Was a Paxton supercharger conversion, now a Rotrex C38-91

[Coops]

Hi every one,
this is aimed at the charger guys,

just bought a paxton sn92 on ebay, needs pulleys and dipstick,

im after as much info regarding VE tables etc for boosted engines,
so we can work out whats best for my car,
(did i get that right Mike?)

is it best to use one belt?
or a seperate belt for the charger?

any one got any dims for a paxton dipstick (no not me ) so i can make one in the lathe,

more questions as i think of them,

[kev_the_mole]

Not a charger bloke but belts and pulley my bread and butter. The charger will be the greatest load on a belt system so I'd seperate the charger from the other systems. Go for a toothed belt on the charger but you keep the serp peripheral drive. Toothed belt gives you no slip and allows you to run a narrower belt than a poly-v. Downside is belt noise but then it's a V8.

Cheers,

Ian

[Coops]

Cheers Ian, means will need a toothed crank pulley and charger pulley then

[topcatcustom]

Tony- are you retaining your interim front cover? If so as I have discovered the blower drive pulley needs to stick out a hell of a long way to clear the cover, its a lot thicker than the later non dissy ones. Looking foreward to seeing your install though!!!

[stevieturbo]

cant actually find any info on them...or not much.

They arent a gear drive, so it appears overspinning is out.

You most certainly DO NOT need a cog drive. A 6 rib serp setup will be more than adequate for what seems to be a small blower.

As I cant find any info....

try and find its maximum safe rpm...and gear it for that at your engine's max

[Coops]

hopefully R2d2hp maybe able to throw some light as he runs the same blower.

[Coops]

will i need an intercooler?
if so what size?

told ya i will ask lots of questions lol,

[stevieturbo]

will i need an intercooler?
if so what size?

told ya i will ask lots of questions lol,

very few FI installs that wouldnt benefit from an intercooler.

as big as posssible works for me.

[Coops]

ta lol,
looks like need to cut the front out the capri to make more room lol,

[stevieturbo]

bound to be bucket loads of room in a capri for a rad and IC with that massive front ?

[Coops]

my fans are quite close to the front grill,
i maybe able to move them towards the engine some more,
have cooling fans and oil cooler in the front too,

still searching for the info on the charger for you.

[Stuball]

Been having a trawl through the internet for Tony to get some details
of the sn92.

Found this site www.superchargerhelp.com

Took a bit of searching but this is what i found.

Max safe rpm is 38,000 "designed" to give 5-6psi

Charger rpm calculation is (Crank pulley diam/Charger pulley diam) x max engine rpm x 4.4

Dont take this as gospel, just what ive read on the above website!



Stuball


EDIT: Had another browse, 750-800cfm seems to crop up a fair bit?
Also apparently 785cfm @ 6psi is a common quote

[stevieturbo]

withought knowing how much air it moves, you cant know now much boost it might ever create on any particular engine.

But I'd still say spin it as fast as possible.

[kiwicar]

Hi Tony
I did some more searching last night, 38000seems to be the max revs, and 10 psi a max on a 302 at 5500 revs (some seem to rev them higher after peek power but they don't flow any more) which would equal a max flow around 750 to 800 cu ft/min if you want peak power at about 550 to 5800 and rev out to 6500 with 6 to8 PSI boost at 5800 thats 400 cu ft/min with no boost and 617 cu ft/min at a VE of .85. It will then deliver about 750 at 12lb boost at 6500 revs which if you take a VE of about .8 at these revs it should be right. So if you gear for 35000 at 6500 it should be spot on, with an internal ratio of 4.4 to1 then that is a drive ratio of 1.44:1 if the bottom pully is 4" then your top one should be 2.9" if you allow for 5% slip. . . so how big is the bottom pulley?
you will need an intercooler.
Best regards
Mike

[daxtojeiro]

Tony,
Ive fitted one to an RV8 before and 7psi is the max depending on if its the upgraded one or not, the original ones were a little less. Dont rev it passed 38000 or it will go bang! I have an upgraded bearing kit for one, but as its a nightmare to split I didnt touch it. You need special oil in it, I cant recall what it was called, but it was hard to get in the UK.
Have a read here:
http://www.extraefi.co.uk/cobra/accobra.htm

Click on Supercharger link
Phil