nskyline34

iTrader: (2)

Ran 190+ at Mojave Mile in April, and going back in Oct. Car i think has the stones to touch 200, but its going to be close. I'm thinking about getting a second hood to cut up - this wont be too pretty, but it will work well, esp at 150+.

I'm thinking something like this RX7 has in this video:

Basically imagine a line that runs straight forward of the TB, cut a hole in the hood and open in up to go to the TB. Now take jigsaw and REALLY open it up about 8" wide and 4” tall or so to 'funnel' the air in.

At WOT normally an engine has a few psi going into it, just atmospheric pressure minus engine vac = the pressure pushing air into cylinders.

With my idea is that the intake will be wide at the hood (4” x 8” oval roughly) and funnel down to the TB/MAF (might change to speed density tune for it, idk yet). The dynamic pressure formula for this is as follows: q = 1/2 * rho * Vtb^2 where Vtb = Vin * Ain/Atb. Rho is the air density, Vtb is the velocity at TB, Vin is the velocity of the air coming into the funnel/scoop = speed of the car, Ain is the area of the intake at the hood = area of a 4x8” oval ~25in^2, and the Atb is the area of a 90mm TB.

100mph = 1.14psi
150mph = 2.58psi
200mph = 4.58psi

This obviously there are a lot of assumptions here like no fiction, all the air coming straight at the intake will enter and not be pushed/deflected by the air over the nose etc. So, to be safe let’s say 50% of this will actually happen (realistically closer to 75-85% of this is true, but we will use conservative numbers). This means that at 100mph it should have about 0.50psi, 150mph = 1.25psi, 200mph = 2.25psi. There should be no difference in this and a turbo (supercharger takes hp to run). From a lot of research it seems that 0-5psi there is a lot more hp/psi gain then diminishes after. From said research it seems that 15whp is very conservative seeing how research showed 20whp to 30whp upto about 6-8psi, then slowly dropped off. Then this should mean that: 100mph = 7whp, 150mph = 25whp, and then 200mph = 45whp.

panic

The size of the scoop opening goes down as speed increases
Ideally, the scoop cross-sectional area expands after the entrance to slow down the air and trade speed for pressure, and the TB is (almost) in still air.
Read this: http://tinyurl.com/hv6xupm

nskyline34

iTrader: (2)

Yes I agree that is ideal, but not sure how to make that work since I only have about 12"-16" of room between the hood skin and TB. I would have to put the MAF right in front of the TB Unless I so a SD tune.

So do you think that my idea wouldn't work as I'm wanting at all or...?

I was thinking the area in my fast 102 would basically be the diffuser to slow everything down before going into cylinders and thus pressure would increase?

panic

I think it has value, but the exact dimensions are a bit of a puzzle.

nskyline34

iTrader: (2)

Ok I understand. I first did it with a 6x12 scoop, but that was far too much (37+ psi) and would be like a big brake, so I reduced it down to what would get me 3-5psi @ 200mph. Basically all I need is a little more umph!

SD tuning for this will be fun if I cannot shove a maf in there...

Might look into a varvaram intake maybe...

Running without a filter makes me nervous, but I think it would be fine since its for 3 runs and will be a total of 5-6 miles without anyone in front of me to kick anything up... Anything 'floating' in the air (pollen, Cotten, etc) will be fine through the motor - a rock...not so much