4722 replies to this topic

[The Batman]

I apologise I struggle to read through all the crap you write

Edited by The Batman, 23 November 2016 - 09:37 PM.

[Nev]

I apologise I struggle to read through all the crap you write

 

If you don't want to read my "crap" that's fine, but then please don't ask lazy questions about it because you haven't read it.

Edited by Nev, 23 November 2016 - 09:44 PM.

[smiley]

[The Batman]

I figured you like to hear yourself talk so was giving you another chance to talk about this awesome design Didn't mean for you to get your knickers in a twist

[Nev]

Think steam ship paddle?

 

How would you attach the "paddle wheel" to the spindle though, so it could take the mild torque (maybe a couple of ft/lb) and also the vibrations and heat ?

 

Bear in mind the "paddle wheel" has to be removable.

 

 

Edited by Nev, 23 November 2016 - 10:21 PM.

[fezzasus]

 

That's the convention. Not sure why you've offset the butterfly axis as you won't be able to fully open

Edited by fezzasus, 23 November 2016 - 10:32 PM.

[Ormes]

Bear in mind the "paddle wheel" has to be removable.

  This is where it falls down as welding in the same way as the butterfly is the obvious method. You could cut the spindle into two sections, drilled down the centre, tap and fix in a similar way to a toe link bar... but the diameter of the spindle may be too small to achieve this?

[Ormes]

Or... another idiot idea Cut a threat into the spindle, weld a few bolts to the "paddle", wind it onto the spindle and set the position with bolts that are also wound onto the spindle, again in a similar way to a toe link/TRE. This would also allow you to adjust it once fitted if that is required.

[Jocke_D]

If you place the valve outside the silencer together with the 180 bend you could use one of fezz' off the shelf options.

You would loose some interior volume but you wouldn't have to worry about the spindle or getting it gas tight.

 

I'm following this build with great interest as I'm also planning a new exhaust for my SC this winter. Since I'm originally a bike guy I seem to try to incorporate bike solutions to my car so will probably not look like yours though. We'll see what happens

[Nev]

Or... another idiot idea Cut a threat into the spindle, weld a few bolts to the "paddle", wind it onto the spindle and set the position with bolts that are also wound onto the spindle, again in a similar way to a toe link/TRE. This would also allow you to adjust it once fitted if that is required.

 

Yep, thanks Alex, your two ideas are virtually the same as mine at the moment:

 

1. cut a thread onto the spindle end for a lock nut that will secure the "paddle wheel" onto the end.

 

2. drill a hole in the end of the spindle for a small bolt, then square off the spindle end such that the 90 degree "paddle wheel" (also with sqare locating hole then fits onto the spindle and is held on with the tiny bolt.

Edited by Nev, 24 November 2016 - 09:14 AM.

[Nev]

If you place the valve outside the silencer together with the 180 bend you could use one of fezz' off the shelf options.

You would loose some interior volume but you wouldn't have to worry about the spindle or getting it gas tight.

 

I'm following this build with great interest as I'm also planning a new exhaust for my SC this winter. Since I'm originally a bike guy I seem to try to incorporate bike solutions to my car so will probably not look like yours though. We'll see what happens

 

I've seen those valves, but as you have noticed there are problems with them:

 

1. They have to be external to the silencer, as the spring and rubber diaphragm would fail with the heat.

2. Nobody I've seen makes one in 89mm diameter, so you can't buy one anyway.

 

Thanks for the kind words, I will try and measure the dB results from each step of the design, so hopefully it will give you a good clue about which of the design features works the worst/best.

 

Edited by Nev, 24 November 2016 - 09:19 AM.

[Nev]

 

That's the convention. Not sure why you've offset the butterfly axis as you won't be able to fully open

 

I'm not sure why you think the butterfly wont open fully when the pictures clearly show it does and my write up even explains the ovaloid shape to achieve this.

 

The spindle offset is for pressure load balancing reasons, same as on some aeroplane rudders etc.

Edited by Nev, 24 November 2016 - 10:14 AM.

[Mopeytitan]

https://www.ebay.com/itm/201723671660 89mm exhaust flap

[Nev]

https://www.ebay.com/itm/201723671660 89mm exhaust flap

 

Thanks, right size, but it would have to be externally mounted, also adjusting these things would require finding difference springs to have control of when exactly the diaphragm would open.

 

Good price too.

Edited by Nev, 24 November 2016 - 11:55 AM.

[Mopeytitan]

You could connect it so a solenoid and be switch operated

[mbes2]

New Exhaust pipe work has been seen being shipped to Nevs address

 

[Nev]

You could connect it so a solenoid and be switch operated

 

On/off function isn't so good really, I'd prefer a slow ramp rate on the noise and back pressure, rather than a sudden increase/decrease.

Edited by Nev, 24 November 2016 - 02:11 PM.

[CocoPops]

So you're relying on pressure to open the valve?
Whilst sat in an IT training course, I was having a sketch as you do and can't see how th valve would open?

Surely the pressure at bottom of valve will try and push it open but the rest of th pressure pushing at the top of the butterfly valve will be trying to close the valve?
Hence why others use external opening forces right? Or it's quite possible that I'm missing something.

[fezzasus]

 

 

That's the convention. Not sure why you've offset the butterfly axis as you won't be able to fully open

 

I'm not sure why you think the butterfly wont open fully when the pictures clearly show it does and my write up even explains the ovaloid shape to achieve this.

 

The spindle offset is for pressure load balancing reasons, same as on some aeroplane rudders etc.

 

 

I think you'll find a central axis will be much easier to open and close, as current design has entire body of flap moving against exhaust flow, where as a central axis as equal surface area moving away from the gas as towards, meaning balanced force and lower torque input.

 

Additionally, your photo doesn't show the flap opening in a full length of pipe (as far as I can tell), if the length of pipe extends past the length of the flap when opened, you'll likely find it fowling 

[oakmere]

So you're relying on pressure to open the valve?
Whilst sat in an IT training course, I was having a sketch as you do and can't see how th valve would open?

Surely the pressure at bottom of valve will try and push it open but the rest of th pressure pushing at the top of the butterfly valve will be trying to close the valve?
Hence why others use external opening forces right? Or it's quite possible that I'm missing something.

I think that is why the spindle is not in the middle. So more force opening the plate than holding it closed.