valve size???
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valve size???
Ok guys, I just got my head from bob aka dopes. I'm slowly going to be getting it ready/building it for boost... my question is what valve size is good to go with from dezod or anyone else for that matter.... standard/oem, +.5mm overbore, or 1mm overbore? i appreciate the help guys!!!
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standard 30mm/26mm valves are fine unless you're gonna gonna completely port and polish the head and do the major valve reconstruction....
I just went with stock size valves and a 3 angle VJ.
I just went with stock size valves and a 3 angle VJ.
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thanks for replying boiler... well before i say my plans i wanna ask you what is the different between a 3 angle valve job and port and polish? sorry this is my first car to mod so i'm still learning alot. anyways my plans as far as the head... i want to do a complete port and polish, replace valves, and valve springs and retainers, crower turbo cam or maybe the crower stage 3 cam, and of course arp head studs... hmmm what else is there that you can do to the head?? lol. i think thats it...
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From: Ft. Bragg/Fayetteville, nc
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thanks triz, i thought so too... i'm really getting into my build now, i just need the money to hold up with my addiction...lol. but i will definitely follow your diy on the retainers and such. unless dezod hooks me up if i decide to send this head into them for the port and polish and i pay for the parts..i.e.-valves, retainers, springs, cams, etc.
Re: valve size???
well i think what boilermaker is saying is that if the head cant flow enough to effectively use the valves its not worth it. The P&P refers to opening up certain air passages to and from the cylinders. the passages to usually are the hardest to get right size and they use a rough surface i believe to create turbulence in the air which is good for fuel mixing. the exhaust usually just gets bored out a bit to get all the exhaust gases out quickly.
the valve angle refers the the shaping the valve seat and valve to allow better flow into the cylinder.
So increasing the valve size will allow for more air to go into the cylinder but if the rest of the head can't give it the extra air it really is pointless.
I'm not sure if it applies to turbo heads as much but i do know if you put too large of a valve it will be shrouded and disrupt the airflow into the cylinder because the side of the cylinder wall is too close. now if that really matters with a turbo forcing air into the cylinder im not sure but i think it could still be a problem.
you can also run into the valve being so large it hits the pistons but thats probably not going to happen with a .5 or 1mm overbore.
hopefully that made some sense im way tired today
the valve angle refers the the shaping the valve seat and valve to allow better flow into the cylinder.
So increasing the valve size will allow for more air to go into the cylinder but if the rest of the head can't give it the extra air it really is pointless.
I'm not sure if it applies to turbo heads as much but i do know if you put too large of a valve it will be shrouded and disrupt the airflow into the cylinder because the side of the cylinder wall is too close. now if that really matters with a turbo forcing air into the cylinder im not sure but i think it could still be a problem.
you can also run into the valve being so large it hits the pistons but thats probably not going to happen with a .5 or 1mm overbore.
hopefully that made some sense im way tired today
Joined: Jul 2002
Posts: 13,151
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From: Washington DC
Rep Power: 424 Re: valve size???
well i think what boilermaker is saying is that if the head cant flow enough to effectively use the valves its not worth it. The P&P refers to opening up certain air passages to and from the cylinders. the passages to usually are the hardest to get right size and they use a rough surface i believe to create turbulence in the air which is good for fuel mixing. the exhaust usually just gets bored out a bit to get all the exhaust gases out quickly.
the valve angle refers the the shaping the valve seat and valve to allow better flow into the cylinder.
So increasing the valve size will allow for more air to go into the cylinder but if the rest of the head can't give it the extra air it really is pointless.
I'm not sure if it applies to turbo heads as much but i do know if you put too large of a valve it will be shrouded and disrupt the airflow into the cylinder because the side of the cylinder wall is too close. now if that really matters with a turbo forcing air into the cylinder im not sure but i think it could still be a problem.
you can also run into the valve being so large it hits the pistons but thats probably not going to happen with a .5 or 1mm overbore.
hopefully that made some sense im way tired today
the valve angle refers the the shaping the valve seat and valve to allow better flow into the cylinder.
So increasing the valve size will allow for more air to go into the cylinder but if the rest of the head can't give it the extra air it really is pointless.
I'm not sure if it applies to turbo heads as much but i do know if you put too large of a valve it will be shrouded and disrupt the airflow into the cylinder because the side of the cylinder wall is too close. now if that really matters with a turbo forcing air into the cylinder im not sure but i think it could still be a problem.
you can also run into the valve being so large it hits the pistons but thats probably not going to happen with a .5 or 1mm overbore.
hopefully that made some sense im way tired today
My Pony Princess is the inspiration for my ride.
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Re: valve size???
If you're going all out (3-angle job, cam, and PnP) and don't need to replace the valves, then stick with stock as they will flow just fine combined with the rest of the work you're having done. The cam is the foundation that you're building on with valve job and PnP, because without a cam to take advantage of the enhanced flow, the other two really don't do dick.
By going with bigger valves, you will be able to stuff more air down the cylinders and get exhaust out faster, but at the extra cost of new, larger valves. Depends on how deep your wallet is and what your goals are Jay. With a good head job, cam, and that GT30 you're buying, you'll easily hit more than enough drivable horsepower on this car.
I'd save the money for valves and spend it on booze and women.
By going with bigger valves, you will be able to stuff more air down the cylinders and get exhaust out faster, but at the extra cost of new, larger valves. Depends on how deep your wallet is and what your goals are Jay. With a good head job, cam, and that GT30 you're buying, you'll easily hit more than enough drivable horsepower on this car.
I'd save the money for valves and spend it on booze and women.
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From: Ft. Bragg/Fayetteville, nc
Rep Power: 273 Re: valve size???
LOL thanks for the lesson Clint. well I'm probably just gonna go with oem replacements. I just bought Bobs vtec head and want to pretty much replace everything and also get it hot tank and all that other jazz. But that's still a long time from now. You'll be back in the states by then and I'll be able to get your guidance face to face and with you being able to check it out in person no less. Thanks again... would rep but need to spread it around some more.
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