I have an LS/VTEC with about 20,000km on it. B18 block and ITR head.

My compression is at 11.8:1 and I am looking to boost by car. Goal is about 300WHP with a full synapse ramhorn kit and a GT28RS turbo.

I want to bring my compression down the the low to mid 9:? range.

Going to be a DD car running 91 Octane

My rods are stock and I have CTR pistons, trying to prevent changing pistons and rods because it might be getting a bore and sleeve next year... which will mean new rods and pistons.

Any way I can get a head gasket thick enough to bring down the compression that much?

If so, any brand suggestions?

Thanks,

 

no........you have to change the pistons.......

 

What about head spacers?

 

to half *** it yes. and yes i mean half assed.

to do it correctly, rods and pistons is the only way.

 

x2..
u could boost it but the sleeves would crack easily,about after 7-9 psi ...and thats on a good tune with 91oct. spend the money n change the pistons

 

where can u get head spacers for a honda.

 

Use a Cometic head gasket 74mm. I have one in my turbo set up with 300+hp in b16 turbo.

Im using 11.5-1 Wiseco piston with agressive cams...

 

74mm? you sure? 74mm=2.91 inches.
i have used it was either a 2 or 3mm headgasket, but thats about as high as id take it. but still i would just wait. you can run the turbo with the high compression. but your tuning wondow is very small.

 

you can get a custom head gasket from comtetic with a huge spacer to bring the CR down......however its a **** poor solution. greater chance for head gasket leaks/failure. also the engine will probably still blow up since the CTR piston is still a weak cast piston and has a huge dome which will give you a poor combustion for FI.

a set of forged pistons can be had so cheap. there are lots for sale in the marketplace....don't be cheap now or you will spend 2X shortly after.

 

u can run a .080" hg to drop ur cr but it wont get down to 9.

 

its better to run high compression with proper quench then it is to run lower compression with out of spec quench. definitely need to change your pistons

 

Sorry my bad, .074mm

 

11.8:1 is risky, no matter how you look at it, especially with 91 octane gas. Changing headgaskets is a quick solution to go down to at least 10.0:1, but to go down to 9 is not needed if the tune is correct. My main concern is the fuel being used for the amount of pressure needed on a Disco potato to reach 300whp.

I'd look into changing rods and pistons and not look back here.

 

I run my set up @12psi 300hp with Shell 93 octne

 

It will be getting a very good pro tune... even 10:1 compression is fine

Changing pistons and rods is about $2500+

2mm head gasket with adjustable cam gears (needed for the gasket) is about $500

Just found out there is a guy in town with a 600HP S2k, running a 3mm head gasket to bring is compression from 11.?:1 down to 9/?:1

I think a good gasket should be able to hold 300HP easy.

http://www.inlinepro.com/s1/p-53-inl...d-gaskets.aspx

 

I didn't say it couldn't be done. I said its risky.. You're also running at 93octane. A bit of a difference in BTUs combusted

 

Replacement stock pistons are <200 bucks man. throw in headgasket is 50 bucks and you're done.

 

From what I have been reading, the rod berrings have to be milled 1mm on each side to fit the CTR pistons... so I would need new rods, bearrings, pistons, rings, head gasket, bla bla bla...

 

what in the hell were you reading?

 

Ya, that sounds weird.

 

i can't find the link anymore... regardless, I have read a few times that CTR pistons do not fit LS rods. (therefore, the rod bearings must have been machined to fit)

 

It has nothing to do with the rod bearings. It has to do with the small end of the LS rod. It is too thick right there to fit into a CTR piston so you get the rod milled slightly to fit. What that means is you can now put any OEM b-series piston on that rod now with no issues.


...or you can shave the piston down instead of the rod, which is the preferred method.

 

Ahhh, okay... thanks for clearing that up.

Ill call the shop tmrw to find out if they machined the rod or piston... these are the times I wish I did my own build and didn't buy a pre-modded... but I did save $10g... lol

 

Yeap its risky, now im using Q16 with 20+psi ectune set up and shell 93 for street tune

 

point blank....dont run 11+ compression on a daily! why have the worry behind your head! just swap the cast for some forged pistons and be happy!