AIRFLOWDESIGN

I'm an old school Drag Racer thats looking to get more into Import Racing. So my question is this, what cylinder heads are most guys having ported? Thanks, Ron

www.airflowdesign.com

aut0tek

Okay... I'm gonna take a stab at this and u tell me if this is what you're asking...

First of all since you're talking about switching heads and stuff I'm assuming we're talking B-Series heads... if not, this post wil not help ;-)

If you're going VTEC and u are turbocharging it you'll probably use either the B16A head or the B18C5 (ITR) Head because the combustion chamber is bigger... Slightly... leaving u with lower compression than the b18c1.

And therefore if u are going N/A and u have like... 10.2:1 compression pistons or something like that u can have the B18C1 heda and have a slightly higher compression and as long as u like to use 93 octane go for it.

As far as the size of the ports and all... They're similar to each-other and if you're porting and polishing **** it it won't matter anyways. lol Just tell them u want the ports "BIG." Say... "I WANT BIG PORTS." They'll do it. hehe

I hope that helped u out a little.

Harry

-KangaRod-

Its not like the domestics where you can buy cylinder heads. I don't know if there are any companies that actually sell cylinder heads for hondas. The most common head right now would prolly be the two mentioned above. A lot of guys are building VTEC motors that wern't origionally intented for VTEC (called LsVtec or CrVtec) and are doing some pretty serious headwork along the way. I'm assuming you do head porting? Bigger isn't neccessarly better on honda's, they are already quite well designed for higher rpms and any headwork should focus on the midrange a little more than the high end. If you over port your head, you'll lose the ramming effect (not sure of the technical name) and will loose power...and worse, your fuel economy will suffer.

GimpyAccord

Honda head selection sure is lacking.. you'd think with all the interest in them there would be aftermarket heads. I've heard rumors of 5 valve designs etc.. but they have never appeared.

My mustang i can literally go blind before looking over all the heads i can buy. And whats sad is I can have a nice set of aluminum heads for like 850, CnC P+P for maybe 500 more... sorry for getting off on a tangent.

I guess this says one thing for Honda.. they probobly one of the best if not THE best factory built heads with plenty of potential within! One thing i have learned over the years and the above poster hit on it: Hogged out valves and runners arent always good!!! you're looking for velocy on intake as well as volume.. we could make a 10 page post on head porting theory.. but just hogging out bowls etc isnt the answer. you need proven flow bench data for the application which you seek.

Another thing i feel people are mistaken on is polishing the intake side.. while it should be smooth a roughened surface promotes air/fuel atomizing. Exhaust is really where you want to make that baby shine like a mirror.

AIRFLOWDESIGN

The ramming effect you are talking about is called Bernoulli's Principle. The points to look at are the port opening, valve size, than the cross section before the short turn. It's kind of like looking down a carb but bending it. Ron
www.airflowdesign.com

Gasoline Fumes

There's an article on DIY head porting in the current issue of Grassroots Motorsports.

InspiredRacer

Do you use a cnc machine, flowbench, what. The heads to learn are B18C, C5,B and B16A. Ive been trying to learn how to do it myself but haven't gotton enough practice heads to start the process.

GimpyAccord

having a CnC machine would be best fer sure... otherwise you'll be on the flowbench a lot making sure everything flows even #'s

TheRooster

For Hondas: the DOHC Vtec heads, and H22/23 heads off preludes would probably be most requested.
A lot of guys don't run Hondas though... there's a fair share of people who run the Zetec engines from the ZX2/Focus, the 20/22R, 2JZ and 4AG engines from Toyota, and then the Nissans, which I admit to being none to familar with. Rotaries are also popular, but thats an entirely different process.

AIRFLOWDESIGN

Having a CNC would be nice but the cost is just out of my limits however I have a JKM 600 Flow Bench and do all my porting by hand.