engine swap from 360 to 258

[Chuck]

Hi gang, I am new to the board. I have a 86 GW with a stock 360 & a 727 tran. With gas hitting $2 a gal, I was thinking of trading down to a 258. I won't be doing the work myself (I know my limitations), but was interested in any benfits/problems. Help

[The Anti-Chrysler]

Don't think I've ever heard of a swap like that - but with gas nowadays, I can see the general idea.

I would tend to think that by the time you shell out all that money for the swap, that's alot of gas that you could otherwise burn. Don't forget that the 258 will be working harder to move the big vehicle, with less power to spare, so the throttle will be on more. You might only pick up 2, maybe at best 3 mpg if you're lucky. And of course you will lose the V-8 performance. A 258 powered A/T Wag is no rocketship. :D

I'd consider a tranny swap to manual first, or if that is out of the question, update the engine you have. A carb rebuild, tune-up and ignition upgrade can get 2 - 3mpg in a out-of-tune engine. For what you would spend on the swap, you could retro your 360 with a TBI fuel injection kit, and a TFI upgrade. That would probably give you the same benefits of going to a 258, or at least close. You're never really going to get good mileage in a FSJ. They're too heavy. My 2 cents.

P.S. Welcome to the board - it's a very good group of people here, as you will soon find. smile.gif

We can help if you still want info on the 258 swap.

[89grand]

Mileage? Grand Wagoneer? Am I missing something here? Those two words do not belong together unless you're talking about how many miles your rig has on it. A 258ci.in a Grand would have to really suck, I wouldn't even considere it. If gas mileage is a concern than you could use the money that would otherwise be used to make your Grand almost umbearable to drive and buy some old beater economy car or truck.

[The Anti-Chrysler]

Stock 258 = 114 HP. 114 HP with Auto Tranny in 5,000 lb. vehicle = :eek:

[Wagoneer622]

It's not as bad as you think it is.

[Max Power]

I've got a '91 honda CRX that gets 36 mpg. Its great for running around town. I get very little respect on the road (compared to driving the Jeep) but it's nimble and I can park it almost anywhere. I got it for $2200.00, not sure how much a motor swap costs.

[andy d]

258s were the base model motors in the wags. ive seen a few 84 and 85 gwags with 258s. Scotty's wag is an original 6. they have the 273 axles which doesnt help the performance much. for what it will cost you, you could prolly buy a 4cyl econo beater. save the wag for week ends. a decent compromise is to get that rig running best you can. that and a light right foot will give the best mpg you can get for the least amount of money and effort.

[mtn goat]

I have a 258, mind you its behind a manual but I have all the power I need. sure wont beat my camero but jeeps shouldnt go fast...you'll miss the trees....I get 20+ mpg to boot.

[Cecil14]

Have you guys ever driven anything with a 258? The 258 has plenty of power. Sure it's not a V8 but you're making it out to be a total dog. It doesn't have a whole lot of horsepower but it's got the torque to make up for it. In my 258 J-10 I got 20 mpg most of the time. That was with a T-176, 2.73 gears, and 31" tires.

I would have to say that it probably won't be worth the effort of swapping out the 360 though. Like has been mentioned tune your 360 in as best you can and do the TFI upgrade. If you can afford it go FI. If you're easy on it you can probably pull 15-16 mpg or more out of it.

Good luck,
Anthony

[sloop]

For those of you bashing the 258 in a GW, have you ever driven one? It isn't a racecar but my 258-powered Wag had enough power for me. I got 19mpg highway on a tired 258. The 258 builds up its torque at low rpm.

But, for the cost of doing the motor swap, I think your money would be better spent on buying a fuel-effecient car.

[ March 04, 2003, 05:47 PM: Message edited by: sloop ]

[brielly]

I have the 258 in my cherokee with a weber carb and it has plenty of power. Its not a race car, but no jeep is. What about swapping in a 4.0 instead?

[Stolen76]

if you are realistic about your mileage goals you can accomplish anything. of course it is very cash flow orientated !

I'm running 14.5 mpg with my 360. Just ran an 850 mile trip with a 6'x12' trailer behind me, we hit the truck scales just for entertainment and found we were grossing a bit over 9,000 pounds. I got 11.2 mpg on that trip.

Holley 600, 61 mainjets, SP2P intake, 31" tires and P/T kit with 16% OD. Otherwise it's stock and needs ignition work in a bad way. I could see hitting 16 mpg with a light foot. You'd save with a 258, but the cost of getting there would be pricey if you have to pay to get it done.

[Mikel]

Buy a 30MPG car. Gas savings will quickly make the car pay for itself and you will enjoy driving the wagoneer much more smile.gif

[dharmabum]

Nothing against the 258 but it would take years of gas savings to pay off the cost of the swap. The 258 is a good motor and if you had one to start I would say to put another one in, but if your 360 is okay than I would work on that for mileage. You should be able to get at least 15MPG out of it. If you are intent on doing the swap you will need a new motor mount (passenger side?) and to reroute the fuel line as well as relocate the tranny crossmember as they were in different spots for 6 cyls and V8s. Im sure there is more to be done but this should give you the idea that you are better off to stay with the 360. I figure gas prices will come down again sooner or later so I'm keeping my V8s. Besides I think my 72 Wag gets better mileage than my 97 Cherokee. :confused:

[ March 04, 2003, 06:57 PM: Message edited by: dharmabum ]

[timmirvin]

My 2 cents.....recently completed the carb. intake and TFI upgrade. The rest of my GW's stats are in my signature block.

I went from barely 12 mpg to 18+ mpg on the intersate @ 65-70 with cruise on. Harley starts better, idles smoother, acceleration is better, runs cooler, etc. etc.

The entire upgrade cost quite a bit less than a used "beater" and I did not double my trouble (insurance, maintentance, liscensing, inspections, titling, etc.).

Gas prices will not remain at theses levels for long. And if you choose to ugrade your GW now, IMHO, you won't be sorry in the long run....

Just my opinion.....for what it is worth.....
tim

[Masato]

The 258 in my Cherokee has plenty of torque (with 5sp manual trans and stock gears) to move the 33" MTR's. Mileage is about 9mpg, although it has seen 10.5mpg when freshly tuned.

In fact i'm thinking of swapping to a 360 figuring I'll get the same or better mileage and torque with more HP.

[The Anti-Chrysler]

Nobody is knocking the 258, it's a **** good engine, but as the post above states, a swap for that reason doesn't make alot of sense.

[89grand]

I wasn't knocking the 258 either I just don't think the swap makes sense. I think my Grand with a 360 is a slug on the street and a 258 could only be worse. Now if we're only talking about off-road use then a 258 is probably ok. I took my 66'Dodge Monaco 500 with a 383 4bbl for a drive the other day and it just made my feeling of the Grands slugish performance even worse. My 65' Dodge Coronet 500 with a 361 2bbl will absolutely smoke my Jeep too. I guess I'm just use to the performance of old cars with V8'S so 6's seem under powered.

[The Anti-Chrysler]

Chuck wanted benefits/problems, and we gave 'em to him!!

I think the concensus is:

1. Tune up and or upgrade the 360 or;
2. Buy a econo-box for commuting and save the Jeep for cruising, etc.

[Chuck]

Thanks for all the great advice!!, it sounds like I will be futher ahead to take the approch that Grease Monkey took. I will begin looking at that. Any advice about that upgrade would be appreciated.
Thanks again for all the GREAT advice.
Chuck

[The Anti-Chrysler]

Which Grease Monkey?? tongue.gif :D

[mark j]

With gas prices up I now drive my '85 cherokee. No where near the power of my wagoneer, but at 30mpg it is not a bad 4X4. Costs me $1.80 per day to drive vs $5.80 in gas. Allows me to spend more on upgrading the wagoneer as well!

[powerfiend]

I was thinking of swapping in a late model 4.0 with a 5spd.(stock 190hp/225tq) in place of the 360/727(Stock 130hp/245tq approx.). That is not much difference in power and my 360 has 168k and is shot. I'm also in CA so the most I can do to upgrade th 360 is the TFI, clean up the ports, an exhaust, and maybe a slightly bigger cam. The 4.0 has additional benefits of being upgradable with 4.7 stroker kits, cams, and superchargers that can pass the smog tests. In the end I think the 4.0 is a better choice.

[89grand]

I would't be fooled by those power numbers. The 4.0 is a great engine but it does not have alot more horsepower and almost as much torque as the AMC 360. The 360 has considerably more torque and probably fairly close in horsepower. Not to metion that that swap sounds extremely difficult i.e Tranfercase,motor mounts,computer wiring etc, etc. The 4.0 moves the Wrangler and Cherokee pretty good but add another 1000lbs. with the Wagoneer and things change quickly

[The Anti-Chrysler]

I agree with 89grand. The 4.0 maximum horsepower number is certainly more than the 360, but it's the torque band that really moves a rig like these. Torque is strictly a relationship of cubic inches. That's why these rice burners can have 200 hp, but still 1/2 that in torque, because they just don't have the cubes. Sure, you could wind out the 4.0 much further, but it wouldn't pull a trailer as well, or be as good as a trail rig. 0-60 time is debatable - it might be a tad faster due to the further breathing capabilitlies of the 4.0, but you'd be heavy into the pedal.

If any benefit there is to the swap is the late-model efficient fuel injection system.