You might be the person who can help me. Forget my limited budget. I’m going to sorta Follow Jaguar's lead. They tossed an Eaton M90 supercharger on their Six cylinder and picked up 115 horsepower. Mmm sounds good.

Ever measure a M90? Then measure the space in a XJS’s engine bay Minus the V12? You know what? They fit!!!! That’s right. Sure you need to make an adaptor, figure out the drive belts easy peasy stuff But once you do, Bob’s your uncle.
Yep a pair of M90’s stuffing into 12 chambers with 7.8-1 compression pistons.

Now before you start to think I own a gold mine or something. You are aware that GM put 10’s of thousands of those M90’s in Chevy’s, Buick, Pontiac’s and even a few Fords. You know what the average price of a good one in a You-pick-it Junkyard is? $35 yep. $35. So two will cost all of $70 in case your calculator is broke.

All that is left is make the English translate to American in some magic black box and that V12 is making 450+ horsepower. Not to mention what E85 will do. ( at least another 10%. A lot More if they are spun near their designed range)

Oh, to be fair, pretty sure if you go the twin stuffer route. Civilized stuff like air conditioning, cruise control, Heater, Power brakes, Etc become persona non-grata in the engine compartment. The alternator will wind up being one of those tiny little ones you find in small cars from Japan. And The power steering pump will be just the pump with a remote reservoir wedged in some corner someplace.

 

MG you immediatly jump to a different topic, that goes from a simple readjustment ECU, to a lot more money and work involved!

 

I told you about my twin turbo’d Chump car didnt I.? I was doing some research on a smashed up XJR I wanted to buy for parts. And noticed the blower. Just a Eaton M90 and it kicked up the power an extra 115 horsepower
Next I discovered they sell for between $35-50 at junkyards typically they put out 8 pounds of boost into about 4 liters.

My solution was to chop the end off, weld on a Big SU or two and go for it. The trouble is an HD 8 will only flow 400 CFM OK let’s try 2 per stuffer. Oops. now it won’t fit.
I still have that new Megasquirt I got with the car. All I need to do is teach the Yank to speak British and the English guy to play nice with boost.

 

My first reaction to your post was wrong. On reflection
I think you’ve got a lot to teach me. Or maybe I can hire your skills?
I’m a life long racer, always looking for affordable ways to go racing.
The cheapest, safest way to more power is put more air into the engine. Turbo charger, superchargers, do that at modest cost. Used turbochargers, superchargers are in hundreds of thousands of wrecked and rusty cars found in junkyards. Some cars pulling one is less than an hours work with basic hand tools. At that point they can quickly be checked for function. Basically give’em a spin. As long as they stop at random spots they are good. ( and not have and weird scrapping sounds) . In that case haul them to the check out and pay your $35-50 bucks.
It’s not that hard to fit them to the car, if you don’t have the fabrication skills there are plenty of people who do.
All that’s left is figure out how to add more fuel as pressure goes up.
That’s where you come in.
Figure out a way Where you can add fuel with boost You can be rewarded.

The earliest Jaguar EFI system had a way to richen and lean the mixture. Using that and the new gold palladium spark plugs which fire even heavily fouled We bought a EFM that worked on pressure to trick the engine into thinking it was going lean. And at full boost (5PSI) another switch turned on the cold start injector.
It was crude and probably cost me a lot of power over a properly developed system but it felt like it doubled the horsepower.