Airbox v hole in the bonnet?

[SM25T]

I like this thread ... we need some levity back in BC discussions after all the corporate secrecy crap flying about.

[Nick Bassett]

Interesting post this - I was considering buying a s/h bonnet recently with a filter cut out as I thought it might help the TBs on my SLR breathe a little better - in the end I decided not to as it would have meant repainting the bonnet, so further expensive etc...

It does beg two questions though:

1. Would it deliver a performance advantage? The existing foam 'sausage' filter does appear quite cramped with bonnet on.

2. If driven in the rain, even though the foam filter is oiled, would it suck in water and cause engine damage or running issues?

Thanks

N.

[EEK]

Plastic bag over the oiled sausage if the car is left in the open and rain is forecast overnight, the bonnet, being a tight fit around the sausage holds in in place.

Running in the wet not a problem, I suspect by the time any collected water on the sausage has been hit by the rush of air into the cylinders it is vapour and as, in rain, normal air has a pretty high humidity, then don't think it will realistically but any different to running in normal wet weather. Also by product of combusting that petrol is water so not really that much out of the ordinary.

[anthonym]

I often wonder if a K&N solution is possible, same as the BDR etc.

 

the base

https://www.efihardware.com/products/2966/CNC-Cut-Air-Filter-Base

UNITED KINGDOM

Send all product or distribution related inquiries to: uk.sales@knfilters.com 
Phone:
+44 1925-636950
Fax:
+44 1925-418948
K&N Filters (Europe) Ltd.
Unit 9 Ashville Way
Ashville, Sutton Weaver, WA7 3EZ
United Kingdom

 

I have enquired.. 01925 that's Warrington. 

 

 

 

[Drumster]

Anthony,

Re water ingress, I wouldn't worry. See my set up below

Jenvey TBs with Emerald adjustable length intakes set at 140mm for maximum torque with Pipercross dual sock filters, so they do rather stick out a bit. Never had an issue with soaked filters or water ingress in engine bay and the car has been subjected to some pretty heavy rain at times.

ETA - this is a standard x/flow bonnet (hole with rolled edge) now with Zetec inside, no fettling was needed to the hole

[Nick Bassett]

Interesting alternative solution Anthony. Certainly the SLR sausage filter isn’t particularly robust and not cheap at £100 ish... I wonder if K&N could be made to work?

So what about performance advantage... any dyno/mapping experts out there have any thoughts?

[anthonym]

Came across this pic just now, actually somewhere near Caterham France Agent in Ales.. I'm hiding under a tree, the region was being flooded and I was trying to escape. A few years ago now, just reminds me it gets wet sometimes:

[Nick Bassett]

So... nobody with any thoughts on if there is a performance advantage to be had with having an exposed (open) air filter?

[7 wonders of the world]

you need to consider, type of filter used, clearance between filter and belmouths etc there are a lot of variables only back to back runs of the rollers will tell you the true story, with the car fully dressed, nose and bonnet on etc

Did this on my K with a Bernard Scouse box, 3 back to back runs: naked, with air box and then with Pipercross cone on the end.

Filter made no difference, box dropped the peak power by about 3 BHP however showed a gain in peak tourque.

Current Duratec: we tuned the inlet length to maximise the gains which in this case left the filter external, again fitted the biggest filter possible with maximum clearances.

Test I've done before show the Pipercross offers little drop off in performance, though cotton gauze types did.

When comparing OE panel filters the OE paper ones flowed better than the K&N, however this is not a measure of the level of filtration merely flow and its affect on dyno numbers.

if your sprinting and need every last bean to help your cause maybe consider a race filter, these offer less filtration protection but offer less resistance to flow too. (ITG offer these)

[anthonym]

What I saw on the rolling road (2 Steves) was a power increase when air was directed straight at the air intake. I concluded this air was cooler, so more dense, which means more power. 
 

aiui cooler air is the purpose of all ducting systems including air boxes. So it strikes me open to the air would be the ideal. The mapping would be affected because cooler air means more dense air in the fuel air mix. Edit ofcourse my ecu has air temp sensor so maybe scratch the remap and just enjoy.

That is my reason for this thread.

aside from I just like a pair of K&Ns poking out, andthe induction noise, since my exhaust has beenthrottled

Anthony

[TomB]

Does the air temperature sensor inform the ECU to optimise for the air temperature anyway?  So any effects of cooler air are reduced by the fueling/ ignition being altered to keep it optimal/ as mapped?  

[anthonym]

I think so. sorry misread, I was hoping 
we get the benefit of cooler induction air

I have enquired...

[7 wonders of the world]

Air temp sender:

It does but in reality have little effect, you also need to be careful where and how you locate them as they are very susceptible to heat soak from the ally back plate, I drilled an oversize hole and isolated it with thick fibre washers either side, watching the numbers on the Emerald that seems to have done the job.

[TomB]

I've briefly looked into moving it, but the consensus seemed to be it had little effect.  

[anthonym]

this from Steve G:

Yes as you say, the air temp sensor does allow corrections to fuel and ignition.
However cooler intake air definitely helps produce better power.
 

which was what I observed although quite a few years ago now when he (they) was mapping my Emerald ecu.

anthony

[admaraujo]

I think the secret is to keep the foam filter oiled.

I use a motorcycle foam filter oil. The brand is Motorex. Works very well.

[revilla]

My feeling is that with a hole in the bonnet but an air filter which does not protrude through it into the fresh cold air, both the Bernoulli effect and the ram effect of air being forced into the front grille will if anything mean that air is forced outwards though the hole. I can't see why it would be drawn in. So all you will be encouraging is the flow of hot air from the radiator over the air filter. Probably not a big effect, but I can't see their being much benefit. For a filter which sticks right out into the cold air flow it would be a different story.

[anthonym]

 I can't see why it would be drawn in

the induction stroke.. does it suck round corners?

[revilla]

Well clearly the engine will be sucking air in. I guess the extent to which this overcomes any outflow of warm air to means that it's pulling in cold air would depend on a lot of factors and you would probably only find out on the rollers. Intuitively I wouldn't expect any big benefits ... probably very little difference at all ... but I could be completely wrong. There are so many things that could affect it one way or another, for example you may be creating a lot of turbulence right by the intake. When you bring the car to the UK for a refresh, will you be putting it on the rollers to tune it up? If so, could you perhaps borrow a bonnet with a similar cutout to see what happens? Mind you even then, they would need some decent fans to simulate the air flow on the road, it might not tell you much relevant to the real world.

[anthonym]

Yes that's all. possible. The dyno does involve big fans. I do have a cutout bonnet ( need to check fit). I guess an air sealing surround would stop internal air. 

[anthonym]

It willbe nice to be tuning for power instead of quietness.