honda b16 intake port Q

[Lee A.]

Hey guys im a beginner porter and im trying to find out where the intake port mcsa area is on these heads? or where would the ideal place be to put it?

The plan is to build a bench end of the year and get pipemax but for now just looking for some input.

doing some research i get valve guide area and throat? but most 4v choke points iv seen are located further up but they are in straighter ports...

working away the excess valve seat area which is probably the biggest problem with these heads cause of the casting mismatch etc creates a pinch right at the short turn apex which also seems like it could be a choke point...

any help regarding what some of you guys have found to work would be greatly appreciated!

specs: 84x89, 11.5:1 comp, 12.5mm lift, 300+ duration, pump gas etc street/race car.

thanks guys

[mag2555]

There is alot of places to have the port choke and if the motor was for all out racing you could get that down to just one location.
You state that your car is street strip and I would guess that the street usage will make up the bulk of that usage.
In that light I would say that for that head you've got the port choke should take place one stroke lenght back up stream from the back of the Intake valve, and since you have two Intake valves that distance gets split in half.
In a production head this may be hard to do.
I`am sure others will offer up suggestions and formulas for ya.
Build your bench and enjoy the jurney!

[Larry Widmer]

The biggest issue with B16 heads is the core-shift in all of the castings produced after 1997. The roof (long wall) of the port extends back under the rear of the valve seat creating a severe dip that the airflow must negotiate.
Until you achieve well over 300 cfm on the intake side, the as-cast cast valve guide bosses don't require re-shaping or narrowing.
I don't recommend going over 88% for the throat to seat OD ratio. The quality of the valve guides, and the valve job are the two most important aspects of the cylinder head. A basic seat combination of 36°x 45°x 67°x 80° blended into the throat will get you where you want ot be on the intake-side.

[groberts101]

A basic seat combination of 36°x 45°x 67°x 80° blended into the throat will get you where you want ot be on the intake-side.

Hi Larry. When you use the term "basic" here.. is that referring to what you would use as a "generally accepted" profile?

Or is its recommendation specific to this particular ports architecture/layout?

Thanks.

[Larry Widmer]

We use some rather complex seat designs with intersecting radiuses for most of our all-out race heads, but on the intake-side, I've found that the (above) seat combination will work extremely well on the B series, K series, and the F20C cylinder heads. In fact I use this seat design with the 45° at 1.0mm wide on several of road-race heads we sell. Airflow is extremely good throughout the range (.050" -.650"), so it's a good choice for pretty much all cam profiles in use these days.

[ou812]

Larry, how wide do leave the 67 cut? I do a lot of Polaris 900 heads but never tried a steep bottom cut like that.
Brian

[groberts101]

We use some rather complex seat designs with intersecting radiuses for most of our all-out race heads, but on the intake-side, I've found that the (above) seat combination will work extremely well on the B series, K series, and the F20C cylinder heads. In fact I use this seat design with the 45° at 1.0mm wide on several of road-race heads we sell. Airflow is extremely good throughout the range (.050" -.650"), so it's a good choice for pretty much all cam profiles in use these days.

Thanks much for the response, Larry.

Wow.. 1.0mm seats. What valve head seat width and overall head profile(backcut?).. did that seat width prefer?

[Larry Widmer]

The width of the 67 degree can be as little as .095" or as long as .250". As you move the 80 degree "up", the port begins to favor the upper portion of the lift scale. I typically don't go that route, as I'm big on mid-lift flow and extreme velocities throughout.
Valve face width wants to be .100" with a 35-37 degree back angle. Narrowing the face to match the valve seat width will kill quality airflow on these heads.

[groberts101]

The width of the 67 degree can be as little as .095" or as long as .250". As you move the 80 degree "up", the port begins to favor the upper portion of the lift scale. I typically don't go that route, as I'm big on mid-lift flow and extreme velocities throughout.
Valve face width wants to be .100" with a 35-37 degree back angle. Narrowing the face to match the valve seat width will kill quality airflow on these heads.

Great info and thanks for sharing it.

It's funny you should say that about the affect of "moving the 80 degree up". I just had a simlar conversation the other day with a fellow that used to help me build motors in Cali. I personally just find that some shapes, bowl depths, etc.. prefer, or allow, a specific profile/transition. From there I try to make fine adjustments to certian portions of the lift curve while trying not to destroy too much elsewhere in the process. Usually seems that I'm just robbing Peter to pay Paul.. but as you mention above.. it sometimes works.

[Lee A.]

thanks for all your response guys.

@mag2555 i hear you regarding the choke point being further back from the seat. i would assume the pinch at the ssr apex would be inline with what you explaining.

for all out drag application does one move the choke to the seat? if so would this work with both 2v and 4v?

@Larry of the few heads ive done almost all apart from one had really bad core shift but weird enough not only in the aluminium but the metal valve seat insert was tapered inwards meeting up with the dip/bulge, wonder if honda did this to help with the core shift. most of the guides i reshape as they quite huge imo.
thanks for that tip on the intake seat angles. they seem pretty close to the f20c stock valve job but the lengths of each angle would change the shape quite abit tho. dont have a Newen but got my ol seat grinder set so that will take car of that. nice to know they work well on all those heads!

[Larry Widmer]

Those castings are all over the place. When we were doing the ITR heads for the Grand Am and SpeedWorld Challenge cars, we'd take new B16 heads, remove the seats, and weld the intake (and exhaust) bowls. Then, I came in and applied my version of ITR porting. The heads were absolutely legal, and they netted an additional 20HP. Many of the drivers and team engineers cursed me heavily because they had to change driving styles and chassis set-ups.....
Note that we even masked the bowls and "sprayed" some faceted stainless shot to give the appearance of a little bare casting for the inspectors to see.
http://www.theoldone.com/components/cyl ... erExh1.jpg

[ou812]

The width of the 67 degree can be as little as .095" or as long as .250". As you move the 80 degree "up", the port begins to favor the upper portion of the lift scale. I typically don't go that route, as I'm big on mid-lift flow and extreme velocities throughout.
Valve face width wants to be .100" with a 35-37 degree back angle. Narrowing the face to match the valve seat width will kill quality airflow on these heads.

Thanks Larry, now something else for me to try...

[mag2555]

I do not recall the stroke lenght of that motor off the top of my head, but from what I recall from working on them the crowm of the short turn sounds about right lenght wise.
Another important slice of the pie is to have this area of the port(pinch point to back of valve) equal the volume CC wise of the cylinder, with each port providing half the needed volume.
Getting this to happen without having excess port volume in regards to the volumetric curve is the issue with a motor like yours that is not full on race, as you still need a decently wide torque band.
I would pack some clay into the port at the pinch point ( really pack it so it will sea and dont forget to seak the valve guidel) and do a CC pour just to get a feel for what you have in regards to that port volume from the pinch to the back of the valve.
No need to go nuts checking this as for your motor the needed amount of port area at the pinch point and having the pinch point near where it needs to be are more important power factors for you.
The 88% throat area as posted before is what you should stick with unless to will step up to bigger valve sizes.
Air flow wise focus on getting the greatest amount of flow around the mid point of your valve lift profile, if this should happen to take place within 4 degrees of cramk rotation where the piston is at its greatest velocity down the bore you will be doing very well in regards to greater power taking place.
Do not forget to do your flow and velocity test with the manifold bolted up.
I have found that with motors built for useage such as yours that I can increase the taper of the Intake runner some in the manifold and shift the torque band uo some without killing off low speed port velocity as would happen from using a bigger pinch point.

[Lee A.]

@mag the stroke is 89 and bore is 84. ive been in contact with another guy and he mentioned the choke on these heads are around the guide boss and that i should leave it there so im thinking i shouldnt make it at the ssr apex as i also read a post earlier that the MCSA should be in the straight part of the port on a 4v so this also adds to the confusion lol decisions decisions.

also came across this topic: viewtopic.php?f=15&t=24476
which tells me mcsa
1. tightest at SSR(very laid back difficult to pin point)
2. just before guide boss

anyone with experience on these heads pls lend me your MCSA location lol

[Lee A.]

here are some molds of b16 ports i found around the net for some visual aids.