Intake length vs torque, Just anthoer carb question No boobs |
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Intake length vs torque, Just anthoer carb question No boobs |
Joe Ricard |
May 18 2005, 02:03 PM
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#1
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
So I have short intakes and 44IDF's with 38mm vents
How long of an intake should I go to with these carbs or should I go to 40 IDF's with 32 vents or 28 vents. I have some longer runner intakes and the other carbs so it's just a matter of experimenting I guess. 2.0L Bus piston Web 86B portmatch intake and exhaust ports. 13lb flywheel Bursch SSI Car weighs 1965 lbs 205/50-15 Kumho V700 R tires. Thought of playing with spacers under the carbs to get more length and maybe spacer under the common length velocity stack. Looking for more torque down lower to pull harder exiting the apex of tight AX turns. Whose got the experience of really been there done that? great gains or don't bother. |
Dr. Roger |
May 18 2005, 05:00 PM
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#2
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A bat out of hell. Group: Members Posts: 3,944 Joined: 31-January 05 From: Hercules, California Member No.: 3,533 Region Association: Northern California |
Well actually it's got way more than just intake length and size.
Skinny intake=higher velocity. Larger intake = slower velocity buy higher max volumnes of air. Longer runners allow air to be "stacked". Stacking meaning.... As the column of air is drawn into the cylinder the intake shuts. At this point pressure ouside the intake is building up for a milli second. Depending on the velocity of the air and the runner size it can maintain a positive pressure for either a shorter or longer time. You might want a shorter time for low end engines and a faster time for high revving engines. Ideally I want the pressure waiting outside the intake valve to still be there when the valve opens again. Kinda' like a blower but not. If I take a straw and fill it up with water. Then remove my finger from the end and then stick my finger back on the end I feel a vacuum for a quick second. The water is acting kinda like the air column in the intake runner. Air has mass and inertia. Having air going in a straight line and making these pressure surges at the right times of intake and exhaust is the key to REAL tuning of the intake and exhaust systems. the same canbe done with the exhaust system. Using the air rushing out the exhaust valve, a negative pressure can be exerted in the exhaust stroke more effectively ridding the cyl of exhaust gasses. Kinda like on my 500cc 2 stroke dirt bike. =-) |
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