Technical > Matt Shaff's Engine Shop
Zoomies vs collector headers
dreracecar:
Plus it keeps the rocks out of his engine without have to use covers
Roger:
I agree with Bruce that a blown car with a lot of exhaust volume probably doesn’t need or work well with headers. For now I don’t have a blower and was looking at this more through the lens of a naturally aspirated engine. It’s interesting that Bill’s cars were a tenth or less slower with zoomies. Having been told they don’t work well in the past with n/a engines I was curious as to how much the engine performance was actually affected and at least in his instance it wasn’t much, if any. Of course the car would weigh less with the zoomies. The ones I have weigh 10# for the pair and the headers I have for the street rod engine weight 34#. Now Jon brings up an interesting point about how far to lay the pipes back from vertical. With the case of big show cars they have a huge amount of exhaust that’s angled rearward to propel them forward compared to a smaller volume and force from a junior fuel car. So while there is some exhaust volume to propel the J/F forward, is there an optimal angle to lay the pipes back to get maximum benefit from the Bernoulli effect? Ya, this is splitting hairs but I’ve always told the kids in my classes that in order to do something right the first time you must have some knowledge of it before you start. Thought Scott’s idea of the test zoomie thingy on Chuck’s car was I good idea. Kind of reminds me of some of those old lakester style headers on steroids!
The pictures show the Bernoulli effect. First photo is a glass of dyed water with a straw in it. Second is the same glass and straw with 60psi blown across the opening. In this case it drew 3-1/2” of water.
George:
Agree. Ya, this is splitting hairs. :o
THE FRENCHTOWN FLYER:
I wonder what 60 psi equates to in FPS/MPH?
dreracecar:
My question on the "tenth or less" statement, was the test done on back to back same day runs??? under the same conditions??
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