I just wanted to check my thinking. Will CTR pistons in a b18c5 give me a higher compression? I wasnt sure because I was sure that it did but someone told me it didnt and it threw me off.

What is the stock compression on an USDM b18c5?
What kinda of compression would I get with CTR Pistons and Eagle Rods?

 

stock compression is 10.6:1
with ctr pistons it will be 12.25-12.5:1
dont use eagle rods. theres no need for them and you would have to modify the pistons

 

I though it was more like 12:0 compression but either way is up there. Use your ITR rods.

 

Steve, just out of curiosity, why the range for the compression numbers? Even accounting for standard or the +.25 CTR's, shouldn't there be a more narrow range?

 

I'm planning on using CTR +.25 with GSR rods... should get about 12.5:1 and then a little head work and a gasket should get me to approx. 13:1 which will mate with JUN III cams and make me happy! question is should I get the rods shot peened? Fluxed? Miked?


[Modified by advanracing62, 5:33 PM 2/24/2003]

 

stock compression is 10.6:1
with ctr pistons it will be 12.25-12.5:1
dont use eagle rods. theres no need for them and you would have to modify the pistons[/QUOTE]


With all due respect if you take a b18c block with ctr pistons will not be anywhere near 12.25, or 12.5:1 that is way too high. as far as 13:1 ??? no way... its actually only about 11.5-11.6:1 with a stock layer head gasket, and no mill on the head. if you put the ctr pisons in a ls block the 89mm of stroke compared to the 87mm stroke on the b18c it will yield a higher compression ratio. but its still not that easy to get that kind of compression. As far as the eagle rods with ctr pistons. its possible you dont need to modify your pistons instead you should be able to rebush the rods to stock oem wrist pin specs.

max-


[Modified by LuckyRacing, 5:46 AM 2/25/2003]

 

Tis, tis. I just checked the compression calculator at
http://www.c-speedracing.com/howto/c...c/compcalc.php and it said that the compression in a b18c5 without going with the oversize ctr pistons is 12.099 and with .25 over (81.25mm) ctr pistons it is 12.157.
Conclusion, Check the calculator when in doubt.

 

You DO realize that the compression height on a ctr piston is .03" more than other
b-series pistons dont you? That is why the compression is so high.

For those of you who like to use c-speed's calculator. Make sure you take that
into account.

 

I heard the calculator was a few points off, conservatively... true?

 

hey advan i dont think its quite accurate. dont beleive anyone who tells you ctr pistons in b18c5 is 12.5:1 or even funnier 13:1 compression or anything ridiculous like that. its less then 11.8:1, oh and btw yes i do know the compression height is taller, thats only obvsious. NO matter how you look at it still not as high as you claimed it is.

let me break it down for you........ a ctr is like 10.8:1 with a b16a stroke and longer rods in a b18c block (b16b stamp) your going to tell me that just by installing a 87mm type r or gsr crank and the shorter rods you go from 10.8 all the way to 12.5:1???? now think about that... if the compression was as high as you claim,there would be no way to run 91 octane with stock injectors on that kind of compression. i do that setup all the time. and never had to use race gas. but when i install a REAL 12:1 forged piston we have to run a 50-50 mix of race gas and pump gas. thats still on a 1.8 1797cc or 1808cc b18c engine. bottom line the ctr pistons work GREAT!!!!! lots of tq. a little hp gain. and you will notice the motor revs higher and climbs faster. i hope this helps. if anyone has questions let me know ill be glad to assist anyone. thanks

BTW PCT pistons (ctr) are B series. (B16B)
max-


[Modified by LuckyRacing, 9:07 PM 2/25/2003]

 

haha

 

my only note to everyone involved in this is...

does anyone else worry about the CTR pistons w. high lift cams and a milled head having valve to piston contact? just think about it...

unless you have someone who is experienced w. building these motors, you better leave some margin for error, especially when you're adjusting cam timing.

just food for thought.

 

hehe..i think ill jump into this one..because i was in the same hole before...i said 11.75 (CTR, OEM gasket)..others said 12.25~12.5 and "c-speedracing is wrong"..then i didnt wanna fight and said 'if its wrong then its wrong'...NOW "57one" says to check C-Speedracing.com and he came up with the number 12.099..And i know that is wrong because he used it incorrectly!!
At the VERY bottom it says "Piston-to-Deck Height" ..You have to make sure you change it to the RIGHT engine!!! "OEM B16A/B" to "OEM B18A/B/C1/C5 - B20B/Z" when calculating for B18 engine!!! B16 and B18/B20 has different deck heights..thats why both engines with VTEC water pumps use different timing belts..! Plus! if C-Speedracing can 'calculate' other Compression Ratios correctly then why wouldnt it 'calculate' this one correctly!?! and if you do use it..Use it Correctly!

Off Subject: But can anyone give me the Part Number for an ITR Oil Pump???


[Modified by 10K2HVN, 4:13 PM 2/25/2003]

 

hi

 

I have said this time and time again.
It doesnt calculate it correctly because it doesnt take into account the .030" difference in compression height.

 

Apparently you can't tune that well if you have to run 50% race gas with only 12:1 comp. There are tons of guys running over 12:1 on 100% pump gas.