Hi all,

New member, not new to looking at the forum...lots of great information here. I'm guessing out of everyone I have talked to about this you guys will consider me the most sane...I'm going to be putting a slant six in a 97' Jeep TJ over the summer. The reason I have chosen the slant six is because of the excellent service record, the high amount of torque and because it is not a common swap choice and I wanted to do something unique. I worked out how the drivetrain is going to work and now I'm trying to focus on the engine. I have a 1981 225 with hydraulic lifters. My question is what performance upgrades should I be looking at to increase the performance and keep the reliability? I'm likely going to stay with a carb.(least to start with) I'm interested in putting a different intake manifold on and headers, what do you all suggest for this? As far as cams and pistons go what is suggested for a daily driver? Sorry to go on and on...I guess I just would like the best performance options for a daily driver.

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New = not always better.

Welcome on the board. First question: Where do you live? There are fewer and fewer places where you can get away with such a swap as you describe. If you don't have emission testing now, you very well might before long.

Second question: Why? The Jeep 4.0 inline Six is just about as durable as the slant, and you can get a lot more power and torque out of it with a lot better fuel economy.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

interesting comparison dan. not sure i agree withyou although i usually do. the slants i have had in a bodies and f bodies(all with stickshifts) consistently got 18-20 around town and 24- 25 on a trip. all went 240k or more. no oil burning or engine crapouts. on the other hand i had 2 jeep cherokees with 5 spd overdrives, the 4.0 six. never got better than 12 around town and maybe on a trip. both were early oil burners and also had rear main bearing seal leaks. one had 150k and the other about 160k when i let them go. i was unimpressed with that engine, although some have told me how good they thought the 4.0 was. i maintained all these engines and took good care of them. the difference may have been the heavier weight of the cherokees( full frame and 4wd) causing more fuel used and load on the engines. what do you think? bob f

Cherokee = much harder to push through the wind than an A-body. Mileage will not go up with a slant-6, it'll go down.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Hey Bob
I have had 3 4.0LHO Jeep Cherokee's and they got 22 to 35 MPG the 35 was a 4X4. This was on straight level country side. None burn any oil and I finally wore them out at about 300K.
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

Yeah, Bob's experience probably isn't the norm. My Cherokee with the 4.0 currently has 270K and runs like new. Uses no oil and gets the 21mpg it's rated at. The only time its ever gotten as bad as 12 is when the o2 sensor failed.

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I had one of the 1992 4.0 HO 4x4Laredo's...it was a good rig until an uninsured migrant worker totalled it while parked outside my girlfriend's apartment. Plenty of power, averaged 18-20 mpg in town, best of 24mpg on the highway...got 26 mpg one time returning from a trip to Bend, OR (down hill the whole way, most of the time coasting....).

-D.Idiot

hi dan and sages- am surprised at the positive comments about the 4.0 . have to conclude my experiences with it were not typical nor representative. mpg experiences really surprise me. with other factors being equal wouldnt the 225 sl6 get better mpg than than the 4.0 jeep 6? my friend dan seems to think not. forgot, but i did have a 73 gremlin with a 3 spd, 232 six and a steep 2.73 axle back in the 70s which did get equivalent mpg with the sl6. the 232(3.7) looked just like the 4.0. it was a good reliable engine, no crapouts or leaks, but got killed in noreaster flood in 91. will be more open minded on the 4.0. bob f

The 4.0 has much more advanced combustion chamber, intake and exhaust tracts, fuel induction and engine management, so the factors will never be equal. You would have a very tough time making a carbureted 225 get equal or better mileage than a fuel-injected 4.0 in a Jeep.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

id stick with the 4.0. thats a beast engine. i always thought it would be cool to swap out a slant and put in a 4.0

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What's that fuzzy blue thing being hurled this way?
::stick::
BOOSH!!!

I live in Nebraska, they actually got rid of emission testing a while back. To answer your second question I guess I should have been more specific about the jeep...its a four cylinder Jeep that I pick up cheap because the engine is toast. I figured for the amount of money the slant six would be more bang for the buck b/c, to do the swap to a bigger engine I would already need to change over the fuel system, transmission (going to a NP-435 and adapting it to a NP-231 transfer case) and the majority of the wiring...plus I tend to do a fair amount of off-road stuff and the slant six is easier to work on in a pinch than the 4.0. Also, not really a fan of swapping to a V-6 or V-8.

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New = not always better.

Thats funny that you mention that. I was looking into off'ing the slant and putting a 4.0 in. Even found the bellhousing to go to my np435

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To many damn dodges and now a slant