Hey,
I took a browse through the new UPDATED Piston data sheet on Endyn. It posts the various compression ratios of the NA/FI high/low comp. pistons in a variety of heads and blocks.

I purchased the RW pistons about 3 months ago from Larry/Rick and ordered the 12:1cr for my B20/VTEC (ITR head). Those are the HIGH compression NA pistons.

Currently they are 84.5mm and sit 0.005" in the hole.

According to the data sheet (half way down): http://www.theoldone.com/components/pistons/

B20Z with ITR HEAD:
NA (High)

Bore Compression Pin Dia Weight
84.5mm 13.09-13.99:1 21.0 mm 342/81 gm
85.0 mm 13.21-14.13:1 21.0 mm TBA
86.0 mm 13.45-14.40:1 21.0 mm 335/81 gm

The compression ratio ranges given above were calculated using the bore diameters specified, stock strokes, stock combustion chamber volumes, an 0.030" thick cylinder head gasket and piston-to-deck clearances of 0.020" and 0.000".

If you take a look at the chart, it says that if you have a piston to head clearance of 0.020" your compression is 13.09:1 and at 0.000" clearance you're at 13.99:1cr!!!!!!!! Which means that if i'm at 0.005" in the hole, then I'm sitting around 13.8:1cr... *NOT* the 12:1cr that I originally purchased.

I'm not really "complaining" per se, since i'm happy with the pistons and happy with the results that they are producing for me, however I am a little displeased that what I got isn't what I originally purchased and paid for.

here's a pic of the pistons I got. You'll notice they look exactly the same as the HIGH COMPRESSION NA pistons:




Can someone shed some light on this?

 

...in case you didn't know, there was a HUGE blow up over on the Endyne board, b/c a guy ordered several pistons of different c.r.'s, and they were all the same.

Go to the hybrid forum and use the search word Endyn. It'll do the rest for you.

For some strange reason, the link to the discussion on T.O.O. no longer works b/c it seems like the thread was removed.





[Modified by eternal21, 12:59 AM 10/18/2001]

 

Endyn sucks

 

I just sent a set of those back! I ordered 84.5mm 9:1's but they IAS sent me 81.5mm 13:1 instead. Larry's magic sandpaper pistons looked pretty good and I am happy my 84.5mm finally arrived after vacationing on Venus!

 

Nice ruler Cresent! I have the same one

 

Its not a ruler its a machinists scale! Get it right!