BadBoy - Venturi Sizing

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Mendoza
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BadBoy - Venturi Sizing

Post by Mendoza » Wed Dec 23, 2015 6:43 pm

Badboy asked a question about Venturi sizing but the post was shut down after people were arguing about the true impact on engine performance. Anyhow I did a quick search and believe the following extract to be accurate based on my experience:

For most applications it is better to select a smaller main venturi diameter than what will provide maximum horsepower output.

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Nitrojedi
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Post by Nitrojedi » Thu Dec 24, 2015 6:05 pm

so here is a comparison of a 6mm, 7mm, and 9 mm insert on my modified Speed running a OS 2090 pipe........then as a reference I have the 9886/41032/9mm combo ....this shows very clearly what smaller sized inserts do..... also I just did these tests today, back to back to back.....and if you think this is crazy you should ee how badly a .28 or 30 is affected by a small insert, this is only a .21 and its being choked badly

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Mendoza
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Post by Mendoza » Thu Jan 07, 2016 6:12 am

Really interesting stuff ... Like I said Jedi I put the 9mm in and with the 9886/41001 combo it gave me the best result by far. Your results seem to demonstrate that you may get marginally better response in the lower rpm from the smaller insert but you compromise a lot of the higher rpm HP. It makes perfect sense to me because at max air/fuel velocity and rpm the smaller bore intake can not provide the same volume of throughput.

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