6-71 blower on a 340

It is all good to quote the charts. They are a good basis to start from. The problem is they are not real life. There are a lot of factors when it comes to measuring real boost. Two of the more important are the cam profile and the flow ability of all the parts of your engine. Remember, when we measure boost we are just measuring the amount of resistance your engine is giving to the flow of air. If there is no resistance, even a 16-71 won't produce much boost.

My engine is a 340, +0.030 with heads that have lots of porting done and a healthy cam. When I run around the street, most of the time my top pulley is a 37 tooth and the bottom is a 33 tooth. That gives me a .89%+/- underdrive and my boost gauge tells me I see 6 lbs of boost. That is the reason I say at 1 to 1 my 340 will see about 7 lbs of boost. Another 340 configured differently will see a change in boost.

Hope this helps to explain my original statement.

Jack