I wanna know if there is different between building a head for NA and building the head for FI? i know that there is a big different on building the block but about the head it should be same since both need better flow (cams, valves, ect...)

 

IM no expert but this is my knowledge.

If your keeping the same size valves, it all depends on how high you plan on reving the engine. If ur taking it up to 10k all day you dont want valves that are only good to 9K. Springs and retaniners should go along with the valves.

As for cams, there is a difference. Some cams have a longer duration over others meaning some are for turbo apps. and some are all motor. I dont know the details and how exactly it works but this is what i understand.

please feel free to correct me as im just building my first motor now.

 

i have all motor cams in my "turbo car"

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dturbocivic &raquo;</TD></TR><TR><TD CLASS="quote">i have all motor cams in my "turbo car"

</TD></TR></TABLE>

i always thought that was the difference. guess i better do some hardcore researching befoer startin on my head build.

 

what's your power goal? What turbo are you using?

Adding CFM to your head is not necessary to have more HP, but it will help in those larger HP applications, such as 400+

For instance, if you use stock cams, don't add CFM, you won't really need it since the lift and duration won't allow for much more CFM intake than it already has. However, if you use some aggressive NA/Turbo cams, then I would try and get a 300+CFM head, which will cost bunches, probably 1500-2000 bucks. The extra CFM will allow for much more HP given your boost settings. For a street car, it's not necessary at all to have a completely re-done head, but in racing applications it's always better because the larger frame turbo's can max out at a much lower boost setting which means you can actually upgrade to larger turbo's for more efficiency, thus allowing for a greater range of HP. Building a head can also do two other things that I've not mentioned. One, it will allow your motor to rev higher and somewhat more reliable, but reliability is hard to promise with anything over the stock rev limit. Nonetheless, you will keep making power at high revs if you have a valve job, springs, retainers, and cams that are up to the task.
Two, it can increase boost response and also reduce the lag time.

In race only applications, NA heads use NA cams, and turbo heads use turbo cams. However, many people use NA cams for a turbo setup and have great results. Sometimes NA heads have welded chambers, which I would never recommend, it's just not necessary to make power. Deshrouded valve pockets, over-sized valves, valve job, spings, retainers and some moderate NA cams should do the trick. You can also get the head ported out for much more air flow, and the best heads will allow about 330CFM to flow thru. But like I said before, you'll need the boost and/or lift and duration from the cams to utilize the 60-90CFM increase in the head.

 

! thing i learned from a friend is make sure you got valve to piston clearence...

a friend of mine put a built gsr FI head that had bigger valves(not sure what side)
on a all motor stock type r block! tuner did basic tunes without cam adjusting.

but when the tuner decided to adjust the cam.....boooooommmmm motor droped a valve at 8300 rpm and kill the head....