4722 replies to this topic

[CocoPops]

But then it wouldn't rotate as the centre section (widest point) wouldn't fit into the cross section of the piper lower down the curve?

[The Batman]

Stop it coco you will get told off

[sford]

Would it be better to have it like the NA throttle body with the slight ramps in it? Rotate the top forward in the closed position and a centre spindle.

Edited by sford, 24 November 2016 - 03:39 PM.

[Nev]

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.

 

If you take a look at the pics, the spindle is offset (not central) such that the pressure is applied in a roughly 70%/30% ratio. Thus the upper side of the spindle will see less pressure than the lower side, which means it will cause the spindle to want to rotate. The rotation effect will be resisted (and damped) by the spring. As pressure increases the flap opening will increase, allowing some (but not all) the gas to bypass.

[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.

 

 

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 

 

 

If the spindle was in the centre then the valve flap wouldn't open itself under pressure.

 

The design is a passive reactive system, (i.e. no input signal or motor etc is required), just the exhaust gas pressure itself will force it open when necessary. It is deliberately simple (but effective hopefully) with no risk of electrical or boost signal failure (which those picture you sent me might have).

 

I agree the photos don't show the flap opening with a pipe behind it, but why do you assume I wouldn't have tested for this?

 

 

[Nev]

Would it be better to have it like the NA throttle body with the slight ramps in it? Rotate the top forward in the closed position and a centre spindle.

 

A centralised spindle simply wouldn't work, please see above.

[Nev]

Stop it coco you will get told off

 

Not understanding something and then asking a question to try and understand is fine, great in fact.

 

It's when people condescendingly think they know more about me, my car and my careful thinking that it's irritating. I'm not some halfwit than need to be lectured on how hard an engine has to work on a track thanks.

Edited by Nev, 24 November 2016 - 04:08 PM.

[fezzasus]

 

Would it be better to have it like the NA throttle body with the slight ramps in it? Rotate the top forward in the closed position and a centre spindle.

 

A centralised spindle simply wouldn't work, please see above.

 

 

All OEM implementations beg to differ.

[Nev]

But then it wouldn't rotate as the centre section (widest point) wouldn't fit into the cross section of the piper lower down the curve?

 

It does if you shave off a few mm of material around the sides, which is what I did (and explained carefully in my write up).

 

With respect, anyone wanting to understand the designs should spend a few minutes reading up - that what it's there for

[Nev]

 

 

Would it be better to have it like the NA throttle body with the slight ramps in it? Rotate the top forward in the closed position and a centre spindle.

 

A centralised spindle simply wouldn't work, please see above.

 

 

All OEM implementations beg to differ.

 

 

OEM systems have an active trigger system that force the spindle open (either electrical to a motor or boost to an actuator) so that "force" turns the spindle. I've just explained mine works in a completely different way - it is passive reactive (ie uses the exhaust flow itself to force the opening).

 

Edited by Nev, 24 November 2016 - 04:14 PM.

[fezzasus]

 

 

 

Would it be better to have it like the NA throttle body with the slight ramps in it? Rotate the top forward in the closed position and a centre spindle.

 

A centralised spindle simply wouldn't work, please see above.

 

 

All OEM implementations beg to differ.

 

 

OEM systems have active trigger systems that force the spindle open (electrical or boost), I've just explained mine works in completely differently - it is passive reactive (ie used the exhaust flow itself to trigger the opening)!!!

 

 

 

and as I said, all OEM implementations have a different approach. Ask yourself why. OEMs do not deliberately add resistance to the system as this adds stress to the actuation device. Loading is balanced to ensure the device remains shut yet needs minimal force to ensure a decade of actuation.

[Nev]

 

 

 

 

Would it be better to have it like the NA throttle body with the slight ramps in it? Rotate the top forward in the closed position and a centre spindle.

 

A centralised spindle simply wouldn't work, please see above.

 

 

All OEM implementations beg to differ.

 

 

OEM systems have active trigger systems that force the spindle open (electrical or boost), I've just explained mine works in completely differently - it is passive reactive (ie used the exhaust flow itself to trigger the opening)!!!

 

 

 

and as I said, all OEM implementations have a different approach. Ask yourself why. OEMs do not deliberately add resistance to the system as this adds stress to the actuation device. Loading is balanced to ensure the device remains shut yet needs minimal force to ensure a decade of actuation.

 

 

Well maybe mine will die, we shall see. Ideally I won't even need to install it anyway (if design #1 or #2 work well).

 

I only see 2 risks with it really: jammed butterfly on the side walls due to carbon build up or stuck spindle due to carbon build up. Both those can be fixed in 30 secs by reaching through the NSR wheel arch and forcing it back and forth a couple of times by hand.

 

 

Edited by Nev, 24 November 2016 - 04:41 PM.

[siztenboots]

i was surprised how crude the wastegate was mechanically sealed and pivots on the turbo, yet it still works in a harsh environment 

[Nev]

i was surprised how crude the wastegate was mechanically sealed and pivots on the turbo, yet it still works in a harsh environment 

 

Indeed, and that only has one sleeve rotating point (on soft nickled iron), whereas mine has 2 on far harder steel in temps that are probably less than 1/2 what the turbo sees.  

Edited by Nev, 24 November 2016 - 04:46 PM.

[The Batman]

 

Stop it coco you will get told off

 

Not understanding something and then asking a question to try and understand is fine, great in fact.

 

It's when people condescendingly think they know more about me, my car and my careful thinking that it's irritating. I'm not some halfwit than need to be lectured on how hard an engine has to work on a track thanks.

 

 

nev get of your high horse... all i said was your car will have higher iat on track than on a straight clear road...

 

you need to figure out that you dont know everything and if you stop being so condescending and arrogant you might not have to argue and find the need to belittle people.

[Nev]

Maybe I over reacted a bit, but I simply don't have any IAT issues, either during spirited driving or flat out endurance tests. Even when I was driving round Llandow circuit for 20 odd laps in the summer the IATs only got to about 35 or 40 degrees (which is lower than my road driving).

 

If anything gets hot on my car it's the oil I suspect.

 

Edited by Nev, 24 November 2016 - 05:14 PM.

[stu8v]

Given the restrictions of the valve surely it makes more sense just to fit a 3" exhaust? Just putting it out there..... On the plus side if you want to use an actuated flap you can adjust it's preload to gain some boost dependant characteristic, assuming it's boost actuated that is? ☺

[The Batman]

I will take that as an apology. Like I said will be interesting to see the difference and I'm happy to be wrong, so hopefully your exhaust will be quiet enough

[The Batman]

Also, is your oil cooler the same as most z20 ones? As they look a lot smaller than the na version Could always fit a mocal laminova cooler like I am if you have temp problems

Edited by The Batman, 24 November 2016 - 05:19 PM.

[Nev]

Given the restrictions of the valve surely it makes more sense just to fit a 3" exhaust? Just putting it out there..... On the plus side if you want to use an actuated flap you can adjust it's preload to gain some boost dependant characteristic, assuming it's boost actuated that is? ☺

 

Could have done, would have lost some power at the top end in my estimation, but it would certainly have been easier, quieter, lighter and cheaper. I chose 3.5" for the carefully considered reasons here: https://sites.google...e-design-topics

 

The valve is not boost actuated, but it will have a manually adjustable crack threshold (an adjustable spring).  

Edited by Nev, 24 November 2016 - 05:37 PM.