Port and Polish

[CB7lx91]

Anybody port and polish heads on here? I was thinking of trying it out myself, I have a packet DIY on how to do it

But if anybody does a good job on here for cheep, it's worth it

[ceelooboob]

wed3k does porting i think.

[CB7lx91]

word thanks bro I'll PM that man. Keep up the info though!

[wed3k]

CHR motorsports does good port jobs, thats what hondafan recommended as well.

i can do them but i dont have a setup on the flow bench for honda h/f series heads yet.

there's a lot more to porting than it sounds. A diy wont really tell you all that much

[KeeleDesign]

obviously this is an old thread, but i figured i'd gove some good info onN/A builds. go to this site...

i am theory of porting and polishing

keep an open mind, from all the hype you have always been told.

[johnl]

If you port, don't polish. Rough walls (within reason) in the ports assist flow, something to do with the behaviour of the boundary layer, similar to why golf balls with dimples fly further than golf balls without dimples. The 'as cast' surface is actually a very good port finish for flow. Reshaping to eliminate any bumps or abrupt port shape changes is a good thing generally, but some engines already have well sized ports stock, and enlarging them can sometimes reduce flow, at least in the rpm range within which you may be using the engine. Typically, if you make the ports too big then you'll lose power lower in the rpm range, but not pick up much (if anything) higher up, unless you also make other changes to improve breathing at higher rpm (i.e. cams etc etc). I'd talk to an expert before doing any work.

[d112crzy]

Who's to say that the ports on the bikes he mentioned aren't all too big and need to be smaller to make more power. He didn't mention any other sized bike beside the 600.

Also, he doesn't compare stock dyno vs smaller ports vs flow benched ports on the same dyno sheet.

For all we know about that last graph, the stock numbers could have been slightly lower than the blue line, which he says are the flow bench numbers. Are we going to take his word for it? He doesn't come out clean and say that the stock numbers were lower nor higher than the flow bench numbers. He only compares to the red line, which are the smaller ports.

For bikes, I think what he's doing makes pretty good sense. Bikes don't have very large engines and spend most of their time in the higher rpm's. It makes sense that higher velocity would benefit them(high velocity= smaller ports).

Bikes don't have much restriction's as far as the intake systems go. Most have ITB's.

But our engines are bigger than most bike engines. We have intake manifolds that limit flow AND velocity. I'm sure that if HondaFan were to use a stock h23 im/tb on his white project, he'd be maxing it out because there's not enough "flow/volume". The small ports wouldn't allow it.

Velocity means nothing if you can't fit enough air inside the combustion chamber due to your intake system not allowing it to.

I do agree on one thing tho, going only by flow bench numbers is wrong. Saying x head is better than z because it flows more at a certain lift doesn't necessarily make it better. You have to take into account the rest of the engine components.

I'm sure that if reducing the port size was really the way to make more power, everyone would be doing it.

[d112crzy]

Just don't ever port and polish like this guy
http://www.audiforums.com/m_693578/mpage_1/key_/tm.htm

[NorcoAccord]

Just don't ever port and polish like this guy
http://www.audiforums.com/m_693578/mpage_1/key_/tm.htm

25 pound bag of sand and an engine running means no go real soon. fudge instead oil equals funny as hell. Someone who really does this means they need a new car i say go electric so they cant worry about a port and polish.

[KeeleDesign]

Just don't ever port and polish like this guy
http://www.audiforums.com/m_693578/mpage_1/key_/tm.htm

ahahahahhahaa i am speachless...

[GenDBlade]

Just don't ever port and polish like this guy
http://www.audiforums.com/m_693578/mpage_1/key_/tm.htm

hahahahahaha......cant....breath...hahahahaha

[wed3k]

which is why it is important to blow out all the glass bead from a cylinder head after beading the ports and chambers.

[johnl]

which is why it is important to blow out all the glass bead from a cylinder head after beading the ports and chambers.

Bead blasting the chambers will give a matte finish, but the chamber is one place where polishing is a 'good thing'.

A high polish in the combustion chamber (including the valve faces) reflects more heat back into the chamber, thus increasing gas expansion and power. Also, a polished surface takes longer to carbon up than a rough surface. Polishing the piston crown is also beneficial for power, and assists in lowering piston temp because the polished surface reflects more heat.

These affects may not be huge, but every little thing helps, especially with a race engine. For a road car it's probably not worth it since the surfaces will probably carbon up in a few thousand miles, unless you were to use water injection.

[flight50]

OMG. I read that whole post on the dude with the Audi. His friend shouldn't be around any cars either. By rule of thumb, if you don't know what the hell your doing, take it to a reputable place and just pay the money to get it done right. Taking shorts cuts will have you SOL.

[TheNextAZN]

phahahahah.. i just read the audi forum post.. hillaaarrriiiouss!!! .. too bad it was just a joke