i6 build strategy

[rufus1138]

trying not to thread jack here, ive been searching all the forums i can find for a discussion on this and im coming up blank everywhere.

heres the deal, everyone talks about 4.0 heads on AMC 258 i6 / 4.2l blocks and building in that direction, theres also lots of talk about 4.0 stroker motors of all kinds, AMC 258 i6 / 4.2l mini-strokers all the way to 4.9 mega-strokers and on to turbo/supercharged 4.0 strokers. heres my deal, im thinking that it could be a good idea for me to prepare a swap-in motor for the CJ5 and leave my numbers matching AMC 258 i6 / 4.2l alone until a rebuild is necessary, ive got a storage unit that im going to attempt to pack with a full backup drive train from wheel hubs to valve cover.

so whats the better path for pump gas torque. a 4.0 stroker or a AMC 258 i6 / 4.2l (stroker? 4.0 head?) everything here will spend time pickled, the jeep is a family heirloom and will never be sold, current thinking is to maintain stock numbers matching capability (no mods to frame side engine mounts or crossmembers, engineering fixes are acceptable)

sorry to ramble. debate go, whats the all out best for low rpm torque from an i6 gasser.

 

[IOPort51]

The problem I have with the strokers is that the HP/torque does not happen until a bit better than 4000 rpms. Or so I have been told by an engine builder who was trying to sell them at a car show I attended.

I like the stealth modification school of thought. It is a whole lot more than what first meets the eye. When the hood is closed you don't see the 4.0 head with three angle valves with the header and the motor craft 2bbl. The MSD 6 capacitor discharge ignition with team rush upgrade is not that noticeable and if you are not looking closely you will miss the Dana 44 axle with OX locker and/or the spartan locker in the front. 2.5" of lift with 1" body lifts gives very comfortable clearance for 33" Swampers and does not look odd with 33" BFG a/t s that I like better on the street. Not many could see a wide ratio T-18 or tera low Dana 20 TC at a distance but this will cruse comfortably at 70 while having a crawl ratio of about 70 to one, which is very respectable.

Do you have the wide or close ratio T-18 ? Wondering i am, will a granny low gear box be a lot of good in the Florida sand??

This is interesting, I like the set up I have very much, for what I like to do. But if I lived in Florida I would use a T-150 and the extra RPMs of the stroker may not be a bad idea. I would be spending a lot of effort keeping water and sand out of the machine.
cant wait to see how this comes out.

 

[rufus1138]

not sure about the T-18 ill pull some numbers when i pop the skid plate to check fluids. thanks for the support on the build, im starting to get the same idea about the stroker motors, everything takes more air to make that rediculous torque number and its hard to find someone to compare the two at say 1800 rpm, thats where we spend a lot of time and where we need to see results in a build. im beginning to think im just gonna find a second AMC 258 i6 / 4.2l and make clones at a local machine shop. blueprinted, balanced, full roller AMC 258 i6 / 4.2l with a lunati torque cam or something of the like should be a great powerplant.

 

[IOPort51]

not sure about the T-18 ill pull some numbers when i pop the skid plate to check fluids. thanks for the support on the build, im starting to get the same idea about the stroker motors, everything takes more air to make that rediculous torque number and its hard to find someone to compare the two at say 1800 rpm, thats where we spend a lot of time and where we need to see results in a build. im beginning to think im just gonna find a second AMC 258 i6 / 4.2l and make clones at a local machine shop. blueprinted, balanced, full roller AMC 258 i6 / 4.2l with a lunati torque cam or something of the like should be a great powerplant.

I have never seen dyno results on a "torque" cam. A roller cam may be kind of cool but truth be told, the stock cam works pretty well. anybody out there want to stick up for the cam they run other than stock? I am of the opinion it is more trouble and expense than it is worth. there are better places to spend money.