What gain will I see in my time slips

Toluene56 said
Depends on the type of porting they do...how extensive, how much they flow, if the camshaft is suited for the combo.

33IMP said
Rough estimation (VERY rough) is two hp per cfm is possible, if everything is right. Therefore, if your porting goes from 240cfm to 270, you can theoretically pick up 60 hp. How much of that potential 60hp shows up on your timeslip is ENTIRELY dependant on how good your car is.
You can go to wallace calculators, and investigate how much power you have now, and get an educated guess as to what it might do with more.
Edit: 60 hp from just porting would be a huge increase, i wouldn't expect to see that on my junk. Still, pocket ported 906 big block heads MIGHT flow 240, edelbrock claims(repeat, claims) 290 from their big block rpms.

@1fastgreencar The above is agreed with BUT....

If your current cam isn’t lifting the valve up high enough to take advantage of the porting & the air flow gains, then the chances are your not going to see a whole lot.

If your porting work goes from 240 to 270 like 33IMP said, that’s a nice gain, but where is the gain? Like the top end of the flow chart. Where the valve is opened up a lot. If the major gains are above .500 or .550 lift and your only lifting the valve to say, .509, then the performance gain in full will not be realized.

You’ll have to look at the flow differences in the lift area. At .509 lift, it’s all valve job and work in the bowl. Normally, not a huge gain, but important nonetheless. And yes, that should power that you can easily feel. As far as time slip goes, this is a good question that no one can answer for you on your car since there is zero information on it. But what others have achieved should be interesting none the less. I’m looking forward to it!