cherokee's gm v6 compared to jeep cherokee inlines

ok so i wanted to put out some info. i am no technical expert this is just info i found on the net.

i just purchased a cherokee that has a 2.8L gm V6.
everyone told me to stay away from it but besides the engine the cherokee is what i wanted. 2 door black stock 5spd. a blank canvas for me to build on. so i got it.

so here is some engine info

jeep 4.0l 1987- 173hp 220lb-ft
jeep 4.0l 1988- 177hp 224lb-ft
jeep 4.0l HO 190hp 235lb-ft

jeep 2.5l 82-86 105hp 132lb-ft
jeep 2.5l 87-90 117hp 135 lb-ft
jeep 2.5l 91-95 130hp 149lb-ft
jeep 2.5l 96-02 125hp 150lb-ft

gm 2.8l 115hp 145lb-ft

so after seeing this i can see that i should be able to perform as well as any of the 2.5L. the 4.0L still much better.

so i looked into the easiest engine swaps. the 4.0L will not swap over without new transmission, new mounts and modification to the firewall.
the GM 4.3L V6 and GM V8 are popular swaps but also require the same as the 4.0L.

i found out that the 2.8l, 3.1l and 3.4l are all gm 60degree engines.
you can find 3.lL and 3.4L in a lot of gm vehicles. GM also has a GM performane 3.4L long block.

there are also companies that sale a 3.1L and 3.4L stroker kits for the 2.8L.

either the swap or the stroker you will use the same mounts the same transmission the only thing that needs to be changed if you do the swap is a nutrally balanced flywheel.

here is the hp and tourqe info

gm 3.1l 135hp 180lb-ft
gm 3.4l 160hp 194lb-ft

so now with a swap/stroker you should be able to perform better then a 2.5L but the 4.0L should still perform better.

Now all of this info is just on "stock" (stroker/swap). I didnt go into MODs like cams fuel injection headers intakes forced induction etc etc.

so anyone who is looking into buying or already owns a GM v6 powered cherokee. when people say 4.0l is better they pretty much are all right. But at least you got the 2.5L tied or beat.

You're gonna want to put a new 5 speed in there. They didn't put the good AX-15 behind the 2.8 v6.

www.60degreev6.com will give you plenty of tech info on the GM V6-60 engine.

The 2.8L is a dog - I had two vehicles (comparable platforms) one right after another - one with the 2.8L and the other with the 3.1L. Night and frickin' day.

The 3.1L/3.4L is a valid swap. If you want just the engine, you can check S-series trucks and F-body cars (Camaro/Firebird), but don't neglect the FWD donors as well. While the OEM FWD engine block has the starter mounting pad on the "wrong" side (would be the driver's side as mounted in RWD,) the Goodwrench Service Replacement blocks have the starter mounting pads on both sides, and can therefore be used in FWD/RWD applications.

Also, if you find a suitable S-series donor, grab the whole drivetrain from 1986-up. The 2.8L in GM apps usually was coupled with the THM700R4, which would also allow you to pick up an overdrive gear (the early THM700R4s, to 1985 or so, had a fatal flaw that was never fully addressed. The best way to fix the early 700? 300# of ready-mix, just like the 2.8L V6.) The S-series 4WD would be something like the 3.1/3.4L, THM700R4/4L60 (don't get the later 4L60-E - too much electronics to swap) and the NP231C or something similar. You may need new driveshafts, and you'll probably have to fab up a mount adapter to go from the A904 to the 700R4, but the 700R4 is often compared favourably to the A904 (and the overdrive thing, which can allow for a gearing change while maintaining highway efficiency.)

The 2.8L also (typically) will either have a Weber carburettor (suitable for scrap) or "toilet bowl" TBI - the 3.1/3.4L will bring MPFI along with it - which is also an improvement. In fact, quite a few people have swapped 3.1L top ends onto the 2.8L long block to gain PFI - which is good for both a performance and an efficiency improvement. And, I think the 3.1L heads breathe better (but I'd have to find my notes on that - I've been working on drivetrain research almost exclusively lately.)

When comparing engines, it should also be pointed out that factory numbers often aren't enough for a comparo when you plan on building up anyhow. There's no reason you can't pull 1-1/4 hp/ci out of an engine these days (173ci would give you a potential of somewhere around 220hp, naturally aspirated) and there's always forced induction and nitrous to consider. "Speed is a question of money - how fast can you afford to go?" (Something I had to teach my boys the hard way - I made them pay for their own mods. "Power is made either by cubic inches or cubic money" is also important to remember.)

And, how far you want to go into the buildup depends largely on what you plan to do - so before you turn the first screw, sit down with some clean sheets of paper and draft plans. Make the first one your "ideal", the second one your "minimum acceptable", then get out catalogues and databooks and start picking parts. The third plan you come up with will probably be in between the first two - with luck, closer to the "ideal" than the "minimum" (if it is, you've planned well and have realistic ideas. If it's closer to the minimum, you were optomistic in your planning, and you can chalk it up to learning experience.)

And, if you have any questions, ask away! I'm sure someone here will be able to help you...

mjma said:

You're gonna want to put a new 5 speed in there. They didn't put the good AX-15 behind the 2.8 v6.

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Dunno - I think some of the 2.8L engines got the Warner T5, which is a solid box (it's also used in V8-powered Camaros and Mustangs, and is a fairly standard five-speed.)

If you want, I can dig up case casting numbers to help ID the thing

The 4.3 is a tight fit as it's the same width as an sbc. The 3.4 is the most reasonable swap. I helped do one on an S10 & it was pretty much bolt in. There was a pretty decent seat of the pants improvment over the 2.8 I just hope your rig was both cheap and clean. What kind of mpg do you get with the 2.8? At $4 a gal a good V-6 rig might make sense but my kid gets 26 mpg in his locked and lifted 95 4.0 5 spd w/31"s. I get 18mpg from my 87 4.0 A/T & 31"s.

the transmission behind the 2.8l at least in mine is a borg warner T5. like 5-90 said these are strong transmission. used in american v8 cars.

thanks for the info everyone the more on here the better for the next guy who is searching for the info.

I've had both an xj and a s10 blazer with the 2.8 and it is not worth putting a dime more than you have to in it. I still have the blazer and its my parts hauler/sometime DD. The 2.8 gets decent gas mileage as long as you go 35-45mph and avoid hills.I paid $250 for the blazer, sold the rack off of it for $150 and I refuse to spend any $$$ on it.
When it dies I will either haul it to the scrap yard or leave it where it sits with a "Free" sign and the title sitting in the window.

If it were mine I would drive the hell out of it and when/if you need more power look for a 4.0 or 4.3.

The T5 used in truck applications IS NOT the same as the "World Class" T5 used in the 80s muscle cars (WCT5, T5WC, whatever).

The T5 is not a strong transmission. The WC version is marginal at best.

I'd look for a different transmission as a long term goal. Run what you have for now if you have to but don't spend any money on adapters for it if you are somehow forced to do so. Move to an OEM transmission that doesn't need adapters or at least a tranmission that is worth spending the money on adapters for (AX-15? NV3550?).

if u are going with a v6 go with gms 3.8l all the rest are crap. try and find a 3800 series II supercharged one. thats what i have in my grand prix and it hauls ass. also gets 30mpg highway

Funny, I was just out at my customers shop and we got into this discussion. I mentioned the 2.8 > 3.4 swap and his first statement was the 3.4 has a better block with heavier/beefier walls vs the 2.8.

toplessxj89 said:

if u are going with a v6 go with gms 3.8l all the rest are crap. try and find a 3800 series

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The 3.8 is not compatible with the 2.8. It has a different bolt pattern[BPO vs Chev]. Yes, it is a better motor, no it won't go in the same hole as a 2.8 Chev without modification or adapters. It's also not as narrow as the 2.8/3.1/3.4 engines.

Run from the 2.8, it's a grenade. A buddy of mine worked for GM in the 1980's in their driveline development group and he once said to avoid anything with the 2.8 because if it hadn't had any major issues it was only a matter of time.

Mark

I'd go with a 3.4v6. Grab alumanium heads off a Grand Am (or other 3400 application) v6 and they have larger valves, (I think) 9.5:1 compression, and flow better than the 3100 heads. This basic engine design lives on in the 3500, and I think the 3600 and 3900 v6 engines as well. GM killed the 3.8 Buick designed engine a couple years back, but that's a different family altogether so I'm not sure how well that would swap.

cherokee chuck said:

The 3.8 is not compatible with the 2.8. It has a different bolt pattern[BPO vs Chev]. Yes, it is a better motor, no it won't go in the same hole as a 2.8 Chev without modification or adapters. It's also not as narrow as the 2.8/3.1/3.4 engines.

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The RWD 3.8 uses the BPO bolt pattern, but the FWD 3800 series uses the Chevy pattern. It is a 90* V6 compared to the 60* 2.8, but in reality it's not too much bigger.

It make sense to me. I was aware that there's a pretty broad interchange on the GM fwd trannys. I was always under the impression that the 3800 was just a 3.8 with additional bosses though. I stand corrected. Of course it still would not be a bolt in swap, but the blown motor could be fun. How much of a pita would it be to convert one to rwd[or 4wd]. Can you use the accesories off the 3.8?

Standard said:

The RWD 3.8 uses the BPO bolt pattern, but the FWD 3800 series uses the Chevy pattern. It is a 90* V6 compared to the 60* 2.8, but in reality it's not too much bigger.

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But check - the FWD engine usually puts the starter mounting pad on the wrong side.

The 60-degree V6 uses the "Small Chevvy" pattern (also called "GM Metric,) which is also different from the typical "GM V8" pattern (SBC, BBC, V6-90, and the like.) The 3.8L is a 90-degree V6, using either the BOP or the V8 pattern.

The 4.3L also uses the SBC bellhousing pattern and mounts - but you can get a mount cradle for it from AA, and the THM700R4 can also be had with the GM V8 pattern (it was used in K5/C10/K10, IIRC.) So, that's still on the table, and an overdrive gear in a DD is always a help with saving fuel.

Just some more food for thought...

5-90 said:

The 60-degree V6 uses the "Small Chevy" pattern (also called "GM Metric,) which is also different from the typical "GM V8" pattern (SBC, BBC, V6-90, and the like.) The 3.8L is a 90-degree V6, using either the BOP or the V8 pattern.

Just some more food for thought...

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you guys pretty much covered it all but i'll add 1 more tidbit..
on the GM 3.8s the 3.8 (231 cid) most people refer to is the Buick engine that powered the Regals and GNs of the late 80s and thats the BOP bellhousing pattern, however Chevrolet did run a 3.8 (229 cid) as well and it has the standard SBC bellhousing. the Buick ran a front mounted distributor and the chevy ran a rear mounted distributor. the 4.3 became the Chevy replacement and the Buick evolved into the 3800 series..

I forgot about the 229 V-6. I was once the unfortunate owner of a brand new 80 Malibu with that pos. After 4yrs & 60K installed a 350/350. I drove it 10 more yrs before it turned into a race car.We always called them 229s so as not to confuse it with the Buick. There was also a 200 cid chev V-6. The 4.3 Vortech had some humble beginings.

i just read this thread lookin for some info on supercharged 4.0's, and glad i did!
im lookin at buyin a 86 jeep MJ that i found for pretty cheap. i currently have a 96 cherokee 4.0 and my brother also has a 96 1/2 cherokee 4.0 so i have access to a ton of parts. i have a 4.0 from a 91 jeep and a AW4 tranny from an 87 alog with manifolds TB starter etc. sittin in my garage.
But, the MJ come with the 2.8L, my intenitons were to throw the 4.0 inthere w/ the AW4 and mate it up to whatever Tcase was in there. But if motor mounts need to be replaced and the firewall needs redoin then idk if its worth the work and $$.

my intentions for the MJ were to eventually supercharge and build a pre runner style truck out of it. so would it be better to drop the 229 in it and just bolt on a supercharger? i hope to run at least 300hp out of it...