With my manual transmission swap functioning, I'm looking towards my next big modification. A few years ago I picked up a couple superchargers that had been unloaded by GM during their bankruptcy. They were cheap. A few hundred dollars a piece.
https://www.amazon.in/EATON-Supercha.../dp/B084RDQ3VP
It's an m122 eaton 3lobe unit at it's core. The STS-v that it comes on from the factory is 4.4 v8 with 440hp stock. I imagine this more modern supercharger while not perfect could potentially bump the STR up quite a bit depending on pulley size. With good tuning it wouldn't be unreasonable to think this could match the twin screw kits that used to be available.
I bought some intake manifold gaskets and the port spacing is almost identical between the jaguar gaskets and the Cadillac supercharger. The bolt holes at the 4 corners even line up close enough that you could retain the same mounting hardware. An adapter would just need to fabricated to account for port shape difference and I presume angle would not be exactly the same. Adapters like that would be very easy to make. I'm having some 3/8" flanges made up to start.

Pulley spacing is important. But even if it's off to perfectly line up, the snout on the eaton unit is fairly long and unbolts easily. It looks simple enough for a machine shop to shorten the shaft, mill a new bearing pocket.

A flange would have to be made up for the intercooler coolant lines as I'm way to cheap to buy the GM one that is several hundred dollars just by itself. But that would also simplify hose routing.

Injectors/fueling would have to be accounted for. I don't know if it would be easier to retain the jaguar fuel rails and plug the cadillac holes or vice versa.

Throttle body is electronic and comes with the supercharger. I'll have to find out if the actuation is close enough to be usable with the Jaguar ECU or would it be easier to adapter the Jaguar throttle body. I imagine you'd lose the EGR functionality.

An intake tube would have to be made. I imagine an aluminum tube that would make it's way over the driver's side (US cars) valve cover would be easiest to meet the factory MAF sensor.

I can't see any other issues other than the big one. Clearance with the scuttle panel/strut brace/hood. I don't know what the overall height would be with adapters. It's tall, but so is the factory setup. Does anyone have measurements of the factory supercharger? I need to do the valley pipe replacement at some point so I planned to get measurements then.

I post this mostly as a means to start a discussion. Hear people's thoughts and concerns. I'd love to hear it if anyone has input. I think the most expensive part about this would be the machine work for the snout if spacing is too far off. That being said, I do almost all my own labor so if you weren't doing this yourself it would get expensive.

 

somebody put the M122 rotor pack in the jag 112 housing using a custom spacer/adapter for a 122 snout (gt500 i think). only issue is that it was set up for a swap into a BMW V8 and he’s not interested in mocking it up for the jag v8.

 

Well that's a snazzy idea. Is there a build thread or more info on that swap?

 

https://www.bimmerforums.com/forum/s...-install/page3

that's all we really know. looks like the cadillac 122 snout and some work was done on it to get it to line up as well

 

I saw those on ebay last year. I looked hard but the fitting is beyond my ability. Sure would be sweet another 10 cubic inches per rev crammed in. And a tvs instead of a gen4. If you do it keep us posted

 

That's really cool. It looks like later on he swapped on the whole m122 anyway. Albeit with new intake runner sections. I don't know if that was to lower the supercharger or just get a better flow path to the BMW cylinder head. the stock cadillac port is pretty wonky shaped.

 

i see it now. that intercooler routing seems pretty straightforward

anybody want to drop off a 4.2 long block to clarkston michigan?

 

Haha. I've been looking at car-part.com for junkyard engines I could use for mockup...

 

Have you seen Avos's Twin Screw setup?
Very well done and for a while he even sold kits for the STR.
He posted a ton of info on how he did it to.
.
.
.

 

I went down that path a few years and purchased one of those STS superchargers thinking it might be a possibility. I quickly gave up on the idea. yes the ports are close, but they aren't a match. I placed the unit on my mockup block and determined that the amount of time and effort involved versus the amount HP return wasn't worth it. I really is most effective to purchase a KB twin screw and re-create Avos' kit.
(I hope you aren't planning on putting a SC on a N/A engine. Too high of compression.)

I originally had 4 different plans for the 4 S-types / STRs I own
1. Get my LS3/TR6060 swap running some day. (I'll probably get old and die before I get back to this project.)
2. Keep one of the STRs stock.
3. Build a super STR engine that uses a KB twin Screw. (Started this project 5+ years ago, no progress in years.)
4. Adapt some other SC to the top of the 4.2 STR engine.

Regarding #4.

A number of years ago, I purchased about every inexpensive supercharger unit I could find that I though might be adaptable to a 4.2 engine. Every one was a no-go without a lot of custom work.
The one I chose to work on the most was adapting a 5.0L Jaguar TVS front fed supercharger. This one gives the best chance of getting closer to the KB twin screw.
I still have a 5.0L machined down TVS supercharger assembly sitting on top of my mock-up block. (Some day I will play around with this concept some more. This really is the most viable and straight forward approach I've found to date)

One of the issues we will always have on our 4.2 engine are the stupid water inlet bosses on the front of the heads that block the area in front of the engine valley. This makes any SC body you chose have to sit a lot higher up on the block in order for the snout to clear the head's water inlet boss.

All this being written, keep life simple and go with the KB twin screw. It is proven and it works!
If you have a mill, and are a good aluminum welder, and love challenges, then sure, go ahead and spend a heck of a lot of time making some hybrid roots blower work on the 4.2 engine, and still not get much more power out of the engine, or ever come as close as a KB SC will .

Edit: Forgot to add that Jaguar's 4.2 SC design is really a hodge-podge of design compromises. It works ok, but really is a poor design. The Eaton Roots blowers are too inefficient, and the air coolers they use are too restrictive, and therefore too much heat is generated if you start modifying the stock flow of the M112. (I am sure that the Jaguar engineers did the best they could considering the real estate constrains they had in order to be able to fit the SC system into many different Jaguars.) The tortuous 180 degree inlet bends where the throttle body is located is one of the worst problems.
(If you take a look at the 5.0 TVS system on the next generation cars, you can see how much of an improvement this design is.)

 

Here are a couple of pics. You have to use your imagination some, but I plan to cut off the the lower outlet runners of the 5.0 SC manifold, and weld on a flat plate with the correct 4.2 inlet spacing. This drops the whole unit far enough down to clear the hood of the car. Then I would machine either adapters or a new inlet manifolds.
(Also not those idiotic water bosses on each head that totally limit how low a SC body can fit into the engine valley.

 

Do you have pictures of the STSv unit on your mockup block? Or dimensions on how high it sits? I was first wondering if it would still fit underneath the scuttle panel with an adapter design or if the intake runners would have to be chopped and rewelded to fit the jag intake ports.

A big displacement twin screw would definitely be the way to go if money were no object but I tend to like fitting parts to cars that really weren't meant to go together. I have an e30 bmw with a turbocharged volvo 5 cylinder and mustang 5 speed transmission. An old trans am with a newer twin turbo fuel injected motor in it. An e30 bmw that I lifted, put all terrain tires and chopped in into a pickup using a toyota 4runner rear window so it rolls down. An alfa romeo alfetta with motorcycle ITBs and fuel injection. I just like to make weird cars. But don't think I don't appreciate your input and suggestion. I have a hard time believing things aren't worth the time until I devote some time to them myself.

 

When I get some free time, I can place it on top of the block. (Not sure if it will be today, but should be easy to do.)

 

3.2 TS and power is never a problem : )

 

whee. That is sweet