Exhaust Porting

[EBInterceptor]

My friend wants to port out my exhaust. He's done it for motocross bikes, but never on cars. How much of a difference is this going to make and is the effort the is involved in doing it worth the gains?

Thanks,
Mike

 

[jared ajlouny]

what is porting the exaust???

 

[EBInterceptor]

He's going to trim the exhaust ports so more air can flow through. But if too much is taken off, then you can run into problems...Sure he is a certified motorcycle mechanic (or soon to be officially certified in the next couple months)....but I don't want to have to pay to fix his mistakes if he blows it.

 

[james t]

huge difference between porting a 2stroke and an OHV car head. DONT LET HIM DO IT.

1- unless you have other mods like headers, cam, etc., it wont make much difference

2- its easy to hit a water jacket (and ruin the head) if you dont know what you're doing

3- he will be learning on YOUR heads

4- you dont want a set of heads someone has "learned" on (they will be hogged out at best)

5- head porting is a science. most guys who port heads in their basement with nothing more than a die grinder are really dissapointed with the results. does he even have access to a flowbench?

once again, DONT LET HIM DO IT. this is just my opinion.

 

[nserafini]

It's not worth the problems you are going to have.

If YOU want them ported, takem 'em to a engine shop.

Some people think a dremel can do anything !!!!

 

[SteveVB]

Porting is fine, but...

If the only thing you are going to do is port the exhasuts its not worth the time and or trouble to remove the heads and valves. Porting is something to do when you rebuild or add a cam. Easiest to do while you have the engine apart anyway.

If you do port the exhausts be careful with the egr bumps - I believe you can grind through the castings if you are not careful. From what Ive seen the bowl can use a little work but dont remove too much from around the stem if you want the valves to last.
If you are going to port do both the intake and the exhaust.

 

[james t]

Re: Porting is fine, but...

Originally posted by SteveVB
If you are going to port do both the intake and the exhaust.

...and for God sakes, work them up on a flow bench ESPECIALLY if you've never done a set before.

 

[EBInterceptor]

Thanks everyone.
It's hard to talk him out of wanting to do it. I told him that it's a lot more work than he thinks. And I agree that I don't want him to ruin my engine, I just wanted someone else to back me up on this if it was going to be a hassle.