i'm building my bottom end right now, since the head is out would it make sense to get stronger and oversized valves since i'm plan on running 14-16psi

what are the benefits of oversized valves?

supertech or ferrea valves?

thanks in advance guys

 

supertech. go all supertech. and id say just oversize the exhaust side. from what ive learned so far, the last head i had done, we went oversize intake and exhaust, and had some issues. just do the exh side. PM me if you want a full low down. and have someone who kicks ass do the head. port flow,alaniz, or baker. lates dave

 

Check the honda-tech FI section for people who have gone with oversized valves. In regards to the b-series you'll notice few made more power (that could be attributed to the valves) with oversized valves compared to stock. Keep in mind the type of grind has an impact of the flow characteristics as well though I don't have any numbers in front of me. For instance a radius'd cut will flow better than a 3 angle. Those who did get larger valves didn't always get a radius'd cut so take all of this with a grain of salt.

Take home message, if you have money burning a hole in your pocket, it could be better spent elsewhere for performance unless you are trying to get ten tenths out of your motor. If you do go larger, get a radius'd cut on your valves. BTW, I don't claim these as ideas as mine. Just basic engine builder stuff .

 

I agree with your logic. You will gains will be very limited by using oversized valves, due to the great engineering that honda already placed in the f20. But if you are looking to get every little bit of better flow, hence more hp, then go for it.

 

the benefit of using oversized valves is more airflow..more air getting in and more air getting out..a benefit when using oversized valves, whether you decide to do ex and in or just ex, is a nice port and polish..this will also increase your airflow and will work amazing with your fi setup...i would go with supertech valves and portflow alaniz and baker are all reputable for doing excellent headwork

 

Good headwork can add 50 or more horsepower. Just changing the valves won't do it. The heads must be reworked to flow better also.
These are 0.5mm oversized:

 

Im doing 1mm oversized on both sides. The head is getting a full race port and polish by Vinny ten one of the best porters in the industry I should have the head back in 2 weeks or so.

What were some of the problems you guys were haivng going 1mm on both sides?

 

problem we had, (ferrea) is that the 1mm oversize intake valve, hung substantially low into the cylinder. like,, the stock valve, is IN the seat. and fits well, you look along the head surface, and its smooth, with the 1mm over, the valve was hanging or would be hanging into the cylinder. and would need to be sunk quite far into the seat to get it flush, well that creates a problem, when you sink the valve, the stem is now to high, and the installed height is all wrong, you have to back the adjusting screw so far into the rocker, now the geometry is all off. how i know this, i threw away a nice ruined set of ferrea intake valves. and went back to a smaller set. this head has ZERO room for error. stock...STOCK, the vtec rockers hit the retainer on the intake side. so if you have incorrect install, or larger diameter retainers, AT ALL. you have serious interference issues. thats why people have frisbee'd retainers. ive been meaning to speak with "skunk" about this.. their K series cams/springs/ret's are supposed to be sick as hell, and work perfect. well if youve seen a K head, its very close. trust me, my research is not over. id like to have a 10'000 rpm stroker. makes me laugh when guys on here say it cant happen, stroke this and that. i know of engines (4cyl) twice our sice, with over 4 inch stroke, spinning almost 15k rpm. with the right rods,pistons,rings combo. this 2.2 or larger will spin 10k all day long. im workin on it. lates, and triple check everything on that head before you torque it down. look at retainer to rocker clearance. lates dave

 

Not to knock anyones work but what about laskeys? Isn't their headwork any good?

 

I brought my head to my porter and he said that doing 1mm on each side would not be a problem at all. The fo;lks at ferrea recomend it as well. Maybe your porter didnt know what he was doing when he put your valves in..