Best path forward? 4.7 stroker / 4.0 forged, supercharger or a combination?

sierradmax

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I recently purchased a project motor. My Jeep is an 05' Rubicon TJ with 6-speed and a strong running 150,000 mile original 4.0. I purchased an 05' long block along with a Magnum Power Super Charger from a local sale. Original user got fed up with fueling issues, overheating, etc. and opted to pull the motor for an LS swap. So, I decided to head down another rabbit hole with hopes for a fun build.

The donor block came with an edelbrock performance head and has some slight scoring on #4 & #5 cylinder. I dropped it off to a reputable engine builder and was told it was salvageable. Now, said builder can't get to tear-down/fabrication for a few months due to other engine builds in progress (I guess a wait means this builder is good). So, I have time to plan out my path forward. I'm rebuilding my NSG-370 and am awaiting an Atlas twin-stick so when the time comes, I'll pull the drive-train and do everything at once. My options are:

1. Hone the cylinders and build the 4.0 back to spec with SCAT rods & pistons & Edelbrock head
2. Build to 4.7L stroker, forged internals & Edelbrock head

Both options will permit me to ultimately decide whether or not to add more power with the super charger install. At least forged pistons and rods will be installed but do I need to decide if the supercharger will be run or not to help the builder decide on camshaft, piston selection, etc? Doing some research, seems like the stroked 4.0L runs hot, adding a supercharger to the mix will probably make it run even hotter. I'm prepared to revamp the cooling system with a new radiator, shroud, E-fan, hood louvers and so-on. I also realize that a good tuner can make or break this build. Looks like this website has brought me front and center to some good tuners still tuning our TJ's.

Your thoughts?
 
Can we ban you?

You can't keep posting cool stuff whilst I'm getting my list together.

Haha! I did my research when it came to this sort of stuff, and as far as I am concerned this is THE BEST way to get a crap ton of power out of the 4.0 (y)

Of course it's not cheap, but still...
 
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Not cheap for sure but neither is a stroker and/or super charger. Interesting how O2 bungs are in #2 & #6 downtube. Then one before and after mini-cat.
 
It’d surely be fun for a while but from what I’ve researched the stroker adds some problems that the supercharger would seem to exacerbate.
 
Need to leave some money for the turbo install too! That supercharger should let the turbo spool up quickly. 👍
 
It’d surely be fun for a while but from what I’ve researched the stroker adds some problems that the supercharger would seem to exacerbate.

What stroker problems are you referring to? A stroker seems like the least complicated option. Power adders add complexity and more intake temperature.
 
What I don't understand about the rod angle being an issue is that a stroker 4.0L has better rod ratio than a 4.2L. The stroker crank used for the 4.6L or what I am building, a 4.7L, is literally a 4.2L or 258 crank in a 4.0 block. Most stroker builds use the 4.0 rods which are 6.123" vs the 4.2 rods which are 5.875".

It's kind of funny that forced induction can benefit from shorter rods. Long rods move the piston away from TDC slower increasing potential for detonation. BMW used a 1.48 rod ratio in a turbo M3, likely for that reason. For comparison a stroker 4.0 has a 1.57 rod ratio.
 
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What I don't understand about the rod angle being an issue is that a stroker 4.0L has better rod ratio than a 4.2L. The stroker crank used for the 4.6L or what I am building, a 4.7L, is literally a 4.2L or 258 crank in a 4.0 block. Most stroker builds use the 4.0 rods which are 6.123" vs the 4.2 rods which are 5.875".

It's kind of funny that forced induction can benefit from shorter rods. Long rods move the piston away from TDC slower increasing potential for detonation. BMW used a 1.48 rod ratio in a turbo M3, likely for that reason. For comparison a stroker 4.0 has a 1.57 rod ratio.

That's exactly what I've discussed with my engine shop. A 258 crank in a 4.0 block bored .060"
 
If you have the budget, do both. Make sure your engine builder (or parts guy) understands that you'll be boosting the engine it'll change what specs to build to (not just stronger bolts etc).

If you have budget for only one or the other, a supercharger is quick, relatively easy, and can be swapped to a stroker in the future. The power is pretty crazy. I've been trying to be careful pulling onto the highway not to burn my 37" tires.
 
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Do you plan to do much wheeling out west? Lately I’ve seen quite a few people with boosted engines complaining about the poor/lower octane gas available when they go west and having detonation issues. Something I never really considered coming from the Midwest.
 

Hi Chris,

I know that this is an old thread, but wanted to get your current opinion on this long header system. I saw in another thread that you dont recommend after market headers due to cracking and other issues, but I see you recommended this one in this thread. Do you think this one is safe to use on a stock TJ with an MBRP Cat Back? Is it worth spending the money?
 
Hi Chris,

I know that this is an old thread, but wanted to get your current opinion on this long header system. I saw in another thread that you dont recommend after market headers due to cracking and other issues, but I see you recommended this one in this thread. Do you think this one is safe to use on a stock TJ with an MBRP Cat Back? Is it worth spending the money?
It’s an amazing system, one I would highly recommended IF you have short arms and don’t plan on running any sort of engine skid. We tried to fit it with my Savvy mid-arm and Savvy engine skid and unfortunately they won’t fit.
 
It’s an amazing system, one I would highly recommended IF you have short arms and don’t plan on running any sort of engine skid. We tried to fit it with my Savvy mid-arm and Savvy engine skid and unfortunately they won’t fit.
Sorry for the newbie questions, but what are short arms vs mid arms, and what is an engine skid? I basically have a stock TJ with the 4.0. I just installed the MBRP catback, and that’s all that’s done performance wise.
 
Sorry for the newbie questions, but what are short arms vs mid arms, and what is an engine skid? I basically have a stock TJ with the 4.0. I just installed the MBRP catback, and that’s all that’s done performance wise.
Short arms are the factory length control arms. Mid-arms are a longer arm that has to be welded on.

The engine skid is a necessary mod if you plan on doing any serious off-roading.