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post #1 of (permalink) Old 04-29-2003, 04:25 PM Thread Starter
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4 cylinder vs 6 cylinder YJ

A friend called me to ask about jeeps. His son is looking at buying a 94 YJ from a local restorer. The restorer has a good reputation for his jeeps. The motor would be rebuilt and under warranty. His son is concerned about fuel economy, and is wanting the 4 cylinder engine. The jeep will most likely be all stock, except maybe 31" tires. No real off-roading planned. My advice was to get the 4.0L HO engine, or else he will be unhappy with the power, especially on the highway. But, he says he believes the fuel economy of the 4 cylinder will be worth it, and that the 120 something horsepower of the 4 cylinder can be improved to somethign like 150 horsepower by the rebuilder. I am skeptical on that point that it will be practical to do so, or that the power will be in a usable range.

Any input on the merits of the 4 cylinder's fuel economy, and whether it has sufficient power for highway travel and hills?
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post #2 of (permalink) Old 04-29-2003, 04:50 PM
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Re: 4 cylinder vs 6 cylinder YJ

Well Tim, if the restorer in question is Glenn of "The Jeep Doctor" fame, his reputation is not as good as you may have heard. Yes he builds nice Jeeps, but many of these are Autopac wrecks which have been rebuilt and repainted. Not to say that this is all bad because if done right it will still be a sound vehicle. I know they do very good work. But the reputation is that he is overpriced and hard to deal with. All the Jeep guys I personally know avoid dealing with him. I would be leery of the HP claim as well.

Also, I'm not sure about this and obviously someone else on this BBS will have the correct answer, but I'm told the 4 cyl is not that great on gas. He may be better off with the 4.0 in this case. Is there any truth to this?
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post #3 of (permalink) Old 04-29-2003, 05:30 PM
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Re: 4 cylinder vs 6 cylinder YJ

If you're willing to pay, get the 4 liter. The 2.5 can be a bit wimpy on hiway driving and I imagine that crossing the vast streches of Canada will take a lot of driving time. You can always add dodads to the jeep later, but replacing an engine can be a pain. I like my jeep, but I think I should have held out for a 6 cyl.


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post #4 of (permalink) Old 04-29-2003, 05:31 PM
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Re: 4 cylinder vs 6 cylinder YJ

if u look at the hard facts, get the 4.0L, it gets what 2 miles per gallon less, and the difference with power is like night and day, tell him if u gets the 4 banger, that he will regret it..
post #5 of (permalink) Old 04-29-2003, 06:08 PM
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Re: 4 cylinder vs 6 cylinder YJ

while the 4-cylinder is quite capable off road (except for deep thick mud) it is absolutely TERRIBLE on the highway. I get approximately 16 mpg on highway and the same in city!! add to that AN"Y incline will slow you down to 60 mph in a second. add to this mix 31" tires that not only create more drag on the tarmac, but also increase vehicle height and you won't be seeing 70 mph in a long time!
however you do enjoy lower insurance, a lighter vehicle, less tire wear (partly due to weight, partly to not being able to roach the tires). and the bragging rights of "well i just did it in my little puny tiny 4 banger!" not that i ever get to say this, but you could, if you could.
from a 2.5L owner to a prospective 2.5L owner, bet the 4.0L you won't be sorry you did.

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post #6 of (permalink) Old 04-29-2003, 07:29 PM
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Re: 4 cylinder vs 6 cylinder YJ

Mileage, smileage.
Get the 4.0L.
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post #7 of (permalink) Old 04-29-2003, 11:05 PM
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Re: 4 cylinder vs 6 cylinder YJ

I own both. I'd say that if any power is desired ..the 4.0 is the only choice. I happen to like my 2.5 ...but it's not a champ on the highway. Mine's an automatic ..so I lose a few horses just in driving the machinery. The 4.0 ...even with just 3.73 gears and 33" tires has no trouble on the highway ..even in head winds.

As far a fuel economy (again mine is an automatic) in REAL WORLD (rushing everywhere and driving as fast as possible in the space alloted) there is virutally no difference between the two. Now if drive sensibly the 2.5 is the champ. I can yield over 22 in stock trim as long as 60-65 is my top speed. The 4.0 with the heavier tires ...yields a constant (since I bought it) 17-17.5.

I would say the 4 banger is okay ONLY if this jeep is a stick. You can then just wind it out to achielve the power that you desire in most demanding situations. You also have the option of not using 5th if the situation dictates. You have no such options with the automatic for the most part ...at least practically speaking.

Me ...I don't need to go that fast ...so it works for me. If I go to taller tires ...I'll regear if I'm not happy with it.
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post #8 of (permalink) Old 04-29-2003, 11:45 PM
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Re: 4 cylinder vs 6 cylinder YJ

Get a 6. I tried ALL I could to find a 6 when I was shopping around and just my luck I found about 6-7 Jeeps ALL with the 4 banger. I had to settle and Im kinda dissapointed. I really could have used some extra power on the trips I sometimes take. And a point that noone has talked about yet and I to forgot about....TOWING!!! I have 33' BFG/MT's on my rig and I have had to tow around a trailer with 2 4-wheelers on it. When I tell you that poor thing wouldnt do over 55, I mean WOULD NOT. I might have pushed more if i was winding out 4th gear at 4 RPM's. I get pathetic gas milage and I would have loved to get my hands on a 6.
post #9 of (permalink) Old 04-30-2003, 05:05 AM
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Re: 4 cylinder vs 6 cylinder YJ

This is easy. Go with the 6.

Its not as simple to think..."Oh less cylinders gets better gas mileage." It doesnt always work that way.

If that little 4 banger has to work its wimpy tail off to move that Jeep, it will do roughly the same MPGs as a 4.0 thats leisurely along for the ride.

The 4.0 is a legendary motor, known for reliability, good low RPM torque, and a fairly strong aftermarket following. Its resale value is also much higher.

A Jeep is a heavy vehicle with the aerodynamics of a barn. A 4cyl might work great in a Geo, but its got no place in a 3500lb 4x4.

The only possible argument I could see for the 4cyl...is that it would come with 4.10 gears....but thats really not an issue anyway...since the YJ NEVER came with a D44 option.

I have personal experience driving a 4 cyl bone stock 5speed YJ. It was a turd. Granted, I've never owned anything with less than 318cid, but I know that it was dangerously slow, especially on hilly freeways or when trying to merge into traffic.

Go with the 4.0!

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post #10 of (permalink) Old 04-30-2003, 09:11 AM Thread Starter
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Re: 4 cylinder vs 6 cylinder YJ

Thanks all for the advice, I shall be more firm in my resolution that he should get the 4.0L engine. It sounds like gas mileage with either engine is unspectacular.
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