Trying to see who is running unmodified PHK pistons with a vtec head.

What cam are you using? What (if any) intake cam advance are you set at?

 

You'll be fine with stock SiR/GSR cams in the VTEC head. Should also be fine with Type R cams WHEN leaving your cam timing set at zero. Just like LS pistons in a LS block (since both have shallow valve reliefs in the pistons), if you advance the cam timing too much with some high-profile cams, like Type R, then your valves are going to want to open up more and start to tap the pistons, eventually leading to bent valves.

 

Hmm. That is part of the problem. I get conflicting reports.....

For example:

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by smokey2.0 &raquo;</TD></TR><TR><TD CLASS="quote">
i never have heard of anyone, running a b20Z bottomend running cams bigger than the 98 ITR cams. i actually measured some B16(del sol) cams on my b20Z bottomend, using a gsr head and the was valve to piston contact way before tdc!</TD></TR></TABLE>

...posted in this thread:
https://honda-tech.com/zerothread?id=722608

 

if i'm not mistaken you have to notch the valve
reliefs,because the valves are bigger on a vtec head.

just like when you do a ls vtec "which sounds like what your doing".if you are going to put a
vtec head on and keep the stock bottom end,you have to notch the valve reliefs,no big deal.

good luck

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlueTeg &raquo;</TD></TR><TR><TD CLASS="quote">Hmm. That is part of the problem. I get conflicting reports.....
</TD></TR></TABLE>
ok, next saturday i'll try on 00 itr cams. these cams i bought off b19coupe, for a friend of mine! i won't be able to clay them, but at least well know if they'll hit or not. if my friend has his skunk2 stage one cams available, i'll try those too! cool!

 

I'm aware that the vtec heads have wider valves than the non-vtec, and obviously the valves are lifting higher w/ the vtec lobe. However I have trouble beleiving that in the 4 years that people have been doing the frank engines that every single B20/vtec guy has widened and/or deepened their valve reliefs.

FWIW: I already have a B20z block w/ Crower stage 2 non-vtec cams. But I'm stuck with this engine package getting choked off after 6000 rpms w/ my non-vtec head. I'm planning on a GSR head w/ stock gsr cams, nothing wild.

Smokey: if you could check to see if there is any piston-valve contact I would greatly appreciate it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlueTeg &raquo;</TD></TR><TR><TD CLASS="quote">
Smokey: if you could check to see if there is any piston-valve contact I would greatly appreciate it.</TD></TR></TABLE>
i'll try to help as much as possible, the main issue is that i have a b16 head and you'll be using a gsr head! i'll post my results by saturday night!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlueTeg &raquo;</TD></TR><TR><TD CLASS="quote">Hmm. That is part of the problem. I get conflicting reports..... </TD></TR></TABLE>

Don't know what others have done or tried (or "heard" or "read") but this is from my own 1st hand experience either on my motor, co-workers' motors, or customer motors. Type R cams with zero cam timing will clear.... barely, but each motor is different (depending on the deck on the head, headgasket used, etc). And depending on how the driver is on the motor, it may never hit or if they like to take it up to high rpms a lot, they may tap slightly and when you take the head off later on, you might see small marks on the intake side of the pistons. For extra assurance, you can notch/dremel the valve reliefs for more clearance, or just get aftermarket pistons (so you can go higher compression.... "stock" B20-VTEC or LS/VTEC really isn't much more in power than a stock B18C GSR motor).

 

Smokey: Thanks for looking into that.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlueTeg &raquo;</TD></TR><TR><TD CLASS="quote">Smokey: Thanks for looking into that. </TD></TR></TABLE>
no problem bro, saturday for sure! i wish i could dremel the valve reliefs while the pistons are in the cylinder, if that was the case i would do that saturday! i might get started friday night(10:30EST), and if i'm done that night, i might take the pistons out and take them to a mashine shop i know is open saturday morning so that they could enlarge the valve relief!

 

I dremeled the valve reliefs in my buddies B20VTEC with the pistons still in their bores (although I apparently didnt need to). Bring whichever piston you are working on to TDC so that no material can get on the sleeves and cover up the coolant jacket with some masking tape. There is a picture of the pistons in this thread https://honda-tech.com/zerothread?id=580827

 

thankx for the info, i might ask my friend for his dremel. it sounds more complicated, thank what i think it is! i'll find out on saturday

 

people just don't listen.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1700anddroping &raquo;</TD></TR><TR><TD CLASS="quote">people just don't listen.

</TD></TR></TABLE>

If you don't have any experience you shouldn't be talking.

You are correct in saying that the valves in a vtec head are bigger, but it doesn't become an issue unless you have cams with greater lift than ITR's and/or change cam timing much. At the time that I dremeled my friends motor I could not find any concrete information concerning the issue. In retrospect, I wish I would have clayed his motor rather than "playing it safe" and losing valuable compression points.

 

yeah i don't have any experience in putting bull **** together,DO IT RIGHT THE FIRST TIME
AND YOU WON'T HAVE TO"PLAY IT SAFE".

for what you were doing,you wouldn't've lost enought to make a difference.

before you start firing,make sure your BULLETS arn't duds. have a nice day.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1700anddroping &raquo;</TD></TR><TR><TD CLASS="quote">people just don't listen.
</TD></TR></TABLE>

WTF is all about??
I hate to be rude, but I'm looking for guys that have hands on experience with this dilemma.

Yes, I know the VTEC valves are larger than the non-VTEC valves. Yes, I know the valve reliefs on the PHK's are too small for the VTEC valve head. The question is, whether the piston and valve will be close enough at TDC (IN cam @ 0 degrees) for the small valve reliefs to be an issue with a mild cam like the GSR....or even the ITR.

I just have trouble beleiving that every single guy who's done the B20/vtec has notched their stock pistons. I mean these frankenstein engines have been around since 1998, so its not like its a totally new idea. You'd think that by now that if there was piston/valve contact on a virgin block/head and oem cams it would be a widely known fact that you HAVE to notch the oem pistons for the engine to work right.

 

B20Z. GSR cams. 0 timing. no reliefs. NO PROBLEM - as long as you use a stock HG and don't have the block decked and/or head milled.

 

^ This is on your personal setup?

 

Not my personal setup. Plenty of experience though. Just like Newman said, I can only say for certain what I have seen, I cannot tell you absolutely that you will not have any problems with piston valve clearance. There are too many variables at play here. For instance, if you have improper valve springs for your cams, your valves can float into the pistons even though you had decent piston/valve clearance at 2 RPMS(whatever you hand cranked the motor to).

 

The block and head have never been milled. oem thickness head gasket. intake cam at 0. GSR cams and valvetrain.

powerofdreams: Your input is appreciated. Thanks man.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by powerofdreams8 &raquo;</TD></TR><TR><TD CLASS="quote">B20Z. GSR cams. 0 timing. no reliefs. NO PROBLEM - as long as you use a stock HG and don't have the block decked and/or head milled.</TD></TR></TABLE>
this has been my setup(b20z/b16 head/gsr cams@0/0), for over a year. my head has never been milled, and my block has never been decked!

 

friday night, i tried some 01 itr cams. i locked the lma assembly on the #1 cylinder, so that i could figure out if there woul be any valve to piston contact! the #1 cyl was brought to TDC, and i manually turned each cam to feel for valve to piston contact. this is what i found: for the intake cam, there was valve to piston contact after a few degrees of cam move ment. i would say 1/3 of the way, before reching the top of the vtec lobe. on the exhaust side, the vtec lobe made it almost to its peak before there was valve to piston contact. i hope this info serves you well!

 

head milled 20k....toda b's.....phk pistons....

no issues