External Wastegate - Diaphragm or Piston

[626gn]

Other than the physical design differences between an external gate with a diaphragm vs a piston, is there a tangible difference with using one over the other?

 

[Chuck Leeper]

For starters......

Synchronic Wastegates - Turbo Magazine

Read about the new synchronic wastegate for turbo applications developed by Synapse Engineering from turbo Magazine.

www.motortrend.com

 

[626gn]

Appreciate it Chuck. I was just reading that article this morning as well as others. Turbosmart uses the diaphragm almost exclusively as far as I can tell and goes on to say one is not superior over the other and it's more application driven (diaphragm units are shorter and wider, piston style ones are taller but narrower). Tial also uses the diaphragm exclusively (I think). Yet others like JGS, VS Racing, and others have piston style ones now. After reading all those articles I still have no idea if one is truly better than the other in the real world. Maybe it really doesn't matter as it's not talked about at all on this board?

 

[TType85]

I have the VS Racing 44mm Gen 3 gate on my car which is one of the piston ones. It works great so far; the only pain has been they were originally advertised with 12lb worth of spring installed and it was actually more like 10lb with zero back pressure so on gate alone I only saw 7-8psi. Full compressor pressure going to the dome I only saw low 20's in boost; no lines hooked up at all I saw 22psi (backpressure only opening the gate, turbo is a HPT-6466). If I was on Co2 it would have been fine, my goal is 15-16 on gate only up to around 30 all in.

VS Racing is still in process of making/getting higher spring rates but I was able to get a heavier spring from JGS that fits and once I fix my fuel pressure regulator leak I will get it out and test it.

The VS Racing one looks like a copy of the JGS; which if I would have known before hand I would have probably ordered the JGS one.

 

[626gn]

I have the VS Racing 44mm Gen 3 gate on my car which is one of the piston ones. It works great so far; the only pain has been they were originally advertised with 12lb worth of spring installed and it was actually more like 10lb with zero back pressure so on gate alone I only saw 7-8psi. Full compressor pressure going to the dome I only saw low 20's in boost; no lines hooked up at all I saw 22psi (backpressure only opening the gate, turbo is a HPT-6466). If I was on Co2 it would have been fine, my goal is 15-16 on gate only up to around 30 all in.

VS Racing is still in process of making/getting higher spring rates but I was able to get a heavier spring from JGS that fits and once I fix my fuel pressure regulator leak I will get it out and test it.

The VS Racing one looks like a copy of the JGS; which if I would have known before hand I would have probably ordered the JGS one.

^^^Good info. Thanks for sharing. What spring did you order from JGS? How you liking that HPT turbo so far?

 

[TType85]

^^^Good info. Thanks for sharing. What spring did you order from JGS? How you liking that HPT turbo so far?

TK188-S3 should be somewhere between 13-16psi I can also add in the 4lb spring that came with the gate to get a bit more if it is not enough.

So far the HPT turbo has been great. It spools fast really and so far even at 22psi it pulls hard. Will love to see what it does closer to 30psi

This car has Champion CNC Irons, a small flat tappet cam, PTC 17 blade, etc.

 

[626gn]

TK188-S3 should be somewhere between 13-16psi I can also add in the 4lb spring that came with the gate to get a bit more if it is not enough.

So far the HPT turbo has been great. It spools fast really and so far even at 22psi it pulls hard. Will love to see what it does closer to 30psi

This car has Champion CNC Irons, a small flat tappet cam, PTC 17 blade, etc.

Thanks again for the info!

 

[xlr8ngn]

In the industrial control valve world, a spring and diaphragm is more accurate than a piston due to less friction. There is an o-ring that creates drag on a piston as it travels through the bore. The diaphragm rolls on itself as it travels and exhibits less friction. This allows a diaphragm to be a little more accurate. In a clean environment, an o-ring will last longer than a diaphragm. If dirty, there will be wear between the o-ring and bore and it will begin to fail. Just like in the industrial marketplace, both will work fine for most applications. If you start having issues or failures, you can evaluate the problem and pick one based on which fits your application the best.

Me personally, I would pick the diaphragm and keep a spare repair kit.

 

[626gn]

In the industrial control valve world, a spring and diaphragm is more accurate than a piston due to less friction. There is an o-ring that creates drag on a piston as it travels through the bore. The diaphragm rolls on itself as it travels and exhibits less friction. This allows a diaphragm to be a little more accurate. In a clean environment, an o-ring will last longer than a diaphragm. If dirty, there will be wear between the o-ring and bore and it will begin to fail. Just like in the industrial marketplace, both will work fine for most applications. If you start having issues or failures, you can evaluate the problem and pick one based on which fits your application the best.

Me personally, I would pick the diaphragm and keep a spare repair kit.

^^^Good stuff. Thanks for the info.

 

[Chuck Leeper]

Me personally, I would pick the diaphragm and keep a spare repair kit.

Me too.
One argument I've seen is the diaphragm is more susceptible to heat related failure.
T/F? Don't know.

 

[xlr8ngn]

Me too.
One argument I've seen is the diaphragm is more susceptible to heat related failure.
T/F? Don't know.

You are correct. The more times the diaphragm strokes, while combined with higher temperature, shorten the diaphragm life. A diaphragm is typically a rubber material with reinforcement in between, like a bias ply tire. If the rubber is compromised, the pressure will begin to separate the diaphragm at the reinforcement by channeling and it will delaminate. You can open and inspect and feel/look for wear and delamination of the diaphragm, which may feel like soft spots or look like bubbles. If there is any of this or simple deforming of the diaphragm, it should be changed for a new one.

 

[outatime86]

How about the new Straight Gate, butterfly valve?

Pneumatic Straight Gate 6psi External Wastegate (Black)

The StraightGate50 from Turbosmart is the world's highest-flowing external wastegate! The StraightGate50 is a zero-offset butterfly-style wastegate that allows enormous flow and almost linear control, and unparalleled boost control throughout the entire operating range.The Boost-Based Pneumatic...

www.turbosmart.com

 

[outatime86]

I haven't used one but maybe it's good enough to not need Co2??

 

[626gn]

I haven't used one but maybe it's good enough to not need Co2??

Interesting... If you could in fact ditch the Co2 and get the same or similar results with this pneumatic unit then it might be worth the price of admission for some. Unfortunately for me my ride is not badass enough to justify using Co2 or spending the coin for this pneumatic one

 

[Mr.Spool]

This is the cheatsheat =
by the time someone,
buys say a regular gate,adds co2,someone is still into the everything for Way less than the electronic gate alone,let alone all the other add ons to make it work,
and still has all the boost control they need with the proper spring with super fast reactions of co2.
water lines,additional black boxes to run the drivers needed for the electronic gates as most computer systems will not drive the gate.
And in the end both setups will run near identical but will just require 2 different approaches to get to the same place performance wise.
But one with nearly double the cost.