Oversized Valves

[JSPEC SilEighty]

I was just looking at Ferrea Valves and I see that they have the stock size head diameter (31.3mm exhaust, 36.6mm intake) and they also have 1mm oversized valves. Just wondering, would that extra 1mm provide anything significant? Or would it just be a waste of time/money to use that? I'm talking about in a fully built KA.

[I am Technoman]

The KA valves are very large. I dont see how there would be any more room in the head for larger valves...

[Tony Starks]

If the stem on the oversized valves are the same size as standard OM would you still need to have the "whole head done"?I figure that if the stem is the same size then all you would have to do is re-seat the head or bore it out to accomodate larger valve seat inserts.

But if you haven't already had a port/polish job done on the head I guess that this would be the time to do it any way.

[Exar-Kun]

you'd have to have the whole head redone, because the inlet into the valve would be too small, and you'd have to rebore the runner inside the heads and manifolds to suit the new valves, allong with creating new valve seats, etc.-chet

[Tony Starks]

you'd have to have the whole head redone, because the inlet into the valve would be too small, and you'd have to rebore the runner inside the heads and manifolds to suit the new valves, allong with creating new valve seats, etc.-chet

I'm sorry but you lost me at "inlet into the valve".When you say runners inside the head are you talkin about the place where the valve guides are inserted?Why you would you need to bore out the runners in the intake manifold?I'm not familiar with your terminology.

[Exar-Kun]

the intake port in the head, that runs from the valve seat to the intake manifold, and even the intake manifold would require porting, IMO to maximise any gains form any valve enlargement.

aslo, shaving off the boss of the valve would be helpfull, but not necessary.-chet

[cnichols]

the intake port in the head, that runs from the valve seat to the intake manifold, and even the intake manifold would require porting, IMO to maximise any gains form any valve enlargement.

aslo, shaving off the boss of the valve would be helpfull, but not necessary.-chet

I agree, but do you think it would be worth it in the end for the price of Extrude Honing the manifold and having all the head work done? It might get kind of expensive....

But....for high boost...don't you think it would be worth it to go all out on the intake side?

[WDRacing]

The exhaust side is just as important as the intake side. If you want more then 500 hp from your KA then I'd consider doing the valves and headwork. You'll also be using huge cams, so you'll need a complete valvetrain makeover.

IMHO I'd just have my I/H/E sent to Extrude Hone and have a full port and polish done. I think the rest is over kill...

WD

[Exar-Kun]

I would do what I said to both sides, I mean if im going to goto the trouble of getting oversized vavles, I might as well go all out.

its kind of like why Im getting a carbon fiber driveshaft made. If im going to trr to reduce weight and increase HP allong the driveline, why not?

-chet