Making an eaton quiet off boost

[The Duck]

Hi guys,
I would like some advice if that is ok?
As some of you know an eatoned polo makes quite a racket which is not a problem when driving hard but does get irritating when cruising around.
So I want to design a way to make them quieter without moving the TB.

This means when off boost I need a 2nd throttle body (75mm) in the inlet to the charger. I can pick up one of these for £100 from the states.
So now I need some way of controlling an actuator that is linked to the throttle. I do not want to do this mechanically as I do not want to put additional load on the throttle cable. (Although I may try this first just to see)

What I really want to do is put a position sensor on the throttle and be able to control the position of a solenoid that is connected to the throttle butterfly.
Can anyone give me some pointers of how to acheive this please?!!
Does anyone make a solenoid I can use? Does anyone know of a suitable sensor?
(Please keep it constructive, I don't need doubters!)

Thanks

Duck

 

[Robin]

bin the eaton.

[DKnight]

doubters 1, constructive 0   lol

i would add some input but its all above me!

[Yoof]

Electromagnetic clutch pulley from a Merc- they used to stop the charger from turning at idle as it couldn't be quietened down much.

If you can't find one of these, PAS pumps, Air Con Compressors etc will all use electromagnetic clutches in systems where speed needs to be limited.

If you want to do it your way I presume you'd want to drive a stepper motor via a 0-5v input tkaen from your current pedal/throttle position?

[Andy]

If you're handy with a soldering iron and an RS catalogue you could probably make a fairly rudimentary electronic controller for the additional throttle based on a PIC processor. I'd mount a potentiometer on the pedal box and derive your load signal from that. Alternatively, you may wish to use a MAP sensor input to give you an approximation to engine load?

Look at throttle bodies from newer drive-by-wire (DBW) vehicles to find a suitable one with stepper motor control for the throttle. Hook that up to your PIC circuit and away you go.

It'll take quite a bit of fiddling to calibrate your new throttle body opening angle to pedal position/engine load though.

If you can find a stepper motor controlled TB that has a mechanically adjustable stop (or modifyable idle bypass setup), you could make a very crude on/off system...

Get a normally-open pressure switch (Aquamist sell them) and set it to close at Xpsi (X might be atmospheric, or slightly less). Above that pressure the switch will be closed, and you could use it to supply a permanent 5V to the TB to hold it open. Below that pressure the switch will be open, and you'll have to adjust the TB (either through idle bypass, or throttle stop) so that in its inactive state it passes enough air to keep the engine running.

Main problem I see with the crude on/off setup is that most DBW TBs are PWM-controlled, so giving it a permanent 5V might burn the throttle actuator out eventually.

[lance]

all seams like a mass of work, id just run a double throttle cable, webber sell them.

[The Duck]

Good work Robin, a well rounded opinion.

Hi Yoof mate, I do like the idea of an EMC pulley and have considered it in the past. However do you think it would be viable to get one to fit on one of the PSD conversions inside a 68mm pulley? I could always run a higher belt speed and use larger pulleys all round. Have you any photos/links to an EMC pulley?

Yup I would like to run something like the stepper motor idea but I was after something I could hijack rather than have to do some development from scratch. Soldering comes easy to ducks...just gotta watch out for the damn pond water. Stuff gets everywhere.

Andy, I like the idea of getting a DBW TB and didn't think of that. I have thought of pressure controlled actuation or electronics but I can not see an easy way to avoid sudden intake pressure changes.

Lance, gives me something to think about though! I will look at the double throttle cable as a starter as I wish to try out the system mechanically before going further!

If you've been out in a cooper S you will know that the eaton is pretty quiet if done right. The trick is to get it recirculating in rarefied air to reduce the pressure wave out through the cone filter. My idea is to give the inlet tract to the 2nd air filter (small one) a good length duct and some noise isolation.

Thanks for the input guys I will keep populating the drawing board in my head with all your ideas!

Duck. 

[Dan]

Is there any way you could use an airbox and fit relevant baffles etc to quieten it down ? Also maybe recirculate air into the air box too ?

[Yoof]

If you're still using a cone filter you've not got much chance, they're just bloody noisey generally. Box it off and you'll find it's reduced alot, mine sits in the front wing in an ally box fed by the foglight, and it's alot quieter than in the engine bay.

You could step up your charger pulley size to compensate for the clutch system and increase the crank pulley size, but you'd also have to increase the size of the alternator pulley so you don't overspeed that.

I thought Mini had their throttle body upstream of the charger too?

[lance]

TB on a mini is pre charge.

mad max spec should do it!

[LiamM45]

Surely when you did the conversion you realised it would be noisy?

Mine is very intrusive but keep it below 70 on a run and it's fine. With a stereo I don't think you'd really notice it, but some boost gauges live where my head unit used to live.

Mine is a daily driver (when it actually works) and other than a bit of a ringing in my ears for a while after my journey it's fine.