Casually I have been looking at the 92-97 Supercharged 3800 POntiac Bonneville technology. Recently there have been quite a few of these blowers on eBay and Craigslist and at affordable prices.
Having researched a blow thru Turbo to cost $1500-3000 and found it hard to do because of shock tower infringement, I have parked that notion away for my 65 Nova. I know some fabricators have worked their way around the towers. I am not sure I have those resources.

So, I was wondering how hard would it be to try to match one of these GM superchargers up to my 250 inline Chevy? Is this going down the same road as the turbo?

Someone on here did this...I don't remember who though.

If I remember right, they adapted a four barrel to the air intake at the back of the blower, and the either used a one off manifold, or a Larrowe and Sons?

It's all kinda foggy - but I know it's been done!

Definitely going to be watching this one...

-Sam.

74NovaGuy contacted me some time back to make him some brackets and an adapter to mount a similar setup on his 250. Maybe thats who your thinking about.

I need to search the post, but it was "Pappy"..Blue roadster with a blower on a Chevy 250..

Sincerely:
Paul...aka xerxes

Edit:...Pappy is "jlgrooms" and the thread started on 5/16/08, titled "supercharged 250 chev".

Sincerely:
Paul...aka xerxes

OKay this is getting interesting. I would like to stay with carb blowers seem to accept them when set up right. If I went to efi I would go MegaSquirt. But I must find those other threads...

This is the one you're talking about.

http://rides.webshots.com/album/551417709MbbrwV?vhost=rides&start=84

That's true but Pappy was very careful to make the plenum large enough to overcome the blower placement. He said the fuel distribution is fine. This is the longest stock snout you can get and it is about 3 inches too short. I've been scratching my head trying to figure out how to extend one cleanly.

Now I remember Pappys set up. So i think I must at least research the Ford set up to see if possible. Good thing my engine is on a stand right now. Lots of measurement to do here.

James

Ok, I have to ask, since this topic is really peaking my interest.

What did the stock 3.8's that these were on have done to them to allow for boost? were they just cast pistons, since it was a relatively low boost situation, or...?

I know those blown 3.8s really went...an ex gf had one. miss the car, not her...haha..

Also, would it be possible to mount the blower 90 deg., with the bottom facing in the ports, and "stagger", i guess, the pulleys like it was mentioned ford did? And would this be an acceptable way to acheive even air/fuel flow within the plenum to the ports?

-Sam.

This is so funny!

panic, why do your posts disappear? A lot of the things you add just aren't there any more and it screws up the flow when someone comments on information thats gone.

When comments are to explain why I'm wrong, or to add information that I already posted, I'm wasting my time and yours.

Since most of your comments don't contribute to the topics anyway....why bother at all.

I don't contribute to the topic? Really?

Let me suggest an alternate explanation: you don't understand what I said.

would it be possible to mount the blower 90 deg., with the bottom facing in the ports, and "stagger", i guess, the pulleys like it was mentioned ford did?

Short memory, have we?

Provided there is enough room in the engine compartment to allow the blower adequate clearance with the shock towers,its feasible to mount it that way. I have seen several race inline engines with the blowers mounted this way. Might not be the most practical approach, but it has been done. And obviously works for them....

Armond,
As far as the snout length goes, Magnuson makes a two-piece drive assembly for eaton 45, 62 and 90 series. According to my catalog they range from 4 to 20 inches. No prices listed but their ebay store has a m90 with a 8.85 nose for $275.00 (buy it now).
z

OKay...so ...we are getting somewhere here. Research is the answer folks. Back to the drawing board.

Here's the link: http://tinyurl.com/dbbrlc

That's a great price, this is the highest point of development of the M series.
You still need the obvious brackets, drive pulley, etc. and must fabricate an intake. My first guess: make up a flat plate with the intake side bolt pattern, and make it anything you want. If you have enough room front to back it can be a 90° turn up to a 4 bbl. adapter as a base.

This is going to sound complex, but there's another way to disconnect the blower discharge position from the length to the pulley, but it's only good for blow-through.
1. locate the blower case so the pulleys line up as usual.
2. rotate the blower 180° so the exhaust faces up.
3. make a cover for the discharge port using the gasket surface and whatever bolts are available, with a 2" long 3" OD cylinder stub over the end of the triangle.
4. 3" 90° bend to a straight 3" tube
5. tube angles away from the blower (not straight across) to align with a normal 4 bbl. manifold inlet (Clifford, etc.)
6. tube enters the carb hat or box from the side

3" is just my guess (same area as a 4 bbl. with 1-1/2" venturis), but since it's dry it doesn't matter. It would be a problem if draw through carb.

Words hurt head. Here are some pictures when I was toying with this subject. Disclaimer, none of these are mine. I was just using them to visualize the project. Supercharger inline

Z

I'm curious Panic..What is it that you find so funny? It's getting by me at the moment. Seems like a couple of members trying to put an idea together. Trying to get information for a potential project. Is that the funny part?

Sincerely:
Paul...aka xerxes

What's funny?
After I post a very long comment, some tells me that I "don't contribute".

I guess "contribute" means different things to different people.
To mean - it's posting something that is:
1. correct
2. useful
3. no one else thought of

And you just read my last 2 posts, and you don't think I did anything at all....

Seems like a couple of members trying to put an idea together. Trying to get information for a potential project. Is that the funny part?

No, the really funny part is that some clever person has decided to make my remarks permanent.

Hmm... what effect do you think that will have?

I guess you'll need to make sure you cross all your T's and dot all your I's then, huh!

...because I always make those mistakes, right?

Better and better.

panic,
it is comments like this and others you have done that hurt your reputation in my mind. there are other times you do contribute in a positive fashion also, that i like. different ideas are good, putting them out like trash is bad. tom

Of course, the criticism and personal remarks about me are all well intentioned and appropriate, right?

It's the strangest thing.
For those of you who are new to this stuff (my 1st personal computer: 1983) there used to be only 1 rule of conduct for a BBS:

"A comment may be made to initiate a new topic, or to reply to the content of a prior topic, but never, ever about the motive, competence, or personality of another speaker".

Not too much attention paid to it here, is there?

No, in my opinion, you don't contribute much useful. When asked to elaborate or explain particulars, you get your panties in a wad and start deleting chit. On these topics, it seems you would rather argue. I sent you a nice "I'm sorry" PM after our last exchange thinking I might have been a little rough on you. To me, it's clear you have limited social skills on this board.

this is a nice way to say i personally would not be offended if you packed up and left.

For all I care, anyone else can pile on. I'm tired of this guys attitude.......

X2

The M90 on ebay has to be the best deal of the century! If I weren't so far along it would have been my first choice.

I took an M90 from a Mustang and installed the longer GM snout, then built an adapter to mount it to a Clifford 4 barrel intake manifold. The openings are almost dead on. Still need to machine the bypass and build a heated connection section. That way as your in cruzin mode without boost, the mixture will have carb heat and when boosted it will be cold. For something different, I'm using 3 Harley constant velocity carbs they are altitude compensating and each will support one hundred hp. Getting the snout longer has been my main question mark. I did look at the Magnuson site and have a copy of their catalog coming but I would prefer to keep it homegrown and cheap, old school. It will go on the 230 in my '41 pickup.

Pics, we need pics! :-)

Sounds neat!



MBHD

I sent you a nice "I'm sorry" PM after our last exchange thinking I might have been a little rough on you

"Apology" is not how I would describe it. Didn't notice any words normally found in an apology such as "wrong", "sorry", "mistake", "apologize", "error", "regret", etc.
Instead, you explained why you were right and I was wrong, why your behavior was appropriate and mine was not, and what you will do if I annoy you again.

By "limited social skills" you mean I prefer to please myself, rather than you? Because the important thing we accomplish here is to make people like you, isn't it?
And if someone says something completely devoid of factual content (I won't elaborate, because the comprehension of this sort of material isn't what I hoped it would be) the right thing to do is to agree - because his feeling will be hurt, and as we all know all opinion have the same value.

What the word I'm thinking of?
Finding the same behavior that you exhibit offensive in others?
Begins the letter "H"?

Sorry I asked.

You just dont get it. I saved the PM I sent you and will happily post it so others can mane the judgement on how it came across. (maybe you are right about how it came across - I doubt it, but its possible). From my perspective, it was a nice statemnt that said we got off on the wrong foot and not start a war over the deal. You chose to blow it off. Fine by me but expect the same treatment in return. You started this mess I didnt. I'm not the hypocrite - I'm treating you as you treat me. I think tlowe and others should feel the same way. Just look at this thread. You took a nice thread and insulted the OP.

Dont put words in my mouth regarding the "limited social skills" comment. I'll spell it out for you so there is no misunderstanding: limited social skills = your post are offensive and condescending.


Moderators: ban this guy. he continually stirs the pot. His posts do not help our club or website. BAN HIM!!!

His posts do not help

You're absolutely right.

Moderators: since you have wisely decided to censor my work, please delete all my previous remarks.

Dont let the door hit you.........

Panic, I don't know where you get the 'censor' idea, your posts have not been modified by me.

Everyone, Let's get back to exchanging ideas, respecting the other person's intellegence, and try to avoid more pissin' contests.

It's one thing to think something to yourself, but a complete opposite when you put it in print. Like Momma used to say, if you cant say somthing nice, stifle it.

Tim Tenold
Webmaster

Your remarks can stay....they just need to delete you!

Isn't that cute!

The VERY FIRST THING you absolutely must do after the Webmaster says "avoid more pissin' contests" is.... make another rude remark.

But, please - don't feel as though there is any need to stop merely because the rules have been explained to you. After all, they don't apply to YOU, so they? So, feel free to add more insults.

I know you won't disappoint me.

Arguements on line is like an arguement with a spouse.
There are two rules:

Rule #1: You never win the arguement.

Rule #2: The next word you say is the beginning of the next arguement.

Mike

cheers to that , mike. well put. now let's quit ruining this thread. tom

Gentlemen, I've been away from the BB for a while, and seem to have dropped back in into a pile of chicken litter.

Back to business: James, Armond, Samwise, there is a cheap and simple way to center the supercharger on the head. But it would not be pretty, and thats the reason I didn't use it on my roadster. You could build a jackshaft, mounted on brackets attached directly to the manifold. (that means a total of 4 pulleys, 2 belts). The supercharger can be mounted with the discharge facing the head ports, and I considered doing just that, but it fit better around my headers like I did it. This winter, I modified the carb to "calibrate" it to supercharger duty. What I did is not easy to explain and the photos did not turn out well, but if you're interested, I will explain it later. Samwise, I have trouble remembering numbers, but I think the 3800's would boost up to 11-12 psi. I limited mine to 7 psi for longevity. I put 6000 miles on it last summer with no hitches. I just now finished putting a little heater (engine coolant) on the bottom of the carb plenum to keep it warm. The main manifold stays warm from exhaust header heat, but the carb plenum always ran COLD with condensate forming on the outside. So I figured the same thing was happening with fuel on the inside, even though I couldn't tell it performance-wise. It's rained here almost every day for 2 weeks now, so I can't tell yet if it has helped. (fuel mileage hopefully)

If I can help you in any way, let me know.

pappy

Hey Pappy, nice to see you back and in the middle of it. I did think of using a jackshaft and have an air conditioner compressor for the shaft and the clutch. I thought what the heck might as well stop the whole thing from turning if it's not boosting. Mercedes did this. In the end, I'll lengthen the snout. The Studebaker is taking all my energy right now. We want to fire it up this week.

Armond, good luck to you & Leo with the Stude this year.
Give Leo a hug for me. just kiddin.
pap

might as well stop the whole thing from turning if it's not boosting. Mercedes did this

That's a useful mod.
If the blower stops, obviously almost all the power lost in the drive comes back (except for belt friction to the clutch, and the clutch hub bearing).
The bypass, of course, now sees only vacuum (since nothing is satisfying engine demand under the rotors), and remains open, diverting air or mixture from the carb right to the manifold no matter what the throttle position.
IIRC Magnuson sells a stand-alone bypass valve.
The Mercedes M62 application (2.3 liter L4?) shows that the bypass area is enough to cruise the car with the blower stopped.
I'll bet the Mercedes clutch is keyed to vacuum so that the blower engages on full throttle, and the boost closes the bypass.
If you're going to use an A/C clutch (which is solenoid operated by a switch) I'd use a relay and a kick-down switch on the carb secondary linkage etc. rather than a vacuum switch, which will operate differently depending on which gear, hills, etc., and may induce knocking.

Easiest (?) would be a jackshaft as Pappy suggested but the idea of incorporating it into the snout extension has some merit as well. It would be clean there. Another way would be to simply have a switch, AK "Road Warrior" style. Switching the blower on and off at the correct times to make a smooth transfer would be the ticket in my eyes. I'm using a carb base as my bypass valve, it's larger than the Mustang's and should support just about all normal driving conditions (HA!, like my foot's going to let that happen). The compressor's pulley is too large and it will be a trick to get it down to size. Just details.

A nice jackshaft feature is that the 2 pulleys need not be the same size or shape.
Depending on what you have for the crank and blower, you may need more or less than the ratio of the 2 diameters: make the input side (crank driven) larger or smaller than the output (drives blower) side, and multiply that ratio by the existing.
E.g., crank is 9", blower is 6" (1.5:1), but you want 2.5:1.
Use a 5" on the drive from the crank and a 3" on the drive to the blower (1.67:1).
1.5 (existing ratio) × 1.67 (jackshaft ratio) = 2.5:1.
Sometimes you have too much ratio: the blower pulley is 3", giving 3:1. Slow this down to 2:1 by using a 4" on the driven side and 6" on the driver side: 4:6 = .67:1.
3.0 (existing ratio) × .67 (jackshaft ratio) = 2:1

In addition, it may permit you to save work in 2 ways:
1. use an existing multi V-belt pulley on the crank
2. use an existing serpentine (multi-rib flat belt) pulley on the blower
How? The jackshaft has a dual V pulley on the input side (common automotive or industrial part), and a serpentine on the driven side.

Yes, quite doable. At heart, I try to boil things down to the very simplest form a system can be at and still be fully functional. I put myself through college building custom choppers. Ended up a licensed aircraft mechanic (helped build the formula racer "El Bandito"), worked as an engineering liaison at an optical firm building prototype production equipment. A bunch of other stuff as well, Bonneville to drag cars. For me it isn't just a machine but an extension of myself and if I'm going to remember how to work on it tomorrow, it had better be simple!

Now the practical questions:
Do you have an extra row on your existing (or spare) crank V-belt pulley?
If not, are there other pulleys available (JY) with extra rows for A/C, etc?
If such exist, what's the OD?
This is going to limit your ratio.
Typically, the M90 doesn't turn very fast, about 2:1 on the V6, but could be faster on your 250 since I don't think you're going for max power at 6,000 RPM?

Ok, I have a 7 inch crank pulley, six rib, no V belt, no a/c. There isn't room for any more on my '41 Chevy truck. Stock 3.8 inch Bonneville supercharger pulley but aftermarket pulleys can go down to 2.8 inches. It is a 230 (3.8L) 5,000 RPM is all I'm going to ask out of it (RV cam). The alternator has a 6 rib pulley and will be the tensioner. M90's have a 1.5 L capacity.

How much boost you want, Armond?

I'd be included to just try it out using what you have.
The worst would be too much boost, and I'm sure there are larger blower pulleys available to slow it down but they need a puller to R&R.
If it's going to be a draw-through you can (temporary) restrict the air inlet at the TB flange which will reduce boost, but I suggest this only for testing since it also increase load and raises air temp.

A friend of mine had an SSEi B'ville for a few months (he worked for a dealership, it was a trade in), IIRC he was saying they were running just over 8 psi on the stock 3800.

I have no idea what size the crank pulley was though.

8 pounds is about what I'm hoping for. It would be good to know what a stock early Bonneville pulley is. Does anyone have a formula for calculating boost? This is the one I have but it seems to underestimate reality.

(Super Charger Disp/1/2 Engine Displacement) * Ratio * 14.7) - 14.7 = Boost Pressure

it seems to underestimate reality???

That's the one i use.
It should get you to within 10-15%.
Your cam overlap and exhaust backpressure have a big influence, though.

FWIW there is a performance blog about one of the T-Bird Super Coupes that a fellah was 'tweaking' that he included the testing he did before and after each mod (along with dyno time IIRC).

Can't seem to find it now, but it goes along with what jlgrooms said, he actually lost a small amount of 'boost' when he got a free-er flowing exhaust on his car, but picked up some HP and Torque as well as lowering the EGT (in the beginning he measured the exhaust pressure to be higher than the boost pressure ).

That was before he put the smaller blower pulley on IIRC (wish I could find it, it was very informative).

Pertinent because it had the M-92 on it as well (somewhat different 'plumbing' though ).

Your cam overlap and exhaust backpressure have a big influence, though

Definitely.
Correct backpressure for blower: zero. If his BP exceeded his boost level he was using iron single exhaust with a bad muffler.

Any improvement to the head or exhaust will reduce boost and increase power. Boost means there's an obstruction.

There's a correction for overlap that can be plugged in to the formula.
1. Take nominal overlap (not @ .050").
2. Deduct 30° (Vizard's correction for ramps in a hot cam).
3. Multiply result by .01
4. Subtract from boost pressure (it's leakage).
Example: overlap is 70°, deduct 30 = 40°, × .01 = .4.

I prefer to move it around:
B = ((ratio × blower capacity × 2 × atmospheric pressure) ÷ engine displacement) - (atmospheric + O/L adjustment)

Example, using 230" + M90 @ 2 × engine speed, overlap is conservative at 50°.:
(2 × 90 × 2 × 14.7) ÷ 14.7 = 5,292.
Divide by 230 = 23.01.
Subtract (14.7 + .2) = 8.1 psi.

That's why I found it valuable and informative, he started with empirical measurements on one that was bone stock (IIRC) then re measured after each incremental change.

Yes, all math predictions are guesses only - not because the math is flawed, but because there's no way to tell internal blower leakage, belt slip, restrictions in the ports, charge temperature increase etc.