2010 Grassroots Challenge Turbo Jeep Cherokee
 

Just wanted to share a build thread for our 2010 Grassroots Challenge Turbo Jeep Cherokee since my turbo and MegaSquirt knowledge came from this site. I mainly copy and pasted my teammate's tread from GRM but I should be able to answer any additional questions.

PART 1 We started the project with a difficult search of finding a two door, two wheel drive Jeep Cherokee. As it turns out one was recently brought up to New Hampshire from Mississippi for us! Talked the dealer down to $600. Let’s face it; no one in New England wants a 2WD Jeep. Good news for us.

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Windshield cracked no title, 243k miles, chunky brown coolant, but running great, no real rust and fairly straight body. The only bad part is that we couldn’t find a manual transmission XJ. The automatic transmission (AW4) is bulletproof though so it isn’t all bad news.

We started the build with finding our starting weight. Not terribly heavy at all, only 2,865 lbs, and began removing the roof rack, rear seats and other unnecessary items like a/c and heater accessories, wiper motors (front and rear) and radio and speakers. We also gutted the hood and installed pins. Final racing weight in Gainesville was a very respectable 2,677 lbs.

Second step was to find a suitable rear axle. Since they are plentiful, strong, come with disk brakes, limited slip, and have better gearing (3.73 vs. 3.55) the Ford 8.8 out of an Explorer was the perfect solution. $100 for a nasty looking one at a junk yard was the easy part. We then cut the spring perches and re-welded them at the proper width for a Jeep Cherokee but flipped them to the bottom so we could convert to a spring-under layout achieving the rear suspension drop of about 4.5". Used U-Bolts attached the stock Jeep leaf springs to the Ford Axle. A $25 adapter from Spicer made the job of attaching the Ford axle to the stock Jeep drive shaft a breeze.

To increase spring rate we used a second pair of junk sagged stock Cherokee springs and doubled up most of the leaves with the original pack. It gave us more spring rate without increasing ride height.

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Finding shocks for a lowered Jeep Cherokee proved to be difficult but after a lot of research on shock lengths and specs, craigslist got us a pair of new Rancho 5000 shocks for a Ford F150 for the front and a pair of used Bilstein shocks off a Toyota Tacoma TRD in the rear. They are both compressed a lot but should do the trick. We may have to look into ways to get more travel out of the system if its purpose expands from just autocross as they would bottom out too quickly for rally-cross duty.

The front axle was much more involved. Since the solid tube front axle could hit the oil pan under full compression we decided to cut and notch it. Having had lifted jeeps in the past we knew the big problems that can arise from changing the angles of the control arms so we needed to address that. The upper and lower control arm brackets on the axle were shortened and lengthened respectively to compensate for the drop in the front. Additionally we made a drop bracket off the axle to use a stock length track rod that still centered the axle after all the changes.

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Since offset front ball joints are way to rich for the budget and we were cutting the front axle anyway we decided to notch and bend the front axle for additional camber. After researching more about the front axle modifications the Archer brothers used successfully racing the Jeep Comanche in the SCCA Truck Challenge series we found that they actually bent the front axle. Since we don’t have the facilities to accurately bend it whole, we cut a pie out of the middle leaving a small portion at the bottom intact and stood on it until we ultimately achieved -2.5 degrees static camber on each side.

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A great deal on poly front control arm bushings firmed up the axle control and a few sections of steel plate were welded onto the stock control arms to box them in for strength. The new axle modifications clear the oil pan with room to spare and the control arms retain their stock angles.

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The driveline was firmed up with poly motor mounts found on eBay for $0.99! They were for a Jeep Wrangler (TJ) so they had to be cut approximately 1” to fit an XJ. We couldn’t find a steal like that on a transmission mount so we injected some polyurethane into the voids in the stock sagged rubber mount and let it cure. What a difference!

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Used crusty Addco anti-sway bars were taken off a parted out Jeep and installed front and rear. They’re 1-1/8" front and 7/8" rear. The rear links are poly bushings with washers and a long bolt and we had to fabricate and weld a mounting location onto the rear axle. The stock front links were cut shorter and rewelded to fit the much lower suspension. The combination of cut springs, stiffer shocks and sway bars results in a very stiff vehicle.

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PART 2 Now the front and rear disc brakes were given some love. New rear hard brake lines were bent up and the stock Jeep rubber hose was attached to the Ford brakes. In the rear the stock rotors were wire wheeled clean and Kool-Vue $7 pads were installed. The front got throw-away rotors and used Duralast Gold pads. The brake lines were bled and everything works well enough. Very surprisingly, and likely the first time ever on a Cherokee, Alan McCrispin described them as 'awesome'... I’m thinking the tire diameter/weight advantage over stock was the largest factor.

Next up was pulling the engine for a good cleaning. Some degreaser and a pressure washer helped get years of oil leak accumulation off the engine and transmission. A badly leaking valve cover gasket was replaced and the engine was ready to go back in. We also removed the engine bay wiring harness for later and relocated it under the dash to de-ugly the engine bay. Only essential interior wiring was retained and everything was run on the driver’s side along the door sill. Huge holes left in the firewall from the removed blower motor, wiring harness, and HVAC lines were patched and painted.

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Next step took us well through the winter: Gutting the stock engine harness and patching in Megasquirt.

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There is very little information on wiring Megasquirt into a Jeep so we were mostly on our own here. A factory service manual and many hours later allowed us to cut the wiring harness in half and in theory have Megasquirt running ignition and fuel using the stock distributor's internal hall effect switch with a Ford V6 6-window trigger wheel. After many, many hours of troubleshooting a no-rpm signal issue we removed all jumpers and modifications to Megasquirt only to find that my very first jumper installed was in the wrong hole on one end. Soldered back correctly and viola! With the wiring harness back in the Jeep it came to life on the first try! It ran amazingly well with the baseline tune (modified 1.6L miata turbo tune...) and runs pretty well with more time.

Running gear is a take-off set of 275/35/15 Hoosiers from a local autocrosser that we mounted on 15x10 steel wheels front and rear. The front wheels have a 5" backspace and the rear backspace is 4" as the ford axle is narrower than the original so the front and rear track width and the bulging tire look is roughly equal.

The Jeep needed to look a little more like a proper race car. We decided on a front and rear bumper tuck. The rear bumper is a basic tuck. Caps were welded on the ends and the bumper painted white to match the body.

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The front bumper was more involved. We discussed blending the bumper to the existing body work and Dave took that idea and created a really nice contoured bumper. We also cleaned up the stock lower valence and riveted on a strip of aluminum to the back to straighten the wavy piece and add rigity.

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The interior also needed a lot of attention. A plastic racing seat was bolted to the stock slider bracket. The stock steering wheel center ring was cut out and a cheap eBay steering wheel was mounted.

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Once the interior was gutted we realized that it wasn’t too bad. The basics were clean but since there was some rust on the flood it needed a clean coat of $0.97 Home Depot white spray paint and some truck bed lining in the rear. We also cut up a 4'x8' sheet of gray PVC to cover the holes left by the interior panels.

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PART 3 Finally last but not least was the turbo. This proved to be the most “interesting” part of the project. A junked Renix (1988) exhaust manifold was cut and re-welded to hang a bit higher. Then a piece of old square basketball hoop pole was cut and used as a spacer to mount the turbo flange too. Then a simple piece of 90 degree bend was welded to the internal waste gate housing to create the down pipe.

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In reality we ran out of time to install the turbo before the event. So we packed up the pieces and headed off the Gainesville Florida. Once we were there the rumors started swirling that we might try to install the turbo down there. We decided as a team that it had to be done. Once we got back from a full day of autocrossing and concourse judging it was time to…drink. Then flash forward a few hours and NOW it was time to start installing the turbo. So at around 11 PM we all gathered in the parking lot and started pulling the stock parts off the Jeep and mocking up the turbo parts.

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The install lasted into the next day and the 15.5 second ¼ mile run didn’t impress many, but it was all worth it. To be able to install that turbo with my friends under pressure was a blast.

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Dave and I want to thank everyone who helped make this a build I will remember for a long time. I especially want to thank Greg, Pat, Tony, and Rob. Without them there is no way this all gets done. Last but not least I need to thank my wife Lindsay for putting up with me and Dave working on the Jeep so many hours and for not complaining about all the spare parts in the basement and race cars in the driveway.

Hopefully we can bring the Jeep back next year with more power.

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I like DIY, pretty interesting project.

Those shoes are classic!
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Awesome build thread, very entertaining. Ever get it on a dyno? 15.5 is not too bad, rofl. Why did you start with a jeep, just for the extra challenge?

:laugh: Classic Wal-Mart

brb, borrowing GF's Cherokee.

My buddy took some video.

We talked about what our next project should be on the way back from the 08 challenge. As a joke we talked about doing a Jeep since no one has ever entered one. Turned out Dave and Jeff were serious and a few months later there was a 2wd Jeep in the driveway.

For the autocross the Jeep was NA. It actually did much better then we thought. One issue we did have was it was lifting a rear wheel and the limited slip was worn out. Since then we have removed the rear sway bar and its now lifting a front wheel. Still need sort the suspension and shim the limited slip.

The 15.5 quarter mile was disappointing. What happened was we lost one of our larger injectors somewhere around 2am the night before. We finished the install 30 minutes before the track closed Sunday and tried running 24 lbs ones but they were way to small. At around 3000 RPMs we were out of fuel at 12 psi. We tried loosening the wastegate to run less boost, leaning the map out to 12:1 but the few laps around the parking lot tuning showed there was not much we could do. We made one light pass with the wastegate open and ran a 17 something then one more with it loose at half throttle and got the 15.5. After that pass the track closed. Hopefully next year we will have it sorted out. I'm shooting for 275-300hp next year and low 13's. I think that's a reasonable goal. We have since removed the turbo kit till we can find bigger injectors and have been autocrossing it with a local BMW club.

Just for an idea my stock 4wd XJ ran 16.3 in the quarter and Dave's with a 4.7L stroker ran mid 15's.

Quick view of what we were dealing with on our second tuning pass in the parking lot. We got to 4000 RPMS and were all done. We also didn't know what the wategate was rated at so I had it pull a bunch of timing above 8 psi. Also notice the 200+ intake temps, lol. Some heat shielding and an intercooler might be in our future.

awesome build.

sweet! I like it! different then the common 6" lift kit for those truck!

My GF does not approve, time for a new model.

MY MEN LET ME START SAYING MY NAME IS RYAN I OWN A XJ , LOOKING FOR MODS ABOUT TURBO I STUMBLE ACROSS YOURE TREAD:bowrofl: IN THE MAZDA FORUM, I LOVE THE WORK YOU GUYS DID, IT IMPRESS ME HOW COMPACT YOU MANAGE TO FIT THE TURBO UNDER THE INTAKE :idea:YOU CAN'T TELL . I HOPE I CAN GET A HOLD OF YOU TO GATHER SOME INFO , I WANT TO DO SOMETHING SIMILAR TO GET LIKE 8 POUNDS WITHOUT INTERCOOLER FOR REGULAR DRIVING AND POWER FOR THE HILLS WHEN I GO UP STATE I'LL BE GETTING A CRANK AND RODS FROM A 258 TO MAKE IT STROKER TOO SO ANY IMPUT YOU CAN GET ME AND LOTS OF PICS WOULD BE APRECIATED SPECIALY THE MODS OF THE EXAUST TO CONNECT THE TURBO. THANKS I JUST WAIT FOR YOUR RESPONSE

Sorry im new at the forum so can't send a pm, if any of the other guys see this please tell pseudosport if he can contact me or pm me thanks

wat?

I need to try this on my GF's Cherokee. Hmmm...

What about 03-04 cobra injectors? 39 pounders and only 75 dollars for all 8. They were in the fire we had, but have since been on the flow bench and worked great.

Can't believe the stock HO can take that much boost!

I heard about this Jeep from one of my buddies (another GRM competitor with E36 V8 bmw) a few months back. Hmm, makes we want to turbo that Turd of a 3.8L in my '10 Wrangler Unlimited.

What an awesome build. Well done.

Jeeps aren't too big amongst many I know, but I had one that was excited to see builds like this ^_^

As a fellow XJ owner, I dig this... a lot.

Sorry I haven’t been on the site much since I sold my Miata. Thanks for all the comments and interest.

shad0ww0lf, I sent you a PM and my email address if you have any questions.

Chpmnsws6, that’s for the offer but I think I have the fuel problem sorted out (at least in my head)

I think we are going to run a free set of 36 lbs injectors with a fuel pressure regulator off an older turbo dodge that should give is 55 psi instead of 39 psi. Only issue is after 95 most injectors are rated at 47-49 psi so hopefully we will get just over 36 lbs out of them and have enough fuel. This should also free up some of the budget since this will be cheaper then using the 24 lbs we had listed. Also I didn’t plan on the 4.0L taking that much boost. I heard a rumor that the 4.0L rods are good for 8 psi but that’s all the info I’ve found and doesn’t really do me any good without knowing the setup. While searching I mainly find rednecks with no engine management or supporting mods. One exception is this guy called TurboTom who is running a turbo 4.0L in an AMC spirit with Megasquirt. I think he is over 400 hp.

Great post, would read again

The Grassroots Motorsports $2010 Challenge issue is out! Here are some scanned pictures from it. Sorry for the poor quality, best I could do.

http://inlinethumb03.webshots.com/46...600x600Q85.jpg
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Great story! Thank you for sharing.

Update:

We just received an email from Scott R. Lear Production Editor at Grassroots Motorsports saying they are going to do an editorial on our Jeep for the next issue!

Dude, sweet build. I bet the guy in the video with the 300ZX felt terrible. Your SUV definitely cornered better than his sports car.:giggle:

We’re going back for the $2012 Grassroots Motorsports Challenge!

After attending a few autocrosses last year we have dusted off the XJ-R made some small improvements the past few months. With only 2 weeks left we are back up and running and are staring to work on tuning. We still have a lot of work ahead of us including a new paint job.

Follow along on our facebook page Jeep Cherokee XJ-R since it’s easier for us to post all our updates in one place.

So the $2012 Grassroots Motorsports Challenge was last weekend. We actually showed up with the turbo installed on the Jeep and mostly tuned. Other then some small tweaks to tip in the Jeep ran awesome. Changes we made for 2012 were:

Installed turbo before event
Welded up a small intercooler from scrap parts (its small but cut 90 degrees from our intake temps)
Ran longer exhaust
Removed rear sway bar
Removed one rear leaf
Smoothed and greased rear leafs then wrapped them in duct tape
Rebuilt and shimmed the hell out of the LSD in the Ford 8.8
Repainted interior and engine bay in hotel parking lot
Painted exterior like Mark Donohue’s 71 AMC Javelin

https://www.miataturbo.net/attachmen...ine=1349379952
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We were hoping our improvements would make a big difference and they did. We ended up winning best under hood detail, editor’s choice, 3 place over all, and 1st in the autocross. Check out our facebook page for some videos.

This car is so awesome! I follow you on Facebook. Congrats on the win....I'm seriously going to buy one of these now..

The best sports car you can buy for $2000 is a Jeep Cherokee, got it.


Congrats guys! I'm gunning for you next year. ;)

Isn't there someone else who is building a Grassroots challenge car?

It seems like the perfect competition for this site, seeing as we are all cheap bastards.

Also concealer you are in Greenwood right? I'd help out with something like this if you need some more hands.

I was there. ;) The Cherokee was AWESOME, and the team is a bunch of great guys!

There's at least 3 cars that i know of coming out of Indy next year, potentially up to 5. I just run my daily driver, so getting it ready is just pretty much a weekend affair. Next year will just be a clutch job, meth injection install, and cleaning it up again.

We'll take help for sure, though! Some of the other cars might need more work than that depending on how far we get and how much time we really have. (Planning on a full solo season as well)

I either work at my garage in Oaklandon or up at my buddy's place in Noblesville. :)

https://www.miataturbo.net/attachmen...ine=1349385151

The devil is in the details, we learned the same thing after bringing Gutty those 3 years running. Winning the third year was a great feeling considering how much time we sunk into the bugger.

Hey, I didn’t know you were on here. Then again it’s been a while since I’ve really been on this board. I actually took a few cell phone pictures of your car but never really had a chance to catch up with your. Looks like you had a busy weekend. How did the tires end up fitting after the late night fender rolling?

Not sure what we are bringing for $2013 yet. I don’t think the Jeep will make it back unless we have nothing else going on and we have trouble going through challenge withdrawal.

You all are fukkin amazing. Thanks for putting everything that I do to my car to shame.

You should sell the jeep on ebay or get jalopnik to feature it and then sell it or something. It really looks REALLY GOOD.


lolol :D

Yeah, i've got a turbo Miata that i don't actually drive. (Hence the sig.)

Funny story about the fenders... they weren't actually rubbing. Ended up beating in the frame/inner fender area with the handy scalpel. (Orrrr... bigass dead blow hammer.) Got clearance for DAYS now! :)

And then... the turbo fell off. Then the clutch started being unhappy. Oh well, car made it back and i'm still daily driving it, should be set for 25-30psi next year. :brain:

What else do you guys have sitting in reserve that could be brought?

Well I have my 75 Datsun 280Z that I’ve been working on. Plan is to fix the rust, paint it, add megasquirt, and a 60 trim T3T4. I have all the parts now it’s just a matter of finding the time.

Another option is I have a 1969 Camaro that’s been sitting in my garage since 1999. I picked it up for $800 since it was rusty and someone drove into the back end of it. Problem is it’s going to take about $600 in sheet metal and paint just to make it look like a Camaro again. I have a $100 LT1 from a wagon and a 200r4 transmission that would drop in but for some reason I kinda want to go with a supercharged GM 3800. Maybe pick up a free 305 V8 and throw a lot of nitrous at it. Drivetrain dones’t really matter. I just want to show up with a shiny 69 Camaro and have Per’s head explode when I hand him my budget.

We made another return to the $2013 Grassroots Motorsports Challenge. We originally said we were not going to bring the Jeep back but after a little persuasion we decided to make a few more changes and drag it back down to Florida.

New for $2013
-Ditched POS engine bay intercooler and small charge pipes for a FMIC and 2.5 tubes
-upped boost from 7 to 12 psi and did some more tuning.
-Modified Auto the shifter wiring so we have full manual control of 1-3
-Made traction bars to eliminate axle wrap
-Painted wheels so they don’t look as stupid

For more pictures check out the feature Bangshift.com just did on the XJ-R.

http://bangshift.com/blog/the-humble...autocross.html

So damn awesome! What kind of 1/4 mile did you get on 12psi?

We ran 12.98 @ 100mph at 10 psi.

haha! That thing hooks up judging from the mph.