intake ducting question

General engine tech -- Drag Racing to Circle Track

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turdwilly
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Re: intake ducting question

Post by turdwilly » Tue Jul 03, 2018 9:30 am

Belgian1979 wrote:
Mon Jul 02, 2018 2:43 pm
With regards to the filters I can add this : I checked while driving without the filters. I didn't give any difference in VE with regards to the fueling my ecu had to use, so my guess is that the filter(s) are not a restriction. Since they are behind the spoiler, there could be an effect of low pressure. I just don't know about that.

Car has 4 headlights, but they are retractable. (Corvette)
Well, rat farts - there goes my idea!

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Re: intake ducting question

Post by hoffman900 » Tue Jul 03, 2018 1:01 pm

So you’re doing something like this?

Image

GM Racing has been using that basic configuration on the C5R-current.
-Bob

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Re: intake ducting question

Post by Belgian1979 » Tue Jul 03, 2018 3:54 pm

Yes, it's similar.
I find something very odd on that setup : the entrance to the boxes seem to have some sort of venturi or reduction in diameter.

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Re: intake ducting question

Post by hoffman900 » Tue Jul 03, 2018 6:35 pm

Belgian1979 wrote:
Tue Jul 03, 2018 3:54 pm
Yes, it's similar.
I find something very odd on that setup : the entrance to the boxes seem to have some sort of venturi or reduction in diameter.
Those are sonic restrictors. You don’t want those. :lol:

Basically, the MCSA is sized using a multidue of factors by the rules makers for parity. The divergent and convergent sections are designed to so it chokes at the highest possible depression. They’re also used in SCCA and FSAE circles. Google “Single Inlet Restrictor” design.
-Bob

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Re: intake ducting question

Post by Belgian1979 » Wed Jul 04, 2018 3:01 am

Ok, I see. I thought these were intended to somehow increase the speed of the air and create some sort of ramming effect in the airbox.

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Re: intake ducting question

Post by peejay » Wed Jul 04, 2018 8:39 am

For what it worth, the Mazda competition manual speciied two separate 4" ducts to feed the airbox, for a 300hp road racing engine.

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Re: intake ducting question

Post by MadBill » Wed Jul 04, 2018 8:53 am

If it will fit, an inch 'too big' is better than a 1/4" too small, but 2 x 4" is way above minimum for 600 HP let alone 300.
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Re: intake ducting question

Post by Belgian1979 » Wed Jul 04, 2018 1:01 pm

MadBill wrote:
Wed Jul 04, 2018 8:53 am
If it will fit, an inch 'too big' is better than a 1/4" too small, but 2 x 4" is way above minimum for 600 HP let alone 300.
My tubes are currently 2X 3.5". The airboxes have about the capicity of 5 liters.

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