i know this has been discussed before, but i had no luck with the search
considering both heads are port & polished and using .5mm os valves. which one performs better?
to my knowledge b16 heads flow better than gsr stock for stock, but what about the p&p factor

 

a bare B16A head that has been ported and polished is basically a Type-R head. im just not crazy about the gs-r heads flow characteristics, but a gs-r head on an engine will raise compression, since the B16A is for high-dome pistons.

 

i was under the impression that itr heads have a mild clean up jobs in the ports, thus not making it a full p&p job which i was reffering to

 

well, BY GOD!!! called me out on that one, didnt you? i was just stating that the B16A and B18C5 heads have the same casting. but the C5 is, like you said, cleaned up with better internals. i like the B16 head better than the gs-r head, and i replaced my gs-r head with a B16A head. way more potential IMO.

 

haha sorry if it came across as calling you out on that one
let's all enjoy one of these e-beer thingy's

anyone else have any opinions on the pros and cons of these 2 heads

 

There are just a few differences besides the main casting... stock vs. stock the P72 cylinder head will generate more power on the same bottom end (it's cam profiles are better than a B16's too)... With a cumbustion chamber volume of 41.60cc's on an 81mm bore block you will notice about a 0.20:1 jump in the compression from that of the PR3's 42.70cc combustion chamber... Most people say that the P72 can't flow as well as a PR3 but that's not necassarily TRUE.. I've seen several flow carts of the P72 out performing the on top end... We will probably have to live with the fact that the GSR will never be able to make the PR3's mid range, but like I said i've seen it better on top end... I personally like the GSR head better but there are not to many people that agree with me... hehe Latez

 

I agree. The GSR head is better in my opinion.

 

Despite cam profiles... put them on the block of a controlled experiment.

b18c1 blocks. P72 head on one and PR3 on the other.

Change out pistons so they BOTH have identical Compression ratios.

Port and Polish both heads and use ITR valve trains includeing cams and valves.


What has more potential? What will deliver the most power in mid or top?
If someone was able to do this comparison I would place my bet on the PR3 head.
Nonetheless I DON'T discredit the P72 head either.

 

First of all, I'd love to see any flow bench comparison of either head. Secondly, anyone who doesn't like the flow potential of any B series VTEC head isn't well schooled in flow potential, because obviously they are all fantastic. Thirdly, what cam profile works best depends upon a ton of factors, so there's no simple write-off to one or another (speaking of B16A vs. B18C1 cams) as to which works best. Lastly, Honda chose to put the PR3 head on the B18C5 for a reason, and I suspect it's because the head is slightly better in flow potential. The additional chamber volume is actually a slight problem here, but they chose to use it anyways.

 

I have compared the two side by side and the stock intake ports on the P72 head are slightly bigger than the PR3's. Also I think the reason that they chose the PR3 head for the type R was because they used a single chambered intake manifold as oppossed to the twin chambered intake from the P72. I know if you have to buy a performance head from somewhere you will pay alot more for the P72. There has to be a reason for that (could just be low supply).

 

http://www.alaniztechnologies.com/b16vsgsrflowtest.html

Texan: ask and you shall recieve above is a flow chart for the
two heads in stock trim.

The GSR head also has a rocker ratio that will in effect create more lift at the valve over the B16/ITR head. Installing Type R cams in a GSR head will create more power, not to mention you have the higher compression... just swap the LMAs to Type R and you are fine. With the GSR you have the ability to
purchase a SK2 single stage intake manifold if you opt for it, sounds like it to me
you have more tuning options with the GSR head... port/polish and mill that bad boy and drop in some ITR intake valves... good to go man

 

Thanks Mike. So basically the two heads flow identically, being less than 1/10th of a percent different if averaged over the .050-.500" valve lifts.

Also, I was under the assumption (from Tuan's supplied data) that the two engine's mid rockers were 1.55:1. This also isn't true then?


Supercompact- Since Honda made specific pistons, rods and cams for the Type R motor, as well as doing some handwork on the head, I don't see why they wouldn't have just changed the intake manifold bolt pattern for the P72 if they just needed a single runner setup using that head. Remember this is a manufacturer, that is the least of their problems.

 

I used the GSR head then I used the B16 head, then I used a type R head...I easily chose the GSR head...High end power was incredible in comparison, not to mention the dyno liked it too... I don't know, but I've heard it both ways...I guess GSR heads are it for me though...

 

As far as I am concerned, I wont approach this from the back end working my way forward. honda might have not used the GSR head on the ITR block for several reasons. if you consider where the R motors come from, they are the next most logical step from the DOHC inline 4 with VTEC they announced in the mid 80s in Japan. More displacement in the B18, single stage intake runner found on both the B16B and the B18C-R. I can see them not using the GSR head for this reason, the GSR was a completely different engineered car than the R. The GSR was made with performance in mind, however not for all out track whoring like the R. Honda knows the potential of the first motor they released the infamous B16a, however the B18C was a side step with the dual path intake manifold and the longer gearing, etc. The GSR was just a different car. Personally, I drive a GSR with an ITR block and all GSR head and manifold components. I have ITR LMAs and Valvesprings but thats it and the motor is good for 158whp/121 on GSR manifolds, stock intake and exhaust on the 10.8:1 compression with the GSR cams, still driven by the OBD2 P72 ecu. Not bad by any means. Also, not what Honda intended... I fully understand that. They also didnt intend this motor to produce 120whp/tq at 5252 rpm to the wheels with the 158whp peak and a 14.85 @ 93.6mph trap. All I am saying is that suprisingly, for the street it is a nice setup which I am thoroughly enjoying with the feel somewhat of a prelude engine. Good torque through the rev band, 105tq at 8K.

When I can afford it I want to put some time into extracting some power from this thing and see where it can get me with an OBD1 computer, a mild 4-2-1 header and either skunk2 1 cams or a Type R intake cam and a K/N filter in the intake box. Since I really dont want to drive this motor too hard through restrictive exhaust, more than likely I would do that first before camming it up too much. For now it gets good MPG and gets me where I need to go without much trouble

 

This topic has been debated again and again over the years. And I have yet to see any evidence that either head is better than the other. And when you consider that there is no clear cut winner, they probably really are equal. Now alot of people think the GSR head is better due to its larger intake ports. But you must keep in mind that the port entry area is not the most restrictive part of the head. Typically, it is the area around the valves. And although I have not compared both heads side by side, I would be willing to guess that there is probably little to no difference in this area.


[Modified by StorminMatt, 2:41 AM 1/15/2003]