SiRstewart99

Hello all, new to the site !

I have a few head scratchers that hopefully someone can help me out with.

First off. I built a b20z2 vtec about three weeks ago now. The build was : rebuilt b20z2 block, acl bearings, arp rod bolts, arp head studs, golden eagle 3 layer head gasket, gsr head, blox mani, skunk2 tuner 2 cams, skunk2 pro series valves and stock cam gears.

The motor lasted 400km and snapped one s2 intake valve from making valve to piston contact. I never read up on valve reliefs having to be cut down with after market cams and valves so this was my own fault. But after reading up on it im guessing when installng any type of aftermarket cams & valves the valve reliefs HAVE to be cut deeper.

I am currently rebuilding the b20z2 again with new b20z2 pistons on stock rods with ARP rod bolts. I will be using a commetic 3 layer head gasket, stock b16 head, stock b16 cams and a set of adjustable cam gears. I think i will be fine with a stock top end because my friend owned my b20z2 block and had a stock b16 head on it with GSR cams with stock cam gears and he just over revved it with stock rod bolts and spun a rob bearing so i got the block for free.

Has anyone had this kind of problem with building a b20z vtec ?

Wondering if I should go ahead and get the valve reliefs cut deeper and the machine shop when I get the new b20z2 pistons pressed onto my rods? Or should I be fine with a 3 layer head gasket and stock b16 top end with adjustable cam gears? If I have to cut the reliefs deeper, how deep do I have to tell the machine shop to go ??

I just don't want to have the same problem this time because Im hooked on b20 vtec's !

Thanks

nealnanoHX

If you run a Vtec piston like a ITR 84mm piston or an aftermarket forged piston they will have enough valve relief cut into them. LS and B20 pistons are not made for the larger Vtec valve heads and larger lift profiles of aftermarket Vtec cams.

g230sport

If i were you, id ditch the phk's and go with either a good forged piston(wiseco,je, etc) or get some rs machine itr pistons for the 84mm. They have oversized as well. Im hating myself now for not going this route on my b20z vtec. I kept the phks and from what i understand is that im stuck having to use itr/ctr cams.

SiRstewart99

Thanks for posting!

So do you think ill be fine with the b20z2 pistons, with stock b16 valves, b16 cams and adjustable came gears ?

I was going to use eagle rods with some better pistons but at the time I was building this on a budget because I wasn't back to work. Now that im back to work for the summer Ill be saving to up grade rods, pistons, valves and a set of cams this winter.

SiRstewart99

What is your top end set up with the itr/ctr cams. Im planning to get a set of itr cams and valve springs.

Just don't want to run too big of a cam with the stock pistons and having valve to piston contact again!

g230sport

Sorry for not being clear. Im on the search for itr/ctr cams. Currently im using stock b16 stuff. Cams valvetrain etc. I do have adj cam gears.ive got close to 2000 miles on it and no problems. Runs great on the basemap.

nealnanoHX

Well a B20Z with CTR/ITR cams can put down 200whp with the right IHE and tuning. A GSR head instead of a B16 to bump up the compression a little more will help some as well.

SiRstewart99

Thanks for the replysg! For now im using a ported b16 head, stock b16 vslve train and golden eagle adjustable cam gears, arp head studs, gokden eagle ls vtec kit, commetic 3 lsyer head gasket to be safe, b20z2 84.5mm fresh rebuilt block, gsr oil pump, gsr water pump, arp rod bolts, gsr timing belt, holley 70mm tb and skunk2 port matched manifold.

nealnanoHX

When using any OEM cams adjustable cam gears are a waste of money.

g230sport

I got them For my build Because i kept reading you needed them for ls/b20vtec. My timing marks are dead on at 0-0. Plus i wanted them for tuneabilty in the future

SiRstewart99

I got my Golden Eagle adjustable cam gears for free, so no money wasted

Builda'Teg_92

All i know for a fact is that ITR cams with the phk pistons will just about kiss the piston...VERY VERY close, no room for error. Clay your motor, try not to mill anything.

H22newschool

my build was similar but kept it non vtec, b20 with RS ITR pistons stock bore (84mm) with Crower 403 cams and Supertech valvetrain. Never had a clearance issue with mine, lol things are always smooth til you do an ls vtec swap.

ivan93egreppin210

Here's my old build thread. Stock b20z2 pistons with ctr cams. I clayed the motor and the valves touched the pistons. I posted pics before and after I knocked the valve reliefs. Hope this helps.


https://honda-tech.com/forums/all-motor-naturally-aspirated-44/ivans-first-b20zvtec-2966992/

SiRstewart99

Thanks for the replys! Just for the rest of this season ill run a stock b16 top end with a three layer head gasket. Over winter i plan to do some bigger cams, pistons, rods and so on.

gutted-dx

iTrader: (1)

https://honda-tech.com/forums/all-motor-naturally-aspirated-44/finally-made-dyno-2921715/

Very basic build and made 201 at the wheels.

SiRstewart99

Thanks!

Ill be using a ported b16 head, port matched s2 mani and port matched to my 70mm holley tb. Should work decent!

SiRstewart99

Just got my parts back from the machine shop today. I have my block together ready for the head. Just want to double check with anyone on my set up.

B20z2 block, phk 84.5 b20z2 pistons, arp rod bolts, commetic 3 layer head gasket, arp headstuds, stock b16 head with a little porting work done, b16 cams, b16 valves & springs, stock cam gears for now, gsr oil pump, ls timing belt and ls water pump.

Think ill be fine with no piston to valve contact.

My buddy ran this same set up, only thing he ran a ls oil pump, gsr timing belt and gsr water pump. Motor ran fine, but over revved it once and spun a rod bearing.

SiRstewart99

Just want to double check, before i slap the head on it. Or, how does one go about locking the rocker arms into Vtec so i could Clay my motor to see of i have valve to piston contact ? Or os ther such thing as locking the rockers into vtec so i get the valves to open as far as they will be when motor running? Ive never claied a motor, but this isnt the first one ive built. Built many but never had this type of problem before because most were stock rebuilds.

Thanks

vteclolz

So you're saying that a B20z2 with stock pistons and a B16 head with ITR/CTR pistons will cause valve contact? I am building a B20/vtec currently and was hoping to build it with out touching the bottom end, meaning changing out the pistons and rod bolts. I was hoping to run the stock b20z2 bottom end with a B16a2 head with CTR/ITR or stage 1 aftermarket cams, upgraded valve train, bolt ons obviously, tune, and safely rev to around 8,700-8,900.

After reading this thread I'm a little worried that I will even be able to run R cams without replacing the pistons. I really didn't want the added cost of labor/parts for changing out the bottom end stuff because I don't plan to build this motor much more than what I have already stated.

SiRstewart99

From what i have learned. Running bigger aftermarket cams in a vtex head on the stock b20z2 block you'll have to cut the valve reliefs down, or buy rs maxhine type r style pistons. I learned the hard,way without reasearching it. I just planned to put the parts i had around into my top end for a,decent build. Everyone around me was spinning rod bearings past 7200rpm so i put arp rod bolts in mine and built the top end. From whar i have read, you can use ite/ctr cams witg stoxk b20z2 pistons as long as head and block hasnt been milled, but i still wouldnt use ctr/itr cams without noticing the piston.

I have my set up in my cae now with 450km's on it running healthy. I ditched my holly 70mm tb because it felt like i was pushing a brick, i used my stock tb. I also went ahead and cut my valve reliefs down a little bit just to be on the safe side. Set ups running geat! Thanks for the help guys!!

vtecmasta85

Nice thread man. Like your work you do. I'm in 512 area not too far from you. As for the OP, you should be good. Just resurface the head get the roughness outta the head and use a two layer gasket and use a colder spark plug and you should be ok! I'm in the process of doin a stock bottom b20z with ported Pr3 head and I'm planning out my setup as well. Want more than 10 compression but less than 11. I'm aiming for 10:4-10:6 compression and im using ctr or blox stage 1/ or skunk stage 1 for the most linear powerband for the street

gutted-dx

iTrader: (1)

B16 cams are fine,all your answers are in this thread. Get a gsr belt, ls wont fit.

bambam

Not true. If any milling or decking has occured they can be off, as well as whenever you do
a non-vtec block with vtec head, the timing will be off about half a tooth. If you have ever
degreed a set of cams, oem or aftermarket, youll see this.

SiRstewart99

Ls timing belts do work. I have a ls belt and ls water pump. I also know of four other friends running that set up.