471 sbc question?

Anybody running a 471 on a sbc? I just got mine running with a 1 to 1 ratio drive and it does not seem to make any boost, even at 3 or 4000rpm, just hoping someone can tell me what ratio or tooth size of pulleys they are running and an approximate boost level? Thanks.

 

Lots of variables affect boost levels. When you say no boost at 3-4k, do you mean sitting in the garage or going down the road.

You can redline an eng. w/ the car sitting still & barely have the throttle open. No boost w/ the throttle barely open.

 

Hook up a smaller pulley on the blower.... And hang on to your shorts!!

 

Got any close-ups of the blower setup???

 

Variables:

What kind of condition is the supercharger in?
How fast do you spin it?
Compression ratio?
How restrictive is your exhaust system?

 

I had a 283 with the pulley set at 1:1 and under WOT it would make 8-11 psi as it wound out.

If you were cruising at say 3000 rpm and floored it it would go from a vacuum state to about 5 psi then the boost would build as the rpms rose

Boost is not linear with RPM you have to have the carbs open to start making boost. Under normal cruising you will be in a vacuum state of mind

Check out the video Squirell posted. He shows the boost.vac gauges while he rides around normally and then hammers it. He's got a gauge over the blower and 1 under it. cool stuff

 

have you got a boost gauge plumbed to the intake under the blower??

 

Tudor brings up an improtant point. When you say "it does not seem to make any boost," is that seat-of-the-pants or an actual gauge measurement? If you don't have one already, you need to put a gauge after the blower stage to measure the boost.

 

gauge is under the blower on the intake mani, fresh built blower from a local blower guy. The 3 to 4000rpm was driving, i understand the at an idle in park deal, still figured it would register something on the gauge! Its a 383 as well and i used to have a 283 in the car so "seat of your pants, hang on thing" is already happening exhaust is speeway build your own lake style pipes ran through "glass pack" style mufflers. 2.5" all the way back, I will post some pics soon

 

You have to get air into the blower to build boost. That requires open throttle plates. Don't expect to see big numbers under low load cruise conditions.