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post #1 of (permalink) Old 12-05-2000, 02:41 AM
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whats the best engine for the job???

so whats the job??? all jobs. trail (medium trails in colorado). moderate mud, and highway performance. i want 250 hp at the wheels bolts directly to a nv4500. and gets at least 20 mpg on the highway. whats the jeep. 1980 cj7 has a 304 in it now.....my guess is a fule inject chevy 350. is this swap practial for the average back yard mechanic to do. i have changed trannys and replaced motors (carberated ones). i'm afraid to tackle the computer controled encgines cause there are so many wires. and swaping it in to a differnt vehical doesn't make it any easer. i'm looking for a used engine with around 50 to 70 thousand miles on it. whats a practial price?? i have a year before i will have the funds to do the swap. i'm just getting started on gathering the information. any info. about ANY possible engines that would do the job would be great

80 cj7 304..
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post #2 of (permalink) Old 12-05-2000, 03:05 AM
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Re: whats the best engine for the job???

Mike, i hate to burst your bubble, but i figure who better than me?

You are NOT going to get 250hp at the wheels, shile acheiving 20 or more miles per gallon, unless you're running some kind of nuclear powered device for propulsion. A Diesel wont get you that much horsepower, and a gas wont make anywhere near that kind of mileage. Like i said, i hate to break it to you.

A more realistic goal would be to decide whice of those two numbers, the HP of the MPG is more important to you. And i dont see the need for 250 hp at the wheels in a Jeep. You will have a transfer case so you can get lower gearing for more torque. And with all that power and that NV4500, i sure hope you dont plan on running anything less than front and rear Dana 60s for axles. Anything less wont live under there for long.

I have never performed a fuel injected engine swap, so i cant speak from experience, but from what i read, i gathered that its not TOO much more difficult, providing you get ALL the wiring harnesses and ALL the computers and electronics from the donor vehicle, along with having a place to mount the various sensors. Be advised the cooling will be an issue unless you get a top of the line radiator.

Your project is ENTIRELY possible, except for the conflicting MPG/HP #s. Other than that, its going to take a LOT of time and a LOT of money to accomplish. Sure would be worth it all when its done. Good luck, and i hope i've helped you some!!

mike

Give me Jeep or Give me Death!!!

(Will trade functioning organs for CJ-7 or flatfender)
post #3 of (permalink) Old 12-05-2000, 03:28 AM
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Re: whats the best engine for the job???

well maybe. the 250 hp at the wheels is more than i need. i hate being passed on the highway going up hills. my jeep is the only way i want to travle. and i do alot of it. so i'm trying to build a jeep that can do everything.

i'm not a hard core rock crawler. or a serious mudder. i like to go wheeing up in the mts of colorado on moderate trails.

is this more realistic 16-18 mpg on the highway at 75 mph. whats a safe crusing rpm for and amc v8? i have a t-5 in my jeep now and run 2000 rpms at 75 mph with my 31s.i drive across the country all the time and i alwasy find time to do a little wheeling where ever i go. thanks for bursting my bubble. i'll take any advice i can get even if its not what i want to hear.

80 cj7 304..
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post #4 of (permalink) Old 12-05-2000, 07:44 AM
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Re: whats the best engine for the job???

I've got a few opinions, and there just that opinions. One option that I would consider if I had your CJ7 would be to convert to a Howell Fuel Injection conversion for the AMC 304. http://www.howell-efi.com It's much easier to remove and replace the same engine in a vehicle, than to convert to a Chevy engine. A couple weeks ago there was a string of posts on "what did you engine conversion cost" I replied with a total cost of about 3,000 for my Chevy engine conversion on my 80 CJ5. Then I spent about another 1,000 for a Ford T-18 conversion. The cost of rebuilding an AMC 304 is not as cheap as a Chevy 350, but when considering there is still aftermarket performance parts for the 304 there is a good chance of getting nearly 250 HP at the rear wheels with an AMC 304 combined with a GM TBI fuel injection system and get close to 17 MPG.
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post #5 of (permalink) Old 12-05-2000, 12:29 PM
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Re: whats the best engine for the job???

thanks alot i was looking at the fule injections kits for them. i was thinking about getting a 360 core and rebuilding it myself. i would keep the 2brl but put a cam in it. then when i can afford it put one of the injection systems in it. thanks for the post i think it would be alot cheeper to do the 360 and the howell throttle body kit. any one else have any ideas?

80 cj7 304..
post #6 of (permalink) Old 12-05-2000, 01:11 PM
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Re: whats the best engine for the job???

Just a little suggestion here. You will be amazed at the amount of USEABLE power guys are getting with a 258 with 4.0 head and FI. Note, I said useable, that is great bottom end for wheeling along with a decent amount of hp for the top end. We're in the process of putting what I guess you would term a "blueprinted" stock 258 in my CJ-7, that low end torque is too good.

Brad
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http://www.off-road.com/land
Vice-Pres. Rock Garden 4 Wheelers, Farmington, NM
post #7 of (permalink) Old 12-05-2000, 01:32 PM
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Re: whats the best engine for the job???

Mike,

To give you an idea of what Brad is talking about, I recently did the 4.0 head/MPI swap.

This past weekend I drove my scrambler on a campout with the Boys Scouts. I had myself, 4 scouts, my m416 trailer (half full with firewood, half full with gear), the back of the scrambler full of gear (stoves, lanterns, packs, etc.). I was hauling a lot of weight. I have the nv4500 and rarely was out of 5th gear. I maintained speeds around 75-80 the whole way except on steep grades I would drop to 4th gear. I have 33's and 4.10s in the axles.

I think this combo is perfect for a jeep. Also, in a cj7 it is even better (less vehicle weight and less room to load with gear). I thought I wanted a V8 until I learned more about this combo.

I have no regrets whatsoever.



-raymo
Scrambler
258 4.0 Head/MPI,NV4500,D300,4.10's,HS9500
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post #8 of (permalink) Old 12-05-2000, 02:44 PM
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Re: whats the best engine for the job???

well i already have a 304 in mine now so a 360 should bolt right in. i dont see the sense in putting a smaller engine in. that mpi cost 1900 bucks. the howell only 1100. i could put that 800 in to buying a core and rebuild kit. i probably could get the power i want out of my 304 by putting a cam in it. and a intake and 4brl. but there is no substitute for cubic inches. 401 would be over the top for what i want. i think i'll go with the 360 maybe put a cam in the 304 till i save up enough for the 360. my best friend has a 258 in his i'll have to tell him about the 4.0 head. is it a direct bolt in? can he use his original intake and crappy carb? i dont think the mpi would work on his cause we pulled the electronic ignition one it and put in points. thank for the info. any more would be great.

80 cj7 304..
post #9 of (permalink) Old 12-05-2000, 03:25 PM
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Re: whats the best engine for the job???

For your friend the MPI kit will work. The kit comes with a new distributor. Just curious, why in the world would you have pulled electronic ignition for points? For more information on the 4.0 head swap see http://www.monsterslayer.com/jeep/. The 4.0 head will work with the 258 intake, but the exhaust manifold does have to be changed. Since you seem to be interested in Howell for your 304 or 360 be aware that they make a great kit for the 258. I have it and love it. Best modification to date.

'75 CJ5,258 w/Howell EFI,T18a,4.27's,33's,On-board air,Warn 8274
post #10 of (permalink) Old 12-05-2000, 04:30 PM
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Re: whats the best engine for the job???

Isn't 16-17 MPG a bit much for a V8 CJ? (Well, maybe with real tall gears.) My 94 YJ 2.5 gets about 16-17 MPG, but I have never had that kind of mileage with any of my V8 CJ's.

Kriss

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