$2010 Race Jeep Cherokee Build

Derick Freese wrote: Any more details on the megasquirt? I have a Renix XJ that I'm planning on 'squirting and any information I can gather is great.

The main problem prople have with setting it up for a Jeep is getting a crank signal for spark. I never looked into the Renix Jeeps. Depending on the teeth and spaces on the flywheel trigger wheel I heard there might be MS code out there. If so you could use the factory crank sensor. If not you can swap in the distributor out of a 4.2L and set MS up for a VR sensor or swap in the 91-93 distributor with the ford shutter wheel and set MS up for a hall effect sensor.

Once you get a crank signal its just a matter of wiring MS into the factory harness. Renix jeeps have the advantage where the computer is already located inside the vehicle.

That's the flywheel with ring attached. Not up on terminology (yet), but there are 3 series of 20 teeth and then 2 missing teeth. I'm not sure it ever changed.

Name me one good reason a turbo needs an airfilter

Guys, Thanks for letting me drive it at the Challenge. It was a blast! The video one of your crew shot is hilarious.

Alan M

admc58 wrote: Guys, Thanks for letting me drive it at the Challenge. It was a blast! The video one of your crew shot is hilarious. Alan M

We've been excited to have you drive it since the '09 Challenge when Dave hinted that we'd be bringing a Jeep. We always kind of thought it would be one of those Challenge vehicles that would be scary to drive. However, after our one autoX test we were happy to discover it might actually be more sorted than we thought.

Are you talking about Silverfleet's video of your 34.8 run?

miatame wrote:

admc58 wrote: Guys, Thanks for letting me drive it at the Challenge. It was a blast! The video one of your crew shot is hilarious. Alan M

We've been excited to have you drive it since the '09 Challenge when Dave hinted that we'd be bringing a Jeep. We always kind of thought it would be one of those Challenge vehicles that would be scary to drive. However, after our one autoX test we were happy to discover it might actually be more sorted than we thought. Are you talking about Silverfleet's video of your 34.8 run?

I believe he's talking about Pat's video where the Jeep goes, then Greg's Miata goes after you cross the line. But it was the 34.8 run.

In reply to Derick Freese:

So far I can't find anyone who has been able to get MegaSquirt working with the stock jeep flywheel / crank trigger. There has been talk of code being written but no info yet. The only options I’ve seen so far are using the older 4.2L distributor, 91-93 4.0L distributor, or mounting up a universal 36-1 trigger wheel to your harmonic balancer. 36-1 wheels can be found on ebay or DIYautotune.com but this option will involve some fab work.

Love your XJ....I have argued for years that they are an excellent platform for road racing, and until the SRT8 came around it was blasphemy to mention Jeep and on-road performance in the same sentence. I have two XJs one lifted and one dropped I also have an MJ that my brother and I are prepping for Lemons. Where did you find the info on the Archer brother's Comanche?

XJguy wrote: Love your XJ....I have argued for years that they are an excellent platform for road racing, and until the SRT8 came around it was blasphemy to mention Jeep and on-road performance in the same sentence. I have two XJs one lifted and one dropped I also have an MJ that my brother and I are prepping for Lemons. Where did you find the info on the Archer brother's Comanche?

Thanks man. Yeah we've always thought they had potential :) Just don't expect to get a pat on the back when you mention lowering an XJ on one of the Jeep forums...they get pretty sensitive! haha I like my lifted XJ just as much as my lowered one.

The Archer Brother's information is scattered and incomplete. I've tried getting more complete info for a couple years now without luck.

This thread on NAXJA has some information but mostly just links to kicka$$ pictures. You can see the wheels turning in my head as we put together our idea to cut and notch the front axle.

http://www.naxja.org/forum/showthread.php?t=952132&page=4

In reply to miatame:

Cool, thanks. Yeah I know all about the resistance to lowering a Jeep.....I was once the poster child for high performance lowered Jeeps back in 90s...NAXJA knows me (hates me) well. LOL I have a never finished XJ project that is lowered called the Cherokee Warrior.....its been talked about on nearly every XJ forum; for better or worse. I also have a 92 XJ (Xnowyte) with bead-locked 35s, 8" lift, caged long arms etc.

FTR, Archer brothers used fiberglass mono-leafs made by Flex-Form, if you look carefully in some of the pics, you can see the sponsorship decal at the rear body-panel and you can also see in fact that there is just one leaf back there. I plan on scavenging some Chevy Astro / GMC Safari composite rear leafs and making my own. http://www.comancheclub.com/forums/viewtopic.php?f=2&t=26305

My 91 5 speed 4x4 MJ Pioneer is a real basket case, low miles but so rusted it shouldn't be allowed on the road..LOL..thats why its being relegated to Lemons and not a full restoration (they are rare and I wouldn't want to potentially ruin a good one).

Here is a site with a lot of racing MJ pics: http://mwphoto-misc.smugmug.com/Cars/SCCA-Racetruck-Challenge/1988-NIAGARA-FALLS-SCCA-RACE/2606062_nvihS

Do you run on the rack with others simultaneously? Or is it solo Autocross?

Years ago when I was doing research on how to lower my XJ and where I could buy an aero kit for it, I actually spoke to one of the Archers, they offered to make me the aero kit (airdam) that they used on their MJs. They said they had the molds and might have one or two units still sitting around. At the time I didn't think to ask him about the suspension setup because to the casual observer that I was at the time, it didn't seem like anything special. There were 5 companies that I know of that made an aero packages for the XJ/MJ: Archer brothers, RSW in Germany (nicest one), Aeromotive, Erebuni in NY, and one other in NY, name escapes me right now. I happen to have one by Aeromotive, I used to be a dealer for them.

HA! No way! You are the Warrior XJ guy?! Back in high school I checked out your site every day. I had an '88 XJ that was my first car. I kept it stock height but put on Addco bars, performance shocks, Scorpion ST (now discontinued btw) tires and some aftermarket wheels. Anyway I wanted to build something like your Warrior concept. I guess I'd like to think I sort of did...aside from the Chevy 350 or whatever you were going to put in that thing! haha

Please let me know if you find a good deal on fiberglass leaf springs. We could lose probably 50lbs out back with those. Do you have any idea what the spring rate is?

Oh and we only run solo autocross but would like to get into rallyX at some point.

LOL...yeah thats me. Edited some info in above post, btw.

miatame wrote:

XJguy wrote: In reply to miatame: Cool, thanks. Yeah I know all about the resistance to lowering a Jeep.....I was once the poster child for high performance lowered Jeeps back in 90s...NAXJA knows me (hates me) well. LOL I have a never finished XJ project that is lowered called the Warrior.....its been talked about on nearly every XJ forum; for better or worse. I also have a 92 XJ with bead-locked 35s, 8" lift, caged long arms etc. FTR, Archer brothers used fiberglass mono-leafs made by Flex-Form, if you look carefully in some of the pics, you can see the sponsorship decal at the rear body-panel and you can also see in fact that there is just one leaf back there. I plan on scavenging some Chevy Astro / GMC Safari composite rear leafs and making my own. http://www.comancheclub.com/forums/viewtopic.php?f=2&t=26305 My MJ is a real bascket case, low miles but so rusted it shouldn't be allowed on the road..LOL..thats why its being relegated to Lemons and not a full restoration (they are rare and I wouldn't want to potentially ruin a good one). Here is a site with a lot of racing MJ pics: http://mwphoto-misc.smugmug.com/Cars/SCCA-Racetruck-Challenge/1988-NIAGARA-FALLS-SCCA-RACE/2606062_nvihS Do you run on the rack with others simultaneously? Or is it solo Autocross?

HA! No way! You are the Warrior XJ guy?! Back in high school I checked out your site every day. I had an '88 XJ that was my first car. I kept it stock height but put on Addco bars, performance shocks, Scorpion ATS tires and some aftermarket wheels. Anyway I wanted to build something like your Warrior concept. I guess I'd like to think I sort of did...aside from the Chevy 350 or whatever you were going to put in that thing! haha Please let me know if you find a good deal on fiberglass leaf springs. We could lose probably 50lbs out back with those. Do you have any idea what the spring rate is?

The stock for 86 Chevy 2.8 V6, balanced blueprinted bored out to about 3.0, increased compression, Eaton M90 supercharger, Weber 38DGAS blow through (still not fully sorted), Volvo Intercooler, 150 shot of nitrous just in case.

No clue on the rate, but since they were designed to hold a substantial amount of weight and I will be shortening them, they will be as stiff as rocks, and maybe capable of holding more than stock springs...not that that matters.

On the Warrior I had a stock pack dearched, I then drilled the eyes threaded grease fittings and put in graphite impregnated poly bushings, coated the leaves individually with POR-15, added new plastic pads and RE clamps, grease fittings on each pad. I had gone this route because I did not want o lose any cargo carrying capacity....I didn't know at the time that composite leaves even existed on anything other than a Vette. They sit under the Jeep as of yet unused and probably will never be used since I most likely will go composite as well.

Ive done tons of research on making our bricks more aerodynamic. I don't know what speeds you get upto but if you want to make your Jeep more slick I can tell you what I know, some of the stuff is just common sense, some stuff if a bit more radical.

Oh and this is our current race car, many of you may know it:

Then:

Now:

XJguy wrote: Ive done tons of research on making our bricks more aerodynamic. I don't know what speeds you get upto but if you want to make your Jeep more slick I can tell you what I know, some of the stuff is just common sense, some stuff if a bit more radical.

Well hopefully we will be going over 100mph trap speed in the 1/4 next year :)

We probably don't go over 50 mph in the autocross though.

We talk about adding a rear "wing" but mostly for aesthetics. Any ideas on a function rear wing?

The wing will only help keep your rear in place when turning, it will not help make the Jeep more slick; reduce drag. Ive driven XJs at 120mph with no aero mods just a big front sway bar and BFG 275R15 tires...they are stable....but can be made more slick, much more in fact.

Are there any body modification limits in your racing class?

XJguy wrote: Are there any body modification limits in your racing class?

Yup...$2011 :) Car can't go over $2011 total. We have a bit of room so I'm open to ideas.

Well, luckily most of the stuff is free or nearly free.

The problem with all bobbed-rear vehicles is that they produce an enormous wake, this essentially drags air behind you and slows you down. In the XJ you also have a very un-smooth underbody, relatively large fender flares with lots of gaps around the tires, and largish side mirrors. To its advantage its light weight, has a relatively small frontal area, and those sharp corners actually help with aerodynamics by making sharp cut-offs for the wind at the rear. If you have noticed the Hybrid GMC Yukon have sharper/more angular rear edges than the regular models.

You might want to look at a site called ecomodder, they are not into racing but do everything they can to be more efficient, there are a few XJ guys there...though I have yet to see any that have really done whats needed, but it might give you some ideas. Also look into the turbobricks site, the Volvo wagon is extremely similar in shape to the XJ; there are many aero discussions there.

To maximize your Jeep I would address the following:

Wheel well air evacuation, Restrict air into wheel wells, Reduce rear wake, Smooth underside, Downforce producing / drag reducing radiator air evacuation,

More radical: Relocate radiator and battery to cargo area, Remove/modify side glass to allow air into and out of tailgate glass opening,

Little things: Racing mirrors...or no mirrors since its Autocross. Light covers, Flush door handles..or no exterior handles, Aero wheels...if heat is not an issue try to cover em up....especially the rear. If allowed close up drivers window.

Rollcage.....XJ's flex that does not help your handling....maybe not as much as in other vehicles since its beam/solid axles.

Check out the front axle on the Archer Jeep

Monoleaf in clear view:

Yeah I've seen those pictures but never noticed the monoleaf until you pointed it out. Interesting... Looks like a much lower front mount too.

Our XJ-R is ready to race!...once the snow melts away...

i dunno jeff, look at the front lower control arm from the side shot... its angled up (granted it's leaning to the left) but our angles are parallel with the ground, though we cant see the uppers so i guess its impossible to see how the pair would act together. but the far more extreme bends in the front axle almost look like it might be to lower the cg of the heavy front unsprung suspension or to facilitate engine placement regardless of oil pan/sump perhaps? just thinking out loud... man i'd LOVE to see that thing on a lift.

I'm talking about the front leaf spring mount.

I think the front control arm is a bent piece like the one that I run on my lifted XJ (except flipped the other way). The extreme control arm angle leads to some increased energy transmitted to the "frame" instead of through the coil springs, and also decreased caster (in a lifted application).

I like our solution better, and we still have plenty of travel before the control arm mount hits the ground.

We need to get ahold of an Archer Brother's team member. I bet they found a ton of ways to get more out of an XJ/MJ.