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M90 max boost

V

Vogey

New member
This isnt necessarily a 3.8 question as it is a m90 supercharger question. Whats the max boost one can get out of the m90 on a 3.8 (given the necessary intake and exuast mods have been performed on the 3.8) and whats needed to get 10lbs, or 14-16? (2000 gtp)
 


I'm sure you could spin it to 15-16+ lbs but at that point it's not even efficient anymore, it creating so much heat that the higher boost levels is just hurting it.


Remember boost is a measure of restriction. So a car that is stock making 7-8psi could make more power if it was modded and making 6psi. Through mods that reduce restriction like exhaust, camshaft, rockers.

It's hard to say exactly what combo will make exactly this amount of boost but if everything was stock just dropping to a 3.4 pulley could make 10psi but I wouldn't suggest that to anyone ever.
 
The boost pressure you make on a 3.8 pulley Gen 3 M90 will vary greatly on mods and how high you are above sea level. So it depends on multiple factors.
 
Somewhere in the low to mid 20's. Drive costs are the limiting factor. The more boost, the more power it takes to turn the blower. So, you will run into problems with the belt slipping.
 
Ive been collecting m90 superchargers over the past summer (i scrap vehicles) ive now got 4 m90s from 99-01 buicks and gtps. I want to build a 700 hp 454 for my 24' carerra ss. A 454 7.4 it has square port heads and open headers threw transom i doubt ill run into problems with it breathing. These heads should support 450-500 hp fairly easily. Being a marine application the operating temps are very cool compared to a car, and it will be sucking cold lake air. The idea is to mount 2 m90s side by side on top of a single plane dominator intake and have a 4 barrel mounted on the back of each. Id like to run 8-10lbs of boost normally. With the option to run 14-16 when i feel like really screaming. Im just trying to figure out if 2 will get the job done
 
there was a guy who ran 2 m90 blowers on a 5.3 LS engine. I really hope I remember right, but he said he ran out of boost on the top end. I think 4 should be enough. it sounds like you will be doing all the fabrication yourself, why not rig up an intercooler with the heat exchanger sitting in the water?
 


Two m90's will flow around 900hp of air if overdriven enough. So, you should be able to reach your goals without any problem.
 
Do you happen to remember how high his top end was? Im looking to have max 5500rpm, you dont think 2 ported m90s with a 3.4 pulley would get it done? Adding more superchargers starts to complicate things. Like was said above u run into drive issues. I feel 2 running on 1 belt is pushing it already. As for an intercooler, i dont understand how it would work with the supercharger, bein mounted straight to top of engine
 
I'll do some checking around and see if I can find links to the thread where the guy built the 2 m90 LS engine. one thing to consider is the actual diameter of the harmonic balancer. a bigger balancer will make more boost, and if the balancer on the 454 is that much bigger, you won't need as many superchargers. if you figured out a way to rig up a water to air intercooler with the heat exchanger sitting in the water, all the inefficiency's of the m90 would be negated to an extent.
 
I did a quick search and i get now how the intercooler fits in there, bein ill be building a glorified "box" to sit a pair of m90s on and mount to a 4 barrel intake (single plane dominator flange) it wont be very difficult to put a few heater cores in there height is not an issue, i could even double stack the heater cores to get 4-5" of intercooler, i could run water lines that get cold water b4 it passes threw the block)
 


You could do an Aussie RWD IC; I think Yella Terra used to make it, no idea if they still do. At least you've got a setup to start with.
 
The main point if this build is economy, i have access to a fully equiped fabrication shop l. And got the super chargers for free, the 454 core i got (99 vortec 4 bolt main roller cam) came with the port injection manifold and a single plain dominator intake) just lookin for forged internals. Lookingat the air to water i/cs aval on ebay i dont have a doubt we cam incorporate that into the build
 
for a few dollars more you can get an M112, on ebay they run for 400-500.

or just keep going with the m90's, it would be awesome to see a dual m90 build.
 
Id be all over a dual m112, but u dont get many lightnings ot jags or gt500s to scrap, i been pullin the m90s off cars i buy to strip and junk (its how i make a living, getting free go fast goodies is just a perc lol) if things go well on the 454 ive got a dodge v10 that might get the other 2. Itll take some grunt to pull the 30' 5th wheel toybox and the 24' carrerra
 


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