Just wondering if we will have ptv contact if we get the VT stage 2 cams. We have the comp 270's right now and have pretty much came to the conclusion that we are have ptv at high rpm's. I called comp and they said that the lifters are pumping up and that is what is causing it. So I just wanted to make sure that if we get the stage 2 we will not have ptv contact.
Vt stage 2 cams
- Thread starter TNstanggurl
- Start date
maddogg545
Founding Member
kboy262
Active Member
I to second the 268H. Grant it they are on my NPI head car, they are great mod. Not too aggressive but helps out a lot in the higher end of the powerband. No problems so far after 6,000 miles.
Dyno results
I know it hasn't been asked but I think this is the right thread to present some dyno numbers
VT Stage 2 cams on stock 00 GT
I know it hasn't been asked but I think this is the right thread to present some dyno numbers
VT Stage 2 cams on stock 00 GT
nickthegenius
Active Member
maddogg545 said:
In the worst cases, it sounds like the clicking of your injectors x 100 and can hear it over your exhaust and everything. Less severe cases you may just hear a light metallic clicking/tapping at higher RPMs. Either way, it is bad for the engine and can trash you pistons, valves, and possibly the head depending on how the piston hits the valve and what it pushes it into.
kboy262
Active Member
prsrizdgt said:I am a little coonfused now. The forged piston is dished 17cc's right? And the comp cam only has .550 lift.Why cut the pistons for valve relief?
Actually I think he says his are the 268H (NPI cams) not 268AH. The 268H have only .500" lift.
prsrizdgt said:I am a little coonfused now. The forged piston is dished 17cc's right? And the comp cam only has .550 lift.
These are ported heads. They were milled a bit to clean them.
The reason they need to be cut is they were hitting the edge. The shop did an on engine manual test. The disk is in the middle of the piston. The outer edges are still high...
Actually I made a mistake the Comp cams are XE270AH. .550 lift Duration @.050 Intake 234 Exhaust 238..
These cams significantly opened up my top end. HP stays flat up top rather than fall off.. 5500 - 6400 stayed at 500rwh..
nickthegenius
Active Member
Don't forget that the lift isn't the only thing that can cause PTV. Another thing with the Comps is the extra 5* advance that is ground into them. Add that to a cam that already has a decent amount of duration and you end up with the valves open long enough that the piston meets it at the top of the bore and *bam*.
