well, just as the question states. I am going to be running a b20 bottom end with a gsr head. everything is stock besides the cams. I have crower 3's but if they are too big even after relief cuts I can use stock gsr cams. How do I cut the pistons. How deep do I go and is it just the intake side that I make bigger. Maybe someone has a pic of a piston that has already been cut??? any help will be great.

thanks.

 

why are you using big cams with stock pistons, you will probably loose power with those. dont cut the valve reliefs bigger, run the stock gsr cams untill you can get pistons. and once you get pistons you shouldnt have to do anything to the valve reliefs

 

Please do not listen to ^

You have to cut even with stock cams as VTEC heads come with 33mm inlet valves instead of 31. You only have to cut the intake side of the piston. The "correct" way would be to remove and mill the piston. The "real" way is to seal the motor and grind out the pistons with a die grinder.

WARNING!!!! You can not spend too much time sealing the motor as it is VERY, VERY INPORTANT!! I cleaned the deck and used race tape, then cellophaned the entire motor and then made tiny slits where the reliefs are.

2mm wider and about a mm deeper

 

thank you ^^^

unfortunately I will probably be doing it the real way as apposed to the correct way. So you think I should stick with stock cams and just increase the intake side of the piston until I can get new sluggs for next season.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AussieB20vtec &raquo;</TD></TR><TR><TD CLASS="quote">Please do not listen to ^

You have to cut even with stock cams as VTEC heads come with 33mm inlet valves instead of 31. You only have to cut the intake side of the piston. The "correct" way would be to remove and mill the piston. The "real" way is to seal the motor and grind out the pistons with a die grinder.

WARNING!!!! You can not spend too much time sealing the motor as it is VERY, VERY INPORTANT!! I cleaned the deck and used race tape, then cellophaned the entire motor and then made tiny slits where the reliefs are.

2mm wider and about a mm deeper</TD></TR></TABLE>
good info dude! what cams are you running in your set up? and what rpms are you taking the engine to(shift point)? i have thought of doing this to my b20z bottomend, but i'll try using some 98 ITR cams before i do it! i'm trying to hit 200WHP without modifying the pistons or head!

 

i ran skunk2 stage 3 cams on my stock b20 bottem end and it was great, it made great power over stock cams, if i were you i would just stick with the crower 3's, you won't lose any power by running them, there is only power to be made.

 

Take the pistons out of the engine...
And take too a machine shop..

 

this sounds like something to experimant with on the dyno. gsr stock vs. crower 3's. My head is p+p w/3angle. nothing to serious. port matched to a skunk intake and a kamikaze header. I am not sure how I feel about the kamikaze header, I think I am going to sell it so someone who is FI. kamikaze claims that there header makes more power than the dc 4-1 though. I dont know.

 

my pistons are untoched. you dont need to notch the piston unless advanced too much or bigger cams.

 

Am I going to have to cut the exhaust side also with the bigger crower 3's? or just the intake side. I am going to clay it anyway, I just dont want to have to clay it 10times because I am not doing everything the first time.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by h22 ef &raquo;</TD></TR><TR><TD CLASS="quote">why are you using big cams with stock pistons, you will probably loose power with those. dont cut the valve reliefs bigger, run the stock gsr cams untill you can get pistons. and once you get pistons you shouldnt have to do anything to the valve reliefs</TD></TR></TABLE>

You are trying to tell me that 190whp and 140 torque untuned is loosing power.

 

Sorry for the late reply

Toda A's in mine at the moment. I want 200 too......

I turn mine to 8500

 

JUN III cams in mine- had to mod the valve reliefs... no biggie, did it just like Aussie said. Took about half an hour, we did both intake and exh. just in case we want to adjust cam gears. If you're going to spend $$ to have someone else do it, get new pistons.. don't screw around with paying someone to do something that you or a friend can do. If you're totally uncomfortable with doing it, then just get new pistons... I'm thinking a machine shop will charge 60 or so to do the work? that's 60 that could have gone to new pistons... Trust me, it will be worth it.

 

finished up on the grinding and and its all good. took it out and hit my best friend vtec a couple times and I think It should pull harder. I am running pig rich I think. I was using h22a injectors on my lsvtec and when I got tuned they had to take a bunch of fuel out still with it at 34psi. I am going to put stock injectors back in and run off of the mugen n1 map. what do you think I should set fuel pressure at???