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

stevieturbo · Post by **stevieturbo** » Wed Feb 10, 2010 11:04 pm

pretty old unit, with no curved blades.

The rebuild kit I mentioned

http://www.superchargersonline.com/prod ... Rebuild-92

Not sure which parts are vital.

SuperV8 · Post by **SuperV8** » Thu Feb 11, 2010 12:43 pm

What power target are you aiming for?? How much power do you have at the moment??

I've done some calculations (someone else may also like to varify this!)

Assuming a VE of 0.85? The 4.6 rover v8 will need 521cfm at 8 psi to make 330bhp.

At 6psi it will be 300bhp.

Your supercharger is designed for 6psi I think up to 8psi max.

Just some thoughts. I've been thinking about the same thing with my setup - is the supercharger capable of supporting my power airflow targets?

Tom.

Post by **Coops** » Thu Feb 11, 2010 6:55 pm

takens me 2 years to get a charger,
dont tell me it aint big enough now

stevieturbo · Post by **stevieturbo** » Thu Feb 11, 2010 7:00 pm

Always buy bigger !!!!

Have you found any airflow figures for it yet ?

Post by **Coops** » Thu Feb 11, 2010 7:06 pm

just asked if any one has any airflow figures for the sn92 on the supercharger forum mate.

stevieturbo · Post by **stevieturbo** » Thu Feb 11, 2010 7:11 pm

can be slow there.

Have you tried emailing Paxton ?

Post by **Coops** » Thu Feb 11, 2010 7:12 pm

they pass you over to another company now as they have no dealings with the sn chargers now, they deal with just the novi's

kiwicar · Post by **kiwicar** » Thu Feb 11, 2010 7:45 pm

Hi Tony
It normally gives 6 to 8 psi on a 5 litre engine (around 250 to 275 bhp NA baseline), on your 4.6 it will be fine for a first supercharger, on the forums I have seen they run out of puff on a 351 when trying to get 10psi out of them, but that is alot more air than you want. I am confident you will see 8 psi at 5800, if it produces only a little more boost as you rev the engine past peak power that will be a good thing as you are running basically stock bottom end. You are running an engine of about 8.5% less capacity than it's most common application so you should be well within what it can deliver.
My worry all along was it would be too big for the CR you have and you would not be running it fast enough for low down power as I said for a first supercharger I think it is about right.
Going straight to a V2 would have been alot more worry when it came to getting it matched, gear it for 35000 to 38000 revs at your red line (6500) and see what happens, I think it will put a nice smile on your face.
Best regards
Mike

Post by **Coops** » Sat Feb 13, 2010 4:57 pm

stevieturbo wrote:Always buy bigger !!!!

Have you found any airflow figures for it yet ?

Stevie one of the guys from the supercharger forum posted this reply mate:

750 cfm from what I have heard, polishing and enlarging the exit tube helps a lot

SuperV8 · Post by **SuperV8** » Sat Feb 13, 2010 6:58 pm

It would be good to know at what pressure it will flow 750cfm at?

A leaf blower would flow over 750cfm but would not do that at a high enough pressure ratio.

Sounds a good enough flow to me though.

Tom.

stevieturbo · Post by **stevieturbo** » Sat Feb 13, 2010 7:05 pm

SuperV8 wrote:It would be good to know at what pressure it will flow 750cfm at?

A leaf blower would flow over 750cfm but would not do that at a high enough pressure ratio.

Sounds a good enough flow to me though.

Tom.

Largely irrelevant.

If the specs detailed are correct, you could assume it will flow 750cfm, at 38,000rpm

Pressure created wont matter, unless its some crazy figure, but that isnt going to happen. Regardless, if the blower is spinning at that speed it will be moving that amount of air. It cant really do much else.

Leaf blower comparison isnt the same. The drive is different, it uses a fan and not a compressor, so there is lots of "escape" routes for air to bypass the actual air mover.

Post by **Coops** » Sat Feb 13, 2010 7:14 pm

that not the info you needed stevie?

stevieturbo · Post by **stevieturbo** » Sat Feb 13, 2010 7:26 pm

At a guess, at around 750cfm realistically its approx a 500bhp supercharger. Give or take.

Just spin it as fast as you can.

Post by **Coops** » Sat Feb 13, 2010 7:41 pm

that will do for me

Post by **Coops** » Wed Feb 17, 2010 5:13 pm

the members on www.superchargerhelp.com are brilliant,
I asked for a few measurements to get a dipstick made,
and one of the members has done a pucker pdf drawing for me,
Just need to fiind some one to price it up and possibly make it now,

when i get five mins i will pop round to the car and measure up the O/E serp bottom pulley so we can work out the correct pulley size for the charger,
i have found some ford V6 idler gear which will come in handy to route the belt round the charger,
will i need a second tensioner? or just the single one thats on there now????

also another thing i forgot about, breather system?
what do i have to do with this

thanks again for your help guys,