Camshaft shift points

[nocooler]

Here is the way I look at it. Let’s figure your are running 2:1 back pressure (which is probably close to where this combo is) so at 25psi there is 50psi in the exhaust fighting the valves. 
Do the cams wipe from to much pressure or not enough so it’s bouncing on the lobe?

[Steve Wood]

I guess I am getting too old for this stuff.  I forgot about the pressure backed up from the turbo trying to hold the exhaust valves open.  I was thinking all we had to do was allow the intakes to close against the pressure form the plenum....

[Steve Wood]

The more I read, the more convinced I am that it takes the pressure to keep the  valves following the lobes....looks like the increase in pressure x the area of the valve is a pretty good multiplier.

[nocooler]

Makes sense to me but I'm a moron - as back pressure increases the more exhaust spring pressure you'd need to keep everything under control. It'd be interesting to put a transducer or simply put a gauge on this car to see what the backpressure actually is at 25psi. Might go faster turned down a few psi a boost just from the backpressure drop and being able to continue to rev 

[Steve Wood]

easy enuf...just turn it down to 20 and see what the rpms do

[Steve Wood]

better yet, make it 15