC

LT1 is considered a Gen II engine. Great engines for what they are but starting to get a little retro at this point.

http://en.wikipedia.org/wiki/Chevrolet_Small-Block_engine#Generation_II

It's a function of what you have lying around and what you want to pay. For me I'd likely go Gen IV LY5. The LM7 would be decent too but you miss out on active displacement with that engine.
 
jeepman121 said:
It would still be cheaper than the stroker kit for the Jeep right? and arent the 305's only like 100 bucks at a junkyard? I also know the 350 is the "king" of mod. But I'm looking for more fuel efficiency/power recipes.

Stroker will be cheaper. By the time you get a swap done you will be into the thousands of dollars easily. Also don't forget the time required.
 
True to that...although I do know its about $1500 for the recommended header and exaust and the injectors. Then the labor for the stroker swap racks it a up a bit also. So what do you think the diff. in cost would be between the two?
 
The stroker will be much cheaper, around $1500 in and running if you can do all but the machine work by yourself. The 305, will have less power and torque than the stroker, and it would not surprise me if you spent $3k on the v8 swap.

Needed for a stroker:
machine work, a full rebuild, new injectors.

Needed for a V8 swap:
engine swap and possible rebuild, new transmission(AW4 will not work), new radiator, fab work for new mounts and crossmembers, new driveshafts, t-case, computer, harness, new exhaust work which can be a pain to route, new gauges if you are newer than 1990 since you will be ditching the computer, possibly a new rearend unless you already have a D44 or better and even now I am forgetting stuff.

Stroker is far cheaper. Add on to this that this is for a stock 305 or 350, you would need to build and add heads and a cam plus some other performance stuff to make the v8 worth it, which costs even more money
 
wolfpackjeeper said:
why? I thought they redesigned the engine bay in 87 when they added the 4.0. The bay looks exactly the same as my cherokee.
yeah yeah, you're right, stupid me...

in either case, the CRD or 4.7, you'll have to do engine mount, tranny mount, and other work... a stroked street MJ would be awesome, keep it mostly stock and you'll probably get rediculous gas mileage and strength out of the 4.7/MJ combo.

The torque of the CRD would be awesome for offroad, very similar to the 4.7, but a good bit lighter and still more efficient.
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To the OP, look at these options, the CRD is VERY outside the box (one person in the middle of the swap, that's all I know of), and probably will come to a similar price (but be easier to fit) as the 305. The NV3550 bellhousings are already there, if you can't get the whole combo (CRD/NV3550/np231) in one piece anyways.

Or you could go for the obvious, and cheapest route, like the other guys said; the stroker!
 
Mr_Random said:
a stroked street MJ would be awesome, keep it mostly stock and you'll probably get rediculous gas mileage and strength out of the 4.7/MJ combo.


yea, I want the 4.7l backed up to a nv3550, put a 2wd tailshaft on it if I cant find a 2wd tranny outright, and run it back to the 9" I have in the garage. The 9" is a shade wide for an MJ at 62" but I can just run a deeper wheel and wider tire. The other thing I noticed about the MJ is that with the bed shaped the way it is underneath, a remote mount turbo becomes a good option. Throw some ford ranger coils on the front and part of an XJ pack in the back to lower it and it should be a nasty little street truck.

.... sigh... maybe in a few years I can have it done
 
wolfpackjeeper said:
And ford has never really made a small block motor that makes better power stock either.

beg to differ, thru the late 80s and early 90s Ford had a better small block hands down. by the time they killed the 5.0L it was rollerized and pushing 245 hp thru stock manifolds. GM just didnt take on the HP challenge till mid 90s and then they totally blew the Ford away. the Ford is smaller dimensionally and alot of people use it for that reason alone. even though i've always been a Chevy guy my current CJ does have a Ford in it and i'm happy with it.

on topic here i'd suggest sticking with a 4.0L based engine. at least there are factory parts available. any non-OEM swap will turn into a nightmare on your wallet.
 
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