Discussion
I can do a nice line in bodywork cutouts. I can even do a mesh grille over them, to stop small children from being ingested by the engine.
Alex, Stig's air filter is a specially designed slimline jobby which actually allows more air in than a standard pattern on, as it allows air to enter at the top, where there would normally be a steel plate.
I think it's just because he's made a bit of a dogs knob of putting the car together myself.
James
Alex, Stig's air filter is a specially designed slimline jobby which actually allows more air in than a standard pattern on, as it allows air to enter at the top, where there would normally be a steel plate.
I think it's just because he's made a bit of a dogs knob of putting the car together myself.
James
Alex said: Stig, I notice that because of the extra height due to the supercharger you have had to use a shorter-than-average filter. Could that be the problem? An engine generating that much power is having to suck in an AWFUL lot of air.
It should make no difference having the shorter filter as I use an XStream filter top. My filter surface area is actually larger than a 6" high 'standard' unit. Also, as the supercharger is mechanically forcing air in (albeit not a lot at tickover), I would think that it's more efficient at getting air in than a normal carb and air cools under pressure (although it's better at doing this when forced through a small hole not a ruddy great 4-barrel carb).
Air isn't like treacle, it's pretty nifty at finding it's way round obstacles!
I think it's got more to do with the 'quality' and density of air that's affecting the tickover.
stig said:It should make no difference having the shorter filter as I use an XStream filter top. My filter surface area is actually larger than a 6" high 'standard' unit. Also, as the supercharger is mechanically forcing air in (albeit not a lot at tickover), I would think that it's more efficient at getting air in than a normal carb and air cools under pressure (although it's better at doing this when forced through a small hole not a ruddy great 4-barrel carb).
When I went to school, air became hotter under pressure. Cold air is more dense, but when you forcibly pressurise air, it heats up.
I would guess that the problem is mostly to do with the air intake picking up very hot and smelly air from the engine compartment, rather than the nice stuff that's just on the other side of the canopy. You mentioned that you see this when the car is ticking over, so you aren't going to be getting any sort of airflow being forced into that nice big hole in the canopy.
I would suggest fabricating some sort of air box that will give you a reasonable seal against the canopy, and prevent you from pulling in hot air from above the manifolds.
James
james said:
stig said:It should make no difference having the shorter filter as I use an XStream filter top. My filter surface area is actually larger than a 6" high 'standard' unit. Also, as the supercharger is mechanically forcing air in (albeit not a lot at tickover), I would think that it's more efficient at getting air in than a normal carb and air cools under pressure (although it's better at doing this when forced through a small hole not a ruddy great 4-barrel carb).
When I went to school, air became hotter under pressure. Cold air is more dense, but when you forcibly pressurise air, it heats up.
I would guess that the problem is mostly to do with the air intake picking up very hot and smelly air from the engine compartment, rather than the nice stuff that's just on the other side of the canopy. You mentioned that you see this when the car is ticking over, so you aren't going to be getting any sort of airflow being forced into that nice big hole in the canopy.
I would suggest fabricating some sort of air box that will give you a reasonable seal against the canopy, and prevent you from pulling in hot air from above the manifolds.
James
Doh! I knew I should've gone to school
I was confusing the effect on temperature when DE-pressurising a gas, for instance, discharging an aerosol or deflating a tyre. It would be interesting to see what effect a supercharger has on the air temperature for the charge that enters the inlet manifold - but that's WAY beyond my technical knowledge (then again, so's torquing wheel nuts).
Either way, the supercharger won't make much difference at idle as the vacuum bypass is open.
As you say, the downside is that the proximity to the canopy makes it suck more hot air from below which is rising and therefore pushing the dense air out. The flipside of this is that as soon as you're on the move, the scoop directs cool air straight into the filter.
I'd rather have the power when I'm on the go than standing still
Stig. You might want to invest in a simple, dual readout, LCD thermometer which will show the engine bay temperature as well as the temperature inside the cockpit. RS do a range of these (www.rswww.com) and they are not expensive (£15 to £30). Most are battery operated so no wiring is involved. Have a look at Stock Numbers 427-411, 231-7619 and 231-7569. I have one mounted on the dash which sounds an alarm when the engine bay temperature exceeds 50 C. When I was building my car, I thought that the underbonnet temperature would get quite high in warm weather or when stationary in traffic, so I decided to fit two 9 inch extraction fans either side of the gearbox. These really do move a lot of hot air. Just a thought.
Steve_D said: Stig
Try putting a household electric fan down beside the gearbox blowing out the back. That should help by pulling cooler air into the roof vent.
If it works then a 12V rad fan switched by a throttle position switch should do it.
Steve
I was just about to recomend a small fan (round radiator style) fixed on or near the exhaust screen to remove the air from the engin bay out the rear. You could have a switch turn it on and off or just have it run off the ignition.
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