Stroker from pile o' parts

[Root Moose]

I've got the following pile of parts I was thinking about using towards building a stroker:

- 258 from ~1979 CJ7
- 258 from ~1983 CJ8 (swapped into `83, true year of engine unknown)
- 242 and all electronics/accessories from 1989 XJ
- 242 and most of the eletronics/accessories from 1992 XJ

The target is a 1983 Scrambler with aerodynamics worse than a brick. The engine needs to have good low end torque, be able to spin heavy 33s at highway speeds (~2600RPM w/ OD AW4 trans) for hours on end, run on 87 pump gas. Oh, and I need to do this as cheap as possible without being cheap on the things that matter.

I was thinking:

- crank from the `79 CJ.
- block/head/rods from the 92 XJ.
- RENIX and accessories from the 89 XJ.
- obtain a WJ intake somewhere.
- overbore the block just the minimum required and get pistons for ~9.2 CR (too high? ends up at ~4.6 liters?)

What should I use for a cam? Injectors?

Better ideas/approach?

Is there any real merit to using the HO style EFI system? Would a 92 vintage HO system be more or less "identical" to a 01 HO system except for the DIS/OBD portion? Just thinking that if my 01 XJ is a different system than the resulting RENIX/CJ system it ends up being another EFI system to get familiar with - or maybe the RENIX is straightforward enough that it doesn't matter?

T!

 

[Blue XJ]

Your better off using the rods form the 4.2 if you are trying to stay on a budget. If you use 4.0l rods, you will need custom pistons $$. I am running about 9.35:1 compression and it runs just fine on regular gas, although it does seem to run better on midgrade.

 

[Dr. Dyno]

Go to these sites, take a look, and decide which stroker "recipe" best suits your needs.

http://www.jeep4.0performance.4mg.com/stroker.html
http://www.angelfire.com/my/fan/stroker.html

My "junker to stroker" site has a comprehensive parts list to guide you through the parts gathering process.

 

[Root Moose]

Your better off using the rods form the 4.2 if you are trying to stay on a budget. If you use 4.0l rods, you will need custom pistons $$. I am running about 9.35:1 compression and it runs just fine on regular gas, although it does seem to run better on midgrade.

Which EFI system?

I read Dino's stroker page with the "4.5L Low-buck simple stroker" which sounds like what you have and would probably be the way I would go but Dino is saying 9.7:1 CR.

How did you lower the CR or is the page incorrect?

What would be the ideal range for CR with the RENIX system and 87 octane? I realize the RENIX can get away with more CR than the HO system... but what is "ideal"?

 

[Dr. Dyno]

What would be the ideal range for CR with the RENIX system and 87 octane? I realize the RENIX can get away with more CR than the HO system... but what is "ideal"?

There is no "ideal". Just keep in mind that as you increase the CR, detonation becomes more likely and the knock sensor will be working harder to retard timing advance. The result is that you'll lose the performance that you would have otherwise gained from the higher CR unless you use a higher grade of gas.
To minimize the likelihood of that happening, you need to build a stroker with as high a detonation threshold as possible. That means:

1. Cool intake air.
2. Cool cylinder head (180* t'stat), aluminium head dissipates heat faster.
3. Coated pistons.
4. Smooth combustion chambers.
5. Match cam to CR.
6. Optimize air/fuel ratios.
7. Tight quench height (not more than 0.060").
8. Longer connecting rods (which require custom pistons).

My 9.3:1 CR stroker doesn't detonate on 91 octane even on a 115*F day so it should run fine on 89 octane in cooler weather (except I can't get anything less than 91 octane over here). I've done 1, 2, 4, 5, and 6 from the list above.

 

[the_bandit87]

just a supposition, but IIRC I heard the earlier AMC/Renix engine blocks are built heavier than the chryco blocks. They weigh more and have a higher cromium content in them (u may want to go with the chryco one because its lighter but that is your decision). Now I think the 96+ block with the stud girdle is the strongest but if u were to run a RENIX comptuer system I think I would stick with the RENIX block because u have to drill and tap holes for a sensor (can't remember which other wise) I would use the head off the 92 H.O because it will flow better than the RENIX Head, and some people have rigged up H.O manifolds to run with the RENIX system too.

 

[Mike1331]

just a supposition, but IIRC I heard the earlier AMC/Renix engine blocks are built heavier than the chryco blocks. They weigh more and have a higher cromium content in them (u may want to go with the chryco one because its lighter but that is your decision).

I was lead to believe this is due to a heavier nickel content in the older blocks, which should ultimately increase the integrity of the metal, I guess its all subjective but I would choose the renix system and block if I had both sitten around. You got the knock sensor, no pestering codes and the computer will be more responsive to whatever you throw at it. Just use the top end from the high output. It is a very easy swap, biggest pain will be the tps.

 

[Slip Kid]

Just thinking that if my 01 XJ is a different system than the resulting RENIX/CJ system it ends up being another EFI system to get familiar with - or maybe the RENIX is straightforward enough that it doesn't matter?

Most of the Renix system can be tuned and diagnosed with a standard multimeter (volts/ohms) and a factory service manual. You're right, it's a whole new system to learn, but it is pretty dern straitforward. The system in the 01 has electronic diferences from both previous systems.

as said, the HO head, intake, and TB are better and can be made to work with the AMC block. Adapting the Renix TPS to an HO or aftermarkert TB is easy.

 

[streetpirate]

I was lead to believe this is due to a heavier nickel content in the older blocks, which should ultimately increase the integrity of the metal, I guess its all subjective but I would choose the renix system and block if I had both sitten around. You got the knock sensor, no pestering codes and the computer will be more responsive to whatever you throw at it. Just use the top end from the high output. It is a very easy swap, biggest pain will be the tps.

x2 cept the tps, heres dino's page on it

http://www.angelfire.com/my/fan/MustangTB.html

 

[philip_g]

My "junker to stroker" site has a comprehensive parts list to guide you through the parts gathering process.

which I think made me more confused :compwork:
(my fault, not your's)