GHOSTOWLGRID

Hey everyone.

I've been looking into this topic for quite a while, and I only recently bought the Eaton M62 Gen III Supercharger from a Pontiac 3800 v6 engine at a junk yard.
Supercharger is in great shape and works.

My vehicle's current specs:
1988 Chevrolet Beretta GT.
3.1L MPFI v6 (I Upgraded it from the 2.8L MPFI)
5 SPD Muncie 282 Transmission.
Stage 1 Centerforce clutch.
AC Delco cast iron flywheel.
Stage 2 Motorvation chip, mapped for boost or standard.


Specs to engine I got M62 from:
3800 Supercharged Compression Ratio 8.5:1
7.0" Crank Pulley
1.84 ratio
Blower @ 10800rpm
Engine @ 6000rpm.


Specs to my engine:
3.1L MPFI Non-Supercharged Compression Ratio 8.9:1
6.1" Crank Pulley
1.6 ratio
Blower @ 9600rpm
Engine @ 6000rpm.


M62 Supercharger:
Pulley: 3.8 Inch.

I noticed a lot of people here are familiar with the 3.1L v6 Engines.
My 3.1L v6 is stock. I never upgraded any internal parts.
I was thinking of trying out about 5-10 PSI at most. My initial task is to simply make this thing operate for now. Later once I get it all working, I'll remove the engine and install stronger internals.

My question however, I have no idea how to make the M62's built in bypass operate. I was considering simply not using the bypass, and buying a different size pulley to help decrease boost if its to high.
But if someone can help me make the boost bypass function, I'd appreciate it, it would save me from having to worry about using to much boost.
(I know its wasteful, but my intent is to make it function at first before I build this up).

But I'm hoping I can get away with the existing pulley size.

My biggest question is how much boost can the stock 3.1L v6 handle?
I want to stay within safe limits.

How much boost do you think this Eaton M62 will give my engine given the specs above?

Do you think its safe? If I have to buy a larger pulley for my M62, what pulley size would you recommend?


Thanks for helping me out, this is the first time I'm doing this.
I have a friend who will help me machine and weld parts. and I figured out where to install the vacuum hoses on the engine to keep them all working normally.
I'm also using the 3800 engine throttle body, I will adapt my TPS and IAC to it.


EDIT:
My 3.1L v6 is the FWD version of your 3.1L v6's.

I forgot to ask, A while back I found this:
https://www.thirdgen.org/forums/v6/6...-fasteddi.html

In there is a video and in the description it says he has about 13.5 PSI boost from his turbocharger.
Did he build up the internals of his engine or is the internals stock? (Internals meaning pistons, rods, etc...)

Six_Shooter

iTrader: (2)

The bypass is not for limiting boost, it is to allow air to the engine by bypassing the rotors when off throttle.

I don't know how you plan to set up the SC, but in stock form, the SC is bolted right to the intake and the throttle body is before the super charger. If you plan to leave the TB where it is on the 3.1 and have the SC before the throttle, I'm not sure how effective that bypass will be. The function of it is to not heat up the air and allow an easier path for air when boost is not required. It sounds like you might be planning have the throttle body before the SC. You can simply wire the IAC and TPS that is on the 3800 SC supercharger to your existing harness, no need to adapt anything to the TB.

Boost is controlled by pulley ratios when an supercharger is involved.

GHOSTOWLGRID

I plan on using my existing intake manifold the way it is. Only modifications to it will be to cuto off the stock throttle body and weld it shut. Then to machine the top flat, and make an adapter plate to bolt onto the top of the intake manifold.

Then the supercharger will bolt onto the top of the adapter plate.

My main concern is that with the pulley ratios I will have, will the supercharger be pushing to much boost for the stock engine?

I was asking about its built in bypass because I wasn't sure if I needed it or not. Chances are I will not use it at all and I will always have boost.

I will use the superchargers 3800 given throtle body, it has a different tps, so I will have to adapt mine to UT, but it should be fine.

I'm not trying to do anything drastic yet, just simply making it function is all.

Six_Shooter

iTrader: (2)

but you won't "have boost all the time", only when the engine is under a high enough load and the RPM is high enough, regardless of the functioning of the bypass or not.

To make the bypass work is as simple as connecting one vacuum hose to a point that would be the plenum below the SC in your proposed installation.

I don't think you understand how a TPS works, you simply have to change the harness for the TPS to plug in. Both the 3.1 and the 3800 SC used a 5 volt reference and the same scale for the TPS range.

As far as how much boost will be made, you'll be better to research that on the Beretta sites, since there have been a few people do this exact modification. The fact that the F-body uses the genI 3.1 the air flow through the intake and heads is different than the genII 3.1 and therefore changes what boost and primarily what amount of air gets into the cylinder. In other words 10 PSIG of boost on a genI 3.1 will not be the same as 10 PSIG of boost on a genII, due to the differing restrictions to flow in each engine.

GHOSTOWLGRID

Well, I finally made up my mind. I will use the bypass. After reading all kinds of posts and articles, its a useful part of the Supercharger and keeps things good.
I was confused there for a while thinking it was only there on the previous engine because of some ECM tuning.

I'm glad that you mentioned that about the TPS. I didn't think it was the same. I have the plug and the 3800 TPS, and I will splice it together.
I kept thinking it was different because I saw photos of someone elses car who already did this, and they modded the 3800 throttle body to mount the 3.1L TPS to it.


As far as my boost, I'll have no idea until I build it and test it to see what I get.

I stumbled upon this photo:
http://farm7.staticflickr.com/6098/6...34cb429b_z.jpg

1 = Boost Bypass Valve Actuator
3 = Boost Control Solenoid
4&5 = Supercharger
7 = Boost Bypass Valve
8&11 = Throttle Body


Apparently the boost bypass valve is serving a dual purpose, it bypasses boost when not needed, and it limits maximum boost.
Now I finally know what the solenoid is for, I can get a controller to operate it, or I can buy a manually controlled turbo bypass valve and just set it.
But its nice to know it is already set to function as far as bypassing unnecessary boost.
This makes it so much easier!

EDIT:
Does anyone here have any suggestions to any electronic bypass/blow off valve controllers?
Something that electronically reads a PSI and then operates the BOV vacuum solenoid I have (or its own solenoid) in such a way to limit the supercharger at like 5-10 PSI?

zs&tas

watching this thread with interest, 88 2.8 been parked up 3.5years, my kids 3.5 years old - strange how that happens !! been thinking about it more recently though, it was always going to end up with a supercharger so im liking your build bud :-)