whats the biggest intake valve ,
11-30-2005, 05:02 PM
#1
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whats the biggest intake valve , exhaust valve, and intake runner on a set of heads for a stock shortblock would you use on the street and why?
11-30-2005, 07:26 PM
#2
Well, for a stock short-block for most power....anything above a 2.055/1.6 valves would be overkill, along with a runner above 225 or so would be too big too. On a stock shortblock, going to big will mean low air velocities...which in turn will cause shrouding of the valves and reduce power.
The more air you can flow on the smallest valves/runners will always net more power because the air velocity will be very high. As I stated in another post...more air doesn't necessarily mean more power, but how fast you can move the air is what really matters.
Example:
1. 225cc runners with 2.055 intake valve flowing 315 cfm
vs.
2. 215cc runners with 2.02 intake valve flowing 300 cfm
Option 2 will beat out option 1 on a same setup strictly because the flow velocities will be much higher then option 1, even though it flows slightly less air.
Make sense?
Regards,
Adrian
The more air you can flow on the smallest valves/runners will always net more power because the air velocity will be very high. As I stated in another post...more air doesn't necessarily mean more power, but how fast you can move the air is what really matters.
Example:
1. 225cc runners with 2.055 intake valve flowing 315 cfm
vs.
2. 215cc runners with 2.02 intake valve flowing 300 cfm
Option 2 will beat out option 1 on a same setup strictly because the flow velocities will be much higher then option 1, even though it flows slightly less air.
Make sense?
Regards,
Adrian
12-01-2005, 04:20 AM
#4
TECH Senior Member
As usual, you can't just speculate that XXX valve is the best. It has to do with overall combo (cam profile, SCR, intake Vs exhaust %, etc....)
2.040 are about the biggest you can use with stock seats.
2.040 are about the biggest you can use with stock seats.
12-01-2005, 08:57 AM
#5
The biggest valves I would use would be 2.08 intake and 1.60 on the exhaust. Although some may say they would be shrouded in a stock bore configuration. The size of the intake runner would be dependent on how wild I'd want to get with the motor, I'd say under 240 CC's for most folks.
