Oversized valves
 

Im getting some machine work done on my head and am getting new valve guides, seals and new 1 mm over sized valves installed. I am also getting rods and pistons installed at teh same time and plan on driving the car NA with the stock cam and spring for about 2k miles to make sure all is good. After that i plan on throwing on the t3t4 and throwing in retiainers springs and stage 2 cam. my question is will my z6 , which is tuned with turbo edit in a crx run okay NA if i tune it or will the oversized valves make it run funny. cliff notes: will 1mm oversized valves make a stock z6 run funny even after tuning with turbo edit or can it be tuned to run right with turboedit?

Re: Oversized valves
 

it will run right on a stock z6 map

Re: Oversized valves
 

thanks thats all i wanted to kno cuz i was nervous the oversized valves would mess with how things ran when NA at lower than stock compression

Re: Oversized valves
 

OS'd valves in a small bore d16 sounds more like a waste of time and headache than anything else. If I were you, I'd concentrate more on getting the most cfm flow out of that head with a good cam/spring setup than worrying about larger valves. It's really not going to make a difference on a d16 once the turbo goes on anyway, more than likely you'll hit the limit of the sleeves before you hit the flow limits of the head.

Re: Oversized valves
 

^^^
+1

Re: Oversized valves
 

OS valves will help if your running 78mm sleeved blocked.

The real gains come not from the OS valves, but the stem design.

Re: Oversized valves
 

see the problem is that one of my valve seats has like a gouge in it wheere if i put OS valves in it will machine away the problem but stock valves it wont seal properly, and im porting and polishing hte head with my friends dad, he builds engine for a living and well be using his flow bench too. i know i dont NEED the OS valves but for the sake of not buying a new head im gunna do it , i already got a crower stage 2 turbo nitrous cam and springs and retainers

Re: Oversized valves
 

well in that case you might as well. it definitly wont hurt

Re: Oversized valves
 

Like Bone said, it's not the size of the valve but the shape. Why can't you just get a new valve seat machined in? How big of a gouge are we talkin' here? Might be able to just machine out the gouge and give the seat a better profile into the chamber, which is usually part of intensive P&P work anyway.

Re: Oversized valves
 

just think.........


it's the shape and not the size that makes them happy.


Apply how you desire :)