Improving Air Flow Into Engine.

[Atari Boy 11]

Okay, an interesting point. I am not suggesting you are wrong Peter and Rich, but my logic would suggest that if cold ‘clean’ air was being pushed into an area via a ram then any warm 'ambient' air from the engine bay would be forced away. Is this not correct?

 

Anyway excuse the drawing nut would something like this mock up be advantageous? Image it without the battery there though.

 

[GilesW 41]

The red pug looks a good idea - albeit you are actually loosing power by running socks - bin them and get a ITG sausage etc. Mate of mine proved this on his escort - back to back on the rolling road he lost 20bhp with them on, so it's not just a myth (for those about to challange!).

[Paul_13 212 1 Cars]

20bhp! Blimey.

 

Not doubting you mate, socks don't have a good reputation on here

[EdCherry 34 1 Cars]

Where you positioned the 'block' by the battery would be a bad idea in my opinion, the air needs to flow through and around the filter, by putting a solid object behind it air will want to move elsewhere.

[Atari Boy 11]

That would imply that my plan to make a fibreglass headlamp air dam is good idea as it is feeding lots of cold air to the filter, yes ?

I hope to be able to get it made before the SCA Rolling Road meet so I might be able to get some with and without figures to prove one way or another.

[EdCherry 34 1 Cars]

Possibly. Your also creating alot of turbulence around the filter which could also disturb airflow. This is why the whole subject is so difficult to get definitive gains.

[mr_exe 1]

I'd say a point here ^^, is not necessarily the channelling of air into the filter/carbs/ITBs, but the shielding of engine bay heat from entering the inlet tract.

 

Indeed I was pondering about a heat shield next, as the underbonnet temperatures seem rather high and I wonder if heat soak was affecting the temperature of the air entering the filter. I did have a quick mess about making a carboard template with a view to getting one made and also using it to fasten the afm to.

[DaveW 6]

Wonder how good that box one worked...

[Henry Yorke 269 3 Cars]

The inlet tends to be a tuned length too so you can asjust your power delivery by the length of your tube. Ferrari 360 GT cars had to reduce their inlet tract length and lost their competitive edge. I knew of someone in the Alfa 155 club that made a nice shiney stainless long one and his car lost peak power but gained torque (or vice versa). Do flap based AFMs respond well to forcing air through them? (thinking of the TT set up here)? Will it upset the throttle body?

 

One of the other things to consider is getting air out of your engine bay to reduce the underbonnet ambient temperature, so possibly vent the rear. Though the overall effect will be minimal on the cars performance so not worth significant effort

[Rippthrough 98]

One of the other things to consider is getting air out of your engine bay to reduce the underbonnet ambient temperature, so possibly vent the rear. Though the overall effect will be minimal on the cars performance so not worth significant effort

 

Not so much a performance gain, no, but keeping the leads/coil packs/wiring, etc, etc, slightly cooler can give big gains in lifespan, so it's worth considering....

[engine killer 5]

The red pug looks a good idea - albeit you are actually loosing power by running socks - bin them and get a ITG sausage etc. Mate of mine proved this on his escort - back to back on the rolling road he lost 20bhp with them on, so it's not just a myth (for those about to challange!).

 

I didn't think that the power lost by running socks was very significant until I have the pipercross sausage filter mounted.

 

The difference is HUGE!

 

ps. I cannot upload anymore pict, it says "Attachment space used 10.01MB of 10MB" & "Upload failed. The file was larger than the available space" but the file I am going to upload is only about 100k. Can somebody help?

[MrG 3]

personally I'd prefer to lose the driving lamp and use that opening to feed the air from there into the location, but that idea of altering the headlamp is great.

Jonny, if you put fibreglass items on, it'll look like a stock car!

[silent_running 0]

Well I don't know much about 205's except yours Jonny, but I have gone through every stage of inlet tract and engine bay layout on the Clio and also on the Subaru. Plus actually done pressure testing, ducted airflow to intercoolers etc. A lot of the general princinples can be found in 'Four Stroke Performance Tuning' by A. Graham Bell. But essentially it works like this. Air pressure flows from high to low. The engine bay of a car is a relatively high pressure area as huge amounts of air are coming through the rad -that is relative to the front of the car where there high speed air is entering. All of this air does exit via the underside of the bay and wheelarches if they are open. Because of the complex aerodynamics of any engine bay the only certainty is that that unless you have a sealed airbox of some kind with your filter enclosed, fed by a ram scoop/NACA duct/other inlet of some kind, that engine bay heat will get back into the inlet tract and that your 'cold air feed' will tend not to find its way to the filter as it has no particular reason to do so.

 

For example, the often seen 'bit of two inch hose' pointing in the vague direction of a cone filter is about as likely to feed cold air into your inlet cone as you are to dilute the sea by pissing in it. When your car is only going to be running the mod for track day use, something like the headlamp conversion is probably a goer as if you're on the move all the time that will most likely see greater fresh air flow through that gap because of its decent size in comparison to say the rad grille and the whole engine bay itself. I'd be happier with a proper duct though as cold air doesn't just find its way into an engine bay by accident, it needs a bit of hand-holding.

 

Best thing if money and time is no object would be to fab up the biggest air box you can around a massive cone filter in your new engine bay void, connect and seal this to a headlight sized inlet duct. As someone earlier pointed out though, your restriction will be your throttle body and ultimately how well your engine breathes.

[andyjstone 5]

Do anything you feel is worth doing, and cheap. Dont go expecting huge gains or masses amount of difference, and I certainly wouldn't chuck aload of money at it, unless you really have to.

 

Why is that? When I load had mine on a rolling road, we did some tests with the filter on and off and it was getting 7bhp more with the filter off, I'm guessing that the difference wouldn't be so great when the car was moving, but surely a bigger/better filter and some means of getting the air to it is potentially going to make a significant power difference?

[EdCherry 34 1 Cars]

For you engine on standalone managment etc it is worth going to the lengths, but on a standard management 2.0 8v engine your chassing small figures, for lots of time/effort which without back to back testing with a datum is pretty pointless.

 

You need to figure a way of testing these sorts of things, and have a datum to work from and to improve on.

[andyjstone 5]

You need to figure a way of testing these sorts of things, and have a datum to work from and to improve on.

 

Yes, I've been thinking about that, but I can't really see any way other than numerous trips to the rolling road at enormous expense!!

 

I need to sort mine this year and I plan to drop the rad as a start, but it's what to do after that - do I just put on a bigger filter or by the looks of what other people are doing add some kind of duct arrangment around the slam panel - as I said you really need to spend a day on the RR with a box full of bits of plastic and tube

[EdCherry 34 1 Cars]

Well there is a few ways you can test it, but as far as I can see on a saloon car it will be pretty hard.

 

Im currently working on improving a nose/crash box of a single seater and the cooling system into the sidepods of the same car. Were just going through a few tests at the minute before we start making changes and using a large fan, some welding wire with a fibre trail to see where the airflow is going/what its doing and a anemometer strapped into different places of the sidepod/behind the radiator.

 

Gives you a general idea of where or what needs improving and you can go from there making mock ups/test pieces before spending all your hard earned shiny gold coins on the full thing to find it is worse than before.

[andyjstone 5]

Well there is a few ways you can test it, but as far as I can see on a saloon car it will be pretty hard.

 

Im currently working on improving a nose/crash box of a single seater and the cooling system into the sidepods of the same car. Were just going through a few tests at the minute before we start making changes and using a large fan, some welding wire with a fibre trail to see where the airflow is going/what its doing and a anemometer strapped into different places of the sidepod/behind the radiator.

 

Gives you a general idea of where or what needs improving and you can go from there making mock ups/test pieces before spending all your hard earned shiny gold coins on the full thing to find it is worse than before.

 

That sounds interesting, I also have some involvement with a single seater and on that the air currently goes in the side, but currently looking at closing it in to duct the air through to the engine (Kawasaki 1200), similar to what they do on the Radical. Be interesting to get the results of your tests??

[Sandy 189]

If you have a 106/205/306/309 etc with an aftermarket ECU, with a laptop connected and go up the road, you'll pretty much always see the inlet air temp drop to about 5-10C over ambient unless the air is literally being drawn off the back of the rad or exhaust manifold, even with rear facing induction. Cold air feeds look good on the rollers but seem to do next to nothing once moving on the road from what I've observed.

[andyjstone 5]

If you have a 106/205/306/309 etc with an aftermarket ECU, with a laptop connected and go up the road, you'll pretty much always see the inlet air temp drop to about 5-10C over ambient unless the air is literally being drawn off the back of the rad or exhaust manifold, even with rear facing induction. Cold air feeds look good on the rollers but seem to do next to nothing once moving on the road from what I've observed.

 

Yes, that's the other problem, air flow on the real road is completely different to that on the rolling road - need a wind tunnel as well.

[SurGie 54]

- need a wind tunnel as well

 

as a very large fan

[andyjstone 5]

as a very large fan

 

Oh, I thought they came as one, that's where I'm going wrong

[Atari Boy 11]

I appreciate that there is no definitive way to improve things and equally I am chasing very small potential gains that chances are I will never notice but it interesting anyway.

I agree also that what one can do on a set of rollers is different to what one will actually see on the road.

Thanks for the comments, interesting stuff.

[Paul Smith 0]

Is there anyway you could shorten the distance between the inlet and the cone, just enough to bring some of the cone in front of the grill for more direct air flow? From what I can see there is minimal amounts you could shorten this by.

 

Also Is there a bigger air flow sensor that is a straight swap that works? Some cars are lucky enough to have options like this?