Air intake

[George K]

Looking at the air intake behind the n/s headlamp it appears to have an external bellows connected to the inlet manifold by a vacuum pipe. Presumably this is to do with emissions? Does anyone know exactly how it works and what happens if the pipe is disconnected, as I would guess is the case when an after market filter system is fitted.

The pipe from the standard filter box to this section appears smaller diameter than the rest of the system and so potentially could cause a restriction. I realise that this is done to compensate for the pressure drop across the filter as it gets dirty, but I am sure that most Trophy owners will keep their filters nice and clean, so this belt and braces approach should not be necessary.

 

[OliS]

I had a look at the airbox, and I can see the pipe that you are refering to, I think it is some sort of breather pipe, but I am not sure what it is actually doing! Some aftermarket kits keep this breather in place have a look at http://www.hillpower.co.uk/newclio172.html.

The pipework for the air intake does indeed seem rather restrictive, both on the inlet to the airbox and from the airbox to inlet manifold, I guess the best thing to do is junk the whole lot and fit an induction kit, but then the warranty is out of the window, and that is something that I cannot risk. For the daddy of induction kits, check out http://www.itgairfilters.com/maxogensys ... gen&ID=19#.

 

[ducks butt]

That will be one for when the warranty has expired. I'm sure someone has it fitted on here.

 

[George K]

Olis, Hullo again - I doubt if it is a breather, much too small in dimater, this sort of pipe is normally used for vacuum/pressure connections to gauges or mechanisms of some sort.

 

[Maverick]

Do you mean the pipe from the elbow on the inlet manifold? That is a crank case breather pipe - it simpler breathes the oily hot air back into the intake for the sake of emissions. You could get rid of it, but you'd have to fit some kind of catch tank or filter.

Or the pipe that is a few mm in dia that heads off towards the passenger wheel arch area? This pipe is connected to a solenoid which actuates the accoustic butterfly valve found at the bottom of the air feed near the horn.

It basically restricts the air flow at low revs (crank case vacuum?) to improve torque, and opens up at higher revs for more power.

I believe this is a major reasopn why most people who fit induction kits without a remap on the F4R experience a loss of torque low down in the rev range.

Hope this helps.

 

[George K]

Maverick, I do mean the latter and in view of your explanation am sure that your assessment of after market kits is right. Many thanks

 

[George K]

Maverick, BTW I was thinking about your explanation and interestingly enough the Mazda MX5 which we have just sold to make way for the Trophy had a canister tee-ed off the pipe halfway between the butterfly and the AFM and this apparently served the same purpose, it was known as a heimholtz chamber and not only changed the resonant frequency at certain rpm, specifcally to increase torque mid range, but also damped out the pulsations at idle so that the AFM could produce a stable tickover.

Going on your explanation it is going to be difficult to increase the diameter of the air intake without dispensing with this facility - has anyone any ideas, know how much the torque is affected, or whether it can be recovered by a good re-map?

Regards