Just thinking about future plans, probably not going to be any time soon, but out of curiosity:
I have I/H/E on my car with suspension, so the next thing I would want to do is draw out more power from the engine. The next thing would be either cams and gears, or compression. Is it possible to raise compression without getting new cams? What all is needed to raise compression? Would something like say Type-R pistons drop into the GSR engine with mild modification? What kind of cost would this be? What are safe compression ratios? What are good pistons? I'm just trying to learn as much as I can about the different things that are possible. The future of my car is a N/A daily driver that is fun to drive. Anyone have any insights?

 

I have never heard of camshafts raising anyone's compression.

 

I understand that cams don't raise compression, but I asked a similar question a while ago and i think someone said that it isn't safe to raise compression without getting more aggressive cams.


[Modified by Kellindal, 8:13 PM 2/28/2002]

 

have the head shaved like what it is .002 damn i cant rememeber what the usual is fgor that but i have heard of up to .003....wiht the head gasket would raise it a little

 

Have your combustion chambers welded when you port and polish your head.

 

I'm talking about upping compression with new pistons, like ITR pistons or something like that. How much compression could you gain with the methods mentioned above? Because I would also plan to have headwork done to my car as well.

 

taking apart the block, honing/bore (you need to bore if you have several thousand miles otherwise you won't get a good seal) dropping in JDM ITR or CTR (watch the CR w/CTR pistons and use high (94) octane gas only. I had estimates of $700-800 not including the $300 or more for pistons & rings. you might wanna upgrade the rods too. = VERY expensive, plus you'll be out a motor 3 days to a week

in a GSR JDM ITR will net you 11.4:1 CR
JDM CTR will net you 12.3-12.4:1
USDM ITR will net you around 10.9ish:1 i think





[Modified by DXhatch, 12:25 PM 2/28/2002]

 

Hi,

The compression ratios with the Honda pistons are about right. There is that cool flash or javascript web app that you can use.

Anyway, you can also mill the head and/or get a thinner head gasket.

The concern with aggressive cams is that bigger lobes could cause piston valve contact if you don't have timing right and high CR. Less room for error...

Anyway, I would def get oversize pistons if you have some miles on your car. I wish I had

FB

 

get a set of cams and a thinner headgasket, you won't be able to advantage of the higer compression w/ say jdm itr pistons w/ stock cams even more so w/ high comp aftermarket pistons
high compression = agressive high lift cams

 

how about getting a stroker kit instead, I mean is her really gunna get a large increase with swapping out stock pistons for Type R ones? actually if you want more power come to the dark side.

 

CTR pistons in a stock GSR head will have a CR of about 11.8:1 which should be safe on atleast 92 and maybe 91 octan... RIGHT?

 

don't go higher than 12:1 on the street... not economical

here's that flash thing you were talkin about..

http://www.bojangz.com/calculator/

 

The thin Spoon sports Head Gasket raises your compression up .4pnts. and shaving the head you could get 10.6:1 easily. Hey same as the Type R's.

 

I raised mine with the Mugen Head Gasket. 11:1 WOOHOO!

I believe the headgasket is the easiest!

 

i thought it was funny how that guys quote is"There is such a fine line between clever and stupid" or something. Sorry about your pistons guy

-in the process

 

Alright, I've run 13:1 Compression on the street, but not on pump gas. I had to use 101 octane to do this. I have CTR pistons in a B18A w/ a VTEC head and JUN cams. The head was milled 3k, stock head gasket (that went bad after 3-4 mos. Cams actually do slightly change the compression in your engine. Higher lift duration means more a/f mix is being drawn in on the intake stroke, if you compress a higher volume of matter, the overall compression (pressure) will be higher, like with turbo, it's higher than an N/A engine. Compression RATIO is an entirely different thing. Say your CR is 10:1-- you're compressing the volume of air/fuel mix 10 times SMALLER at Top Dead Center than it was at Bottom Dead center. As you can see, increasing your compression ratio isn't linear, but geometric: for every little more you do, it's not like the last point buy multiple that. Ok, no more confusing stuff. You can safely run 12:1 compression ratio on pump gas. B16A pistons in a GS-R block will get you pretty close, but under 12:1.

 

So what kind of gains did you guys see with all this done?

 

Well, I had my whole motor put together like that all at once, so I can't denote a specific gain by just raising the compression. Of course all the other modifications are going to build on eachother and create more of a beast. All together, though--- with all the modifications (B18A .25 over CTR pistons, stock rods & crank, GS-R head, JUN 2 cams w/ all the valvetrain, only exhaust piece attached is the DC 4-1 header (only at the track and a little after becuase I was too lazy to put the exhaust back on) Civic R transaxle w/ LSD, 4 puck xtreme w/ 8lb flywheel) I dropped a good 2.4 seconds off my et. Dyno HP (remember I live at 5280ft) was 176 to the wheels. et was a 14.21 @ 95.64, drop about a second and a half off to covert to what everyone knows as standard 1/4 mile times. I think that our altitude drops 17-19% power off the dyno, but don't quote me there.

 

actually they wont increase static compression but can modify - raise/lower dynamic compression.

 

wrong sorry - CR in a ITR engine would be 12.0:1 - the GSR has a smaller combustion chamber (in the head) therefor you are looking at 12.3 to 12.4:1 you really only need compression this high if you are running toda B's, Jun 3s or Skunk2 stage 2 or 3's IMO. yes you are correct in the fact you can get away with running 12.0 or a lil higher on 92/93/94 octane gas

 

Hehe,

That's from Spinal Tap, a lot of you are probably too young to be familliar with it, lol.

FB