AdrenalineAngel

Don't tell me what supporting mods I need...this is a very simple question. I'm building a B20vtec turbo using a B16 head and aiming for 450-500whp. What compression ratio pistons should I use? and should I use flat faced valves? I was thinking 9.7:1 pistons with flat faced valves, but I wasnt sure if the CR would be too high. Tell me what you think I should run and why...

nealnanoHX

If you are using a B20B block with stock pistons with an un milled B16 head 9.16:1, if using a B20Z with stock pistons 10.4:1. Both good for boost but the B20 has thin sleeves that like to crack past 350whp. If you plant to go to 450-500whp then you need to do pistons and rods and sleeves or go with a B18 block that has thicker and more reliable stock sleeves but with your goal you would be pushing the limits of B18 sleeves as well. I would go with about a 10:1 compression.

jdmh22eg2

Personally i like higher comp when turbo 10.5-11.5:1. Deff want to rethink that b20 bottom for that hp. Unless your sleeved then have a ball. Comp ratio does not matter as u tune it with proper gas and all other normal stuff

AdrenalineAngel

again...dont tell me about supporting mods...my block is sleeved amongst other things....the question is:

what compression ratio should i run?

turbohf

sleeves are not thinner, they are weaker. the calinera are ctually thicker than B18.


personally i like high compression motors. even better if you can run e85.

jdmh22eg2

Iam pretty sure i did *** hat. And the thing is you did not specify enough info on your setup, i and the others were only telling you the common issues with turboing a b20. Secondly why not do some research for YOURSELF and pick a comp ratio. Lastly why not talk to your tuner and what he is comforable tuning.

nealnanoHX

How is having a properly built motor a supporting mod? It is not it is a correct setup. Pick a compression ratio that you are happy with. 10:1 at the least is what I prefer, higher compression makes for a more responsive motor on and off boost. Dont be such a dick, you gave next to no info on your setup and goals so you got generic answers.

nealnanoHX

B20 sleeves while different than all other B series sleeves are still thinner. Bored to 84mm instead of 81mm. B20 sleeves are a well known weak point in that motor. I have seen 300whp well tuned B20's crack sleeves at the top.

seelback

Ive seen a stock sleeve 84.5mm b20vtec with a ge block guard make 696whp and a stock sleeve, piston, rod, no block guard b20vtec make 450whp, both tuned by the same guy. You guys need to sit a b20 block and a b18 block next to each other and look at the difference in the sleeve material and you will realize you can make more power than you think with a stock sleeve b20. To answer the op's question, go with cp 9.7:1 pistons and ferrea valves, if you use flat face it still wont be too much compression as long as you use good fuel and a good tuner. So your good either way.

nealnanoHX

^^^ pushing the limits of the block big time. I bet in a year or so those motors wont be alive anymore. I call BS on 450whp on a stock B20 bottom end, if the sleeves dont fail either the rods or rod bolts will under that much power. Maybe just a dyno queen but no way a stock B20 could live long at 450whp.

seelback

The 600+ is still running. The 450whp broke a piston due to the dizzy issues and imo doing a 93/110 mix, owner pulled piston and rods out and put in je pistons and eagle rods and car is still making 450+ on the stock sleeves(i got to ask owner if he put a ge block guard in when he put in the forged internals). And no on the dyno queens. Im making exactly 200whp on the same dyno and im running 12.5's@106mph, full interior ek hatch minus seats, a/c, and exhaust. The car that made 450 is a full interior crx with a 320lb driver and it ran 10.70@132mph with the stock internals. Dyno quennsss?????????

turbohf

this isnt 2003 anymore. people have learned a lot over the years tuning. my buddy has tuned a stock piston/rod/sleeve LSVTEC motor to 601whp. not advisable, but has been done many times.



i would suggest asking whoever is going to be tuning your car these questions.

turbohf

so you have both a B20 and another B-series side by side? cuz i have. and the distance between the coolant jacket and the pistons is greater on a B20B than a B18C.

Brett Dillon

2019 still plenty of b20's haha

JRCivic1

Great first post rookie... very helpful. Glad you dug up a six year old thread to offer your insight.

Welcome to the board.

Batillac

Haha, interesting how old threads get brought back up...I figured since I'm bored and this came back up, I thought I'd share what I did at least. I went with 8.5:1 JE Pistons, Crower Rods in my sleeved B20Z block mated with a built B16 head and a T60-1 way back in the day. It was good for 627whp @ 38psi (high boost) and 442whp @ 22psi (low boost).