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A few weeks ago I talked to a place about doing some head work. One thing I inquired about was porting and polishing it since it's seems to be something that's quite common, but upon asking them, they actually don't do it, and that it would need to be flow benched if it was done, which isn't cheap. For what he was talking about, it makes alot of sence, but people who p&p their heads, is it typically a DYI job or had anyone has it professionaly done? If it's not professionally done and tested, how do we know if there are any benefits to having it done?

there's definitely some power to be made with port work. Im currently trying to have a guy from Canada do my heads for my Charger. He's known for his cars he built and I wouldnt trust many local guys. If you don't have it bench tested you will not know how much cfm flow you've increased. You do however can dyno it afterwards to see how much hp you've increased.

You might as well look into a 3 angle valve job, too. Is it for a ZE? If not, I'm wondering if they could be milled for higher compression without the extra inertia of flat top pistons.

On these heads a port and polish is a waste of time, the average cfm is in the range of
230cfm @ standard lift i can't remeber the Hg figure we where using.

the basic thing that can be done to these heads is to knife edge the divider on the inlet
ports, given the port to vavle ratio, the klze head ports are certainly on the large size and
need the port floors filled to gain anything.

tidying up the area where the steel valve seat sits, smoothing out where the cutter has been
is really the only thing else that i will do.

rasing compression is another myth, waste of time

i am going to have my ze heads sent out to be checked and rebuilt,,,is this knife edging the inlet ports helpful? i do run about 5psi of boost....is there some other things i could bring up to the attention of the machinist???

rasing compression is another myth, waste of time -
If so, why is it a standard on any racing engine, including the ZE?

perhaps he means the gains from a safe level of skimming (keeping it non-interference) would be negligible?

Knifedging the divider is not going to make a difference at all. Also who mentioned doing a 3 angle valve job, Have you had a valve out of these heads? They all ready have a 3 angle valve grind. You can clearly see it.

The only thing that is going to make our heads flow better is straightening out the top part of the port where the air gets stuck at high rpm's Thats it. And its more so just re-shaping it actually. And no need to polish the ports. You will actually loose power doing that. polishing the valves on the other hand will help.

like john said...there is already a three angle valve job from the factory... which is nice, becuase My Z didn't come with that....

Anyway, if you get the heads milled for more compression, it will not make any gains unless you get adjustable cam gears to bring the cam timing back into the right spot.

what happens is, the gears move closer to the engine because the the head is milled, and it changes the location the belt ride on the gear.. hard to explain, but common for the civic N/A guys when they go for bigger compression. and if you let the gears stay where they are, it will advance one side, and retard the other, thus negating any compression gains because it move the cam timing around.(in a bad way)

I am a race engine builder by trade, and I do a lot of porting and polishing, and flowtesting everyday, and yes, ZE heads are already pretty big, and won't respond to porting like the old school heads used to. But it would be a good idea like autozam said to knife edge the intake separator, and clean up the area under the machining area(under the seat). I guess it wouldn't hurt to use some flapper wheels in there and polish the intake runners a bit also, just in case

Even then though, it will not increase the CFM numbers much, but if you can do it yourself, it will be a 'peace of mind' kinda thing.

I hope that helps, and if you have any other questions, just put them here, and I will see it soon.

cheers

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^^^^I never said to knife edge the seperator. Just leave it alone. You won't gain a thing by doing that. The only thing that needs to be removed is the hump on the upper ceiling of the port. You will only gain a few ponnies by doing this. It is true like Seven said that most engines today head porting is NOT beneficial like most older engines used to be.

Also regarding shaving the head. I personally have shaved 0.010 off a ZE. The little difference there aint going to throw the timing off. It also won't gain anything really. Its not sitting much closer to the head. Technically it is yes because in the combustian chamber it can make a difference. If you want to raise compression than simply get higher compression pistons. I am at work right now, when I get home I will post some pics of teardowns that show what needs to e removed in porting heads.

Of course John is right...except I am talking milling a lot more than 0.010" off the heads....I have done as much as 0.110" on a toyota stock car engine....and it needed quite a bit of offset in the cam gear setup to run right.....

We degree'd the cam setup after the mill job, and it was way out.

After it was setup properly, that thing had a MEASUREABLE increase in power. That was with only two cams though...it would take a while to do this with a 4 cam engine like ours.

Oh, and I probably should mention, We had a high lift cam setup in the head, and we had to fly cut the pistons a bit because the clearance just wasn't there.

And one other thing....knife edging the separator only takes a second with the right tools, so why not

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Good info!
I am an Old Skool backyard hod rodder, and never had my KLs apart. I should have assumed that those "Hot Rod" tricks have been applied by now.

does n e one know if n e body ever put up a sticky for DIY porting and grinding or whatever to make better air flow and i went to a head shop yesterday and he told me i could get a 7 angle valve job, would this help out more than a 3 angle or is it just not worth it, he said he could do it for 500?

There is info and how to's on probetalk on all this stuff. Its actually got tonnes of info. Your best bet is talking to KLZE_Porsche and Leo323 on that site. I will post up the links when I get home, lol I forgot to last night.

so why does everyone say to swap out the ze valvetrain for the de stuff? couldn't i just put some titanium retainers instead of reusing old parts????