I always hear people on here saying a valve job can increase flow. I noted someone saying it in a h22 vs k20 thread. They said that a h22 when given just a valve job can flow 300 cfm. So what are the optimum valve job angles and how many. I have a b18c and i had the machinist use the type r specs. Please keep this informative in nature, I think more than i would be interested in the theory behind this.

 

anyone?

 

Your looking for a trade secret that isn't going to be posted by anyone who really knows.. If it was as public as HT , everyone could produce a 300 cfm head.

 

Not to mention that different porters like different valve jobs. So there is no such thing as a univerally superior valve job.

 

0-90 and none

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PocketRockets Racing &raquo;</TD></TR><TR><TD CLASS="quote">0-90 and none</TD></TR></TABLE>

LOL

 

id be willing to bet the itr angles are optimum for most builds honda knows what they are doing im sure their engineers are more experienced than anyone here in the performance industry.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtecmissle &raquo;</TD></TR><TR><TD CLASS="quote">id be willing to bet the itr angles are optimum for most builds honda knows what they are doing im sure their engineers are more experienced than anyone here in the performance industry.</TD></TR></TABLE>

Honda might be close to nailing it when it comes to factory parts, but there are experts who machine heads that are better suited for higher output engines. Honda is good, kudos to producing a very good cylinder head from the factory, but they aren't the best.

Portwork only does so much. Combustion chamber size and shape, along with the valveseat area are what create the best heads, and one size and shape and angle cut may work best for one application, while another will be better for the next. It all depends on a large list of variables, and these experts know how to build a head for each application.

 

Larry had a few questions for you ... i sent you an email

i'm sure he'd give you good advice, he's not gonna be secretive about it unless its some special head he's gonan do for you.

Greg

 

For low lift cams do a shallower angles. For higher lift, faster opening cams do steeper angles.

That is the general relationship.

 

tell him thanks for the info. Also thanks rocket for the info

 

how many of the porters here prefer discreet angles (eg. 3 angle) over radiused blended angles (eg. 5 angle or more valve job) ?

or maybe I shouldn't say the word prefer...can you achieve the same flow volume (say 345 cfm at 28") using a discreet approach vs radiused?

and same flow volumes in terms of

mid lift to max lift...

vs. low to mid lift.

here's R&D Dyno's H22 "advertisement flowbench" for comparison purposes.





how many of you porters subscribe to the low lift reversion story being significant?

when I looked at Joe Alaniz's B18C flowbench on his "competition ports" the low lift flow volumes were no worst or better than Endyn's purported antireversion radiused "racing ITR" ports at low lift flow volumes.


when I was looking at the Pro Stock chatter on the other forums, people were saying that they found the flow efficiencies near the approach to the SSR was important if you had a motor screaming up past 8000 rpm on their heads at high lift ranges. They would have a head stop flowing at those rpms with big lift cams...i.e. there was no advantage to going huge on the lift if the SSR was too steep. So there was a balance for a given valve area and lift in which the flow speed just died after those rpms when your SSR was made too steep.

So I can't imagine it's only the valve angles.

My take on it is that you have a certain valve area and the concentric diameters along the length of the port from the IM to the seat are dictated by what you want to achieve in terms of flow volume and flow speed for a specific rpm range.

It's not zeroing in on one aspect of the port or another but rather a co-ordinated shaping of a series of port cross sectional areas along the entire path dictated by the valve area and max cam lift.

Am I off on this?

 

interesting info!

 

Ive noted your absence here on ht for some time and wonder if you are here for a while or Just bored because its cold in the northlands.

 

......(anxiously waiting for a reply to the theory stated above)..........

 

There stock H22 intake flows 280 ..
The Highest i have seen on my bench is
274 @ .500 lift

 

^^True to the bone. My head flowed 274 (@ .500) on your bench Brad. Flowbench races aren't anything like et's at the track