Heres a question for you folks:

I know headwork (pnp/valve jobs) can free up a bit of flow (and power) at higher rpms, but do they have any negative impact on the low/midrange? I'm planning my crvtec build, and its for an autocross car, so usable torque across the powerband is my major concern. Should I bother having the head worked on while its off the car? If so, what kinda headwork would you recommend? Like I said, I'm not really concerned with peak power, more with a fat powerband. So give me your $.02

BTW, likely setup is looking like:

B20 shortblock
balanced and knife-edged crank
probe or IB rods ( <--- input?)
11.2-11.5:1 compression

B16A head
BC racing spec iii cams (<--- what valvetrain would be suitable to these cams?)
arp fasteners all around

shooting for an 8k redline.

input please! TIA

 

Porting and Polishing a cylinder head can take on infinite degrees of work, from mild to wild. As long the head shop is competent and you communicate what your goals and desires are, they should be able to produce a cylinder head that meets your goals.

Keep in mind that a typical mild P&P generally does not involve increasing port size signicantly, generally its simply sufacing the ports to remove casting flash and provide a surface finish which minimizes boundary layer effects at the wall and minimizes separation. Both boundary layer effects and separation will in themselves reduce flow capacity. Because port size is not significantly increased the entire powerband will benefit from the reduce boundary layer and minimization of seraration. Its when you get into increasing port size and bowls you can begin to sacrifice low engine speed volumetric effeciency.

So talk with the head shop. Communicate what you want. Get some references to confirm their work.

 

thanks for the response I'll admit, I don't know a lot about headwork, flow characteristics and their effect on power (duh!), but what you just mentioned is pretty encouraging.

Any more input?

 

bump for more info!

 

AS WAS STATED ABOVE mild port werk can increase the VE (volumetric efficency) of a motor. this will help with hp through the entire rpm range. when the port sizes or shapes are dramatically changed you will gain in certain areas and you may lose in otheres. so just be specific with your head guy and communicate your goals so that he/she can take the necc. route when porting. and remember pretty looking ports does not mean good ports.

 

well, if thats all there is to it, looks like its time to start shopping around for a head guy.

Thanks for the help fellas!

 

pro series street heads 1280.00 port/polish valves, dual valve springs, retainers flow 285@500 28ft.. excellent for street car!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HOOKUPS &raquo;</TD></TR><TR><TD CLASS="quote">AS WAS STATED ABOVE mild port werk can increase the VE (volumetric efficency) of a motor. this will help with hp through the entire rpm range. when the port sizes or shapes are dramatically changed you will gain in certain areas and you may lose in otheres. so just be specific with your head guy and communicate your goals so that he/she can take the necc. route when porting. and remember pretty looking ports does not mean good ports.</TD></TR></TABLE>

Werd.

 

ROCKET please give me a call at my shop i am interested in dyno testing some of your cams and possibly stocking them as a distributor for you HOOKUPS IMPORT TEK 909-373-RACE (7223)

 

Will do sir.

 

thank you

 

Hey, I heard your Jason's cousin? I met Jason and Derek a lil while back.

 

YES JASON IS MY COUSIN AND DEREK IS A GOOD FRIEND , WE HAVE ALL BEEN AT THIS GAME FOR QUITE SOME TIME i just want to try some of your cams because i have heard nothing but good ish about them. i just dyno tested the cams that jason sells( he gets them from a local guy that we both do buisiness with) the results were terrible. 90 crx with b16 making 163hp consistantly with 2000 itr cams, made 3 pulls yanked thenm out and replaced them with these regrind cams after 3 runs the car made 150.5 hp at the wheels put the itrs back in =163.8hp so please let me know what you need from me to get a set of yours

 

Cool. I am super busy as of late but I'll give you a call.

I am pretty good friends with a friend of Derek's and it was actually Derek that showed me that working on Honda transmissions didn't require a bunch of special tools.

 

YA I HEAR YA BUSY AS HELLL US 2 LET ME KNOW

 

.

 

.???

 

I'll call you. Still crazy busy.

 

i got mine done by portflow they did a awsome job! go to the pros

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Quitripin &raquo;</TD></TR><TR><TD CLASS="quote">i got mine done by portflow they did a awsome job! go to the pros</TD></TR></TABLE>

How do you determine that they did a "awesome job"?

 

opinios are everywhere i use what i know werks PERIOD! the dyno doesnt lie. and i did post flow #S but to most they arent important dyno numbers are. OUR heads work period i dont know about toms (portflow) although there are a helluva lot of fast cars sportin his sticker.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HOOKUPS &raquo;</TD></TR><TR><TD CLASS="quote">opinios are everywhere i use what i know werks PERIOD! the dyno doesnt lie. and i did post flow #S but to most they arent important dyno numbers are. OUR heads work period i dont know about toms (portflow) although there are a helluva lot of fast cars sportin his sticker.</TD></TR></TABLE>

I realize everyone has their opinions. This site is loaded with opinions, TOO many opinions. I am not questioning anyone porting work. I simply asked the question thinking the gentlemen might provide some dyno data, flowbench data or some form of data to back up his "awesome job" statement, which would substantiate his claim, changing it from an opionion to fact. Thats what I wanted, data, facts, etc.