Hey guys. Need some advice:

I'm building a Darton sleeved 84mm b18c turbo using a B20 crank, Manley B20 rods and GSR head. The idea had been to deck the block to B20 height.

I purchased a set of Wiseco K545M84, -18cc, 30 compression height a while back, and based on the advice that they're too low cr, decided to sell. They were listed at 8.4 to 8.8cr.

I'm considering a set of K649M84, -10cc, 30 compression height. Trying to get to 9.2cr.

The problem I have is that the Wiseco pistons are too generic regarding compression heights. I technically don't want to skim the block to B20 height, but still want to use the B20 crank and rods. This means that at a compression height of 30, the squish clearance is going to be too large. Technically it's too large even with the block skimmed, given the Wiseco compression height of 30, irrespective of what block the piston is going into.

My question is, what piston can I use that will allow me to use a standard deck height b18c with B20 rods and crank, but maintaining a proper squish clearance?

 

1.) I don't think you understand what compression height means. 30mm or 1.181" is stock Honda piston compression height.



2.) Use this compression calculator to figure out how much piston to deck height you would have with your combination of parts.
http://www.zealautowerks.com/bseries.html

3.) Dont deck the block to achieve a fancy quench. Just enjoy the extra clearance.

 

That's exactly the calculator I've been using and stock compression height on a b18cR piston is 30.23, as per this calculator.

 

I know you had these pistons in your car, but that was a B20, so higher cr, but seriously,
8.23cr? And I''ve found that this calculator tends to calculate at 0.2 higher than factory
quoted compressions, so we're looking at 8.1. Thats too low.

I don't want to skim the block or the head.

 

Then go with K623M84 or K567M84 or K594M84. You dont need to have exactly 9.2:1. If its 9 or 9.5 even 10:1 that's close enough. Its silly to obsess about this.

 

Yes, I think K645M84, also as per TheShodan's advice a while back.

Truth be told, the build has changed a bit since, & I've learned a bit more tech, which always leads to more questions.

But, It seems the original advice is still the most viable option.

Without a skim on the GSR head or B18c block, using B20 internals, I should get around a 9:1 cr.

 

You know what setup I have, more or less, & that I don't intend running on pump gas. Most likely avgas.

Darton sleeved 84mm B18c GSR, Pro1 cams, Skunk2 Pro Intake. Probably a Ramhorn manifold, Turbonetics T61 (non bb), ID1000cc, NepTune, etc.

Looking for around 550whp.

 

Lol, the tuning aspect is always a continuous issue that I'm all too aware of, but like we discussed previously, we'll set the NepTune up & perhaps tune at SpeedShop or Christy....We'll cross that bridge....