I am about to buy some .25mm overbore ctr pistons for my b16 block.....can my stock sleeves be bored slightly (and safely) to accomodate these? If so, by how much? If not, TELL ME NOW!!! I am about to send the money order off. I saw a thread about this the other day, but couldnt find it in a search. Thanks!!

 

.25 is safe enough to run in your b16a. You will be fine.

 

Solid......im guessing the machine shop will know how much to overbore the STOCK cylinder walls....

 

But when you over bore don't you lose CPR?

 

Anyone? If I lose CPR by overboring, can I compensate by milling the head? How much does everyone recommend milling to achieve 10.8:1 - 11.0:1? Bottom line...its a daily driven car that needs to be reliable. Show love!!

 

I wouldn't mill the head. Just go with a 2 layer head gasket.

 

My thoughts on the this question is no... You don't lose compression with boring.

Reason... because you are buying piston with a specific CR to begin with.

If anything, you may be raising it a little.

Reason... Because now you have a bigger piston (more surface area) so that when the piston compresses all the air into the combustion chamber, you are adding more air into the same size combustion chamber, thus more pressure.

I don't know if this is correct, but it seems logical. Correct me if I'm wrong though.

I'm running 11:1's in my B18C with 85mm bore and I'm not having any problems with 93 octane and stock timing.


[Modified by Shft@9GSR, 6:08 PM 10/24/2002]

 

You raise compression.

 

Dont forget that those pistons WONT fit on your stock B16 Rods. You will either have to get the pistons machined, or the rods shaved.

I would recommend getting the pistons machined, but many haven't had any problems shaving the rods shaved either.

 

I have done both on different motors. Either way is fine. I had the rods machined on my b16a with ctr pistons though. It seems to still be running fine with the new owner.