Well, I bought these B16B pistons from a guy and he said that they were 12:1 compression pistons. That what he thought they were. He said he was pretty sure. I look up the B16B CTR pistons and they are only 10.8 compression. I got flat Supertech Racing Valves to bump up the CR a lil more to maybe 11.00
or 10.9. So What I am asking is is this what the B16B pistons really are, and if so would it be a bad move to shave the head .010. I would do this only to bump the CR a hair higher, i will be using 91 Octane gas to let ya know. What else should I do for CR better? In the low 11's is fine, but the only thing i cna do is to shave the head .010. I am also getting alot of head work done too. What do ya think?

 

CTR pistons actually "stick out" higher than regular pistons from a b16. When you calculate the compression ratio, you actually have to factor in a lower deck height (.000) to compensate. If you just plug in the numbers, you get 10.8:1. However, the compression is actually 11.4:1 with an OEM headgasket. With the flat face valves, you're looking at a 11.5-11.7 compression ratio.

With the already high dome height of the PCT pistons, I would definitely not mill the head at all.

 

Hey man, thanks for the info I woulda killed myself If I milled the head, and also I guess it is good I am using the 3 layer head gasket. to space it a lil more. Are you 100% sure about that. I appreciate the info alot. thanx. U said it was like 0.00 deck to piston height?

 

No prob. I looked into all of this when I built a b16 a couple of years ago. Most people used the compression calculator on c-speed's website, but did not factor in the deck height to compensate for the b16a block height being 7mm shorter than the b16b and b18c. I had a number of conversations with omniman (if you've ever heard of him) to talk about compression. He put up a few threads on various Honda boards to confirm that the compression would actually be 11.4:1 vs. the 10.8:1 most people were claiming.

I milled a head, but wouldn't recommend it after doing so. It's an easy way to "cheat" and raise compression, but afterwards the timing marks on the cam gears are off. It's not bad, but you have to make sure they are set properly for tuning so you don't have any valve to piston contact.

I'd consider going with a nice set of aftermarket pistons (Wiseco, CP, etc.) for the fact that if an off-the-shelf won't put the compression where you want it, you can get a custom set for not much more money. Leaving the head alone and raising compression with pistons (and the flat face valves you got) is the best way to go.

 

Yea actually I DO know who OmniMan is. I bought his 91 Octane 1595cc Stock Block 200HP Street B16. That's where I got alot of the ideas for my project, ie the flat racing valves and such. I jsut bought the B16B pistons cause I got a deal on them. New Pistons, Wrist Pins, and Rings for 175. I hoped on it real quick. So I am not going to mill the head at all, I don't want anything to be off. But my question is, there won't be any Piston to valve contace will there? Also, the compression will be decent enoguh to get me going good correct. I image it should be. How much will the flat racing valves bump up the compression, like .2 or so? If u have any other info I should know jsut drop it by and let me know.

 

Because of the large dome on the CTR pistons, you'll defintely want to clay the motor to give you the advance/retard limits of the cam gears to avoid valve to piston and valve to valve contact. You can get an idea of how to do this on http://www.c-speedracing.com under the "how to" section.

What cams are you going to use? I ran Skunk2 Stage 2 cams on about 10.9:1 compression, and they ran fine. They aren't really considered "big" cams compared to some others out there. If you're going to run something huge, you'll definitely want high compression. Read up on static vs. dynamic compression to get an idea of what's going on in the combustion chamber while the engine is running.

Flat valves are nice if you just need a little nudge to put the compression where you want it. They don't offer anything substantial overall, so expect a .2 to .3 bump.

 

I am running CTR Cams. What were ur limits on ur Advance Retard? I have stock cam gears, so I don't think it matter much, right?

 

I didn't clay my motor because I didn't know to do so at the time. When the car was tuned, we ended up at +2 intake and -1 exhaust. We didn't want to move the cams more than a few degrees because we didn't know the limits. As it turns out, +2/-1 was perfect and we didn't want to work with any other settings.

CTR cams are pretty small, but an excellent cam. If you're going to use stock gears, you don't have anything to worry about. However, with as much compression as you're planning to run, a bigger cam would definitely be a benefit ... and a lot of fun. If you plan on using adj cam gears in the future, you'll definitely want to clay the motor now and write down the numbers. As I learned, it's better to plan far enough in advance so that what you're doing now works in the present and in the future if/when you change parts.

 

What would be a better cam to use on it? I dont want to screw the valves with a huge cam.

 

What are you looking for ... top-end rush ... a big hit in the mid-range? Will this be a street/daily driven car or just a fun project? Do you plan to take the car to the drag strip, track days, autox?

What you plan to do with the car will dictate the cam choices you should consider.