Another OHV M90 build

[jd4242]

Are you going with a smaller pulley JD? Any idea about what size I should get for mine? I think going 6 rib is best to try first. Thanks for catching that.

yea because custom 8 ribs for everything else would cost alot.i dont think you have anything to worry about with slippage.unless your pulley gets real small or high boost.thats a real small pulley on there.have you done your boost equations yet?i have a 3.2 and a 2.7,im running a 3.2 for now to get 5.9psi then going to a 2.7 for 9.8psi.i have a 6" pulley and yours should be the same.pulleyboys is a good place for pulleys but you maybe able to get them on ebay.your charger is pretty conman.every psi will gain you about 15-17hp.i say a little less with your motor sense you dont have as high compression and motor work as i do:Based on that i could be looking at a 120hp gain,dont think ill get anywhere near that but hey i can dream

Yes it will get you close.

To figure pulley size from required boost level:

Step 1: Theoretical pulley ratio = ((14.7+Boost) / 14.7) x (engine liters / 2)) / Supercharger Size liters

*Assuming "0" inlet losses and 6.5" crank pulley.
For 6 psi boost with a 1.5L supercharger on a 4.0 engine: ((14.7+6) / 14.7) x (4.0/2))/ 1.5= 1.878 ratio

Step2: Supercharger pulley size = Divide the pulley ratio(1.878) into the crankshaft pulley size (6.5") to determine supercharger pulley size (3.46").




To figure boost level from known pulley size:

Step 1: Pulley ratio = crankshaft pulley diameter / charger pulley diameter 6.5" / 3.46" = 1.878 ratio

Step 2: Theoretical boost = (charger size in liters x pulley ratio) / (engine L / 2) x 14.7 - 14.7

Example: (1.5 x 1.878) / (4.0 / 2) x 14.7 - 14.7 = 6.0 lbs boost





The Eaton M90 displaces 90ci of air per rotation so that converted to liters would be 1.5 liters. I changed the examples above to reflect the engine and supercharger in this thread.

Pulley ratio 6.0" / 3.2" = 1.875 ratio

Theoretical boost = (charger size in liters x pulley ratio) / (engine L / 2) x 14.7 - 14.7

(1.5 x 1.875) / (4.0 / 2) x 14.7 - 14.7 = 5.97 lbs boost

Based on that you can estimate a rough gain of 90rwhp give or take. Of course how aggressive or how conservative the tune is, engine flow efficiency, camshaft specs, supercharger inlet flow efficiency, drivetrain losses, etc will play a sizeable role in determining your total number.

If I were you I would figure for 15-17rwhp. Twin screws and modern TVS make in the 18+ area but I don't usually see many Eaton's doing it according to my recollection. Use 15rwhp per psi and if you get more then be extra happy.

 

[jd4242]

i have two press on pulleys also you can have it they fit you charger.also if you go smaller than 2.7 you need to mill the snout of the charger.how much boost are you wanting to run?if i was you i would get a modular pulley system so you can switch pulley real easy if you want to throw a small one on for the track,especially sense you can tune real easy

 

[Dono]

Sounds like something like a 3.2 inch pulley would be lots for me. Im betting that would register a higher boost than you anyway, as my motor doesn't flow like yours.

 

[Dono]

Im not going to be tracking this thing, I just want a vehicle thats more fun to drive. Im better off than I was, but I still dont exactly have an accelerating monster on my hands.

 

[jd4242]

Im not going to be tracking this thing, I just want a vehicle thats more fun to drive. Im better off than I was, but I still dont exactly have an accelerating monster on my hands.

so how much boost you looking to run?you should be flowing pretty good too.your not stock either:shifty_eydid they do a valve job when they fit your valves or just fit them?you ported your LIM a little to right?in between my heads,ported and match every thing to the max and straight pipes, ill be moving some air

 

[jd4242]

i have a 3.8 press on you can have but think it wont give you barley any boost

 

[Dono]

thanks JD, Ill look around pulleyboys for a 3.2 pulley then. yes, a 3 angle valve job was done to mate the si valves, along with some p&p. def better than stock flow.

 

[jd4242]

thanks JD, Ill look around pulleyboys for a 3.2 pulley then. yes, a 3 angle valve job was done to mate the si valves, along with some p&p. def better than stock flow.

How much boost you wanting?

 

[Dono]

Im thinking 8 lbs tops.
I just looked at pulleyboys. Confusing.

It does appear my pulley is 'keyed'. I just pulled the lock nut off to have a look at it. So factory for a supercoup (Depending on year, of course) is 8 rib, around 3.8" keyed pulley.

So, that means I need a 6 rib 3.2" keyed pulley. I dont see that anywhere on pulley boys.

What if I ran a 8 rib pulley on a 6 rib belt? Turnig in to to much of a junkyard build? I know, no one wants serpentine belt issues as the 1 belt runs everythnig. I wonder if I need to email pulley boys.

 

[jd4242]

I dont know but i know they make them.try all years.ive seen them on trucks so.or maybe they use the press on m90s i dont really know.pull the pulley off and measure the shaft.

 

[Dono]

That will be a tomorrow thing. There certainly isnt any standards, even within Eaton

 

[rpcaster]

Im thinking 8 lbs tops.
I just looked at pulleyboys. Confusing.

It does appear my pulley is 'keyed'. I just pulled the lock nut off to have a look at it. So factory for a supercoup (Depending on year, of course) is 8 rib, around 3.8" keyed pulley.

So, that means I need a 6 rib 3.2" keyed pulley. I dont see that anywhere on pulley boys.

What if I ran a 8 rib pulley on a 6 rib belt? Turnig in to to much of a junkyard build? I know, no one wants serpentine belt issues as the 1 belt runs everythnig. I wonder if I need to email pulley boys.

Had it that way for 5-years and no problems! 8-rib pulley and 6-rib belt.

 

[Dono]

Ah, thank you Ron!
I think I'll try the existing pulley and see what kind of boost I get.When I put a tape measure across the diameter of the pulley (End to end) i get 3 1/2 inches. So, it looks like the diameter of the pulley without the lip is about 3.25 inches.

This pulley might just be fine for me.

 

[jd4242]

Had it that way for 5-years and no problems! 8-rib pulley and 6-rib belt.

really?i would think it would or could jump a rib and become off aligned with the other pulleys and cause it to pull off the other pulleys.

 

[rocket 5979]

really?i would think it would or could jump a rib and become off aligned with the other pulleys and cause it to pull off the other pulleys.

If the pulleys are aligned then the belt will not want to jump ribs because there is nothing pulling it out of alignment. Path of least resistance will make it stay on the ribs. It is not an uncommon thing to run a wider ribbed pulley than belt. My 8.5" crank pulley on my Explorer with the KB supercharger on it is a 10 rib but my whole serpentine system is an 8 rib. It works just fine.

 

[jd4242]

If the pulleys are aligned then the belt will not want to jump ribs because there is nothing pulling it out of alignment. Path of least resistance will make it stay on the ribs. It is not an uncommon thing to run a wider ribbed pulley than belt. My 8.5" crank pulley on my Explorer with the KB supercharger on it is a 10 rib but my whole serpentine system is an 8 rib. It works just fine.

yea key word if they are alignedi personally wouldnt trust it,but if the pulley he has is the size he needs then yea run it but if you getting a new one because of size, i would get a 6rib just for piece of mind.these are one off kits not a system that been in production or ran by others before so alignment may not be ideal

 

[Dono]

Were going to find out.

At least I can run it and see what kind of boost I get. The pulley on the sc right now has taken a bit of a 'bang' on the ribs. Not too bad I don't think. It will be worth trying, and saving myself $100.00 though. Only paid $75+shipping for the whole SC.

 

[jd4242]

Were going to find out.

At least I can run it and see what kind of boost I get. The pulley on the sc right now has taken a bit of a 'bang' on the ribs. Not too bad I don't think. It will be worth trying, and saving myself $100.00 though. Only paid $75+shipping for the whole SC.

$100? pulleys go for about $30 where in the world did you find a sc for $75?is it good still?what kind of millage is on it?any coating left on the blades,any play in the snout or clunking?

 

[Dono]

I think I was lucky. blades look good, no pitting visible. snout has a fresh oil change. spins smoothly. It was on the supercoup forum. Ebay is expensive for this stuff.

on the pulley, I must have been looking at pulleyboys specialized pulleys. They were 75.00

 

[phix-]

it was a long walk (apparently I stalled out on page 1) to get that video/picture of the relocated coil pack bracket. Here it is.
http://www.youtube.com/watch?v=ULMzobA5Mlo