domani2k

is there any one running a b20 vtec setup with stock usdm phk pistons? I've heared that if I was to use the stock 9.6:1 pistons, I'd have to get the pistons intake valve reliefs notched. At the same time I hear of people using this set up without any valve tapping at all.

LEITNER

usually you cut the valve pockets because you have decked the head .080" to get 11:1 compression and it is required to not bend valves at high rpm....otherwise you should have no problems if you dont cut the head.

zeeman

iTrader: (1)

this only goes for stock b16/GSR/ITR cams. If you use any other cams than stock, you'll be taking your chances with the stock valve reliefs.

The problem with notching the valve reliefs on the stock pistons is that if you remove material from the pistons, you NEED to balance them. Which require disassembling the engine, which then requires new piston rings, honing and rod bearings (at least). At this point you might as well just use aftermarket pistons, be it RS machines cast 84mm pistons or your choice of aftermarket forged pistons. These pistons will have deep enough valve reliefs to not have to worry about this and you will be able to buy pistons to acheive your desired static CR without milling the head down a whole bunch.

I've done several stock as stock can be b20vtecs without ever notching pistons, keep the revs down to 7500rpms and you'll be fine with the stock cams.

CivicOnBlades

Hows the rebuild going bud? Got your pistons yet?

domani2k

thanks everyone......

I've got the .25 overbore phk pistons and getting the block borred tomorrow. I've gotta see if I can find some ARP rod bolts before I take the pistons in with the block. I've been swapping some key components from my b16 block over to the b20.. ie water neck/ oil pump/ 22t gears...... the build coming along well.

CivicOnBlades

Good stuff. How come you're taking the pistons in with the block? I thought you were assembling it yourself?

zeeman

iTrader: (1)

if you grind them *****, balance the rotating assembly.
unless you remove the exact same amount off every piston, they'll no longer be balanced...rev a 84.25mm x 89mm to 8500+rpms enough and you could have problems.

I don't know what your plans are here, but i'm just saying.

ARP rod bolts are cheap, but make sure to install them properly. You're going through all this trouble to build a decent setup, balance the rotating assembly for extra peice of mind.

domani2k

I would rather not notch them at all if I don't have to. I'm gonna run itr cams and valvetrain with 0 deg cam advance. I'm planning to also stay below 7200 rpm.

domani2k

so they can bore to exact clearances

CivicOnBlades

Okay gotcha....cause you're going .25 over bore...i forgot....my bad.

Mugen Power

if thats the case, u might aswell stay non vtec. u'll still make a good amount of power

domani2k

Most stock dohc vtec motors redline at 8000rpm. I believe h22's don't even rev that high. I've owned my fair share over the years and found that I've rairly ever needed to wind it out to 8000rpm.... And that's in torqueless motors like the b16 and b18c. Given the torque from the b20, I can't ever see myself needing to rev past 7500rpm. Besides, most b20 vtec motors don't make usable power up at that rev range anyways. ******** sells chipped p28's with b20 vtec maps programmed. The vtec engagement is lowered to 4800rpm I believe, so I'm still using all the benefits of the vtec head.

zeeman

iTrader: (1)

um....what?

b20vtecs can make power up to 9000+rpms.

I wouldn't just use some chipped ecu with a b20vtec map programmed on it.
GET IT TUNED!!!!
Every engine is different and has different fueling/timing requirements, so tuning is extremely important.

Besides the place you are referring to is overpriced.

Vtec at 4800rpms is most likely too low for a stock b20vtec, all the ones i've ever tuned want vtec at 5300-5500rpms (proven on dyno).

Making power past 7500rpms is upto the setup. A stock b20vtec using a stock b16 head and stock b16 intake manifold will most likely peark AROUND 7500rpms, but will still make good power past there.

domani2k

I still plan on getting it tuned.... But I think its a good point to start off from. I would never dream of revving to 9k on stock internals... I just want a strong street motor, not an NA monster. There is no stock motor making power in 9k.

zeeman

iTrader: (1)

depends on what your definition of "stock" is...lol.

Are you going to be using a b16 head or GSR head?

domani2k

Lol... Stock components... Lol I'm using a b16 head. I'll have a little less cr with the b16, but I think its a better set up with it