Air Filter

Tanz · Post by **Tanz** » Sun Mar 23, 2008 17:28

Decided to change the air filter today for the first time since I have owned the car. I undid the clips that hold the box on and pulled the filter out. As I did so, a black rubber seal also fell out. I assume that the rubber seal with a slit in it, fits around the metal edge of the filter - but it won't go all the way round. It is too short. Am I mising a trick here? This should be a five minute job.

Should the seal go around the outside edge?
Should it go all the way round?

Cheers,

Phil

chrisw2811 · Post by **chrisw2811** » Sun Mar 23, 2008 19:03

Phil, I did the same and the seal in the Fram box was like yours - too short to go round the edge of the metal frame of the filter

. As well as being too short, the Fram seal was also a narrower gauge so I re-used the seal that was already there. The existing seal gives a good airtight closure to the filter assembly, but the one in the Fram box seems to be incorrect. Do you still have the old seal?

Tanz · Post by **Tanz** » Sun Mar 23, 2008 21:25

Hi Chris - The new filter didn't have a seal. The seal in the picture is the one that was already on the old filter. The groove in it is a very loose fit which makes it very difficult to fit. Maybe if I contact Lotus bits they may have an old one knocking about. Need to get it sorted before Saturday. I guess air has been getting past the filter for as long as its been in,

Cheers,

Phil

Redexcel · Post by **Redexcel** » Sun Mar 23, 2008 23:57

Whether you refit the short old seal or get a new one, you must ensure that the join of the seal is along the top edge of the filter. If it was on the bottom edge, its theoretically possible that petrol could leak out on to the dizzy and cause a fire. Sorry if this is a grandma/egg sucking scenario

dpr59 · Post by **dpr59** » Mon Mar 24, 2008 10:09

Redexcel wrote:If it was on the bottom edge, its theoretically possible that petrol could leak out on to the dizzy and cause a fire. Sorry if this is a grandma/egg sucking scenario

Bloody hell.....

I'd looked at airtight seals but not considered the reverse. Scary.

I've just re-oiled mine for this year and thankfully the seal on mine is OK.

ylee coyote · Post by **ylee coyote** » Mon Mar 24, 2008 13:36

bloody hell 2...

Is it a big problem ?

the last owner took off the airbox completely and ran with open trumpets
I have fitted itg socks over the trumpets but it sounds as if I need to protect the dizzy too ?

AndyC · Post by **AndyC** » Mon Mar 24, 2008 13:59

Personally I wouldn't go with any sort of foam filter on a Lotus 9xx engine.
They can easily have a flame back situation, in a normal paper filer that has a nice long tract that's not too bad, but a foam filter mounted like the ones I've seen will simply burn. And we all know what that leads to on a Lotus.

If you're going to use a foam filter without the airbox, I suggest having a very fine metal mesh to act as a flame retardant barrier (think of the mining safety lamp).

Andy

Danny · Post by **Danny** » Mon Mar 24, 2008 14:49

Hi all, when I first started racing my car one of the first things I considerd doing was removing the lotus air filter housing and fitting an aftermarket filter, be it K&N's of pipercross etc. Having spoken to most of the perfomance filter makers at the Autosport engineering show the general opinion was that I should remain with the Lotus airbox but replace the paper panel filter with a high flow panel in its place.The reason for this is the ability to trunk cold air to the engine. I currently use a "Green Cotton" panel filter although I believe K&N make one also.When I converted the engine to injection, when the car was being set up on the rolling road we carried out power runs for the engine with the filter in place and with it removed to see if there was any drop in performance, there was no noticable drop. We did not unfortunately try the standard paper filter as a comparison. Perhaps when I get the car on the rolling road I will check this, or perhaps II remember when I next speak to Lotusbits I will sugest this to Mike for future reference. He might have done this already and have some knowledge of power drops.

Hope this is of interest

Regards Dan (racingeclat22)

Redexcel · Post by **Redexcel** » Mon Mar 24, 2008 15:14

AndyC wrote:Personally I wouldn't go with any sort of foam filter on a Lotus 9xx engine.
They can easily have a flame back situation, in a normal paper filer that has a nice long tract that's not too bad, but a foam filter mounted like the ones I've seen will simply burn. And we all know what that leads to on a Lotus.

Andy

Hear, Hear.
The standard airbox is made of special flame retardent fibreglass for a good reason.

This is also why the 'two prods on the throttle' cold start procedure is risky. The accelerator pump nozzles are much closer to the bellmouths of the carbs on the Dellorto than the Weber, with the result that splashback into the air filter can occur. You now have neat petrol in the air filter box or on the filter. Couple this with the fact that a backfire is highly likely with a cold engine and a weak mixture and you can see the enhanced fire risk. Always, always, use the choke on a car with Dellortos.
People think that because you can do it the 'two prods' way with Webers,its OK with Dellortos. You might just find out that it isn't.
If you find your air filter is burnt next time you look at it, you've had a lucky escape.

dpr59 · Post by **dpr59** » Mon Mar 24, 2008 16:41

Redexcel wrote:
AndyC wrote:
This is also why the 'two prods on the throttle' cold start procedure is risky. The accelerator pump nozles are much closer to the bellmouths of the carbs on the Dellorto than the Weber, with the result that splashback into the air filter can occur.

If you find your air filter is burnt next time you look at it, you've had a lucky escape.

Mental note.
Reassess start process.
OK, only one press of the accerator, however I've been doing this since I got the car.

ylee coyote · Post by **ylee coyote** » Mon Mar 24, 2008 18:36

interesting
mine starts on no presses first turn....(dellorto's)

looks as if I am going to fab up some sort of cover/airbox..just to be on the safe side

Tanz · Post by **Tanz** » Mon Mar 24, 2008 22:43

http://cgi.ebay.co.uk/K-N-AIR-FILTER-LO ... dZViewItem

Hi Danny, is this the kind of filter you mean? May be I will get one next time I change it,

Cheers,

Phil

Tanz · Post by **Tanz** » Mon Mar 24, 2008 22:48

For the record - I just pull out the choke fully, turn the key and it starts. Tick over is about 700RPM. As soon as I touch the accelerator the revs shoot right up and I have to push the choke half way back in.

Cheers,

Phil

Tanz · Post by **Tanz** » Mon Mar 24, 2008 23:16

I have fitted the 'short' seal by gluing one end, letting it dry, then stretched the seal all the way round and glued the other end and clamped it with molgrips until dry. Just hope I can get it off next time I change it

I did this before I read the posts above on the fire risk. The joint is on the side so should be OK

Cheers,

Phil

Wootan · Post by **Wootan** » Tue Mar 25, 2008 15:41

The seal had broken on mine aswell, just to let you know you can buy a new one from S J for under a £10.

Thanks

Paul

The Lotus Grand Tourers

Air Filter

Air Filter

foam filers - erm

air filter

Re: foam filers - erm

Re: foam filers - erm