1PSI AT 5K??SN2000

[blackmach1]

I bought a sn2000 from craig at paradise for my 351c with 4v heads(big port) and no matter how tight i make the belt,even to the point were i might ruin the blower or my main bearings boost goes from 3lbs at 3500 rpm to 1psi at 5k.IT'S NOT BELT SLIP.Rotational torque on pulley is 25inchlbs.
I guess I should mention that before i fabed up the blower to the car i was making 300whp.Are the balls slipping?Or is the blower maxed out?
Running a 3.75 pulley with a 6.5 crank pulley.HELP

[pavement pounde]

At 25 inch/lbs the balls should not slip or at least not that much, so your 100% about not having beltslip, now check for boost blow-by along the hoses/tubing.
Did you check for bracket flexing ?

[blackmach1]

I checked for boost leaks,belt slip,the only thing left is internal slip.
The bracket is very stout metal.Forward and back flex is next to nothing with all my weight.Craig said that 25inch/lbs is within spec but I could tighten it up alittle should help maybe to 35.How tight should the socket head cap screws be under the dust covers?Mine were somewhat loose maybe 10ftlbs.

I really want to keep this blower setup cause the custom setup on my cleveland came out so nice but it's really testing me.Is there anyone local in illinois that knows anything about these blowers cause I couldn't find anyone.

[pavement pounde]

10 fl/lbs is not much, I got mine way tighter and.... the balldrive gets tighter when torquing these front coverbolts, so I would torque them somewhat more but, don't be an ape here, it is all aluminum .

[blackmach1]

:happy: thank you i gave them a 1/4 turn each probably around 20ftlbs.
Sucks just found a dr2 drivers side mount kit forsale locally for under 2k.:angry:
Pavement pounde what engine and what blower are you running now?

[blackmach1]

Man, were's speedy been he used to hit the forums.

[speedytang]

351C and a SN2000. Not a good mix. Your valves and head surface is huge and the SN2000 will not build enough pressure to fill them for you to get over 4psi no matter how fast you spin it. The faster you spin the engine the less time the SN2000 has to fill the cylinders...So no boost. Cam selection also causes the valves to open at a duration that does not allow the pressure to stay in the cylinders long enough during the power stroke so your boost is dropping at the higher rpm. The blower is now a restriction and your probably making less power with the SN2000 than when it was not installed. 351C needs at least a 1200cfm Supercharger to show a gain.

[blackmach1]

Speedy your the smartest man on the forums!!!!! Thats what I thought was the problem and I had a friend who owns AES engine shop in elk grove IL. told me the same thing.
Tonight I tightned up the front allen bolts alittle and now I hold 4psi to about 4500 then boost comes down just alittle maybe 3psi.
I def. picked up some power from the blower but all below 5k.Now I must shift at 5k when it was n/a I would shift at 6600 and it wanted more.
Damn I hope craig makes those vr4 upgrades.

Any advise?

[pavement pounde]

Bigger blower like the VR4 or Novi 2000 or maybe twin blower.
I have heard rumors that Cundracing would show up with VR4 upgrades any day now.
I have the stock bottomend '91 454 engine withe a blowercam and ported aluminum GMPP heads and opened up intake and enlarged trottlebody with a VR4 getting 9 psi.

[pavement pounde]

:happy: thank you i gave them a 1/4 turn each probably around 20ftlbs.
Sucks just found a dr2 drivers side mount kit forsale locally for under 2k.:angry:
Pavement pounde what engine and what blower are you running now?

Check my signuture

[blackmach1]

Right now I'm waiting on the vr4 upgrades to become available.According to craig he wants 15 people to purchase the upgrade before he makes a batch.
I was thinking of starting a group buy.

I have too much effort to get this kit on my cleveland to change setups