Bonnet Scoop - Air Vents for Cooling

[MX5CHIC]

I have read so much in the forums regarding Cold Air Intakes, in fact I purchased one from Sliq not so long ago which leads me to an Engineering question.
The MX5 has an engine bay which gets very, very warm, so why has no one produced an efficient way in which to force cold air into the engine bay or more accurately, to the Air Filter? ....... yes there is a manner via the hole in the firewall but I would not consider that to provide either high pressure or totally cold air as heat is picked up off the bonnet before entering below the windscreen.
Before fitting the cold air intake I played with running a tube from the radiator intake area up through a hole (behind the left headlamp) directly to the filter intake, when the car was moving forward this at least provided some positive pressure. The hole I mention is on all NB8A's from the factory. My next idea would be to aquire some fog lamp trims as per Miata's in the USA and run a tube up from the rear of one of them to the Air Filter ... any thoughts?
So, by reasoning, a Cold Air Intake is not exactly correct if it still recieves it's air from under the bonnet ....... has anyone ever fitted a neat and functional Bonnet Scoop or Vents? - I thought the Puegot 307 (306?) type vents would look tidy

[grump]

I was eyeing off some very stylish vents at repco the other day, it means cutting a hole in your bonnet though.

[philz]

Look at how the Garage Vary car is setup up.

It has a mini ram scoop, for cold air to get in from the bonnet for it's ITB, and a Garage Vary vented bonnet to disperse hot air.

[MX5CHIC]

The Garage Vary setup looks like it would be effective as a vent may be unlikely to increase positive pressure and a scoop would require placement in a high pressure zone to be effective, although both options would certainly reduce the air temperature at the filter which is always going to be a big positive. There must be someone on the forum who may have run pressure tests using a Magnehelic Gauge ...... ?

[sliq]

Magnehelic Gauge

errr..... ha ha

[Okibi]

My CAI uses the air pushed through an NB8B fog light hole.

[fastfreddygassit]

There must be someone on the forum who may have run pressure tests using a Magnehelic Gauge ...... ?

I have thought about it but am really only going use them if I eventually go FI. Good idea though.

Magnehelic Gauge

errr..... ha ha

The Magnehelic's are pretty awesome gauges. ALL our pressure readings at work use these with ranges from 0-500Pa up to 500kPa+. Very, very accurate gauges.

[93_Clubman]

MX5CHIC, TG also recenly asked about measurements & testing in relation to airboxes & CAI - you may have seen the thread - if not it follows:

viewtopic.php?f=29&t=33434

The bottomline seems to be there hasn't been much that anyone's talking about, if it's been done at all, beyond what's mentioned above.

[SuperMazdaKart]

some Familia GTR bonnet vents would look awesome on an MX-5

[MX5CHIC]

Thanks for all the information, I'm into efficiency as a method to get more power and response from the motor, although a supercharger does sound good!
I'd like to go for the Fog Lamp air inlet option as I beleive that position on the car will have a high positive pressure, I think that the forward area of the bonnet on an NB would have a low pressure or even a negative pressure - the rear of the bonnet should see a much higher pressure.
So far I cannot find any values on the Web other than NA figures, which whilst a good guide cannot be relied upon for an accurate application to an NB. It is interesting though that the firewall hole option does in fact provide more than enough pressure to overcome the negative restrictions on the filter and inlet system and also lowers the inlet temperature compared to an under bonnet system by a vast amount.
I'll get back to you with the modifications ......

[Okibi]

If I could get the equipment cheap enough i'd be happy to do some tests with my foglamp intakes.

W.A.s probably a good place to test the temperatures as we well, have a lot of radiant heat off the road.

[MX5CHIC]

I did have a Magnehelic Gauge somewhere from my previous HVAC Engineering Business ..... but in the short term I plan to test the under bonnet temperatures at the Air Intake and do a comparison against the ambient temp using a Data Logger. It is certainly going to be a very large differential temp so the next step is to consider the available options :

1) At least in a NB8A there is a large diameter hole for the Fog Lamp intake to provide plently of cool air.
2) The hole in the firewall option.
3) The most complex is to fit a bonnet scoop which requires plenty of engineering to prevent water ingress to the filter.

Does anyone know where to purchase he NB8A Foglamp Bezels

I have also just seen this thread regarding power output of 90kw - "NB8A, K&N intake (pod) vs Stock airbox" - what is the potential addition to this if the K&N Intake was breathing fresh cold air at high pressure ..... ?

[Alex]

I have also just seen this thread regarding power output of 90kw - "NB8A, K&N intake (pod) vs Stock airbox" - what is the potential addition to this if the K&N Intake was breathing fresh cold air at high pressure ..... ?

That thread is to highlight that with just a pod filter there is only a small gain over the standard airbox.

I wonder if a different setup with less restriction would make it a bit leaner in top end, as seen on the other thread as the redline apporaches the mixture becomes richer, not sure if this is because of restriction from the intake or the ECU overcompensating.

Instead of looking at pod filters you could try extending from the airbox, I might look at it during my holidays but I was thinking of sealing off where the current inlet tube is (on the unfiltered side of the airbox) and cutting a hole out at the front with some extra piping leading into it from the front bar
I wouldn't want it too low because althought water might not flow upstream it would be more likely to take in dust from the road surface. (fog lights too low?)

another idea would be just to attach piping onto the current inlet tube to extend it further, or back to the firewall with some holes in the bottom of the airbox to allow water to runoff since it would pool at the base of the airbox otherwise, but not enough to bring in too much hot air.

Also while you are at it you might want to look into getting one of those heat resistant gaskets that goes inbetween the head and the intake manifold since I'm sure there is alot of transfer there as well which would lead to premature heating of air. (didn't someone here have one they hadn't installed yet?)

[Okibi]

The SMB system puts the filter in the passenger side wheel well



Something similar could be built to place it in the drivers side and avoid the air heating up and it passes past the radiator.

If you use an enclosed system (like those used for firewalls) you could ram air from the foglight intake into the filter but you'd have to be cautious about accidently hitting a deep puddle. You could build in a rubber safety valve similar to those used on snorkels but you have limited room before the filter.

[MX5CHIC]

I experimented with a tube from the standard air box with the inlet coming from the front of the radiator, it worked in principle but I used expandable 2 1/2 inch flexible aluminium tube which I considered was losing any advantage by causing more restriction via it's length and bends, a much larger intake area and larger tube diameter would have worked much better. I ended up removing it when the car was dissasembled for it's respray.

I am no expert in engine performance but what I am hoping to acheive is to "push" as much cold air in to the air filter as possible rather than having the engine struggling to "suck air through a straw", hence I need to locate the best high pressure air location and catch as much air as possible. Does this principle seem sound in relation to engine performance or am I likely to cause more problems with the ECU etc?
I have been reading a great deal on this and other forums and tech sites and a lot of it sounds contradictory BUT; one thing I always notice when driving my car (and feel free to question me on this) is that in cold weather, my car seems far more responsive and smoother RE: dense cool air.