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Discussion Starter #1
I was looking into buying some .5 or 1mm oversized valves. Some of them have nitrade coating so how would u lap them in or do a 3angle grind without the coating comeing off?

Also how much would it cost to get the head machined to work with 1mm oversized valves?
 

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you won't be able to run 1mm over on both sides, and further, really don't need to run oversized valves probably at all. Unless you are really planning on reving your motor to the moon, or are increasing the displacement significantly.... I wouldn't bother. You'll need to get the pistons machined too - if you're running any kinda agressive cam to have bigger valve reliefs.

My motor will be running 1mm over on the intake side, and 0.20 over on the exhaust....with nearly 1.9L of total displacement, high compression, ported head and an agressive cam ....to give you an idea :).

Nathan
 

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Discussion Starter #3 (Edited)
With this build i intended to go all out on the head. I already have 2 sohc zc like the the d16a6. One has eagle rods, je pistons,kms block gaurd,and a beter cam/valve springs. The other has crower rods, je pistons, ductile iron sleeves, z6 head with zex valve springs.


I have another 1.6 zc single cam head and i was planning on doing a full head job since my 2 other blocks are pushing 17-22psi and over 8,000 rpm. I was thinking .5-1mm oversized stainless steel valves maby with nitrade coating, best cam possible, new guids,zex/compcam valve springs /retainters,and extensive port/polish. With the block i was thinking of going even more extreme witha built d16 but adding the 01+ d17 1.7l crankshaft to stroke it out and boring the ductile iron sleeves out to make it 1.8l. There is a full set of 16 1mm oversized valves, why wouldnt they work on the itake side?

I consider turbo more demanding for flow,strength,and reliability, than n/a. Also i have stock compression pistons and mite even get low compressin pistons so i wont have as bad of a valve clearance problem as you.
 

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I run them without any problems, and I dont need bigger valve relievs
 

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eg4 said:
I run them without any problems, and I dont need bigger valve relievs
Imean the valve relieves in the pistons ;)

The head must be machined
 
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nathan said:
My motor will be running 1mm over on the intake side, and 0.20 over on the exhaust....with nearly 1.9L of total displacement, high compression, ported head and an agressive cam ....to give you an idea :).

Nathan
Internal specs. Very interested in crank, rod, piston, combos and sizing. Not trying to thread jack.
 

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Discussion Starter #9
It doesnt look like there is alot of material to remoave 1mm from the valve seat. Also wouldnt back cutting valves like i did in auto mech class mess up the nitrade and other coatings. I would get this done at a shop along with the new valve guides.
 

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Actually, you can have 1mm over on both side's and there is enough room on the seat's, But i woudnt do it at home, have a good head / machine shop do it for you. thats how i got mine done and it works great's.
 

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1mm OS valves aren't gonna help much if any, too close to the cylinder walls, may HURT flow!

Now if you had a 78-79 mm bore, then you'd see the advantage.

D15, 78mm bore, .05mm OS on intake, 1.0mm OS on exhaust, good enough for a 10 sec CRX :)
 

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Discussion Starter #12 (Edited)
Im shure high boost would see the advantages of larger valves just as much as a larger bore. Also they would help the portnpolish, and bigg cam flow beter. I also said it was going to be stroked(.1L) and bores out to 1.8L(78mm .1L)
 

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whenever i build a head i would use a tad bit bigger valves like .5 over. but like everyone else said, youll be fine with standard. your local machinest should be able to handle it
 

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Discussion Starter #14
I know you will be FINE with standerd, but im not going to run oem valves, i want to get a set of stainless steel ferra valves and go ahead and go oversized while im at it to help the port/polish, and bigger cam flow beter.
 
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