Im a toda/spoon ***** (now i guess) and toda is claiming with a stock (.6mm) headgasket toda pistons (81mm) give you 12.3:1 compression. WTF? Thats a big increase from stock. I want to get the toda spec'bs and since im going all out with cams, gears, timing belt, valve springs, headgasket, etc etc might as well get pistons too. 12.3 is going to worry me. Should it?

 

What's so unbelievable? They are high-compression pistons...

Suprdave

 

Try these links:

https://honda-tech.com/zerothread?id=352391
https://honda-tech.com/zerothread?id=320693
https://honda-tech.com/zerothread?id=243861

 

the higher the better!

 

There are many people here who run 13:1 daily driven.

 

thats not high, buddy of mine is running 14:1, race gas only

 

bisi the drag racer has 18 somthing :1 thats crazy compression

 

Muscle cars in the 60's ran 11.0:1 and 12.0:1 and higher compression... Why is is so suprising that our cars run or can run higher compression?

A.

 

hell yeah.....

 

If 12.3:1 compression shocks you as being "high as hell", don't you think that's a sign that you're not ready for it?

What are you planning to use for engine management?

 

is there any pistons that wil give you 12.3:1 with out any mods? if so which ones?

 

def agree with Reid on this one..

 

Toda pistons will.

 

12.3:1 is out of my comfort zone.

That's why I'll be using P30 pistons in my new motor. 11.5:1 with stock headgasket. I know I could go higher with my planned setup, but I don't really need to.

 

With going with a higher compression piston will it alter the ride quality in any way... maybe louder, lumpier, or etc...

 

In a well-tuned motor, how far can you go in compression with 91 octane gas?

 

My Motor is about 13:1 running Spec C Todas and I have no issues running 91 octane gas on the street.

If your installer knows what he is doing, then you will be fine. I dynoed at 231 hp to the wheels NA and I daily drive my R with no issues. It's all about the install.

 

Holy ****! 13:1 on 91 octane? That's insane. What are you tuning with (Hondata, Standalone, AEM EMS, VAFC, etc...)?

I want to know if altitude affects what octane you should run for your compression. I'm at 5500ft above sea level (I think) here in Utah and I wan to run CTR pistons with a mugen headgasket and sk2 stage 2's in my b18c5. The best we have available here is 91 octane unless I drive 30 mins to a chevron that sells 100 octane unleaded. should I just plan on running only the 100 octane, or could I mix half a tank of 91 with half a tank of 100?

 

YUM, fill up a few gas cans with the 100 octane and keep it home. Then you can dump the good stuff in whenever you want.. Saves you from having to drive 60 miles to get goot fuel..

 

so the 91 won't cut it with that high compression? 12-12.5:1'ish?

 

engine management would be Hondata...maybe 310cc injectors too but i dont know really.

 

I've run 13.2:1 on 93 octane with no problems whatsoever..

 

baah, Mercedes deisel motor. 22:1 CR

 

The high over lap cams bleed off a lot of that compression... it's not a big deal, as his effective compression is probably in the high 11's... Too tired to add elevation to the soup... I'm sure someone else will chime in with a better explaination...

Zeus- who's tired as freakin' hell...

 

Not looking for a detailed technical explanation of how altitude will affect it, I just want to know if I will need higher octane with 12.x:1 compression because I'm here in Utah, or if the altitude will actually lessen the octane requirement and i'll be good with 91.