NC 20BPP Time Attack / Track Car - Build Thread

Magpie · Postby **Magpie** » Sun Mar 23, 2014 1:41 pm

Engine start date?

Postby **orx626** » Sun Mar 23, 2014 1:49 pm

Magpie wrote:Engine start date?

April

Postby **Okibi** » Sun Mar 23, 2014 2:05 pm

Regie · Postby **Regie** » Sun Mar 23, 2014 2:11 pm

orx626 wrote:
Magpie wrote:Engine start date?

April

might be worth a trip to Brissy for this

Magpie · Postby **Magpie** » Sun Mar 23, 2014 2:13 pm

I agree on the trip to Brisbane, I suggest 11/04

Mokesta · Postby **Mokesta** » Mon Mar 24, 2014 10:39 am

Hey Danny, great CAD work again.

I wonder if it isn't worth trying to move the filter upstream a bit. I reckon it is worth maximising the volume of the filtered air chamber. The logic I am following is that the filter presents a small but important pressure drop. Each intake stroke creates a pressure drop in the plenum space that is quite large and the instantaneous flow rate is quite high. The filter has a large influence on high flow rates. With a large volume after the filter there is more air at 1 BAR to fill the chamber before it needs to draw through the filter. The filter sees more of the average flow rate, rather than the peak.

Checking out F1 airboxes on Racecar Engineering shows that they try to get monster plenums after the filter and move the filter as close to the intake ram as possible (given filter area constraints).

Of course at 9,000rpm the individual intake pulses are pretty close together so the flow may approach an average level anyway...

M

Caffeine · Postby **Caffeine** » Mon Mar 24, 2014 10:49 am

Mokesta wrote:With a large volume after the filter there is more air at 1 BAR to fill the chamber before it needs to draw through the filter. The filter sees more of the average flow rate, rather than the peak.

Like a big pneumatic capacitor

Postby **orx626** » Mon Mar 24, 2014 11:29 am

Mokesta wrote:Hey Danny, great CAD work again.

I wonder if it isn't worth trying to move the filter upstream a bit. I reckon it is worth maximising the volume of the filtered air chamber. The logic I am following is that the filter presents a small but important pressure drop. Each intake stroke creates a pressure drop in the plenum space that is quite large and the instantaneous flow rate is quite high. The filter has a large influence on high flow rates. With a large volume after the filter there is more air at 1 BAR to fill the chamber before it needs to draw through the filter. The filter sees more of the average flow rate, rather than the peak.

Checking out F1 airboxes on Racecar Engineering shows that they try to get monster plenums after the filter and move the filter as close to the intake ram as possible (given filter area constraints).

Of course at 9,000rpm the individual intake pulses are pretty close together so the flow may approach an average level anyway...

M

Hey Mark,

That is what I tried to achieve, but of course there is always got to be a compromise. The upshot is that the panel filter to inlet throttle size ratio is around 10:1. However, due to where the engine sits in the chassis I was concerned about the path the air was to take prior to the filter as well. Further to this I needed to ensure that the airbox (amongst other things) didn't encroach on the space needed for the heat exchanger assembly ducting that goes over the top of the front part of the engine. So that is about the best position to accommodate all of the requirements. BTW the inlet size to the plenum is 4" and will have some high pressure air feeding it from a yet to be determined entry point. At the end of the day a dyno run with and without the filter will highlight any shortcomings.

Cheers,
Danny

Postby **orx626** » Tue Apr 01, 2014 8:42 pm

So I have the panel filter...its to suit a Porsche 968 3 litre. Materials for the fixed section of the air box have also been ordered. I hope to have them early next week.

The drivers seat and rail have also arrived and are now in the car. It is a Bride Gardis III. I'm very happy with how well it fits in with the cage and hardtop.

The design of the aero package is underway with AMB Aero completing the solid model of the standard body. This image was before the hardtop was added.

This image is of the first CFD model so that we had something to benchmark the aero package.

Cheers,
Danny

Magpie · Postby **Magpie** » Tue Apr 01, 2014 9:00 pm

Do you have a solid model of a stock NA6 with hard top?

Postby **orx626** » Tue Apr 01, 2014 9:03 pm

Magpie wrote:Do you have a solid model of a stock NA6 with hard top?

I don't sorry Mark. Andrew has had to produce this for me.

Cheers,
Danny

Magpie · Postby **Magpie** » Tue Apr 01, 2014 9:13 pm

No problem, it was worth a shot. I'll hopefully duck in on 11/04 to pick up some stuff that Jason has collected for me as the family makes the move to Blackwater.

Magpie · Postby **Magpie** » Wed Apr 02, 2014 7:31 am

Danny I was just emailed this article (light reading on page 36) http://viewer.zmags.com/publication/bce6d939#/bce6d939/38

Postby **orx626** » Wed Apr 02, 2014 10:29 am

Magpie wrote:Danny I was just emailed this article (light reading on page 36) http://viewer.zmags.com/publication/bce6d939#/bce6d939/38

Thanks for that Mark. I had a quick peruse and it looks like an interesting insight into Andrew's world. I look forward to taking time to read it through.

Cheers,
Danny