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Discussion Starter #1
Last week I ordered a Sprintex Supercharger (w/ intercooler) for my 2011 Jeep Wrangler Unlimited Sahara. I figured I'd post a review of the experience so far.

First a little background. A couple months ago, I put in a new reman engine to deal with excessive oil consumption on the original engine. After swapping, I discovered at least a couple of exhaust valve guides on the original engine were excessively warn. (There was oil dripping into the exhaust...) The new engine has had a 300 mile break-in-period, followed by a 3000 mile regular driving period. All of this is with 5W20 conventional.

My 2011 JK is a 6 Speed Manual Transmission. I upgraded to a centerforce high performance clutch in prep for the supercharger. So the break in period let me get the clutch broken in as well.

The jeep also has 3.73 gears in the rear and stock Sahara tire size. I also have the 10A bumpers and a few other things that add weight.

My reason for updating to a Supercharger was because I was tired of being unable to pass on the freeway, as well as getting out of my Mazda RX-8 and feeling like I was moving backwards in the JK. I don't expect the JK to feel like a sport car, but the 3.8L was awful in the acceleration department and I was always having to down-shift to accelerate or pass on the freeway.

I decided on the Sprintex unit over the RIPP (which I had also been looking at). I preferred the more OEM look of the Sprintex. I was also looking for the more conservative power increase over the entire power band of this style supercharger. I don't really care about performance difference at 5k RPMS, I never drive up in that range.

I ordered the unit from Summit Racing last week. It showed up on Wednesday (late), I opened it and inventoried on Thursday and realized they never sent me an intercooler. To Summit's credit they quickly remedied the problem and ordered the missing intercooler on Friday, but it means I'm having to install this in stages. Unit w/o intercooler and when the intercooler arrives I will do that next.

Diablo Tuner
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I started with setting up the diablo tuner. I will say that the software upgrade process was completely crap. It first ended up going into a loop for the first stage of the upgrade. At which point after googling I found I had to 'delete a file' and reboot it. After doing that, I further updated it.. and it AGAIN looped on reboot. Deleted the magic file again and then it was ready to plug in and read the VIN. Once I did that, I was able to connect it to my computer again and it downloaded some last software and finally gave me the option to install on my Jeep. (The Diablo has a 'wifi option'. I tried that, and it either showed no networks or locked up the unit each time.. So I had to use my computer.)

Needless to say, I'm not a huge fan of the software quality control on the Diablo Tuner. WAY WAY too fragile, but once it worked -- it finally worked 'well'.

Installation Experience
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Since I had previously done an engine swap, I knew where pretty much everything was and how to do everything including injectors. Following the instructions was pretty straight forward. My only complaint were in a few places it said things like "install the bolts", but never told you WHICH bolts went into which holes. If I hadn't previously installed the engine this would have been more difficult to get right.

Disassembly... getting things stripped down took some time, but slow and steady and no problem at all. I ended up doing a few things out of order based on how I had previously assembled the engine.

Injectors... getting to the fuel rail and replacing the injectors was pretty simple. It turns out the injectors in the Sprintex kit are Bosch 0 280 158 193/FoMoCo(Ford) MOTORCRAFT CM5153 injectors. These are the same injectors on the Ford 2009-2015 E250 5.4L V8 engine. The injectors also appears to be used in a lot of upgrade kits for the Mustang from some good searching.

Modifying the injector/throttle body wiring harness was pretty easy per the instructions.

Installing the new drive belt pulley went well (or at least I thought so.. I screwed up, more on that later.. This was purely my fault and nothing bad about the kit or instructions.)

Swapping the valve covers was the next step. However, there is one step that I still don't understand -why- they had me to it. It said to remove the alternator, but I can't for the life of me figure out why that was necessary. (Wiring was in the way, so that part makes sense.)

Cutting and prepping the new fuel line was simple. It ships with crimp style fuel clamps, I don't have a proper crimp tool and wasn't going to use an end cutter and say 'good enough'. Instead I went to the local auto parts store and got Fuel Injection rated screw type clamps and ended up putting two of them on the line in opposing directions.. (no leaks)

Adjusting the fuel vapor line was pretty simple, as well as drilling the battery box to re-route the line.

Installing the intake (supercharger unit). Pretty straightforward after doing everything else. Put it on the lower intake and bolt it down with the supplied bolts. However there is -one- bolt, under the cast aluminum intake that you only have a few inches to get to and tighten down with an Allen wrench. My hands were physically to large to fit in the space. Luckily my daughter was able to assist with her smaller hands. (If anything, this is the number one complaint I have with the system. There HAS to be a better way to get to that bolt...)

Installing the belt was the next step. I noticed that the pulley I installed earlier looked a little off, but it was getting dark so I didn't think twice.... turns out, I hadn't tightened it down all the way and due to the light I didn't notice it hadn't bottomed out. I was going by all of the other bolts that were 10nm torque.. It must have hit a burr which caused it to get to that point where I stopped... (my fault for not paying more attention here..)

Got the new MAP reinstalled, purge vacuum line (which didn't fit the barb fitting very well) and brake booster all installed and verified.

PCM Programming
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Used the diablo and programmed the computer. There was really only one option. Sprintex Supercharger. Total programming time took about an hour and a half for everything. It took about 5 times between programming, loading and verifying to finish.

Startup
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The jeep started right up, first turn of the key.....and then all of a sudden the dash lit up like a Christmas tree and I turned it off quickly... Turns out the belt had slipped off the pulley (that I didn't tighten enough) and ended up shredding itself all over the engine.

There was enough belt left for me to re-adjust everything and try again... but not enough for me to feel comfortable driving it. So I got the pulley correct, adjusted the belt and this time everything worked perfectly. At this point I stopped for the evening. First thing in the morning I bought a new belt, got it installed and went for the test drive.

Test Drive
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The last vehicle I had driven before the test drive was my RX-8, so I was a bit underwhelmed when I did start the test drive. There was a satisfying supercharger noise starting at about 2k RPMS. I wasn't really sure if there was much more power or not -- but everything worked properly, no CEL, etc...

I did some more driving later that day and I could start to feel more power while driving. I don't know if this is because I was getting used to the Jeep or if the computer was learning as I drove and was giving me more power.

The power gains (without the intercooler) are certainly modest.. But on the freeway (70 MPH limit) near me there is a hill that the Jeep always lugged down on. It can now hold it's speed without me down shifting. So that was one of my immediate goals. It still doesn't have enough power to accelerate (much) in 6th, but in 5th gear I can -easily- pass most other vehicles, including driving into the wind and uphill. So I certainly do not have any regrets with the upgrade.

There were reports of surging with the cruise control. I did play with it, and there is minor surging. It feels like the computer is over correcting the pedal deceleration/acceleration for the cruise. It's not that bad, but if you or a passenger gets car sick -- I could see it being a problem for some.

Driving with the pedal, I didn't experience any surging.. there were a few times where it felt like the computer was still learning and being cautious, when all of a sudden it would accelerate through a 'low' spot in the fuel map.. but next time it didn't have that problem. (I've only driven 100 miles on it since installing the supercharger, but each time I drive it -- it seems to be getting better and smoother.)

Finally idle. The idle is significantly more stable then it was before the upgrade. I know this is minor, but sitting waiting in a parking lot with the A/C on.. before it would idle down and shutter slightly.... it no longer does this, and I've checked and the idle is down in the 600-650 range.

So all-in-all, my review of the Sprintex install w/o intercooler went well. The performance wasn't as much as I was hoping for, but it certainly improves the overall driving experience.

When the intercooler shows up, I will update this experience with more information.
 

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Discussion Starter #2
Update. Got the intercooler in the mail on Thursday and got it installed yesterday.

Installation
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General instructions were fairly straight forward. However there are a few things I would do a bit differently then the order in the instructions.

The EGR tube. Install this -before- you install the belt. It is much easier to position everything.

The intercooler bracket on the -bottom-. Install this before the upper bracket/intercooler. If it does not fit, there is some plastic at the bottom (air dam?).. Make sure you have that clear and then it should fit well.

Once the bottom fits, then install the top bracket, and -then- install the intercooler. Much easier to get everything to fit then trying to do it all at once.

Finally, they seem to want you to route the hoses from from the grill back. This is odd, MUCH easier to route the houses from the engine compartment INTO the grill and attach it after the intercooler is already in place.


The upgraded pulley was not as easy as the instructions made it sound. You need to follow the instructions, but there simple wasn't enough room to slide the magic plastic tool they give you between the housing and the pulley to separate it from the seal journal (that they warn to try not to remove.) Well I had to remove it, I simply didn't have a choice.

Once I removed the pulley -and- seal journal, I had to move it into a vice, and then use a metal putty knife to slowly separate the seal journal from the pulley. Once there was a gap -then- I could use their plastic tool.

Reassembly (new pulley) worked fine, and I had no issues.

Filling the intercooler radiator took a bit more fluid then the instructions said (1350 ml, was closer to about 1500 ml -- maybe a bit less.) Definitely follow their instructions and remove the pipe plug from the radiator when you fill it. Ends up taking about 1300 ml of coolant, seal the radiator with the pipe plug and then fill it the rest of the way (slowly).


PCM Programming
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Since I already had the Diablo tune loaded from the initial install, there was nothing else I had to do here.


Startup
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When turning the key there is a new audiable 'click' when the circulator pump starts up. (The pump is powered from the fuel injector power.. so it only runs when the injector is powered up.)

Otherwise completely un-eventful. Fired no problem the first time, definitely more supercharger 'whine' then before.

Before it started to be audible around 2k RPM. It's now all the way down at idle. (Not really annoying, just an observation.)

Test Drive
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Wow, the smaller pulley, intercooler upgrade really does add a lot more power to the existing system. This is very much the power I was looking at add when I bought the system originally. I am extremely pleased.

After driving for about 20 minutes (45-70 MPH) at about 70F out, the intercooler radiator wasn't noticeably warm. Under the hood, the compressor side was definitely warmer then the intake (boost) side. So it felt to me like it must be doing something, but the intercooler is very efficient.

The computer is still learning, so there are a few 'flat spots' in the tune, but they are getting better each time I drive the jeep. I found a tech note that said it can take 20-50 times (from cold start) for the PCM to be fully trained. (I'm probably only on 10-12 since I first installed the tune.)

If I had to complain about anything. With the intercooler installed.. changing the belt every 30k miles will require a partial disassembly of the (engine bay) side of the intercooler. So a belt change just went from 15 minutes to probably 1-2 hours.
 

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Update, as the ECU learns.. Wow.. the vehicle is able to drive much better. I also need to watch my speed now.

Before I could get up to 75 MPH.. and then not pay attention to the speedometer, since I knew I couldn't really go much faster in 6th..

I found myself following a car today using the same strategy.. I looked down and I was doing 90 and accelerating UP A HILL on the freeway in 6th! That was the point I slowed down, set the cruise and was amazed..

The 3.8L engine in the JKU could -finally- 'get out of it's own way'...

After only 2 tanks of fuel, my MPG has dropped nearly 2 MPG.. but I suspect a lot of that is me playing with the 'go fast' pedal, and the computer is still learning...
 

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Im curious if the performance of a 3.8 with a supercharger is about equal to that of a stock 3.6 or is it much more?
 

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Discussion Starter #5
I haven't driven a 3.6L in a -Jeep- before. But my parents had a 300S with one and a new 2017 Pacifica (minivan) with one. I can easily out do the Pacifica.. I'm guessing the 300S (being lighter) was still faster.

But my urge to 'get out and push' is now gone.. :D
 

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An update. I've had the supercharger roughly a month now. I've put a bit over 1500 miles on it so far.

A negative. 1st and 2nd gears are simply too low, and the engine has 'too much power' for the way those gears are setup. With even light pressure on the clutch (Centerforce Dual-Friction Stage 2 clutch, standard fly wheel), it can slip.

From driving this w/ the 3.8L (no SC) for the last 6 years, I'm used to having to slip the clutch in first to get rolling, then shift to second.. let it slip slightly at first and then everything is 'normal' after that. Now if I let it 'slip slightly', the SC will simply overdrive the clutch. Having to re-learn shifting in this is taking more time then I expected.

Also, I still have a low spot (lag?) around 1900 to 2000 RPM only in 2nd gear.. (if I'm really being gentle.....) Since it's a manual transmission, I have no idea why only 2nd gear seems to be affected. (Load is the only thing I can think of.)


Mixed... Fuel mileage if I absolutely baby it is roughly equivalent to before. City mileage is about 2 MPG lower then before, highway mileage (especially above 70 MPH) is much (at least 1 MPG) better then it was before... and as I said before, I can maintain speed in overdrive, and even accelerate if necessary. My average MPG has dropped from 17.6 to 15.1....


Positives... everything is still working very well. No signs of check engine lights, predetination, engine over heating or anything else that everyone always seems to say goes wrong with super charging. It "just works"!


Overall impressions, I'm still very happy I did this. There have been a few times driving that I needed to pass, or was on an on-ramp where I needed to get up to speed 'quickly'. While I'd have down shifted and still struggled before, there are simply no concerns anymore. It's nice to have confidence in the vehicle to get up to speed when necessary.
 

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Another update a year+ on..

I've retrained myself on first gear in the last year and are much better at controlling the start in first... but the gearing is still too low for the power IMHO, while second is just slightly too high. (JKU 6 speed manual w/ 3.73 gears in the back and the stock Sahara 30" tires..)

I suspect if I went to a larger tire, 1st would be more forgiving.


I've had an on and off again vacuum leak in the evap system for the past 6-7 months. I FINALLY tracked it down last week. The elbow fittings from Sprintex to relocate the fuel vapor line are complete and utter garbage. Both of the elbows had cracked to the point that the computer was convinced I'd left my gas cap off.

A quick removal of the fitting and replacement with a small length of fuel hose, and everything is working perfectly. (No check engine light, etc.)

Speaking of check engine lights, I'd regularly been monitoring the jeep for codes and such. In the last year, other then EVAP issues mentioned above, I did have one instance of throttle problems. It turns out that the line from the supercharger to the evap canister under the hood had fallen off the barb fitting, letting in a massive amount of air. This was an easy trail fix (just put it back on the barbed fitting and make sure it was secure..) No problems since that point, no engine related codes thrown in the last 9 months.

Fuel mileage is now consistent, about 2 MPG less then what I was getting before the swap... but as I said before, no more desire to get out and push... :p The engine and Jeep are performing like I wanted.

One other thing. I did have to replace the drive belt at about 10k miles. I was doing a regular inspection and noticed that there was a small tear (1/8 - 1/4 inch) in the belt. I have no idea how it got there, but figured it was best to replace it before it caused any problems. The system I have has the intercooler and different drive pulley on the super charger. Servicing the belt was a lot more work then I'd expected... and certainly took me 2x-3x what a normal drive belt service would take.

Also the supercharger does use a -very- small amount of oil in normal operation, so it is important to follow the maintenance requirements and check things. In about 13k miles it's used a bit less then 1 oz of oil. Certainly enough I needed to top it off.. but I've still got a way to go to get to the 20k change interval. (I expect to do that in the spring.)


Final thoughts...

Would I have done this again, now knowing what I do?

I would not have gotten the intercooler knowing what I know now. The performance improvement was simply not worth the added complications of installing the intercooler, fluid pump, pulley and different drive belt. But there is a small power increase the the power is 'safer', especially in hot climates, with the intercooler. Additionally the intercooler system drive belt is for a 2005 Ford Thunderbird.. meaning it's special order everywhere. While the non-intercooler is the standard Ford F series V10 drive belt, which every auto parts shop seems to have one in stock...

But what about the super charger? If you are keeping your 3.8L wrangler, I think it is worth it... It boosts the performance to what it SHOULD have been for the weight of the vehicle from the factory, but you have to be willing to pay for the reduced MPG and higher cost premium fuel.

Manners are good for a daily driver, with the knowledge that 1st gear takes a bit more finesse that with the stock engine (on stock tires), and the power certainly makes it more fun.
 
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