Porting and Polishing

Is there anything in the P&P area that you can do to your car, without having to be like ultra exact in doing it? I know when porting the chambers, you have to CC match and stuff, but is there any area where you could smooth out the casting, and get better airflow, without worrying about getting everything exact? :?:

You want to be as exact as possible - you don't want radically different flow rates and velocities to each cylinder. Does it have to be absolutely perfect? No - I've seen professionally ported heads quote differences in flows between each runner - small variations, but variations nonetheless. A smidge here and there won't be the end of the world, but you do want to take your time and do it as well as possible. We're not building Top Fuel motors or heads for LeMans cars here, ya know.

Heres pictures of mine to give you some ideas.

http://www.pbase.com/dkauer744/cylinder_head

Despite what people like to say around here, on a postitive pressure engine P&P (but mostly polishing) is basically a waste of time. After all the work is likely to net you perhaps 1-2hp. I have a friend that owns a performance (ford) shop and he wont recommend it to any of his turbo/supercharger customers.

See, no offense but I don't belive that for a moment. My cylinder head and intake had major restrictions in them, and True forced induction can make up for alot of that but porting/polishing done right along w/ match porting and other work can net HP and more than 2ponies.

Doug

Craig,
Maybe you should tell that to Jack Roush. .

I think that the reason the shop owner is not recomending port work is that usually the gains for money spent are not real favorable for most people who can better spend their money elsewhere. Headwork can be very labor intensive (at least to maximize a head).
There are basic things that can be done by almost anyone. You can smooth out the ridges left by the macining or casting processes. Some gains can be attained by doing a little work on the bottom of the port right in front of the intake valve (short side radius) if you feel adventureous. Remember tho its usually easier to screw up than do it right. Also as far as the money spent, headwork does not wear out or go bad it pretty much lasts the life of the motor so if you look at it that way the cost is a bit more justifiable. Dan24tic

That is, unless you tottaly crack/wrap the head.

But he's right, it's not cost effective when there's other easier bolt ons available but it does help.

What you guys are leaving out is that all of those "bolt ons" work WAY better when headwork is put into the equation.Add a cam with more lift and duration, and more airflow at whatever rate the ports will allow, up to whatever point ve maxes out at. So you might gain 12hp. Port the head so that it takes better advantage of valves that are open bigger, you might gain 20hp. Open up the exhaust and port turbine housing and it will improve exhaust flow up to the point of the ports. Open those ports and even those bolt ons are better.

Not doing headwork is false economy in this sense, as it makes all of the other mods you put you hard earned pesos into work better. Which is why people like Mika A are hesistant to give hp improvement stats for things like cams, etc. It's all interdependent.

And headflow is important. Why don't you try welding up your intake ports until they are the size of drinking straws and tell me how much power you have. The truth is you could conceivably run enough boost to cram enough air through those drinking straws to have decent power.
The point is optimizing headflow is a key factor in maximizing breathing and volumetric efficency, which means the engine will breath more air when subjected to less boost. You can either have good headwork done and run say 18psi or you can not have headwork done and run say 21psi.
Which one is going to need higher octane fuel first?
hth

Couldn't agree with you more.

Drove mine around the shop today (before I lost a plug again) and at 5psi it's already loads better than stock (what it was).

Now, I am running a 60/48 and a VX now, and an IC but still, the car just sounds different.

Are you talking about doing your own porting and polishing, or having it done at a shop? Can you get a good result if you do it yourself. I've got a spare head and I was thinking of going at it myself over the winter.

If you are just going to remove casting errors and such you can try it yourself!

But of course the best is to have a wrecked head to do all the mistakes on first....

I did my own, took 8-10 hours [did it a while ago]. Five stage process on mine, intake ports were much easier.

http://www.pbase.com/turbo745ti/inbox&page=4

and

http://www.pbase.com/turbo745ti/inbox&page=5

and also did my intake before the head, which took 4-6 hours or so [i don't quite remember, that was done way before the head was].

:mrgreen:
[it is my goal to have one or more icons in my posts ]

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