Intake pipework

[drjim]

Chaps

My BMW 316 track car is nearly done, but I am not 100% happy with the air inlet situation, I have a large ebay cone filter connected to some B&Q finest Marley aluminium ducting - as used for kitchen extractor fans - with gaffer tape ensuring a good seal to the airbox inlet (which is exactly the right size), and the filter which is a little bit bigger. Ideally I suppose I need a piece of ally pipe and a 90ish degree bend, but the ducting only cost a fiver and works. Anyone else used it?

Advice??


Jim

[terence]

As all it it doing is moving air from one place to another,why not use what you have.If it works,you can change to solid wall tubing at a later date.

[1200Datto27]

Just as long as it doesn't constrict on itself under engine load it should be fine.

[drjim]

I was sort of expecting loads of "no that will be disastrous once you exceed 7000 rpm as the aluminium falls apart" type responses, but none appeared, so I'll carry on as I am. Will keep an eye on it.

Ceers

Jim

[dtype38]

I've got finest B&Q aly flexible ducting from the hole in the front of my bonnet, up over the rad and pointing at the air filter. It's stayed there in tact for more than a season's racing, so it shouldn't be a problem from that point. Only thing you really need to keep an eye on (since yours is after the filter) is you don't poke too many holes in it when your working on the car!

[phoenix]

Originally Posted by drjim

Chaps

My BMW 316 track car is nearly done, but I am not 100% happy with the air inlet situation, I have a large ebay cone filter connected to some B&Q finest Marley aluminium ducting - as used for kitchen extractor fans - with gaffer tape ensuring a good seal to the airbox inlet (which is exactly the right size), and the filter which is a little bit bigger. Ideally I suppose I need a piece of ally pipe and a 90ish degree bend, but the ducting only cost a fiver and works. Anyone else used it?

Advice??


Jim

Being pedantic, maybe, but a smooth bore pipe will have less losses due to wall friction than the corrugated pipe you are using. Some wire reinforced plastic or 'brake duct' type piping has a smoother bore and might be a better choice. If you go to 'solid' pipework, it would be better to have two 45 degree bends than one 90 degree bend to make the change in direction you want as this would also reduce the flow losses.

However, the gains to be found are really very small. But if you are looking for every 1/2 horsepower you can find, these things should not be overlooked.

[drjim]

Thanks for the thoughts chaps. For now it's more a case of getting to some trackdays for a blast at the moment, may worry about absolute HP eventually but I won't be doing any racing for the forseeable future. Even the power level as it is with a quick guess at a map for running in is plenty fast enough, once it's been run in and got a better exhaust than the current ebay standard special fitted I reckon the proper map will be sufficiently mental.

I say it's working and running in at the mo, but I was stranded at the side of the M60 yesterday, lost power suddenly, and am no longer able to hear the fuel pump whirring when I try to start - I think that's a big clue both to what's wrong now and why, fuel pumps shouldn't make the noise this one did. Fortunately I have a spare, just got to find it!