Supercharging my 4.0 ohv.

[AllanD]

Guys...


There is absolutely NO NEED to "upload pictures" to resize them (smaller)
you all use windows computers so all you got t do is go to the image file in Explorer and RIGHT CLICK the file then choose "edit" from the drop-down menu
and you can resize the picture right on your own damned computer...

 

[ColinwiththeblueRanger]

Heck ya. You got my sub!!! I have a 4.0 ohv in a 91 ranger that I would love to super/turbo charge. I can't wait to see how yours turns out

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[nesralyrrej]

Thanks man! This project has been slightly delayed, due to destroying my brakes, so I've been dealing with that (by ignoring it and driving my mustang) but snows on the the way and the mustang/ turbo ranger can't move in the snow lol, should have updates on the supercharger here ina couple days

For now enjoy these pictures of my destroyed brakes!

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[ColinwiththeblueRanger]

Dang. That's not fun. I'm trying to get my truck to pass emmisons (without luck)

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[MagicMexican]

Thanks man! This project has been slightly delayed, due to destroying my brakes, so I've been dealing with that (by ignoring it and driving my mustang) but snows on the the way and the mustang/ turbo ranger can't move in the snow lol, should have updates on the supercharger here ina couple days

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While you're down there, it might not be a bad idea to put disk brakes in the back from a mustang GT. It's not that much work and it'll help you stop once you have all that power...

 

[nesralyrrej]

That's a swap I haven't seen yet, on the explorer axle?


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[stmitch]

I believe the Explorer axle has the "big bearing" axle flanges. The factory Mustang GT caliper brackets will bolt up to "small bearing" flanges only. Places like North Race Cars offer adapters that would let you run the Mustang discs on your "big bearing" 8.8. Personally, if you're considering the disc swap I'd suggest the Cobra discs. They have a slightly larger diameter than the GTs, but they are vented vs the GTs solid rotors. They'll take a lot more heat before they warp or crack.

As for your pulley size/boost level situation, you need to find compressor maps for that Eaton supercharger. It shouldn't be too hard since the Eatons were fairly common. It will tell you how efficient the supercharger is at various RPMs. If you know how fast you want to spin the blower (you'll probably want the low end of the efficiency window), and you know your crank pulley diameter (or whatever pulley is running the supercharger belt) then you can do some math to determine the ideal diameter of your supercharger pulley.

 

[don4331]

Mustang Cobra (at least through '06) are smidgen smaller than Explorer (11.65 versus 11.87) although they do have advantage of being vented. But they require Mustang calipers which at only 38mm for pistons are significant reduction from the 48mm pistons in the Explorer.*

So, as you are replacing both rotors, and caliper; I would at least try '10-11 Ranger rear discs. They should be direct replacement. They have advantage of still being 48mm pistons, while getting you vented rotors. They are a hair small than the Cobras, 11.62 (but same amount thicker) but they retain the drum parking brake (which you may/may not consider an advantage).

(Trying the newer caliper/rotor is on my brake investigation list along with the front rotor upgrade).

*There is the '93 Cobra setup which has 10.5" vented rotors/calipers with 45mm pistons.

 

[nesralyrrej]

Thanks for the info guys, I'll get you updates as soon as I can


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[brokecanadianstudent]

An M112 is a massive supercharger for a 4.0. an M90 would be a better choice for 4-5 pounds of boost. A 4.0 will inhale 2 liters or 122 cubic inches of air per revolution. Since an M112 moves 112 cubic inches per rev, you need a pulley which will give you an overdrive ratio of about 1.1 to create 1 atm (0 psi) of boost (14.7 psi absolute). This would require a 5.5 inch driven pulley, assuming a six inch drive pulley. Assuming no loss from drag/heat/efficiency, a 3 inch pulley would give 2 atm, or 14.7 psi of boost (29.4 psi absolute). Compare this to an M90, moving 90 cubic inches of air per rev, would require an overdrive ratio of 1.35, or a 4.4 inch pulley to make 1 atm of boost. Of course, due to efficiency losses, your actual pulley size will need to be slightly smaller to maintain boost at higher rpm.

 

[nesralyrrej]

An M112 is a massive supercharger for a 4.0. an M90 would be a better choice for 4-5 pounds of boost. A 4.0 will inhale 2 liters or 122 cubic inches of air per revolution. Since an M112 moves 112 cubic inches per rev, you need a pulley which will give you an overdrive ratio of about 1.1 to create 1 atm (0 psi) of boost (14.7 psi absolute). This would require a 5.5 inch driven pulley, assuming a six inch drive pulley. Assuming no loss from drag/heat/efficiency, a 3 inch pulley would give 2 atm, or 14.7 psi of boost (29.4 psi absolute). Compare this to an M90, moving 90 cubic inches of air per rev, would require an overdrive ratio of 1.35, or a 4.4 inch pulley to make 1 atm of boost. Of course, due to efficiency losses, your actual pulley size will need to be slightly smaller to maintain boost at higher rpm.

Wow, I've been turning wrenches a decent time and I don't think I had to re read something so many times to fully understand.. now I would definitely have considered an m90, but I'm much to far into this project to go back now lol. So, 6" crankshaft with a 3 supercharger will make 14.7, so if I up it to a stock size 4.5" pulley I should make something like 8-9? If my top of my head math is close..


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[nesralyrrej]

Crankshaft pulley on the ranger currently is 6.25"


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[nesralyrrej]

Some small updates

pulling the studs from the intake.

studs removed

spacer and m112 adapter

bolted down with these flush allens

supercharger bolted on, ranger tps and iac valve on the charger.


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[don4331]

nesralyrreg:

Nice work cutting out the plates; I assume you used lock-tite on the bolts, so they can't accidentally work free.

I forgot to comment on the blower calcs. The 122 in^3/rev assumes 100% filling of cylinder - which is only achieved at with camshaft-less valve technology and/or tuned runner lengths. A number of between 80-90% is better for production engine.

I have a spreadsheet from when I was considering putting a blower on my 3.0. It suggests pulley of 4.25" for 8 psi on 4.0. and results in about 300 ft lb torque and 210 hp (assuming no other changes to engine); you'll want 24lb/hr injectors from a 4.0 SOHC.

 

[Blown]

The mounting plate looks good! Nice job! I would like to see the bottom of the blower?

I think it is smart to have a couple, if not a few different pulley combinations available to be able to adjust boost. On your build, 8-9lbs is pushing it on high octane pump gas without an intercooler. The tune would need to be good to prevent predetonation. I would shoot for 5-6lbs and get it running and tuned well before you go to more boost.

I speak from the experience of popping a head gasket when I went to 9lbs of boost with a poor tune some 13 years ago.

One advantage of the larger blower is that it should make the boost you want with less work and heat.