I just talked with the shop who, several years ago, built the bottom end of my motor. He was telling me that he sent off a set of aluminum L98 heads for porting and the flow test results showed a 70% increase in flow after porting! Can I expect the same results from my cast iron L98 heads? If not, can I expect something close to 70%?

I’m going to be removing my TPI intake and replacing it with a LT1 intake. My plans were to have the LT1 intake port matched to the heads and have the heads ported for maximum flow. I just can’t justify spending over $1100 for a new set of heads. I’ll change out my cam while I’m at it. Are the gains from ported L98 heads at all comparable to new heads (like Edelbrock or AFR)?

Any ideas/suggestions?

 

Does a 70% increase of a dollar sound good to you?

or a 70% increase of $10s sound better?


Yea you'll see an increase, but you start off behind the game with the cast iron heads becaues they dont have D port exhaust, you'll remain with your current compression instead of the increased compression of alum L98's, and the knock tollerance of aluminum.


In my humble opinion PAYING shops to port stock cast heads is on the verge of rediculous, they charge you the same price as they would to port aftermarket heads, and for the price of SOME peoples porting jobs you can get a bare set of Dart Iron Eagles or some other worthy after market head.

 

This should answer your question.
https://www.thirdgen.org/techbb2/sho...n+head+project
But in short, you can get good results porting the stock heads, but for the expense to pay someone else to do it, your probably better off buying a set of aftermarket heads. If you can do the work yourself or have a buddy that will help, or have to run stock heads for some reason (I just like it for bragging rights) then consider the porting.
You can reshape the exhaust ports to the d-shape btw, and it helps flow tremendously.