Project Shoehorn - M90 into a 4.0L

[SolarBell]

From an information page on the Thunderbird SC (which my M90 is from):

The Super Coupe's comes equipped with a 3.8 liter V-6 powerplant that is force-fed with an Eaton Corporation supercharger. The 8.2 to 1 compression ratio, combined with six computer controlled sequentially fuel injectors, completes the well rounded underhood package. While running at a maximum 15,600 rpm's, the supercharger provides 12 psi of boost and as a resultant it develops 210 bhp at 4000 engine rpm's. The engine develops 315 lb-ft of torque at 2600 rpm. The supercharged V-6 delivers ample power without much noise but an underdrive kit and a performance chip are available to boost the horsepower rating to 255 bhp.

Redline on the 3.8L V6 is 5600 rpm, the stock pulley is 3.3" in diameter. Stated max supercharger speed is 15,600 rpm. Drive ratio would be 2.786 to get that supercharger speed, which means a crank pulley around 9.2" (?!?!?)

The XJ has a 6.375" harmonic balancer and I put on a 3.0" pulley. That is a drive ratio of 2.125. At the 5250 rpm redline on the 4.0, I will get a supercharger speed of 11,200 rpm.

That is an output that is reduced 21.8% in raw CFM numbers (since the rpm of the supercharger directly correlates to CFM). Along with the 5.63% increase in displacement, I think the boost will be reduced by approximately 25%. That would result in approximately 9 psi of boost.

 

[SolarBell]

That's an AVR-P20 board similar to this one https://www.olimex.com/Products/AVR/Proto/AVR-P28-8MHz/

the socket in the middle looks like you are going to put an Amtel ATmega8 into and use for an arudino type project, without seeing the underside of the board, I have no idea what you are trying to do.

Good call. ATMega328P.

 

[yossarian19]

That would result in approximately 9 psi of boost.

Which should translate, roughly, to 310 horsepower at sea level on a stock motor.

That will be real fun drive when it's done.

 

[SolarBell]

That will be real fun drive when it's done.

That's the idea.


Got started on the mounting bracket for the supercharger itself today. I had it CNC cut, but my measurements were off by about 1/8" so I cut the center bolt tab free and welded it back into place with all the bolts in to get everything lined up.



The hoop in the back is to make it all more structural and to provide a mounting point for the bracket I'm going to fab that will connect to the motor mount so the weight will be supported properly. It's too tall right now since I made it to clear the entire input port.

The whole thing will eventually get bolted or welded to the A/C compressor mount I already worked on. Not sure which to do yet, as I want to retain some adjustability to line up the pulley as precisely as possible. But the A/C compressor mount has some play to be able to move front / back and twist about 1/16".

 

[rav]

looking good so far do you plan on running an intercooler?

 

[SolarBell]

looking good so far do you plan on running an intercooler?

This setup will be capable of it and I know exactly what I would put in (3" inlet/output air/water setup). However initially I will not have one, for two reasons:
1. Money
2. At the moment I have absolutely nowhere to put the dang radiator. My engine bay airflow already sucks.

 

[O-Gauge Steamer]

This setup will be capable of it and I know exactly what I would put in (3" inlet/output air/water setup).
2. At the moment I have absolutely nowhere to put the dang radiator. My engine bay airflow already sucks.

Aye, there's the rub. No Room. Vents in the hood helps the flow through the bay but what good is that if the heat exchanger can not be mounted?

To install the heat exchange you have to loose the A/C condenser. Which is fine for a trail only rig... For that matter, giving up the A/C creates a near perfect compressor mounting location...

But, I sort of like my cold air in the hot months thank you very much.

Seriously though, where to mount the heat exchanger is the issue. Room can be found for the intercooler under the hood.

I even considered running lines through the A-Pillars with a roof mounted exchanger laid almost horizontally. It would work but, boy oh boy would it be fugly...

 

[rav]

just a wild thought but how about fitting a slim & long one in the front bumper housing and drilling some holes in the bumper to let the air in?

 

[rav]

Something like this guy:
http://www.performancetrucks.net/fo...trailblazer-ss-infinitely-going-build-486139/

It looks like a front skid plate...

 

[SolarBell]

Interesting thought, but not viable for what space I have. I already have a transmission cooler mounted behind the front crossmember and there isn't a whole lot of room inside my winch bumper. I could add a factory front skid and put it there, but that is prime placement for getting smashed on a rock since I do wheel a couple times a year.

 

[rav]

Makes sense. Luckily for me I have a 5 speed. Just curious what location did you have in mind if and when you did one.

 

[SolarBell]

The air/water heat exchanger would mount right in front of the brake master cylinder on the fender well, and the discharge hoses would just extend over. The radiator is the hard part. The two options I have found that have enough cooling capacity are 12x12x2 and 12x24x1. There are smaller ones, but the ability to reduce the water temp is much more limited.

If I didn't have my A/C the 12x24x1 is a perfect fit where the A/C condenser sits. If I did the roof mount as O-Gauge referred to, the 12x24x1 would be good as well. In theory a hood mount similar to the WRX is possible, but there is already so much heat in that space that I don't think there would be that much cooling occurring. And it would look much uglier than mounting one on the roof with a nice shroud. The crossmember is only 7" tall, so fitting the 12x12 low in the front would be difficult. It might work with a rear window mount, but not ideal for a family vehicle.

 

[O-Gauge Steamer]

IF...

If a roof mount was done with the 1" thick heat exchanger, then the total height of the thing would have to be a minimum of 3" in order to get enough air through the thing. The exchanger would be not quite flat eh?. IMO, it could be done and look semi-presentable if the lines can be routed through the a pillars and the shrouds are intelligently designed and fabricated. There is a possibility that it could resemble the Yakima air deflector that is used on roof racks...

This would allow a full 3" opening at the front. I would want to run a "yarn test" on the air flow across the roof prior to committing any cutting. If the rig is trail dedicated, one could remove a rear side window, duct air, from the roof, to the exchanger and fan force it to the outside.

Options become quickly limited for Streetable Jeeps.

Unless, of course, you just do not care what it looks like...

 

[yossarian19]

What about using the factory steering skid and cutting enough holes to get some airflow through it? Not as good as in the open but real estate is limited and the front skid is a cavern back there.

 

[O-Gauge Steamer]

You are right about there being room. I placed my fan forced transmission cooler there. I also spaced the skid down 3" as it is rather worthless in the stock position once you lift the Heep...

You also have to drop it for the exchanger to clear the front sway bar unless you fit a Currie AntiRock.

My concern about a heat exchanger mounted that low is it could easily get packed with mud and other junk from the road...

 

[yossarian19]

My concern about a heat exchanger mounted that low is it could easily get packed with mud and other junk from the road...

A good way to see how likely that is would be to look at the components immediately behind where the steering skid would be. On my jeep, it's all pretty clean back there - excepting the trans fluid slowly leaking from the lines. YMMV.

 

[rav]

What about using the factory steering skid and cutting enough holes to get some airflow through it? Not as good as in the open but real estate is limited and the front skid is a cavern back there.

The more I think about it I really like your idea!

 

[SolarBell]

Got the front of the supercharger frame connection to the A/C compressor mount worked out today. I'm not happy with the appearance of the welds, but I'm pretty sure it will be strong enough. The two 1/2" bolts are directly in line with the snout drive and the front mount hole is slightly larger than 1/2" to allow +/- 5 degrees so I can align the drive pulley. The rear mount will have adjustment capabilities as well.



I'll admit, the clearances are a little tight. But it clears.

 

[SolarBell]

The intercooler mounted on the skid is a pretty interesting idea. I'm pretty sure it would get quite full of snow or mud on occasion. Something to consider though.

 

[yossarian19]

I'd think the air charge temp would be high enough to melt snow off of it. Doesn't help with mud, but perhaps some expanded metal tacked in over the airflow holes would keep the worst of it out?