Project Shoehorn - M90 into a 4.0L

I haven't seen a lot of this out there so I figured I'd start a thread on it. I'm attempting to put an Eaton M90 supercharger into a 2000 XJ without cutting the hood or removing the A/C. (Hence the 'shoehorn')

Couple of notes before I start:
- This is going to take a while. If I get done by spring I'll be happy.
- I do not have the skill and experience like Talyn or O-Gauge-Steamer. I'm learning as I go.
- Please no pissing matches in here. If people start pulling that, I'll ask the mods to delete the thread and I'll take it elsewhere.

What I'm starting with:
2000 XJ with 172k on the body and 50k on the motor (Replaced due to a failed head and coolant in the oil)
California-spec emissions (3 cats, 4 O2 sensors)
62mm throttle body
Dynomax cat-back exhaust
AW4 transmission
242 transfer case
Dana 30 / 29 spline 8.25, 4.56 gears
4" lift
33" tires

This started when we bought a pop-up camper. At 3300 pounds it tows like a dog, especially in the mountains. After running the numbers, adding horsepower is more cost-effective then replacing it.

I had looked at the RIPP supercharger kit, the Sprintex kit (if I could even find one), and the Rimmer eBay M62 installation kit. I also sat down with O-Gauge-Steamer for a couple hours talking pros, cons, and options. I'm lucky, he lives 10 minutes from one of my work offices. After even more research, I decided the best option was to try to come up with my own. I found some threads where people had deleted the A/C compressor, but my wife likes the A/C when we're driving long distance in the summer so I'm going to try and avoid that.

I found a local guy selling an M90 out of a Ford Thunderbird complete with intake and output fittings. Since I'm going to be putting the SC on the passenger side, having the intake and output fittings saves me a bunch of fabrication work. My initial tape-measure sessions look like I might be able to install the M90 so the snout is below and slightly outboard of the A/C compressor. I will probably need an idler pulley to make sure I get enough wrap on the M90 pulley. I will have to relocate the battery to the back and the coolant overflow bottle to the corner the battery came from.

Other note - I am specifically upgrading to larger injectors rather than running a seventh injector. It's just plain cleaner.

Here is what is on the parts list so far:
Eaton M90 from a Ford Thunderbird (have)
3" Intake piping
AEM F/IC-6 controller
Venom 30# injectors
AEM AFR, boost gauges (have)
PCV oil separator
Full set of frame stiffeners
Rear lunchbox locker
Sealed battery mount / case with cabling

I realize some of this should have been done a while ago. Oh well, now's the time.

The majority of the fabrication is going to be the mounting of the M90 and the probable idler pulley. The intake of the M90 will need to be modified to fit in the engine bay and to locate the throttle body. I need to make sure I retain the bypass valve and have plenty of vacuum ports.

I realize cooling will be an concern. I have already put in an aux fan-driven Derale transmission cooler to offload the transmission cooling load. I just went over the entire system with a flush and new cap and thermostat. I cool pretty well with the stock single core radiator so I'm going to leave that for now until I run into issues.




Here is where it all begins. I have already started tearing it apart to rebuild it. I found no oil in it, and all of the lobes had oil on them so I need to get it completely apart, cleaned, and rebuilt. I feel a touch of rubbing at one spot in the revolution so I'm probably going to replace all of the bearings in the process. Of course the gear plate between the snout and the main body doesn't want to separate from the main body..

Looks good so far. My advice is take your time. This is a very interesting approach. The best part of this idea is that it leaves room over the Jeep intake manifold for an intercooler.

SolarBell said:

I will have to relocate the battery to the back and the coolant overflow bottle to the corner the battery came from.

Click to expand...

One minor update - I was looking at air intake layout today and realized that if I move my air intake completely to the passenger side, not only do I get somewhat cooler air by not being 6" from the exhaust, I also open up a really nice space to put the battery without having to run it all the way to the trunk. Considering the price of large gauge battery cable these days, I'm calling that a win.

SolarBell said:

One minor update - I was looking at air intake layout today and realized that if I move my air intake completely to the passenger side, not only do I get somewhat cooler air by not being 6" from the exhaust, I also open up a really nice space to put the battery without having to run it all the way to the trunk. Considering the price of large gauge battery cable these days, I'm calling that a win.

Click to expand...

There are mounting holes for the battery tray on the left side. I am not sure if the tray for left and right are the same, but they definitely made it able to be mounted on the left side.

I am curious how you plan to keep the AC compressor with the supercharger underneath. My plan was to ditch it since it is just acting as an idler pulley in my MJ.

If you don't have A/C, it's a near-perfect spot to put it. If someone were to make a nice bracket for it they could probably sell a dozen.

I finally got some time with the real M90, a tape measure, and my engine bay this afternoon. Not encouraging. Not enough room between the A/C compressor and the alternator to fit the M90 due to the length of the snout. For some reason I thought there was about an inch or two more than there actually is. It will probably end up much further outboard than I originally plan. The other challenge is that only about 3" outboard of the serpentine belt is the hard piping for the A/C condenser, so they are going to be in the way. The is going to take some serious creative thinking.

As I recall, the mounting holes on the left side were for RHD vehicles. Talk to someone in Europe about hitting a breakers yard for one maybe, if not that, fab something up or maybe harass Max @ DirtBound into making them... he already makes an Optima mount for the right side, and a lot of people are looking for the left side mounts to do dual battery overland type setups anyways so there is probably a market for them.

This looks like it'll be a really neat build, I can't wait to see what you rig up to make space in there for the supercharger.

With the battery moved you can probably modify your AC piping somewhat, it's just aluminum, as long as you use the right fittings you can reroute it as long as you have tubing benders and/or someone who can do airtight TIG welds on thin tubing. The latter is probably harder to find.

kastein said:

As I recall, the mounting holes on the left side were for RHD vehicles.

Click to expand...

I have seen them on diesel XJ and MJ models in the USA and Europe.
http://www.youtube.com/watch?feature=player_detailpage&v=Dce6maYuIfs#t=11

http://www.volvodemort.com/technical/jeep/photos/hi_res/image001.jpg

There is also this mounting option for the supercharger.
http://www.youtube.com/watch?v=uYywU1Wkikw

Re: Re: Project Shoehorn - M90 into a 4.0L

Alexia said:

There is also this mounting option for the supercharger.
http://www.youtube.com/watch?v=uYywU1Wkikw

Click to expand...

I saw that video when doing my research. Couple of thoughts about it after I learned more:

- I'll bet that belt squeals like a pig if the A/C compressor ever kicks on. Very little wrap.
- I don't see any kind of bypass valve or piping, so he's probably sitting in boost at idle.
- All that work and the throttle body is still on the driver's side. Seems a waste.
- The discharge output narrows to a pipe very quickly. Probably has efficiency and discharge temperature issues.

That being said, it's a creative way to try to fit an M90 in that space without removing the A/C. Mine will probably be within a few inches of where that is.

SolarBell said:

I saw that video when doing my research. Couple of thoughts about it after I learned more:

- I'll bet that belt squeals like a pig if the A/C compressor ever kicks on. Very little wrap.
- I don't see any kind of bypass valve or piping, so he's probably sitting in boost at idle.
- All that work and the throttle body is still on the driver's side. Seems a waste.
- The discharge output narrows to a pipe very quickly. Probably has efficiency and discharge temperature issues.

That being said, it's a creative way to try to fit an M90 in that space without removing the A/C. Mine will probably be within a few inches of where that is.

Click to expand...

Yeah, the belt wrap on the alternator looks terrible too. Mounting an extra idler pulley in there certainly could help.

Alexia said:

There is also this mounting option for the supercharger.
http://www.youtube.com/watch?v=uYywU1Wkikw

Click to expand...

The belt wrap is atrocious all the way around... The discharge requires 3" pipe and that appears to be 2", possible 2.5". No bypass in the system which is , IMO, a fatal mistake.

And how about that custom dent in the discharge pipe.

It is interesting though that he had relocated the PDC to make room.

SolarBell, according to my parts list, the part number for the Diesel battery tray is 5517 4970, the gasoline battery tray part number is 5523 5294. Maybe the part number can help you find a tray. Very few diesels (1985-1987) were sold here. May want to look at eBay in England. In Europe and elsewhere, the diesel was available from, 1985 to 1994.

Can always just fab up a battery tray. Just remember to have the battery temperature sensor installed as the PCM uses it to determine charge voltage. Lowers the voltage when the battery is warm.

kastein said:

Talk to someone in Europe about hitting a breakers yard for one maybe, if not that, fab something up or maybe harass Max @ DirtBound into making them... he already makes an Optima mount for the right side, and a lot of people are looking for the left side mounts to do dual battery overland type setups anyways so there is probably a market for them.

Click to expand...

Response from DirtBound customer service was less than positive. I probably can buy their universal Optima mount and fab it into place. Not the greatest option but I can make it work.

SolarBell said:

Response from DirtBound customer service was less than positive. I probably can buy their universal Optima mount and fab it into place. Not the greatest option but I can make it work.

Click to expand...

The mounting space on the left side is the same as the right. It is likely you could just drill new holes through the inner fender for new bolt holes for the right hand battery tray.

Anyone ever have any issues with the gear and rotor plate on an Eaton getting stuck to the body? I can't seem to get mine to separate. I got the snout off after some coercion with the rubber mallet, but that plate just doesn't want to come free and I am really hesitant to beat on it.

I'm hoping tonight to go and pull out my battery and tray to start getting a better idea of fitment. I also discovered that a friend of mine's shop just got a CNC router that they'll let me use for the cost of materials.

They can be a bitch to get apart. Just keep at it.. maybe spray it with PB Blaster.

My tactic for anything that will not separate is to lightly heat the part with the hole in it around the part with the shaft.

Be gentle with the heat. It is a good technique as is using dry ice (if available) on the inner portion of the puzzle that is stuck into the outer. The idea, of course, is to cause the materials to change size allowing the disassembly.

I use this method when assembling tight tolerance parts so as to not have to apply force. In particular, installing a new ring gear onto a flywheel. Same principle applies here.

The goofy thing is that the issue isn't not thing inside the other - it's 2 plates that make up the main unit that won't separate.



It's the bit on the right - there is the plate that holds the gears and bearings for the rotors that is face-mated to the main body with the intake and discharge. I can't get those two components to separate even though they are supposed to just be free as soon as the snout bolts are removed.

There are two dowel pins that could be stuck. Or its just the sealant holding it together.

I wouldn't use too much head as there are seals behind the gears that keep the oil out of the rotor area.

It may not seem like a big deal, but tonight was a big step. I took out my battery, battery tray, and coolant overflow bottle to get a real idea of whether or not the M90 was going to fit in the way I wanted it to. In short- it's tight but it's going to fit. It ends up being a straight sideways mount parallel with the side of the block. And not only that, the stock intake and discharge plenums fit as well. There is maybe 1/2" of space between the discharge plenum and the fuse box. The mounting brackets for the coolant bottle will need to be cut off of course.





The intake plenum has to be turned 180* so I lose 2 of the intake plenum mounting bolts, bit that can be worked around. And not only than, in the new location it makes for an almost perfect location for the throttle body. I'm going to cut the stock intake plenum right after the mounting brackets and have a throttle body spacer welded onto the aluminum as the throttle body mount, and good access for vacuum ports.



As for the belt I'll only lose about 10* - 15* of wrap on the A/C compressor, and with adding an idler pulley I'll be able to have lots of wrap on the M90 and the alternator pulley. I am still going to have to do some work to wedge the idler pulley in there, as the smallest one I've located so far is a 3.5", and there may not be that much room.

Couple other notes from doing this:
- I only have to change / bend / relocate the upper (?) pipe on the A/C condenser. The other one is well out of the way.
- The oil filter is going to suck to reach for oil changes after this is done.
- I may have to alter the oil dipstick tube a bit, but I won't know for sure until I can get it closer to a firm mounting spot.

Next steps are to start working out dimensions for fabricating the front mount for the M90 and the idler pulley, and to work out how to alter the pipe into the A/C condenser.

Oh, yea. I know my engine bay is filthy. One of these days...