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CJ8 monster build

Posted: October 2nd, 2023, 12:55 pm
by akadeutsch
Hi again. It's been a few years, and well, it's time for another Jeep build. This time the base model is an 81 CJ8.
Id like to incorporate what I learned building my first stroker and then build it bigger by adding an M90 super charger. Id like to use the same recipe I used on my first build. Does Anyone see a problem throwing 8 psi at this recipe?

2002 WJ block, decked -.025, Bored +.030, Aline Honed and Maged
2000 0331 cylinder head, Milled .006, CCed to 53.5ccs, pocket ported, intake is port matched, and exhaust is polished, 3 angle valve job
1981 4.2 12 cw crank
1988 4.2 con rods came with the crank
Sealed power 802CP+.030 hyper pistons
Comp 68-235-4 cam/Lifters/Timing set
mopar performance Valve Springs/Keepers 5642464
Stock valve Locks
9.547", 5/16 diameter, 210°double ball end, .080 thick pushrods
stock valves
Molly rings
clevite bearings
fel pro gasket set
Melling oil pump

I'm just not sure what it will take to add the M90 force induction device. Any one have thoughts? I'll post pictures of the Scrambler ASAP

Re: CJ8 monster build

Posted: October 2nd, 2023, 8:22 pm
by amcinstaller
My knee jerk reaction says the hypers lady but like much/any boost, and a lower compression ratio would make the engine happier when it saw boost. Someone here put an m90 on a stroker, but that was a few minutes ago. Try searching in the project section

Re: CJ8 monster build

Posted: October 6th, 2023, 5:49 pm
by akadeutsch
After a little searching I am happy to see the world of parts has changed significantly since my last inline 6 build a decade ago. It appears all of the questions in regards to this build have been answered. I guess we are still waiting for a cross flow head. LOL counting the days...
One thing I have been reading a lot about in regards to this build is uncontroled intake air temperatures leading to little real effect from forced induction coming at great cost. It seems like I might end up asking the question, What good is boost if I have to run Race gas? THen I quickly thought maybe the answer is a bi turbo set up. A little one that is already spooled up and then a bigger one. This way a guy could use an intercooler. But at a creep theres no ram air, making intercoolers worthless. Leading me right back my first question....Whats the best way to Force feed this thing? :deadhorse: Any off the wall Ideas?
Maybe Im best running big valves, a 3" exhaust all the way back, a 90mm corrvett TB and upping the injectors before I consider Forced Air? Im just happy to be thinking about a Jeep again. Cheers Guys. Its been too long!

Re: CJ8 monster build

Posted: October 9th, 2023, 8:04 pm
by akadeutsch
I'm still thinking about controlling IAT. I found the short stack intercooler designed for the M90 and the honest reviews that say it doesn't hurt but it doesn't do much past 8or9 psi either. Could have some value allowing another lb or 2 of boost without ping. And It's obvious why this doesn't work better. The surface area of the air exchanger is too small to be effective and it creates massive flow restriction! And IMO the solution is kind of obvious as well. There needs to be a plenum between the SC and the intake manifold. As long as the SC feeds the engine directly there can be no control of the ITA. So why not create A simple box shaped two chamber manifold that could both divert air coming out of the SC to an intercooler and collect cool air coming from the intercooler before feeding cool Air before the intake. A dual chamber brick or box shaped manifold with the intake pattern cut out of one side and the SC base plate pattern cut out of the opposing side would allow for mounting of the SC unit and provide a path for the air to flow. Short, hard intake tubes could direct air through an intercooler cut into the drivers side fender and back to the plenum while electric fans could provide the ram air. The only fabrication besides cutting and welding together a few plates would be cutting and then welding onto this cast aluminum intake manifold. Im going to take some measurements under the hood of the scrambler and come up with a plan. The brake booster may be in the way. I'm just brainstorming here. See any problems? Do you need a visual? This makes good sense in my head. Lol