Before the "veterans" of H-T attack me for asking n00bish questions, I want you all to know that I searched for about 30 mins unsuccessfully for an answer to my question - so here it goes....In a CRVTEC swap, how big of a difference would aftermarket pistons with, say an 11.5-12:1 compression, be compared to the stock b20z pistons in terms of power and reliability? This swap is going into a daily driven ek hatch, so I know the more reliable the pistons the better, but i doubt the engine will ever see over 8k rpm except to tune and time it. I guess the question boils down to: How much more HP would aftermarket 11.5:1 pistons give me over b20z pistons?

 

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It should make a good difference, but aftermarket cams would be best to take advantage of a CR that high.

 

to answer the question that it seems is being asked.

yes, you can spend $$$ on pistons and rods,

but no, the performance increase may not justify the costs.

if you are poor like me, i cant justify it yet...

but if you are able to, a fully built B20 will be better than one with stock pistons and rods...

better yet, grab some dyno graphs (using search) and compare a fully built VS stock bottom end and make the decison yourself...like i did.

HTH,

t..

 

I actually have the b20b/b16a engine in my civic with unfortunately stock pistons and rods, will be changing them before the year is finished.
I can not give u exact figures for HP increase with increased compression, However my mechanic has built 5 of these engines in the last few months 2 with high compression pistons(je 11.5:1 or 12:1) and they are a fair bit faster than the stock ones running between 13.9 - 14.1 seconds while my car runs about a 14.5 all of them on street tyres, stock heads.
Also the stock pistons will probably hold up to high revving abuse but there have been guys who have f***ed stocked rods so be careful.
One last thing to take into account are u going to stay N/A? If planning on forced induction u can not go with high comp. will have detonation problems.
Sorry i was so long wined tried to keep it short.

 

IF you're building a b20vtec, please get aftermarket pistons before you put it together, if not, at least get your pistons shaved so that it'll clear the vtec valves when the cam timing is advanced.

Jay Kim

 

Yeah....my next question was going to be if since i have to re-size the valve reliefs on the b20z pistons before they can be used, i might as well get new pistons anyways. How much does a machine shop charge to re-size valve reliefs?

 

when i had mine done they just charged me their hourly labor rates

 

if you want cheap hp just keep it all stock and shave the head about 1mm. that should give you 20hp +or- and a cam upgrade. and you will be good to go. you might be able to shave it more. i think the b20b is like 8.8:1cr. if you shave too much you can always get a head gasket up to 3mm in depth.

 

oh, good - so i am on hte right track...?

t..