i am having my head rebuilt (actually the whole motor) and was told to go with larger valves, another shop that i will have my project tuned on a dyno said that going with .5 millimeter larger valves will not help me at all but may actually make me lose power..... I am also running 7 psi with a JRSC......... anyhelp would be cool, Thanks

 

.5mm oversized valves for a jrsc is a pretty good way to go

.5mm oversized on a N/A motor does pretty much nothing and will hurt bottom end just a hair

I'd say go for the oversized valves, it will give u more power up top

 

stick with stock valves and spend your money elsewhere

 

Put the money in a header and exhaust. I'd say Kamikaze and thermal 3".

 

My advice would be to oversize just the intake valve and leave the exhaust side alone. I would buy good valves for it though like the Ferrea because they have a really good valve design and work well with forced induction. I would also consider porting the head since it is already apart, buy things once not twice! I think if you put to big of an exaust valve in it , it will lose power and be sluggish on the street.
I think your money is well spent here, especially since your motor is already apart you can always do bolt ons later. And if you get the head ported, do your homework and have someone experienced do it, it is even better to find someone who is interested in your project and will do a good job because of that. Good Luck!

 

I think maybe going with .5 mm bigger on exhaust maybe better for a super charged motor as you are creating more exhaust on a blown application than the factory originally had in mind. good head porting will also help in your set up. Try giving Headgames Motorworks a call, great pricing and Dave is one of the best porters outhere does all my heads with great results, he also does the heads for Bullish Racing. The number is (609) 586-0354

 

ivw heard before that over size valves will kill performance in a n/a vtec engine....If its boosted,then it can help a bit.

 

There is a great deal of flow potential left over on a Honda head; this is not traditional domestic stuff when it comes to airflow improvements. Hence larger valves are something you don't need to think about at this point, focus instead on the two main areas of FI Honda weakness: tuning and the exhaust. This is where your money will be best spent.

 

WTF were did you hear that?
.5mm over sized valves won't hurt your performance... you just have to tune your motor well.
It will propbably feel really slow at first but once tunned there is a difference.
-vtec and .5mm go well.... in between 6000 and redline is when you will mainly see the power increace.
**rev that sucker to 9-10k