Say you have a B20 pistons that's "rated" at 9:1 CR witha B16 head.... what happens to the CR if you slap them in a B16?

thanks,
-S


[Modified by shingles, 11:17 PM 6/3/2002]

 

i assume it will go up due to the smaller combustion chamber. i dont know how much though. 10.something:1 maybe????

 

opps, sorry I changed the post on you there a little...

the stroke is much shorter on the B16... so wouldn't it be lower?

thanks,
-S

 

you have a point there. just dont bother with those. get some oversized pistons that tell you the CR. im getting a headache

 

yeah I think I will just have to custom order these.. .I was just hoping to find a "simple" way out.. thing is I am "scared" to order custom piston... they ask a lot of really hard questions hehe...

-Shing

 

yeah. its probably better to get higher comp. pistons that were made for higher compression. even if the crv pistons raised the CR, they might not last under that compression very long since they were made for 9.5 or whatever it is.
good luck.

 

WTF?

B20 pistons in a B16 block?

wont you have to bore the block to fit 84mm pistons?

or have i missed something?!?!

t..

 

yeah. i believe thats what he wants to do. or resleave it.

 

hmmm,

sounds tricky eh?

i could ask 'why not get a B20 block' but that would not help the question raised.

i belive the goal with this is to keep the 1.74 RS ratio and use a bigger displacement piston to increase capacity??? true?

it depends on hte pin location of hte B20 psiton compared to the B16 piston and any change in the area of hte piston to work out the CR (i think)

pretty hard to measure exactly...

hope this may help (probly wont..)

t..

 

i was under the impression that all b series motor pistons were interchangable...that the stroke is different...im kinda throwing this out as a "tell me if my sources are wrong" sort of thing.

 

all pistons are the same bore except for the B20B, which has a 84mm bore as opposed to a 81mm bore in the B16A, B16B, B18A, B18B, B18C and the B20A.

oh, also the B21A engine has a different bore too, but no-one here talks about that unless they are dissing its RS ratio...

i actually think there are heaps of differnt types of 81mm bore pistons from Honda, so they are NOT just "interchangable"

HTH,

t..

 

PS here is some great info on the variety of piston specs

(with thanks to Katman!)

http://ff-squad.com/pistons.htm



[Modified by tinkerbell, 8:18 PM 6/4/2002]

 

thanks for the info...this helps me too...i was thinkin on doing a b20 build also, but it sounds like i should just resleeve...

 

http://www.c-speedracing.com/howto/c.../compcalc.html

Calculator says if you run B20B pistons in a bored B16 block with B16 head, you get 8.17:1 compression.

Same combo in a B20 bottom end gives you 9.1:1 compression.



[Modified by dbman96, 7:38 AM 6/4/2002]

 

yes that's exactly it... keeping the rod ratio up there.

Well the block is going to be GE re-sleeved... I figured, WTHeck.. might was well bore it out to 84mm and see how much we can squeeze out of it... the motor is going to get some boost.

thanks for all the info.