well i have a cheap but effective idea in mind. im thinking about buying a low milage 98+ GSR with the b18c1 which i think has a 10.1:1 compression ratio. im wanting to go all n/a with the car becuase i already have a boosted crx. i was wondering if there would be a way to raise the compression ratio up to par with the Type R compression which is 11.1:1 without actually building the block. i was thinking of maybe using a different headgasket with a fully ported and polished head milled down to also lower the compression with a whole new valve train including cams and about all the external boltons. with a different headgasket and with the head milled down do you guys think it could be done and it would be worth it? its cheaper than buying a complete b18c5 swap. i just want a very streetable integra with c5 power and a little more (200 whp). any opinions are more than welcome on this subject.

 

IT depends on the cams you want to use. You could mill the head .030 and use a two layer head gasket and probably come close to your 11.0:1 compression ratio. But with high lift cams you could be dangerously close to piston-valve contact.

 

i thought the itr motor had 10.6:1 compression? at least for the usdm motors. thats what it says on the hmotorsonline.com website.


i have a jdm gsr motor and the compression is 10.6:1, the same as a usdm itr motor..... according to the above website.

i raced my friends eg hatch with usdm itr motor with my eg hatch with jdm gsr motor, he pulls me on top end. time for me to get some EK9 cams

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by asubennett &raquo;</TD></TR><TR><TD CLASS="quote">IT depends on the cams you want to use. You could mill the head .030 and use a two layer head gasket and probably come close to your 11.0:1 compression ratio. But with high lift cams you could be dangerously close to piston-valve contact. </TD></TR></TABLE>

yeah i never thought about the valve to piston contact. thats very very true.

 

Possibly the best way to raise compression is to have your chambers welded. Not only will this raise compression without without tearing down the bottom end or causing decreased piston to valve clearance. It will also increase detonation resistance by increasing quench area. In addition, there is a certain school of thought that you get a better burn with flatter pistons than the more domed pistons used in Hondas utilizing the PR3 head casting. I am not sure how true this is, though.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StorminMatt &raquo;</TD></TR><TR><TD CLASS="quote">In addition, there is a certain school of thought that you get a better burn with flatter pistons than the more domed pistons used in Hondas utilizing the PR3 head casting. I am not sure how true this is, though.</TD></TR></TABLE>

This very true. The less dome volume the piston has the effective the combustion. But, you can not NOT run a large CC dome and achieve the crazy compresion numbers that are all motor sets up like.

 

i have a few thoughts. #1 dont mill the **** out of the head. once u mill it u cannot put it back the same. if it aint broke dont fix it. milling the head is the cheapest way to get compression. it changes the whole cam timing vs crank timing characteristics. put some pistons in there and be done with it.
as for welding the chambers, yes it works, but its more expensive than just throwin in some OEM ITR pistons and once u start welding on the head u actually change the strength of the stock aluminum. u can get shiftin in the valve seats too. just some food for thought.
pistons
milling head
welding chambers

 

very interesting...im sort of confused on what i want to do now. thanks for the inputs so far.

 

I will never mill a head again after having valve to piston clearance problems using aggressive cams. Last time I rebuilt my motor I put in S2S2 cams, springs, and retainers, JE 11:5.1 pistons, assembled and clayed the motor, turned it over dry with a used head gasket and decided to put a thicker head gasket in to have a little bit more clearance. Once it is milled there is no going back!

 

Changing the pistons would be the most effective way to raise compression, as well as being reversible. My old GSR set up was very simple with ITR pisons, CTR cams, and the bolt ons, and dyno'd 180/128 with a lot of usable power in the middle. For a mild street motor, it was a great set up.