I have tried to do a few different things with my 11JKU. I worked with Inertia Motorsports to make a 4.0 stroker using the Dodge Nitro Block and after 5 months of back and forth both of us decided that it can be done but entirely too much work for the cost.
I have sold that engine and instead of a hemi/LS swap, I am wanting to build a modded 3.8 w/ supercharger. Since I have a small intake oilleak I am going to add a SC when I repair and go through the engine this winter as it will hit 100k miles.
So my questions are directed at the readers who have added a SC.
1) What bottom end preparation did you do? Do you perform the same prep as a V8? (ARP Bolts etc)
2) Since the engine will be torn down I am going to go with 505 performance Heads and Cam. Would YOU additionally go .30 over on the block?
3) Gears will be done at this time, I have 3.73 with an auto and only will run 33's would you add in 4.10s or 4.56? This will never see rocks.
4) I plan on using the Magnusson or Sprintex SC. Anyone have any experience with the Sprintex?
I don't have a SC but I really think you will be MUCH happier with 4.56's and 33's. I would not pay money to go to 4.10 with 33's. Most who have SC's use the same gearing that the non-SC guys use. I honestly still wonder if you would be happier with 4.88's but if you live in a flat area and you never tow anything the 4.56 might be great.
Just perusing threads and stumbled across this and I can definitely contribute.
We work with Sprintex. Before my tenure at JKS, I worked at a high performance 4x4 shop and threw forced induction on everything I could. I was never happy with anything for the 3.8 for various reasons, whether it was install, performance or tuning problems.
When I started with JKS I inherited the JKS 2 door with an unintercooled 1st gen Sprintex. After hashing out some tuning issues, we decided to throw the Stage II kit with a smaller pully and intercooler and their new Diablo tuner and the difference it made is unreal. The JKS 2 door is a full 1000 lbs overweight on 37s and 5.13 gears, and it's still quick! Pinging is minimal and only at high altitude (I throw a bottle of octane booster in there for those trips). I haven't blown the 3.8 up yet! It's got some serious grunt in the low RPMs, it falls on its face a little on the freeway, but still a huge improvement over the anything else I've driven. Fuel economy is better than expected. Sprintex with help dial in the tune to get it just right. While the hardware is good, I'm convinced the tuning is what really sets things apart.
With my experience, I would not touch the block. There isn't that much meat there. Heads and cam would be sweet, but I might suggest running the full supercharger package first.
The stock 42RLE is already on its last legs, even though you won't be moving anywhere near as much weight or tires, I'm not sure it can handle any more than what we're cranking into it.
Reading this back I sound like a Sprintex commercial, but I really want to support quality gear that works for the Jeep market, and there are few things that really deliver like the Sprintex has for us. They've also had extremely good technical customer support and customer service, things that we value.
Besides the performance aspect, having a Jeep that sounds like a TIE fighter/vaccum cleaner is fun! DO IT!
Just perusing threads and stumbled across this and I can definitely contribute.
We work with Sprintex. Before my tenure at JKS, I worked at a high performance 4x4 shop and threw forced induction on everything I could. I was never happy with anything for the 3.8 for various reasons, whether it was install, performance or tuning problems.
When I started with JKS I inherited the JKS 2 door with an unintercooled 1st gen Sprintex. After hashing out some tuning issues, we decided to throw the Stage II kit with a smaller pully and intercooler and their new Diablo tuner and the difference it made is unreal. The JKS 2 door is a full 1000 lbs overweight on 37s and 5.13 gears, and it's still quick! Pinging is minimal and only at high altitude (I throw a bottle of octane booster in there for those trips). I haven't blown the 3.8 up yet! It's got some serious grunt in the low RPMs, it falls on its face a little on the freeway, but still a huge improvement over the anything else I've driven. Fuel economy is better than expected. Sprintex with help dial in the tune to get it just right. While the hardware is good, I'm convinced the tuning is what really sets things apart.
With my experience, I would not touch the block. There isn't that much meat there. Heads and cam would be sweet, but I might suggest running the full supercharger package first.
The stock 42RLE is already on its last legs, even though you won't be moving anywhere near as much weight or tires, I'm not sure it can handle any more than what we're cranking into it.
Reading this back I sound like a Sprintex commercial, but I really want to support quality gear that works for the Jeep market, and there are few things that really deliver like the Sprintex has for us. They've also had extremely good technical customer support and customer service, things that we value.
Besides the performance aspect, having a Jeep that sounds like a TIE fighter/vaccum cleaner is fun! DO IT!
I have been running the RIPP Gen 2 SC for over 3 years, 30k+ miles.
I did not do anything to the engine besides spend about 8 hours bolting on the RIPP.
Definitely regear your Jeep before you splurge on the SC. If you don't, you'll end up with broken drivetrain parts...
i.e. 37's with 4.10 gears and supercharged = one slightly twisted front driveshaft:
Sorry, I've very little time to chat ATM. I'll be back later and you can ask me more questions.
Thank you for the reply. However, I stay away from RIPP. I am not wanting to start a flame war, but for brevity sake, I do not agree with them and their horrible customer service. (My opinion only) With that said, I am glad you are enjoying yours.
Also, the twisted drive shaft reminds me of my family's drag racing habit before we got out of it. Used to race a naturally aspirated 347 ci Pinto.
I currently live in Massachusetts attending law school (and at 36 FU Boston Traffic) as soon as I graduate school I am returning to Louisiana where the food is 1000% better and I dont have to listen everyone talking about Tom Brady.
As for gears, 4.56 would be my limit to keep highway RPM's down with 33's. Since I will have the gears out, I will add Detroit TrueTracs front and Rear.
So, I have it narrowed to:
1-Freshen up block with ARP bolts
2-Magnusson Supercharger
3-505 Performance Cylinder heads and Cam
4-Pacesetter Headers
5-Regeared for 4.56 and TrueTracs.
I think I can get all of this done for under 10k installed. Thanks alot guys.
I love my TrueTracs front and rear. Great on street and trail. DD 80%.
Tuning is most critical on any supercharger kit. Intercooling is a must.
Most use 6 bigger injectors and reflash the stock ECU.
I choose to leave the stock injectors and ecu just as Jeep intended. Cold start, idling, A/C, cruise, OBDII/EPA, etc.
Instead I use a 60lb/hr 7th injector to add all the fuel needed only when under boost. It is controlled by it's own standalone/piggyback controller. This Split Second FTC1 controller controls the 7th injector and also retards the timing when under boost. The fuel is injected after the TB and before the SC and as it goes thru the SC it cools the SC and air. It acts as 'chemical/liquid' intercooling and removes 60-80* from the charge air temps.
Be sure to use MLS head gaskets. That is about the only really needed item, everything else is all extra. I wold NOT use a different than stock cam. A different cam will require different tuning. Big valve ported head is fine, stock cam and roller rockers will work just fine. All a cam does for the most part is move the powerband up higher in the rpm range. The SC will take care of the power you want.
You can PM me if you have any other questions about supercharging the 3.8L or 4.0L.
I have tried to do a few different things with my 11JKU. I worked with Inertia Motorsports to make a 4.0 stroker using the Dodge Nitro Block and after 5 months of back and forth both of us decided that it can be done but entirely too much work for the cost.
I have sold that engine and instead of a hemi/LS swap, I am wanting to build a modded 3.8 w/ supercharger. Since I have a small intake oilleak I am going to add a SC when I repair and go through the engine this winter as it will hit 100k miles.
So my questions are directed at the readers who have added a SC.
1) What bottom end preparation did you do? Do you perform the same prep as a V8? (ARP Bolts etc)
2) Since the engine will be torn down I am going to go with 505 performance Heads and Cam. Would YOU additionally go .30 over on the block?
3) Gears will be done at this time, I have 3.73 with an auto and only will run 33's would you add in 4.10s or 4.56? This will never see rocks.
4) I plan on using the Magnusson or Sprintex SC. Anyone have any experience with the Sprintex?
I will hazard a guess that you've search this & other Jeep forums about the proposed upgrade you're looking at. I can attest to regearing of a four door JK -particularly one w/a slushbox transmission - being a significantly beneficial upgrade to start with. I can also referrence the actual engineers who were tasked with designing the 3.8l v6 (3.3, 3.5,et.al.)for Chrysler suggesting it simply is not a good candidate for many power add-ons. This info can be , also, found on the interwebz. I only chime in because whenever I read or hear of the 3.8l being targeted for turbos, SCs or stroked I am reminded of this frustrating but informative post on this very forum.
that being said, it is none-of-my-business whatcha do with your Jeep and I hope it works exactly as you want it to & that you are out ripping up the dirt or road or trails with power to spare as soon as possible
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