WickedC5

iTrader: (3)

I'm thinking of swapping from my current 4.00" 8-rib pulley to possibly a 3.90 or maybe a 3.85. I run an 8" IW crank pulley and a direct drive, so no belt slip at the moment with my A&A bracket.

Just wondering if anyone has successfully run smaller then a 4.00" pulley without belt slip on a C5.

Also, I'll be over spinning the blower from the rated 74,000rpm to about 78,000...I'm looking for ~23-24 psi. Currently I'm at ~20-21 psi. Hoping this isn't over spinning the blower too much? This is on a forged 347.

TIA

ajrothm

What kind of power are you making with the 4.00/8" combo? That is already a bit past max impeller speed at 6800. I don't think I'd spin it any harder, its just gonna crank up the IATs.. You MAY gain some power...maybe... Or you could lose power from high IATs and timing reduction.. Depends on how much meth you're putting in it.

With a 4.25/8" I see 22-23 psi at 6800 with and F1R on a 402 with a small 226 cam... Was right at 900rwhp SAE on mine with 17*.

Bob@BruteSpeed

iTrader: (16)

I wouldn't overspin it by that amount. Bob

WickedC5

iTrader: (3)

I'm right at 775rwhp on a very soft tune. My car is an A4 with 3:73 gears and a 3600 stall. I was going to pulley down more and get an aggressive tune this time around. I'm spraying a lot of meth. Goes thru VP M1 meth pretty quickly when I get on it.

Yes, im over spining by a little but not too bad. I think I might just get the tune as aggressive as I can and see what it makes...just wanted to get it all done at the same time since my tuner is not local.

Thanks

Detoxx03

iTrader: (14)

Yeah I wouldn't push it anymore than you already are.

I8UR4RD

iTrader: (16)

your around the boost limit of a 4 bolt block. id stick where i was till i had the money for more motor and more blower.

WickedC5

iTrader: (3)

Guess ill stick with the pulley combo I've got for now. But I'll have my tuner put it on kill mode. Thanks for everyone's input.

I8UR4RD

iTrader: (16)

id focus on seeing if i could make it flow better, thereby lowering boost but raising horsepower. less pressure is better. better heads, exhaust or intake/tb ect....might be able to make some gains there.

ajrothm

Wicked C5,

Have you made any pulls without the air filter/inlet piping on? You really need to try a 5" velocity stack on the blower instead of the filter/pipe. Mine picks up 44hp with a stack, no other changes. It gains 2 psi. I'd try that first. Then get a little more aggressive on the tune depending on where its at.

Dual nozzle meth? m10/m15 nozzles? With a few changes, I think you can still gain some power. Ofcourse, the harder you push it, you know what happens..

Kill mode suggestion..(track only)

3.90" pulley, velocity stack, dual m15 nozzles, shell URT or MS109 fuel (for safety) and dial in the AFR/timing for peak power...(probably around 11.2 AFR and 18* ball park) and let it eat.. That's probably 50-75hp over what you have now... But it's not feasible or safe for daily driving/racing and you would have to switch tunes back and forth.... BUUUTTT.. That's what I'd do..


In the mean time, just throw a velocity stack on it on the Dyno and see what you gain.. You'll be surprised for sure. You need a 5" OD velocity stack to clear the radiator.

WickedC5

iTrader: (3)

Thanks, aj. I appreciate the input.

I definitely want to have my tuner try a couple pulls without any filter/tube to see what it picks up. I did see on CF where you picked up some really good power going with a velocity stack.

Where did you get yours from?

Thanks!

ajrothm

You can find cheapies on eBay. 4" id and 5" od... About $50.

Definitely try it first before you do anything else. F1s don't like anything in front of the inlet.

Firehawk441

iTrader: (41)

Since you're spinning the supercharger "HARD", I'd suggest sending the Volute to Steve Morris for CNC porting.