Can i use the CTR piston in my ls/vtec? Can i use the stock ls rods?

 

seeing as how i just researched this all yesterday, i will be happy to enlighten you to (what i believe) are correct answers.

the LS rods (PR4) are wider at the bearing end and the (wrist) pin end than the 'R' family of pistons are. therefore, if you wanted to put CTR or ITR or GSR pistons onto LS rods (which you need for the LS crank), you would have to remove some material either from the sides of the pin end of the rod, or from the inside of the base of the piston, to allow the pin end to fit into the piston with ample clearance.

there are (at least) two other options, however, and from what i understand, both the USDM (PR3) and JDM (P30) B16 pistons will fit onto LS rods without modification.

the USDM (PR3) and JDM (P30) pistons, on LS rods, will result in a C/R of somewhere around 11.3:1 and 11.5:1, respectively.

NOTE: if you were able to put the B16B pistons on LS rods, you would end up with a C/R of somewhere around 13:1, so you wouldnt want to do that anyway.

 

well said was in the process of responding to this had to do something and got logged off. but i think the p-30 yeilds a slightly higher compresssion ratio than the b-16 11.3 to 11.5 sounds about right. thats with no gasket thining or head shaving. also i think the compression ratio of the ctr's on a ls crank rod and in the block will be 12.5. oh were you saying the b-16 will give you 11.3 and the p-30 will give you 11.5?

 

yea i was tryin to say this, sorry for the confusion:

USDM B16A = PR3 = ~11.3:1

JDM B16A = P30 = ~11.5:1

the difference in dome is very slight, so it doesnt change much...
also, all those numbers are assuming an OEM 3-layer HG and no head shaving or decking...

 

so 13.1:1 compression is to high for pump gas and dd?

 

no you can go with the p-30 and even get them oversized from the factory and you will be fine. 93 octane required.

 

yes. you will not be able to properly tune a 13:1 setup on pump gas without fear of detonation in summer in FL.

if you live somewhere that is more moderate year-round, it might be possible, but with 100 degree heat and outrageous humidity, you will get detonation.

the PR3 or P30 (mid 11:1) is perfect for a solid N/A daily driver, but if you wanted to go slightly higher, a 2-layer headgasket would do the trick.

*EDIT*
ok, so i may have exagerated slightly. it is POSSIBLE to tune a 13:1, but IMHO, it is way more trouble than its worth... and you will just keep shifting your powerband upward, so on an LS bottom end, that doesnt like high rev's with its 1.54:1 rod:stroke ratio, this is actually counterproductive.

 

ight so i fin to go with jdm b16 p30 pistons and use a new oem headgasket, and should get around 11.5:1 compression on 93 pump gas? How long should i break in the pistons?

 

there are approximately 84053 ways to break in a motor, most falling into some version of one of the following two:

1) those who break it in nice and gentle, dont get on it hard till after 1500 miles

2) those who believe you need to 'load and seat' the piston rings immediately for a good seal, and suggest idling for 10 min and getting on the street and doing 75% pulls IMMEDIATELY.

it is useless to argue about which is better, who likes what, etc, cuz any decently built motor will hold up, and UNLESS someone can provide a documented experiment with two identical motors, lets not get into which is better.

use Google. find a method you like. good luck.

 

to fit the ctr pistons you have to shave 1mm off of the inside of the pistons on each side. call around to see how huch it would cost and post it. interested