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Tuning Ram Tube Length

Author: Hilborn | 11/17/2018 < Back to Motor Life Home
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What difference does ram tube length make?


IR manifolds are unique in that changes to intake runner length are easily achieved. Changing this length can have a profound effect on where the engine makes idea power for your particular combination. In general, shorter ram tubes will provide more top end power at the expense of low speed torque, while a taller ram tube will increase low speed torque while losing some top end power.


Racing Applications


Racing applications involving lightweight cars with high revving engines, such as FED or Jr. dragster, will typically employ a shorter ram tube to move the available power band to the higher RPM. Heavier applications such as door cars, or other racing venues that involve getting on and off the throttle will typically use a longer ram tube to achieve a balance of power throughout the operating range.


Street Applications


With street applications, many use the ram tube as a focal point. Whether you want them sticking out of your hood, or under the confines of a stock hood, length plays a critical function aesthetically. This typically means that a compromise of sorts has to be made with respect to the ideal ram tube height for that particular engine combination. But what we have found is that the torque generation of an IR manifold is so much better than that of a common plenum manifold, that for most street applications ram tube height has little bearing on performance. So put the ram tube height where it looks the part and enjoy the additional torque regardless of that height.


Ideal Ram Tube Height


What is the ideal ram tube height for my combination is a common question we get but is very hard to identify. Sure, there are numerous computer models available along with dyno testing which are all popular tools to help identify ram tube height. But even with these tools at our disposal, they have the inability to factor in all of the dynamic conditions of a race car. It is only through track testing that the ideal ram tube height can be determined.


The Ram Tube Bell


At the top of a ram tube is the bell, and this is where all the magic begins. It has been identified on Indy car engines that the entrance speed at the bell of the ram tube exceeds the speed of sound which would not be possible without a properly designed bell. The bell provides the proper transition of the air into the ram tube which is an important process for the high air speeds generated by an IR manifold. We would like to suggest that the bell not be removed from the ram tube if at all possible.

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