im trying to find an 84mm piston to go into a b16 that will give me a 12.5:1 compression ratio. since the oem b16 piston is taller (thats the reason ive been told) all other bseries pistons cr drop about 1.4 going into a b16. My builder even contacted cp (thats who he really likes) to get a custom piston but they said they make 1 over about 11.3. does anyone know of someone who makes 1? all the other stuff has been already ordered to build the b16 and i dont have the money to buy a gsr block. all help is greatly appreciated!!!!

 

One company I know of is Diamond Racing. You can have them make completely one off custom pistons for your setup. They are more common in the american scene, but a local machine shop owner I know is a dealer for them. He uses them in all of his personal motors and any customer motor that needs a custom made piston. Their prices are reasonable if I remember correctly.

Diamond Racing Website: http://www.diamondracing.net/home.asp

Page for Custom Pistons: http://www.diamondracing.net/custom_pistons.asp

Give them a call. I'm sure they'd be more than willing to help you out.

 

Just to note: the reason you are having trouble finding that high of compression for a b16 block is due to the stroke on the b16 vs. all others b18, b20, etc.. A piston with 12.5:1 compression in a b16 is going to have a very tall dome. In engines with a longer stroke, there is more volume to compress therefore bringing the effective compression ratio up. You are going to have to be very careful for spark plug clearance and may have some issues with flame travel due to the huge dome. Just FYI

 

So you have had your block sleeved to go out to 84mm bore?

 

my question also i would hope so being he is talking about 84mm pistons

 

e a sleeved b16 block you still have the option to go with a 89mm stroke with custom pistons that have a different pin height.

 

thanks everyone. yeah the block is out being sleeved right now.

 

how did you not have the money to build a b20 block but youre getting a b16 sleeved?

 

Or even a B18a/b block.

 

makes no sense to sleeve a b16 block for an allmotor setup...but omniman made 200whp on 81mm p30 pistons on a b16..i doubt you could make any more than that...put 11:1 compression and spend money on a good intake manifold/header combo..there more ways to make power than just compression...

 

there's always room for more power while keeping it a 1.6

 

sorry for the late response to this. I meant that I didnt have the money to buy a gsr short block and send it out to get sleeved.

I wanted to go with the b16 for the rod/stroke ratio and the more reliable higher rpms. its a time attack car on a short technical course that theres alot of times that i have to shift up to just shift right down 1 second later. theory is that if its built to run alil higher than i can keep pushing it and not have to shift up then back down losing time and it should last longer at those rpms if its built for it.
my short block is all built and put together. sleeved and bored to 84mm & crank balanced. for some added compression i went w/ flat valves but im still waiting for the builder to work the head and assemble the whole thing. ill post a dyno sheet when its done.

 

flat face valves will raise comp between .3-.5 and wont decrease p2v clearance. just another fairly cheap option if your really trying to raise comp

 

I'm using 83MM short skirt custom CP pistons on my B16 block.. I'm pretty sure they'd do a 84mm one... and my stroke's been bumped up to 87.5mm... dont see why CP wont make one for you...

 

Interesting theory. Shifting is racing. deal with it. But you'll actually be out of its powerband on the shorter courses due to the B16's lack of torque. (Yes, even at 84mm, since it would only produce about 15ft/lbs of torque only, vs a longer stroke. ) The R/S ratio math never seems to work in real life. But if you spin it hard enough in the mid-sized courses, you might have a chance. But in direct answer to your question, Diamond would make the custom pistons you're looking for.

Your theory is interesting indeed.

 

Now you have a SLEEVED block I would use as much stroke as you can forget all this rod ratio talk,any short coarse engine needs TORQUE and a 89mm crank with STD length B20/B18a-b rods and custom single ring pistons, TODA have been using and selling this type of piston for many years with there B16a stroker kit.

 

What is the comp ratio spec for ur pistons and what compression does it actually build, if youve checked? My bottom end is built with 12.5:1 supertechs and the spec in a b16 w/ b16 head drops to 11:1. then im at 3000ft above sea level so then it drops another .7 down to 10.3:1. im curious if ur pistons dropped the 1.5cr points compared the manufactorers specs between a non-b16 and a b16 when both have a b16 head.

-on why cp said no is because we had some false info (different pin heights compared to top of the piston) on why the comp drops so much, so we were asking if they be able to move the pin down.

 

I deal with the shifting now but if i can cut down some time and on wear on the clutch (very minimal but still some) then why not. On my local course i am in the powerband im am always in the 6500-9000rpm range around atleast 90% of the track. as for the R/S ratio the opinions seem to be 50/50 but when professional race teams (ive read numerous places) engineer for the "ideal" ratio im gonna believe them and go with it. I know there is probably just as much arguements between pros on it too.

 

Not enough room for the pistons in that block. Get wat fits and hit the gas Or save and do it right

 

Because no one can predict that, and you'd be silly to try to. Either you're going to drive the car for the course and do what needs to be done or stick to Forza with the automatic transmission setting. . You'll only kill your throwout bearing if you don't know how to drive.

You'd be there at almost anytrack because of the your effective rpm range and lower final drive. That's actually the area you kinda want to be in.. (Do you circuit much outside of the smaller course, or is this the extent of your experience? Serious question here..) If not, stop trying to overtheorize your parts for each course. you don't have the finances or adjustability to be able to do that. Stick with a better torqueband formula and stop crying over shifting.
And it won't help you a bit on these smaller displacements. Ask my local guys from Ka-tech, to Ligenfelter. Even they don't worry about that and have been racing for 30 years.
Not outside of theory, no.

 

[QUOTE=TheShodan;47998594]Because no one can predict that, and you'd be silly to try to. Either you're going to drive the car for the course and do what needs to be done or stick to Forza with the automatic transmission setting. . You'll only kill your throwout bearing if you don't know how to drive.

LOL Im not trying to say that i was trying to predict that. just saying logically/theoretically the less you are actuating the clutch the less wear the friction plate will have. I havent killed a throwout yet so i guess im not doing too bad.


You'd be there at almost anytrack because of the your effective rpm range and lower final drive. That's actually the area you kinda want to be in.. (Do you circuit much outside of the smaller course, or is this the extent of your experience? Serious question here..) If not, stop trying to overtheorize your parts for each course. you don't have the finances or adjustability to be able to do that. Stick with a better torqueband formula and stop crying over shifting.


-yeah I know thats where I wanna be i was just responding to your saying i would be out of the powerband on the shorter courses. my biggest problem will be on anything longer 5th since i have an ls 5th in it right now (it was a 50mile a day daily until very recently) ill probably go back to the b16 cause i have to replace the diff anyway (obx went out, have a wavetrack waiting).
-right now no that is the only circuit Ive been on im planning on venturing over to arizona (Im in far west Tx and my local is Arroyo Seco Raceway in NM, youtube it) next time work and an event coincide. but 90% of my racing will be on this track. I havent even ever dreamed about thinking about different parts for different courses, Im barely saved enough after 4yrs to be able to build the engine right for long term reliability.
-Im not crying about shifting I do it now (well did before the obx went out) just saying that if i can shave time then i will and I suck at heel toeing so itll cut down on my bad trys at rev matching more (less rotating assy shock).
-ive already put almost $6k in the build (with labor including a bunch of other stuff going to be done at the same time) so I couldnt afford a stroker kit too without saving another few years.