how much HP gain could i expect from having my heads ported and polished? im running a 98 3.8 w/ a magnaflow muffler..

 

It depends how crummy the ports are on a 3.8L. On a 3.4L, for example, I'd expect a dozen(ish), since the flow is so bad, but the cam and valve size are pretty good.

Conversely, some engines have heads that are pretty well done up from the factory.

 

Agreed. The most I have heard/seen with just heads is barely even 20 hp.

 

I wouldnt bother unless you will be running forced induction or Nitrous. Porting the Heads will give better flow, but it will also lower your Compression Ratio.If you port them you may see around 12-15HP for a 3 angle cut. I would advise porting the Throttle Body and do a recalibration which will give you almost that much combined with a K&N. If you port it, make sure you replace the MAF screen or you will be kicking MAF codes non stop.-Tim

 

Good tip...thanks!

 

You dont needs heads until after you do a cam.


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