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Long Tubes? Short Stack? What's The Difference?

Fuel injection, long vs. short ram tubes
Posted December 16 2010 09:07 AM by Scott Ross 
Filed under: Miscellaneous

Long ram tubes ("velocity stacks") on the "Yankee Peddler" AWB Dodge helped boost power at low RPM.

A question was raised about the length of the ram tubes used on the mechanical fuel injection systems on race cars like the AWB Dodges and Plymouths of the early/mid '60s.

An overly short answer is the question, "Where do you want to make your power?"


 

Long ram tubes ("velocity stacks") on the "Yankee Peddler" AWB Dodge helped boost power at low RPM.

Long tubes (as seen on the "Yankee Peddler" AWB '65 Dodge we saw at the Performance Racing Industry (PRI) Show) were used to get more low-end torque out of the engine, especially if that car was running an automatic transmission.


"Long Ram" induction in street form: the long-tube intake used on the letter-series Chrysler 300s.

This was for the same reason that you saw the long ram intake manifolds on the Chrysler 300E, 300F and 300G "letter cars" of yesteryear...the pressure wave inside the tube took longer to return to the intake valve than a shorter tube would, which helped fill the cylinders with the magic air-fuel mix at lower RPMs...like off the starting line on the strip, or on a freeway on ramp in the case of the "letter cars."


On the other hand, short tubes (like on Sox & Martin's '65 AWB Plymouth) help boost power on the top end (high RPM at or near the redline).

Short intake tubes (as seen on the Sox & Martin AWB '65 Plymouth), on the other hand were there to boost top end (high-rpm)  performance...as in the case of a manual-transmission car that would be shifted at or near the engine's redline. The pressure wave inside the tube takes less time to return to the intake valve, which results in the opposite effect of the long tubes...namely, more power at high RPM. (Need I mention what happens when you add a driver with the quick-shifting reflexes of Ronnie Sox?)


"Short ram"-equipped Max Wedge in an early B-Body Dodge.

"Short ram"  was the same idea used in the intakes that you saw on Max Wedges starting in '62....for high-end power.





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