trying to see the difference between SI head and GSR head...

i know the sotck GSR has dual valve springs on the exhaust side, wondering if the stock SI head had dual valves springs an all? and also wondering the what RPM both stock head can handle. I know the GSR head can handle 7800-8200, do anyone know what an SI can handle? thanks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lo0nY &raquo;</TD></TR><TR><TD CLASS="quote">trying to see the difference between SI head and GSR head...

i know the sotck GSR has dual valve springs on the exhaust side, wondering if the stock SI head had dual valves springs an all? and also wondering the what RPM both stock head can handle. I know the GSR head can handle 7800-8200, do anyone know what an SI can handle? thanks
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i don't know anything too technical, but i also think there maybe a valve angle differnce as well.

someone with more technical experience chime in though

 

anyone??????????

 

Si motors rev to 8k stock and I have read of people running them to 8500-9000 or so on stock springs. Only to 9000 if it is done very rarely but its still pushing it. Anything more than that and your going to end up floating valves. Personally I would not go over 8500.

 

it isnt recommended to go to 9k on any b series head with stock valvetrain, unless you're ready to fix some parts.....

physically the 2 heads are different-- the bolt patterns for the intake manifold are different from the two, as well as the ports and bowls of the head... an itr head is basically a b16 or Si head with work done to it (mild p&p, valvetrain) from the factory.... hope this helps...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by self.one &raquo;</TD></TR><TR><TD CLASS="quote">it isnt recommended to go to 9k on any b series head with stock valvetrain, unless you're ready to fix some parts.....

physically the 2 heads are different-- the bolt patterns for the intake manifold are different from the two, as well as the ports and bowls of the head... an itr head is basically a b16 or Si head with work done to it (mild p&p, valvetrain) from the factory.... hope this helps...</TD></TR></TABLE>

you might have more luck in the all-motor forum

you're also right about the itr matching (ie: poor-man's R is a b16 head with b18 shortblock)

 

I though it was only CTR and ITR motors that had dual valve springs but whatever. Also b16 head flows alot better then GSR.

 

there was a post i read the other day with this covered in it and it showed dyno charts... b16 better high end.

 

all i know is my boy is in his low 14s with his gsr block and b16 head with intake and exhaust

 

b16 flows better...gsr has higher comp

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Art In Motion &raquo;</TD></TR><TR><TD CLASS="quote">b16 flows better...gsr has higher comp </TD></TR></TABLE>

 

questions hasn't been answer yet about the rev limit? and the stock valve spring in an si head?

 

you can rev a stock gsr or si head to 9k no problem only the itr and ctr have dual vlave springs on exhaust si and gsr hove them only only on intake the heads flow rate are close really close the gsr can flow just as much as a si head will they are designed different because of the intake manifold were designed different a gsr head can be reshaped to that of an si head, its just a preference.

 

so the gsr and si have dual valve springs on the intake side? so would someone use a GSR or SI head for LS/VTEC setup?

 

the GSR heads have a partial combustion chamber (not the correct terminology). the combution chamber stops after the valves and becomes flat, (_) like that. while a b16 head has a "full"combustion chamber that extends all of the bore. like this O.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rjay8604 &raquo;</TD></TR><TR><TD CLASS="quote">the GSR heads have a partial combustion chamber (not the correct terminology). the combution chamber stops after the valves and becomes flat, (_) like that. while a b16 head has a "full"combustion chamber that extends all of the bore. like this O. </TD></TR></TABLE>
gsr = pentroof style chambers.

after much research, that is the only thing they have over b16 heads.
you can also weld the b16 chambers and reshape to pentroof style...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EVOL &raquo;</TD></TR><TR><TD CLASS="quote">
gsr = pentroof style chambers.

after much research, that is the only thing they have over b16 heads.
you can also weld the b16 chambers and reshape to pentroof style...
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actually the floor of the intake port on a gsr head sits 5mm higher than a b16 head. and the intake ports are very different in shape as well.

 

what is a pentroof? and does that mean the gsr head is better?

 

the flow difference between the 2 heads is very small, not much of a difference. imo gsr is a better head

 

Any other opinionS

 

Hmmmm, my opion:

I have both heads and have searched and done some checking into this myself. Fisrt let me start off by saying that both heads are very good! Stock for stock they are very close in power, usually within 2-4 hp of each other. The gsr (p72) head seems to outperform the b16 (p73) head in the lower rpm under 5000rpm, and the b16 one makes a similar amount more over the 5000 rpm range.
The gsr has a square quench area bumping up compression slightly, the b16 head is a larger round quench area which seems to work well as rpm rises.
Once either head is modified, both heads work equally work from what i've seen.
I have decided to use the gsr (p72) head on my B18C5 block and some jdm itr pistons to bump up comperssion while rebiulding my engine up with stage II skunk cams and valvetrain, it should make some good power.

Deetz