Hi, I will attempting a budget LS Vtec Turbo build with B18B Block
I was considering using Nippon Turbo Pistons and I noticed the loss of compression when used with B18c head.
Nippon states Turbo Pistons result:

• B18A/B Block and Head 9.23:1

• B18A/B Block with B18C1 Head 8.74:1
  
  

But if you attempt LS VTEC on stock motor, the compression is always higher when using VTEC head but in this case it loses compression with VTEC Head, is that a typo?

 

The vtec heads do have a smaller combustion chamber so it should net a higher compression ratio on the same piston.

Maybe they have two different part numbers? VTEC heads might need a bigger valve pocket in the piston?

If they are the same piston for both applications then the marketing team messed up.

 

Use the zeal calculator and plug in the specs

 

Vtec head should have the higher compression of the 2

 

Always, regardless of which VTEC head you use.

 

Do the pistons have two different part numbers?There might be a piston meant for the B18B, and one meant for the LS/VTEC which would explain the difference in compression ratio.
If they are the same part number then I’m not sure what to think.
Also, if you are going turbo, I really think it’s worth it to spend the few hundred extra $ on better pistons than Nippon. Nippon are stock replacement. Unless you plan to never go over about 275hp, then you’ll be alright with Nippon.

 

We’ll it says they are good to 450hp, but that’s still a lot lower than other aftermarket pistons.