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Noise reduction - S2000 with Omex throttle bodies


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Dave Eastwood (Gadgetman) - Club Secretary

There’s a few in this thread.

 

 

including.


293E34F2-5E7F-449C-8D6A-B1C615EBB695.jpeg

 

and


31151E2E-F215-449C-BB0B-377EF661EA70.jpeg

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BenD
Chris Broster - Bristol & Bath AO

There's the clue to how the NACA duct 'follows the nose curve' - its riveted down at the corners to hold it in place.

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DMc

I have a NACA duct for my intake. 
 

mine is mounted on the underside as I think it makes a neater job, plus you can fill any gap from the curvature with sealant etc. 
You just have to make sure you make a god job of cutting the hole out 😬
 

best pic I have at the moment - 

 

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Davemk1

Well that’s not ideal.

 

I just set up a remote temperature sensor right where the air enters the filter in the right front wheel opening and it gives interesting results. Once the engine is up to temp (making the radiator warm) the air entering the filter is hot when on the move and drops when the car is sitting still (but still idling).

 

The ambient air temp was about 70°F and when cruising at 60 mph the air temp at the filter was near 90° but when I stopped the air temp dropped immediately to the mid 70’s. This tells me that air is passing through the radiator and out the front wheel opening and right past where the air intake is. Not ideal!

 

Right now the intake does not stick out into the airstream and my hunch is that if I reconfigure it so it protrudes into the airstream it could be good. This points toward a nose mounted NACA duct being a much better way to go but if I can avoid cutting a big hole in the bodywork I’m going to take it and leave the NACA as a last resort.

 

Dave

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Chris Broster - Bristol & Bath AO

Very interesting thread...Have you considered routing the inlet from the Bonnet Scoop rearwards and then into the airbox from the rear (Don't know what S2000 clearance is like up top?  Whilst not a direct flow from external to airbox it may give you an easier and less intrusive access to that magical cooler air?

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Dave Eastwood (Gadgetman) - Club Secretary

You know the duct doesn’t actually have to be that big or intrusive, if the induction system is done right?

 

All the ducts pictured above are really designed to be an “active” device in their own right, in terms of drawing in air moving over a flat panel with minimal drag, so that they can be used to feed a passive air using device, like a cooler of some kind.

 

The induction system isn’t passive though, it’s actively sucking in air, through any opening it has.

 

Take a look at the induction system of a Caterham 620R, it’s more than capable of supplying enough airflow to maintain the output of a 300bhp + engine at speed, (ok, the charger will increase the suction), but the same style system is used almost throughout the range to great effect.

 

here’s the air box, with inlet circled.

 

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And then, as it was the first one I found, what the same style intake looks like on the bonnet of another model.

 

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Dave Eastwood (Gadgetman) - Club Secretary

In a Westfield, you could use the rear V8 bonnet openings for the same purpose, (it’s on my list of things to do, just need that bit of under bonnet area closing off from the rest. 
 

Here’s one from a SEiGHT

 


 

 

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Davemk1

The Pipercross airbox has a nose that is long enough that it comes pretty close to the scuttle and it would be very tough to get a nose on the end of it to turn sharp enough to get it to point toward one of the openings in the engine cover. I played with that idea for some time.

 

One could, as Chris mentioned, run a big hose from the engine cover scoop over the exhaust and around the backside of the engine to the airbox. This has two issues from what I can tell. The first being what I mentioned above about how close the box comes to the scuttle. The second being that you have a long hose directly above the headers so it will get heat soaked and no doubt no deliver the coolest air.

 

Does that make sense?

 

dave

 

 

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Davemk1

I tried two other temp related things today -

 

 - I removed the hose from the airbox so that the box was drawing air from the engine compartment and then checked the air temp as it entered the box. This was not good. The opening is in front of the engine cover scoop so it sees very little outside air so the air it does get has passed through the radiator. The ambient air temp was about 75°F but the air entering the filter went up to 135° once on the move....and the faster you went the hotter it got. Like I said - not good.

 

 - I went back to using the hose routed to the right front wheel opening but this time I was able to push it out further into the airstream with the filter being tucked into the center of the lower A arm right behind the shock/spring. This worked very well. At lower speeds up to about 50 mph the air temp was basically the same as the ambient. Once up to a higher speed of 80mph more air passed through the rad and passed by the intake and this caused the temp to go up about 3°F over ambient. That's not bad. I'll try it this way for my next race in about 10 days.

 

The above convinces me that a NACA duct in the nose is the way to go. It makes sense to pull air further away from the dusty and hot pavement to get the coolest and cleanest air. What I'm not sure of is how one fits a filter in inline between the NACA duct and airbox nor how to deal with driving in the rain so that you don't suck water into the airbox.....that and I'm not excited about cutting a big hole in the nose so I'll try my current set up for a bit and see how it goes.

 

dave

 

 

 

 

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CraigHew
DMc

I decided that the NACA on the nose was the best option when I looked into this myself, nothing scientific about my decision it just seemed like the most logical option for cool, clean air, 

I worried that an intake too low near the wheel ran the risk of ingesting water.  
 

rain has never been an issue but I did drill a small drain hole in the filter housing just in case. 
 

here is a pic with the nose cone off which might give you some routing ideals - 

 


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Davemk1

 

Another interesting test today….”interesting” might be a relative term! Nerd alert.

 

Nonetheless… I placed the temperature probe in the airbox itself (between air horns 1 and 2 and more or less against the backing plate) The sensor is small and the wire coming from it is thin so I could just put it in there and close the box and drive. It’s a warm (80°F) and sunny day here and the temp in the airbox rose slowly as I warmed the car. I drove easy on back roads in 6th gear at about 50 mph (low throttle opening and not drawing much air) and the temp climbed to about 92° and stayed there.

 

I then stopped and let the car idle and get heat soaked. I let it idle until the fan cycled on/off twice. The temp in the box rose to 115° which makes sense seeing as the fan is blowing hot air at everything and there’s no air passing over the car to cool it. I then drove away much the same way as I drove before cruising at 50ish mph and the temp dropped to 98°.

 

I’m guessing that the difference between the cruising temp early in the drive (when it made 92°) and the post head soak drive (98°) was due to the radiant heat coming off the ITB’s and the aluminum backing plate keeping the air in the box well heated. That coupled with the fact that I was cruising with a small throttle opening and not pulling that much air through the system allowed it to get that warm.

 

Now the question - the air temp in the box seems to be about 15° above ambient and I wonder if that it good or bad? Obviously it would be better is if was cooler but how cool can one expect it to be? I regret not doing this test with the old set up of a sausage filter and no cold air supply to see what the temp was with that.

 

Thoughts?

 

dave

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