Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (
-   Hotrodding Basics (
-   -   Junkyard mods...Twin M90 Supercharger 302 (

67MercCat 07-03-2011 11:00 PM

Junkyard mods...Twin M90 Supercharger 302
I've been told in other forums that this concept is insane...but.....Thats what experiments are for. All theories are welcome! I want to specifically use the M90 because of they're readily available from junkyards in various mid 90's Fords and Buicks.
This concept was spawned by the website I know I'm going to need some fabrication, some imaginative intake, intercooling and belt driving system. But I think together we can come up with something great. I'm also aware that Fuel injection is the best way to distribute fuel for this application, but for the sake a the challenge, I want to use a 850 CFM blow thru carb, similar to the one centrifugal blowers use.

High nickel Mexican Block
Forged crank
H beam forged rods
Forged pistons
Crane Cam Hydraulic with matching valve train (
Gt40p ported heads
1.6 rollers rocker
Edelbrock Performer intake
HEI distributor (GM Style)
Long tube Headers
3 inch pipes w/Dual Flowmaster


lowROLLERchevy 07-04-2011 01:39 AM

66 Attachment(s)

Austin martin 5.4l

Made 550 hp and 555 ft·lb tq, upgraded to 600hp in 1998

67MercCat 07-04-2011 10:03 AM

wow thats what I'm talking about, it looks like a really clean... smooth set up. I like the intercooler set up that gave me some mounting ideas. I only have a certain amount of engine bay space though, that's why I'm trying to mount them up top like this...[IMG][/IMG]

But 550 HP huh, oooooohhhhh...sounds about right

el pollo 07-04-2011 10:06 AM

Meh. Using a twin turbo setup will net more power.

67MercCat 07-04-2011 10:58 AM

oh yes u better believe it. A single m90 doesn't move enough air for a 302, it would actually cause a blockage after 3000 RPM and make the car loose power, but two m90 is like having an M180...(I think) but I've been searching the net for flow luck yet, even on the Eaton website.

cleanspeed1 07-04-2011 12:13 PM


Originally Posted by 67MercCat
oh yes u better believe it. A single m90 doesn't move enough air for a 302, it would actually cause a blockage after 3000 RPM and make the car loose power, but two m90 is like having an M180...(I think) but I've been searching the net for flow luck yet, even on the Eaton website.

Do it! Call Magnuson, since they rebuild these things all the time and can give you all the particulars about the supercharger.

67MercCat 07-05-2011 03:16 PM

Cool I'll call them today and gather that info. I went to their website and was please to hear they also make longer shafts for special applications like this. As for the drive belt system. I can maybe use the pulley set up from the Ford Explorer I got my GT40p heads from. Adapt them somehow to include the two blowers. They also have a 6 rib belt set up.

67MercCat 07-06-2011 10:08 PM

According to my research, GT40p heads don't make good candidates for supercharging. I've been told that they are designed to work within a certain temperature and will cause detonation if I try to use forced induction.
I wonder if some Valve overlap or intercooling would help with combustion chamber temperatures...any ideas?

What heads make great supercharging candidates?

cleanspeed1 07-07-2011 01:37 AM

I wouldn't accept that premise. The GT40 and GT40p's are good cylinder heads, and have been used with forced induction of all types for years.

Me, if I were using a Roots style or screw compressor style supercharger that boosted right off idle, I'd go for something that was a little larger in port runner than what would be normally run since you don't have to worry about port velocity ( the superchargers will see to that ) and then cam accordingly.

For example, I'd do something crazy like find a solid 190cc intake or larger head ( up to 225cc as long as it wasn't something that I had to get special headers for it ). If it was naturally aspirated, it'd run like a 4 valve Cobra, kinda low on bottom end torque. But since the boost curve is flat from the time you hit the gas till speeding ticket time, plenty of torque from the bottom to the top. Besides, with all that port area, you can make more power on less boost, which means less heat and detonation sensitivity.

Just a thought.

67MercCat 07-07-2011 08:54 PM

oh thats good to hear. I never heard that theory about GT40 heat until I started talking about supercharging to the fellas. I also read on the Magnuson site that Eatons M90's actually dont generate much heat either, which is why most of them come from the factory without intercoolers. I'm bouncing between a boss 302 FMS block or a 351 for this project now that I've done a little reading.

cleanspeed1 07-08-2011 05:05 AM

As long as you are not running excessive intake temperatures with too lean of a A/F ratio, you'll be OK. It seems Fords and forced induction belong together. ;)

With what you have listed in the original post, except maybe for the Performer intake, the combo is solid. You didn't mention about how much boost you want to run and how high you wanted to rev the thing. If you keep a 6000 rpm or so limit and the boost level low, you may not have to go to an aftermarket block.

There was a turbo 351 combo that I was in the process of putting together a few years ago that was centered around a set of Ford Racing's N351 iron heads ( 379.00 a piece ). These need a few special pieces to run, but running mild boost and a custom cam it sim'd out at over 640hp. I too was a fan of the crew, especially after the 900.00, PVC piped turbo 351W they put together.

Intake wise, I'd go single plane just because the superchargers are going to be doing the work, and the air and fuel does not need to be "tricked" anymore to produce velocity at atmospheric pressure. If you want to go dual plane, the Performer Rpm for a heavier car or if you are going to be cruising off boost most of the time.

Wonder what your motor would do with a pair of ex-Terminator Cobra blowers?

67MercCat 07-08-2011 12:46 PM

The performer intake was something I picked up cheap so I was using it for now, but I didn't really know the difference in dual plane and single plane other than low end torque and streetability differences. So supercharging will deal with that single plane low end torque issue?

I want to race occasionally, but I'm new to the drag strip, and i don't know what RPM's would be suitable so I dont get totally chewed up at the track. As far as boost, I thought 9psi would suffice. But then again, I'm really limited in the knowledge I have for psi in a twin set up. It's going to take a lot of guesstimating.

67MercCat 07-09-2011 11:59 PM

also, The m90's have their inputs on the back and discharge on the bottom, it would prove to be extremely difficult to use an intercooler with that sort of set up. The problem lies more in the engine bay size than the set up itself. How did your buddy have his intercoolers set up? That Bonhams set up in the picture earlier in the post is perfect, but my engine bay proves to be too small..

cleanspeed1 07-10-2011 04:40 AM

I don't think I said anything about blower orientation, but given that it's cramped inside the Cougar engine compartment, maybe it would be a good idea to get rid of the shock towers with a different front clip, then mount the superchargers side by side similiar to the Aston set up.

Where did you intend to put the blowers?

67MercCat 07-10-2011 11:41 AM

At first, I wanted to put them on top, kind of the traditional set up. Like the photo earlier in this post. But the orientation of the S/C won't allow it. The Aston Set up seems to be the best choice. removing the shock towers would be great, but thats a whole different beast. I would image I would have to do some major suspension upgrades to keep up with the new found power anyways. Do you know of any major suspension upgrade kits?

All times are GMT -6. The time now is 10:48 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.