I’ve got a set of Trick Flow 64CC195CFM heads coming along with a COMP .495/.503 lift cam. I already have TES headers. Cars a 5.7 converted to a 5 speed. I’m trying to decide weather or not to send my stock 48mm out for a rebuild or step up to a 52. Just looking for opinions

 

The 48 is probably sufficient IMO.

But the way to tell would be to look at the MAP sensor data during a WOT pull up to your max expected RPM and see how close to 100 kPa you're getting.

If there's a restriction, youll see something significantly less than 100. At which point it could be something in the intake tract... from air filter to possibly the throttle body.

I was thinking about a 58mm a while ago but with my 52, I found I was getting about 97-98 kPa even at 5500-6000 rpm. So it wasn't worth it.

Back in the mid-90s i blindly put the 52 on since a bigger throttle body was "thing to do" back then.

 

100 KPA only applies near sea level. The Baro at key on is as high as the MAP can possibly read without forced induction.

Thing is a 52mm definately makes a difference. Even an airfoil makes a difference.

 

Problem is everything I fine is a 58mm. Doesn't seem to be any 52mm available. I think 58 is going to be to big

 

58 and 52 make no difference power wise as long as the 52 flows enough. 58 will just have more aggressive low throttle response. Its not like putting too large of a carb on.

 

Well that changes things. Thanks