i had a blower set up on a stock bottom end 302 for 2 years with a csu carb set up i have recently purchased a bulit 347 and i am thinking about going with a t 70 m/p turbo with a pony down hot side. i would be sending the carb back to csu for recalibration, but i wanted to know how much more difficult it is to get good a/f with a turbo compared to a supercharger..... any input would be a great help

 

boost at the same temp is boost, the carb ain't gonna care where it got it my uncle's twin turbo , twin air to water 496bbc was so easy to tune all we had to use was a screwdriver to adjust a/f at idle using a c&s 900cfm carb with a ev pro hat and the a/f ratios are always purdyyyyyyyy his bds 8-71 blown 540bbc was harder to tune and had to be tuned more often!

 

I would not use a 70mm on a 347. It will be close to the choke line. The extra back pressure may mess up the tune. I would cal CSU.

 

I think the biggest difference in tuning will be with your power valves .

Chances are , your carb will come back with dual BRPVs . They will be adjustable for when they open . The PVCRs should also be adjustable .

Its just a matter of finding out what jet size your motor likes out of boost . Then adjust your PVCRs to get the right WOT AFR .

Always start big and work backwards .

Once you get the WOT right , then you can experiment with WHEN the PVs open . Most turbo cars like them opening later than blower cars .

 

I went from an F1-R to an 88mm, and I didnt see a difference in the tuning on the carb..

 

Were you using BRPVs with your F1-R ?

 

Is it apples to apples?

WOT, well that is the easy part

Boost level, combo and other variables come into play.

A small bower/turbo may play similar although I feel Blowers take a little less around town tuning.

 

THANKYOU ALL FOR YOUR INPUT I WILL CALL KEVIN AT CSU AND PICK HIS BRAIN A LITTLE BIT MORE.

 

Buddy of mine said a blower is a bit easier since you know when the boost is in with the RPMs. Just a thought.