I just put a D1 supercharger on my basically stock 350 tpi. The supercharger pulley is 3.85 and the crank pulley is a little under 8 inches. At 5000 rpm I'm only building up to 5 pounds of boost. I'm trying to get ten pounds, so what pulley size should I get?

 

i dont remember the gearing of the d1, but that seems like a pretty aggressive pulley ratio....? need to figure out what the gearing is on the d1 and go from there using a impeller speed calculator.

 

If he didnt have such a massive boost leak that D1 and pulley woud have made MORE than enough boost to grenade that motor.

 

it is 4.44/1

 

Well with a pretty much stock car and 4" pulley this is what I got. Your pulley is probably slipping or you got a nasty boost leak, here is a tensioner idea you might want to look into https://www.thirdgen.org/forums/powe...ed-spring.html

RPM--PSI
3000-2.5
3500-3.5
4000-4.8
4500-6
5000-8
5500-10
6000-12

 

sweet thanks for the info!

 

the belt is slipping, i run a 4" pulley and make almost 14

 

it was slipping a little, i tightened it up and did another run but i still only made 7.3 psi at 5000rpm in 3rd gear. i called procharger, they said i should be making more psi, I checked for any possible leaks in the piping and couldnt find any. The only other thing i could think of is my cam has too much overlap and letting all the boost just go out the exhaust

 

i do live at 5000ft above sea level i dont know how much that would affect it

 

Whats a good way to check for leaks?

 

I'd bet the belt is still slipping, or your BOV is opening early.

What are you running for a BOV?

-- Joe

 

prochargers "Big Red Race Valve"

 

You said stock L98...

 

not completely the guy I got the engine from payed someone to put a cam in it, he had no cam card or any info on it. he thought it might be an RV cam. all I know is it's not stock

 

I used to live at 7000ft. With a couple turbos and an sc.
At altitude you will see less boost than at sea level.

 

Whats a good way to check for leaks? try getting or making a boost leak tester . (youtube how to make one ) make sure your leak free before you do anything else

 

at 5k ft u will make 2-3 psi less then u would at sealevel.

if u have a vacum/boost gauge in the car u will notice with the engine off the gauge will read below 0 vac

im at 6500ft above sealevel and i need to make 3/4 psi of boost depending on weather conditions just to get back to sea level power wise

at 6500 ft engine off my map sensor typically reads around 80kpa , u should be around 86ish kpa if im not mistaken

 

well the belt was definitely slipping I tightened it up more was able to build up to 8.5 pounds of boost but that was at 5200 rpm. when the car was naturally aspirated horsepower start falling off at 4600 which only puts me at about 6 pounds of boost and I'm just not sure that's gonna be enough to make the horsepower I'm looking for. plus I think I tighten the belt too much because after making the run the thing start falling apart

 

So how much boost do you thing it would take to make 400+ whp? N/A the car had 260whp at 4600rpm.

 

does anyone have any ideas at all??

 

7-9 psi should do it

 

Cool thank you for the info. Would you have any idea on pulley size?

 

I'd be careful about trying to pour a bunch of boost to a stock motor. More boost doesnt mean your going to make more power. Just my .

 

I will definitely be careful. I did order a 3.55 inch pulley but I'm not even gonna put it on until I see what the 3.85 inch does