Best engine: Not your typical thread.

[Eric Flewelling]

Ok, I'm curious as to what peoples opinions are about the best engines used in ANY jeep, including but not limited to FSJ's. This can also include engines not made by jeep and company, such as a chevy nova engine in a dj-5. However, I would like to limit it to 4 and 6 cylinder engines.

Now I'd like to define "best" best meaning fuel efficient (that's a relative term ), power (that's also relative ) easy to work on, reliable, overall just something that gets you from point a to point b. No power contests, no off roading matches, or tug of wars. The first one that pops into my head is the 4.0 HO. I've heard plenty of good things about it and seen dozens run for 200,000+ miles. I'm also curious about other engines though (232, 134 etc.) What do you all have to say?

[addicted]

Any of the I-6's are going to live a good long life and be pretty reliable if they are taken care of. You already named the best one of them ever used in a Jeep, it is basically the same design as the 258 and its' predecessors only a lot more refined. It is also going to be the most powerful and efficient of them all.

[ClovisMan]

4BT

[Artisan]

It has not been introduced to the world yet (or it is right under our noses) and it's a stump pullin' road racin' 20MPG? DIESEL... If I were a bazillionaire I would stuff a Duramax in a Jtruck and call it good, realllllll good. HA!

[Wagonforever]

From what I've seen the 4.0.

[JeepsAndGuns]

Yes, the 4.0L is my vote for the best engine jeep ever used. 255k on the one in my 93 YJ and still going strong.

[Hankrod]

I would agree with the 4.0. I have a 95 efi 4.0 in a 82 waggy - was a stock 258 truck. Its great, would like it to have a 700r4 and some 3.73 diffs. Still its a heck of a good setup. Hankrod

[PlasticBoob]

MMMhmmm 4.0.

[reece146]

When I first got into Jeeps I wasn't much of a fan of the 4.0. After driving SBCs and lots of high revving Japanese engines I found the 4.0 a bit of a dog. Sure it had power in it's way but it was slow to rev and had lots of vibration compared to what I was used to. It also didn't really make that great of a noise.

Couple things have changed my feelings over the years.

First, I got used to the noise. In fact, if you listen carefully there is a hint of the old Go-Devil sound mixed in there. Maybe I'm delusional? If you've been around the really early Jeeps it makes a "correct" noise in comparison.

The vibration and slow revving nature of the engine... well, I just got used to that. As long as you don't rev much past 4500 RPM or so it's all good.

Then one day I threw the serpentine belt while driving (lack of maintenance on my part - don't go there). There goes the water pump. I had my two little boys with me and it was the middle of winter. I kept driving until the gauge was in the red... pulled over, let it cool, drove again. Did this a whole bunch of times; ended up covering a lot of distance. That engine to this day runs like a top with the only thing done to it is the replacement serpentine belt. If I was in a Land Rover I'd expect I would have lost the engine if I gave it the same abuse.

I have since bought more Jeeps. Bought a YJ with a tired old engine and was planning on swapping my spare SBC into it. Kept going back and forth on it and eventually decided to not bother and sold all that Chevy junk. I bought another XJ for the 4.0/AW4 drivetrain instead.

I'm on this forum because I love the old FSJs and some day I likely will have one. When that day comes I'll do a 4.0 drivetrain without even thinking about. If the FSJ proves to be too much weight for the engine (doubt it) then it'll get a stroker.

$0.02

[joe]

350 Buick

opps missed the 4 or 6 only part. For revs speed I'd vote 4.0 For grunt/stump pulling 258.

[fulsizjeep]

I can try to look at this from another perspective. I sure like the 90 XJ 4.0 that is in our Eagle. Even with the older fuel injection is gets better mileage than a carbed 4.2. My brain equates best as 401 though. Oil burner, Bowtie and Ford voters need not look here.

[Oolah10293]

The Chevy 4.3L is a powerful V6 engine that revs and pulls well. I don't know if I would say it is a fuel efficient engine though. You could also use it with a GM th400 if you have any older FSJ. Another good GM V6 is the 3.8L which came naturally aspirated and i believe supercharged from the factory. Never driven one but would probably be a good engine too.

[jeeperjoe]

i love the power and sound of the v-8, trade off, economy, cruising back country, a huge waste of low rpm mileage, the 4.0 i agree, is the greatest comprimise jeep ever released, giving the present satisfaction of the 3.7, in their intro. living on a mountan, the amc 4.0 ruled the econo hill climb, and unfortunately saw its daimler demise, the chev 4.3 is a powerhouse older v-8's would regret testing from a dead stop, still economy is king, and im running the 4bt, just replacing the v-8, allowed twice the fuel range, now im looking at 750 miles, vs 350 in range, the future conversion motors will always be in someones eco-budget, and i belive we have not scratched the surface, but on my mind, one things for sure, the amc designed 4.0 will be tough to compare, in power and reliability, and will be sorely missed.

[CJ the noisemaker]

When it comes to efficiency, I'd go with either the 242 or 258. Both are real reliable and efficent.

but when it comes to a powerful engine, I'd choose the Ford 460