18 replies to this topic

[Dusky]

Hi.

 

Next year in march I'll be starting my carreer in Belgian slalom.

TO compete in my division it is forbidden to use non standard air filters.

So I will have to ditch my K&N cones. But what are my options? Were there coopers that came with the Chrome pancake filters? if so :

can someone 'prove' this with pictures/brochures,...?

 

Or is the metal airbox the only real standard filter? What would be the best filter element in that case? Anything I can do to improve the flow with the metal box?

Will I need alot of adjustment when comming from cones?

 

I could try another division, but then I'd need a rollcage, safety harness,.... lots of expensive things... although finding a metal airbox isn't easy here in Belgium  either.

SO I'm hoping someone there are other options

 

 

All the best

Diego

 

 

[jaydee]

Its actually depending if they want it to be original for the car you have (mayfair, cooper etc), or you are allowed to use original equipment parts fitted to another mini. 

 

First coopers came out with some sort of pancake filters, one of them had an intake for the crankcase breather. These filters wont be easy to find though.

Cooper conversions were fitted with KN pancakes and its plenty of JCG brochures over the web.

Whatever you do, fit stub stacks inside the filters. (but this wont be possible if fitting the metal airbox)

[Dusky]

Its actually depending if they want it to be original for the car you have (mayfair, cooper etc), or you are allowed to use original equipment parts fitted to another mini. 

 

First coopers came out with some sort of pancake filters, one of them had an intake for the crankcase breather. These filters wont be easy to find though.

Cooper conversions were fitted with KN pancakes and its plenty of JCG brochures over the web.

Whatever you do, fit stub stacks inside the filters. (but this wont be possible if fitting the metal airbox)

I'm only allowed to use things that came with a cooper from factory, I do have K&n Cones with stubstacks now but I'm not allowed to use those ( sadly).

 

Do you happen to have a link to one of those brochures? 

 

Would a airbox lose lots of bhp? Because the most original looking is probably an airbox, although I think I can use a pancake if I have enough documentation about them being fitted by the factory......

[jaydee]

Beware minis are slow anyway..but the metal airbox is as restrictive as a rag clogging up the manifolds..try one and see how it will strangle your carbs.

Out of the factory or out of the authorized dealer will make a HUGE difference in the specification

And if your car is produced between 71 and 90 cant be a factory cooper anyway, but it can be built to a cooper conversion spec, a vortz spec or whatever, you need to walk on the borderline of the regulations

If a picture like this might be of some help, theres a JCG page on FB full of documentation

[timmy850]

The 997 Coopers came with steel ribbon pancake filters like the set in this link. They were replaced by the air box after a while. I'll try to find you a better picture...
http://morrisminicooper.com/2.html

Graham Russell's testing suggested the standard airbox was actually pretty good. They would be fitted with some KN filters (two of the HS2 filters). This is what I'll be doing for my engine
http://russellengine...small-bore-pt3/

Edit: press photo

Edited by timmy850, 04 November 2014 - 12:24 PM.

[timmy850]

Sales brochures too!

http://www.minipassi...er 1963 997.pdf
http://www.minipassi...er 997 1962.pdf

[Dusky]

It is factory, sadly. So I will need to use the metal housing it seems.

 

Beware minis are slow anyway..but the metal airbox is as restrictive as a rag clogging up the manifolds..try one and see how it will strangle your carbs.

Out of the factory or out of the authorized dealer will make a HUGE difference in the specification

And if your car is produced between 71 and 90 cant be a factory cooper anyway, but it can be built to a cooper conversion spec, a vortz spec or whatever, you need to walk on the borderline of the regulations

If a picture like this might be of some help, theres a JCG page on FB full of documentation

 

 

 

The 997 Coopers came with steel ribbon pancake filters like the set in this link. They were replaced by the air box after a while. I'll try to find you a better picture...
http://morrisminicooper.com/2.html

Graham Russell's testing suggested the standard airbox was actually pretty good. They would be fitted with some KN filters (two of the HS2 filters). This is what I'll be doing for my engine
http://russellengine...small-bore-pt3/

Edit: press photo

I can't really find anything about the filter on that page, am I really looking that bad?

 

Cheers! and thanks for you rinput guys!

[carbon]

Cooper metal airbox is not that bad. Main area to work on is the inlet 'trumpet' into the airbox which can usefully be shortened to get it away from the exhaust manifold, and also try to get as large a radius as possible on it in keeping with the regs. If you're allowed to use K&N filters inside the box then go for these.

 

I think this set-up will flow much better than the metal 'pan-scrubber' filters, and your engine is also likely to suffer a lot less from bore wear if you use decent filters.

[Dusky]

Would attaching a cold air duct to the trumpet work?
Will be using k&N element in it :)

[jaydee]

Its the size of the inlet that provides the restriction

And the other restriction being the two horrible elbows from the the carb 

[jaydee]

As long as blueprinting is allowed and they wont check the internals you could give a go at modifying the manifold and the butteflies as per vizard, it may add velocity to the intake charge

Pay a lot of attention to carb balancing under load, i've seen that the lack of balance between the two carbs can cause a loss of dynamic compression across the two ports, resulting in a loss of power at top end

Edited by jaydee, 04 November 2014 - 10:41 PM.

[timmy850]

Keith Calver did a test on a 998 using a K&N cone filter, and a K&N in the standard box. I'm not sure how well this applies to twin HS2's, but I'd think a similar theory would apply..

 

http://www.minimania...les.cfm?id=1288

 

 

 

the cone filter actually made less power. But why?

Experience and a great deal of testing over the years suggest the answer is in the way the standard filter case is designed. The A-series engine with its Siamese 5-port design causes some very powerful shockwaves within the induction system. I believe the elbow on the back of the carb and the volume of the filter case dissipates these very effectively. The cone/pancake type filters reflect these shockwaves back into the induction system, causing induction pulse problems.

 

 

 

[Dusky]

As long as blueprinting is allowed and they wont check the internals you could give a go at modifying the manifold and the butteflies as per vizard, it may add velocity to the intake charge

Pay a lot of attention to carb balancing under load, i've seen that the lack of balance between the two carbs can cause a loss of dynamic compression across the two ports, resulting in a loss of power at top end

I already 'vizardised' the throttle shafts etc :) 

They do not really inspect the engine very carefully, they 'just' give it a quick look, so as long as it looks stock everything is fine.

WOuld drilling holes in the backside ( so it isn't really visible) of the airbox work to? I know these are usually drilled in the front...

 

Carb balancing under load is probably done at the rollingroad? They are ( now) balanced @ 3K rpm

 

 

Cheers

[timmy850]

Here are some photos of a standard airbox. The throttle body on the HS2 carbs are 32mm (1 1/2") in diameter. The inlet pipe is about 48mm in diameter

And the holes that the carbs attach to are about 51mm in diameter. Keep in mind that the elbows have a slightly smaller diameter as they slot inside these holes.


My standard HS4 air filter housing (like in the article) has an inlet pipe diameter of about 41mm, compared to the 39mm (1 1/2") throttle size, so it is a bit on the small size compared to the carb.

I'm not sure if you'd see the same gains drilling holes in a twin carb housing, but seeing that they are so expensive I'm definitely not going to try it with mine!

[Dusky]

Here are some photos of a standard airbox. The throttle body on the HS2 carbs are 32mm (1 1/2") in diameter. The inlet pipe is about 48mm in diameter

And the holes that the carbs attach to are about 51mm in diameter. Keep in mind that the elbows have a slightly smaller diameter as they slot inside these holes.


My standard HS4 air filter housing (like in the article) has an inlet pipe diameter of about 41mm, compared to the 39mm (1 1/2") throttle size, so it is a bit on the small size compared to the carb.

I'm not sure if you'd see the same gains drilling holes in a twin carb housing, but seeing that they are so expensive I'm definitely not going to try it with mine!

 

Thanks for the measurements!

 

So basically the ( I think its called like this in english) the cross-sectional area of 1 carb's throttle body is 3215.36 mm, the cross sectional area of  the air filter pipe is 7234.56 mm

SO basically the inlet pipe should be more than adequate for feeding 2 carbs ( 6430.72 mm if they'd breathe toghether)  ).

As Keith calver experimented with the standard HS4 filterbox, eh drilled holes because the inlet nozzle was a bit smaller( being restrictive), so we probably won't see any gains ( except noise maybe ) by adding extra holes..

It's also the same housing as used on a cooper S, or not?

 

I think I'll ' experiment' by adding a cold air duct pipe to the inlet pipe of the filter though :) 

 

cheers!