Headwork

[Matra et Alpine]

Originally Posted by johnnynumfiv

That man is a genius, I highly recommend picking a copy up bluey. I would think that his theories would work with other older engines such as the L series.

Thank you ... and David Vizard was quite smart too

I agree that his descriptions can guide workign on any head, but the actual details and optimum are really only foudn through trial and error. So getting a Ratsun book woudl be best.

[Blue Supra]

Im not so keen to do the intricate stuff myself. I dont really have the tools or technique.

Thanks for all the advice guys

[hightower99]

Originally Posted by Matra et Alpine

Is there a magic pixie altering your posts then ?

Clearly your message DOES suggest doing it.
YOU know what's easy/hard but BS can't

Just for you Matra here is a play-by-play with commentary...

Originally Posted by hightower99

If you aren't looking to use too much cash then you should stick to the easy stuff that you could do yourself (without messing anything up).

Initial info stating my intent.

Originally Posted by hightower99

I would suggest that you at least match the manifolds (both intake and exhaust) to the ports in the head.

This is the only thing I would suggest that he do himself, as it is relatively easy, doesn't require special tools and is not a dangerous thing to do. It is also very hard to do this incorrectly.

Originally Posted by hightower99

A few things to know:

The heading for a list. the operative word here is "Know". Had I written "Do" instead you would be correct.

Originally Posted by hightower99

Never polish the intake ports (smoothing out casting flash is fine).
Exhaust ports can be polished.
You can grind the intake valve guide so that it is close to flush with the port roof in the intake ports but you should never grind the exhaust valve guides.
Don't go crazy and try to open up the ports as much as possible this will kill charge velocity and hurt performance.
3 angle valve cuts, when done properly, can help alot.

Helpfull hints and guidelines so that if he takes it to a tuner he doesn't get screwed out of his hard earned cash.

[Matra et Alpine]

Self-ownage
Go back and read wot you wrote
"YOU CAN grind the intake valve guide"

Another petrol can job, well done.

[hightower99]

Originally Posted by Matra et Alpine

Go back and read wot you wrote
"YOU CAN grind the intake valve guide"

Yes being completely different from saying maybe "You should" or something alittle more long-winded like "I suggest you grind the intake valve guide".

Besides I wrote it...

Regardless of how you decide to interpret it I have told you how it should be understood...

[Matra et Alpine]

ht, your English comprehesion sucks
Trust me, contractual law on major contracts is VERY clear about the meanings of can, should, could, would etc.
At least now it's cleared up and woudlnt' have needed a long debate if you'd just owned up first time questioned !!!!

[revetec]

This is a really cool process to port and polish....

Extrusion Honing


A good finish on an intake port is a slightly rough to feel finish that is not wavy. I have heard that bead blasting an intake port is the best because it creates small vortices that create a kind of an air ball bearing effect from the port to the intake charge. I'm trying to find more information on this.

One thing I can quote is the porting article on Wikipedia which states, "Flow bench testing shows that the difference between a mirror finished port and a rough textured port is typically less than 1%".

One thing that can be said is that when porting a head, it is easier to see the variations of port surface when polished. After you have completed a port and slight polish and inspect, a good practice would be then to rough up slightly the surface or bead blast the port. But then again it is stated as a 1% variation in performance between the two.

[hightower99]

Originally Posted by revetec

A good finish on an intake port is a slightly rough to feel finish that is not wavy. I have heard that bead blasting an intake port is the best because it creates small vortices that create a kind of an air ball bearing effect from the port to the intake charge. I'm trying to find more information on this.

A good finish is a relatively uniform roughness. The reason is because on the intake side you want to diminish the slow moving boundary layer to help keep the fuel airbourne (by making the boundary layer turbulent). For the exhaust ports and manifold you can actually get better performance (not necessarily more flow) by polishing the ports smooth because for the exhaust you should be more concerned with maintaining laminar flow. I would think that a uniform, one-way pattern would get the best performance through the intake manifold and ports. I always think of shark skin.

Originally Posted by revetec

One thing I can quote is the porting article on Wikipedia which states, "Flow bench testing shows that the difference between a mirror finished port and a rough textured port is typically less than 1%".

Yes and this is important for 2 reasons. One, getting your ports polished is expensive and it will only net roughly 1% more flow and two, polishing increases the boundary layer and you will end up having fueling problems and probably combustion problems as well.

Originally Posted by revetec

One thing that can be said is that when porting a head, it is easier to see the variations of port surface when polished. After you have completed a port and slight polish and inspect, a good practice would be then to rough up slightly the surface or bead blast the port. But then again it is stated as a 1% variation in performance between the two.

It stated a 1% difference in flow. Engine performance will be much more than 1% between and engine with smooth polished intake manifold and ports and the engine with uniform, one-way roughed manifold and ports.

[jugga]

alot depends on the original manufacture and design that has gone into it. for instance the head on a type r is alot more refined then on a 1.3 civic. But then if you compare the efficiency of those to a ford/renault they probably alot worse on similar models. in any case try to find a trustworthy tuner with proven experience with the engine you want to modify.

i have heard alot of differences with intake ports there is alot you can change , not just with the surface, or the bore, but with the actual path the charge has to follow to reach the cylinder.

its all fun and games