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| Home > Help Needed / General Tech Chat > Actuator take off position | |||||||
 (2)[/url] by [url=https://www.flickr.com/photos/150672766@N03/]Rod Sugden[/url], on Fli) 5988 Posts Member #: 2024 Formally Retired Rural Suffolk |
8th Jan, 2010 at 05:15:54pm
On 8th Jan, 2010 Ben H said:
Yes, but part throttle creates very little boost, but what it does create can be seen on the boost gauge, which is connected to the manifold, so where is the problem going to come from? At part throttle I doubt that you even trigger the actuator, especially if you have a boost controller or MBC. But my point was that if you control the actuator from where there is very little boost at part throttle - because the throttle plate restricts flow hence drops pressure - you just don't know what the compressor outlet pressure is at part throttle and obviously the actuator won't operate as it has a "false" (low) signal. The actual compressor discharge pressure must be higher than the manifold with a partly open throttle plate - providing there is enough exhaust gas to drive the turbine - the point I suggested is that there is probably so little exhaust gas, the amount the compressor is being over-driven is minimal, but may contribute to perceived better responses. Schrödinger's cat - so which one am I ??? |
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 11046 Posts Member #: 965 Post Whore Preston On The Brook |
8th Jan, 2010 at 05:40:07pm
On 8th Jan, 2010 Ben H said:
Yes, but part throttle creates very little boost, but what it does create can be seen on the boost gauge, which is connected to the manifold, so where is the problem going to come from? At part throttle I doubt that you even trigger the actuator, especially if you have a boost controller or MBC. I would tend to agree, but what about the question of why the OEMs do not use this method? If anything, if there was any benefit in increasing response/ reducing lag, that was as simple as moving the actuator pressure take off point, costing next to nothing, did not have any detrimental effect, it would be on every petrol turbocharged car. Would it not? So there must be a very valid reason why all OEMs that spend millions of pounds on engine calibration, do not. On 26th Oct, 2004 TurboDave16v said:
Is it A-Series only? I think it should be... So when some joey comes on here about how his 16v turbo vauxhall is great compared to ours, he can be given the 'bird'... On 26th Oct, 2004 Tom Fenton said:
Yep I agree with TD........ |
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 3329 Posts Member #: 184 Senior Member Melton Mowbray, Pie Country |
8th Jan, 2010 at 05:44:22pm
I have to say that I will always connect the actuator on the compressor side of the butterfly and I totally agree with your concerns with the wrong signal getting to the actuator. But I can see why in most circumstances in the real worl that it makes little difference. Of course if you have throttle bodies you have no choice, but lets not go OT. http://www.twin-turbo.co.uk
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3329 Posts Member #: 184 Senior Member Melton Mowbray, Pie Country |
8th Jan, 2010 at 07:38:18pm
In fact thinking about this some more. Looking at Paul's graphs it shows full boost at part throttle. However, the boost signal is taken from the MAP, therefore regardless of actuator signal you can get a situation where you might think that there is more pressure behind the butterfly, but Paul's graphs more or less prove that this doesn't happen. If he has a 10psi (sorry not looked at the actual boost) actuator and it is controlled before the butterfly and he is reading 10psi MAP then the boost throughout the system must be similar. I think anyway. http://www.twin-turbo.co.uk
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11046 Posts Member #: 965 Post Whore Preston On The Brook |
8th Jan, 2010 at 08:01:50pm
We will never know unless some one decides to fit a boost gauge pre throttle and post throttle.
On 26th Oct, 2004 TurboDave16v said:
Is it A-Series only? I think it should be... So when some joey comes on here about how his 16v turbo vauxhall is great compared to ours, he can be given the 'bird'... On 26th Oct, 2004 Tom Fenton said:
Yep I agree with TD........ |
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 8604 Posts Member #: 573 Formerly Axel Podland |
8th Jan, 2010 at 08:05:01pm
The actuator signal is taken from the same point as the MAP sensor in my case.
Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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3006 Posts Member #: 2500 Post Whore Buckinghamshire |
8th Jan, 2010 at 09:40:44pm
My brain hurts now. |
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3329 Posts Member #: 184 Senior Member Melton Mowbray, Pie Country |
8th Jan, 2010 at 09:47:31pm
Dam you paul, if you had the control on the non butterfly side we might have an answer. Oh well, I think I will leave mine where it is. http://www.twin-turbo.co.uk
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2395 Posts Member #: 229 Gavin@minispares.com kent |
4th Feb, 2010 at 04:41:56pm
On 8th Jan, 2010 Paul S said:
The actuator signal is taken from the same point as the MAP sensor in my case. The pressure upstream of the butterfly will be higher, but I doubt by much. The actuator should be open a bit more than it is, I guess. I would then get lower boost for a given throttle opening. Probably a little more control and less of an on/off switch. I've just checked the compressor map and at a calculated air flow of approx 8 lb/min at 4000 rpm, when full boost comes in, I have about 8 psi in hand before the surge line. So I'm relaxed about it. Why would the pressure be higher after the butterfly? Surely it would be highest just before it? |
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 10022 Posts Member #: 1456 Mongo Barnsley, South Flatcapshire |
4th Feb, 2010 at 04:51:05pm
Arrgghh! This has been bugging me for last couple of weeks. The way I understand it (rightly or wrongly) is if the actuator feed is before the butterfly the wastegate is going to open when the throttle is closed, however if the DV acts quick enough hopefully this won't happen and the shouldn't slow too much.
If something is worth doing, it's worth doing half of. |
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