matt_gsxr
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| posted on 15/2/11 at 11:38 PM |
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Testing a wastegate actuator
How do I test a wastegate actuator?
I have a td04-16T (from a volvo T5) that I have plumbed into my gsxr1100 engine. The actuator is an after market item (looks like Forge design, but
isn't branded as such) that came with the turbo.
I know I could plumb in a bike pump and a gauge, but that wouldn't take account of the forces on the wastegate from the exhaust gases.
What is the trick with these things? I know how to derate it (additional external spring), but don't know whether I need to.
I'd prefer not to blow my engine up first time out, although I am tempted to give it a go, and log what happens!
Matt
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coyoteboy
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| posted on 15/2/11 at 11:51 PM |
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Bike pump is about your only method, the forces on the wastegate will not really be quantifiable as it depends on the valve size and pressure
difference across the turbine. Bear in mind that the WG will crack long before the rated pressure anyway, it's a bit of a dynamic process, a
curve more than "open/shut".
Most of the internal wastegates I've seen are aided in opening by the exhaust gases, so worst case scenario you'll get less boost than you
measure with the bike pump.
[Edited on 15/2/11 by coyoteboy]
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Strontium Dog
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| posted on 16/2/11 at 12:21 AM |
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Er, fit a boost gauge and see what boost it holds. Take your foot of the gas if it starts to overboost. Shouldn't blow it up then. In fact I
would say a boost gauge is prerequisite if using a turbo Also, does your ecu allow for fuel or ignition cut on overboost?
As Mr coyote said, the gate will open at less than it's rated pressure. If you want to rig a gauge and bike tyre pump to test it, rule of thumb
is 50% of rated pressure!
Edit to say
My genuine Forge 1bar actuator holds bang on 1bar on my 3SGTE with electronic control turned off!
[Edited on 16/2/11 by Strontium Dog]
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matt_gsxr
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| posted on 16/2/11 at 10:55 AM |
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thanks guys,
I've got megasquirt, so I should be able to do anything!
I will do a bike pump look-see test, and investigate fuel cut and boost gauge.
Thanks,
Matt
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matt_gsxr
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| posted on 25/2/11 at 09:34 PM |
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I plumbed the wastegate into the compressor today, and as the compressor pressure built up measured when the wastegate opened.
Turned out its between 1.2 and 1.5 atm (i.e. 18-22psi). This is loads more than I want.
I also measured the area (3 sq inch) and the force required to pull the rod (4stone), I weighed myself when pulling on the rod and when not (which is
why the force is in Stones). This gives the same sort of value (i.e. 4 stone = 56lbs, so 56 lb/3 sq inch = 19psi), all a bit bodgy, but it gave me
some numbers.
I was aiming for around 4 or 6psi, as I can control it with the clever Volvo pressure modulator electrical thing.
So, my question is, where can I find a weaker spring. The wastgate is an after market Forge knock-off. i.d. is 47mm. Anyone know a decent spring
supplier?
Matt
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prawnabie
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| posted on 25/2/11 at 10:04 PM |
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Id use a mityvac
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matt_gsxr
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| posted on 25/2/11 at 10:19 PM |
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quote:
Originally posted by prawnabie
Id use a mityvac
I had to look up what a Mityvac was. Can they do positive pressure or just below atmospheric?
Anyway I have done it now, and just ordered the most expensive spring in the world from Forge. It should be cheaper than 4 pistons and a new block
though!
Matt
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prawnabie
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| posted on 25/2/11 at 10:19 PM |
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There is a switch so you can suck or blow lol
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prawnabie
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| posted on 25/2/11 at 10:20 PM |
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http://www.mityvac.com/pages/products_hvpo.asp
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matt_gsxr
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| posted on 25/2/11 at 11:02 PM |
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Cool, maybe I need one of those as well as all my other tools.
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Bare
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| posted on 26/2/11 at 04:59 PM |
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Couple of things I've learned;
1) that's some big turbo for such a wee motor. I'd be surprised by boost production below 5k.
Try using Saab bits, at least the actuator diaphragm unit without the (imo essential Electronic managements ) will blow ex gases /dump boost at
approx 6 psi (.4 bar?) and is adjustable.. using a real (not retail) boost gauge. running/driving the engine under the load conditions that will
really generate boost.. Heavy accel up a looong slope
simply by turning in/out the adjuster on the wastegate connector rod.
As a guess 7/8 psi 'should' be safe.. maybe :-) on yer GSXXR
Although doesn't the goofy Forge unit have similar rod adjustments.. still I'd opt for the IMO better quality Saab unit.
[Edited on 26/2/11 by Bare]
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Strontium Dog
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| posted on 26/2/11 at 06:14 PM |
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quote:
Originally posted by Bare
running/driving the engine under the load conditions that will really generate boost.. Heavy accel up a looong slope
simply by turning in/out the adjuster on the wastegate connector rod.
* The adjuster on the actuator rod is for waste gate preload, NOT boost control and will effect the spool time if slackened off to much. Boost
pressure should be adjusted by the spring rating, using a spring close to the required boost is good for faster spool and then use an electronic
solenoid valve to regulate and control actual boost. (mechanical bleed valve can be used but are inferior to a solenoid)
As a guess 7/8 psi 'should' be safe.. maybe :-) on yer GSXXR
* That's entirely dependent on comp ratio used and mapping, knock control, water/methanol injection etc.
Although doesn't the goofy Forge unit have similar rod adjustments.. still I'd opt for the IMO better quality Saab unit.
* Why? The Forge units are superior to most OEM stuff I've seen, that's why they are considered an upgrade. Can you replace the springs in
the Saab unit with different rated ones for instance?
[Edited on 26/2/11 by Bare]
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