from what ive heard you need to change the pistons since the valve reliefs arent deep enough.. Is this true? Ive seen other people say they just "put a vtec head on a stock b20z bottom end" trying to figure out what the deal is on this idea.

 

you can put a vtec head on a b20 bottom end. there is a severe clearance issue with the pistons valve releifs though. chances are on stock parts (even itr cams) you wont have any issues but with any form of cam gear adjustment you run a big risk of hitting valves to pistons. this is due to the fact that vtec engines have larger intake valves. anything over R cams is way to close.

one thing you can go to alleviate this is to open the valve releifs up to accomadate larger valves. this should be done at a machine shop so that an equal amount of material is taken off each piston to maintain a proper balance in the rotating assembly.

 

so i could put a b16 head on and lets say the itr cams and id be all set? JUst have to use factory cam gears... what would the gains with the b16 head give me? Any more than redoing my p75 head with cams etc?

 

i'd go with the PR3 head....vtec makes power theres no way around it. And as much as i hat e when people say take somthin to a shop or have a professional do it, this is one of those case where you REALLY need to take the pistons to a shop and have the reliefs done, even though i know people that run vtec heads on stock 2.0 bottom ends, i think it would be worth the piece of mind.

 

http://ef-1.zeroforum.com/zerothread?id=181

 

ive seen that before but again i think its a bad idea. each piston/rod assembly should weigh the same so theres an equal load on the crank. when your fighting engine geometry on a ls/b20 vtec setup i dont think this is the place to cut corners.

 

ya thats why i think ill just stay non-vtec for now, i have 3 other b18b blocks in the garage to build so ill just get the whole b20 head worked through and just build up my ls motor's.. thanx alot :D

 

If you really read the post, you should have seen that it was just for a few races and that Ek and I said not to do this yourself- Especially if it's a daily and you don't have spare parts laying around. The motor ran just fine, and there were no issues. I'm pulling the head in about a month, along with the bottom end for it's yearly rebuild. I was running JUN III cams in there so that's why we were hitting, and it was just barely hitting at that!

 

damn ya im puttin p30's in my b18b block for my "temp" motor until i get around to building the b20.. just was looking for info to see if it was possible to use daily with stock pistons.