As we all know, the smallest changes all have a measurable impact on how an engine runs, how an engine performs, and ultimately how much power it makes and where that power is made in the range of RPM. This short and sweet video shows a killer 572ci Chrysler hemi making two dyno pulls. The engine is identical both times aside from the height of the stacks on the Hilborn injection manifold. While the end result is not the shocker and certainly follows the path we thought it would, the numbers generated and the difference between the stubbier and the taller stacks is really interesting.
For many people they want the Hilborn look because it is classic hot rod, classic drag racer, classic land speed racer, however you want to say it. With the company having long offered the iconic looks with the accuracy and efficiency of EFI instead of the more thirsty mechanical injection, hot rodders can have their cake and eat it too. Yes it looks old school, but hot damn it works perfectly in the modern sense as well.
This big, aluminum hemi is going to be a killer engine on the street and frankly the owner can make a performance tweak depending on how he is needed this engine to run on a particular day.
Watch the video and tell us not if you are surprised there is a change but if you are surprised at the variance between the two heights.
Interesting results. I was actually surprised when the short tubes made less overall torque than the long ones but both peak torque numbers were at the same 4700RPM.
I was told by a few of the original drivers that the short tubes made the most torque at a lower RPM and that THAT was why Chrysler put them on the automatic equipped AWB cars in 1965. And that the 4 speed cars got the long tubes because they made peak figures at a higher RPM and naturally those guys would be leaving the line at higher revs.
But then again this is a much bigger engine with completely different internals so I’m sure that makes this an apples and oranges thing.