REFLECTOR: Turbo concerns

Chris Barber cbarber at texasattorney.net
Tue Aug 21 16:16:26 CDT 2012


Replaced my plugs yesterday and they looked exactly as I had hoped. Textbook example of "normal"

Sent from my iPhone 4

On Aug 21, 2012, at 3:59 PM, "Scott Derrick" <scott at tnstaafl.net> wrote:

> The mixture would be screwed up as the servo is expecting a certain amount of air with the turbo but is not getting it.  I imagine its running really rich with or without the turbo.  You could verify that by checking a plug.
> 
> Scott
> 
> -------- Original Message --------
> Subject: Re: REFLECTOR: Turbo concerns
> From: Laurence Coen <lwcoen at hotmail.com>
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Date: 08/21/2012 12:56 PM
> 
>> Chris,
>> 
>> I think you do have a turbo problem but I think there is more too it
>> than that.  The numbers that you supplied suggest that the computer
>> controlling the spark advance and gas air ratio is getting different
>> information with the turbo connected and disconnected.  If you look at
>> the 2000 RPM data the engine gets the same RPM with two very different
>> manifold pressures.  In both cases the engine load is the same (the
>> prop).  The only way you could get the same RPM with an increase of 1.8"
>> manifold pressure is to retard the ignition or screw up the mixture.
>> 
>> Larry Coen
>> N136LC
>> 
>> 
>> --------------------------------------------------
>> From: "Chris Barber" <cbarber at texasattorney.net>
>> Sent: Tuesday, August 21, 2012 9:32 AM
>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>> Subject: Re: REFLECTOR: Turbo concerns
>> 
>>> Scott,
>>> 
>>> Thanks, that gives me some specifics.
>>> 
>>> Chris
>>> 
>>> Sent from my iPhone 4
>>> 
>>> On Aug 21, 2012, at 8:56 AM, "Scott Derrick" <scott at tnstaafl.net> wrote:
>>> 
>>>> You definitely have something not working in your turbo setup. I'm
>>>> assuming you measuring upper deck pressure?  Ala intake pressure
>>>> after the intercooler and servo?
>>>> 
>>>> problems.
>>>> 
>>>> 1.) turbo is not spinning freely due to internal obstruction(I've
>>>> seen rags), bad or incorrectly installed bearings, bent fan, etc.  It
>>>> should spin very freely by hand, take a long time to come to a stop.
>>>> Blow a vacuum cleaner through the turbo and see how she spins, with
>>>> an open turbo(no back pressure) it should spin up very fast with a
>>>> large canister style vacuum.
>>>> 
>>>> 2.) waste-gate opening prematurely. In your case immediately. Can you
>>>> see the waste-gate operation when the engine is running? Make bright
>>>> marks on the moving parts to make this easier.  Note its position
>>>> before start, then at idle, then a varying degrees of throttle
>>>> position. It should be completely closed until close to mid throttle.
>>>> At least the tio520 operated in that manner.
>>>> 
>>>> 3.) pop-off opening too soon.  Tie a rag or something to the opening
>>>> that will flutter around when it opens. Do this at the same time your
>>>> observing the wastegate.
>>>> 
>>>> 4.) If all the above are OK, its possible your intercooler is
>>>> restricting flow. remove the intercooler and run without it.
>>>> 
>>>> Scott
>>>> 
>>>> 
>>>> -------- Original Message --------
>>>> Subject: REFLECTOR: Turbo concerns
>>>> From: Chris Barber <cbarber at texasattorney.net>
>>>> To: REFLECTOR <reflector at tvbf.org>
>>>> Date: 08/20/2012 07:18 PM
>>>> 
>>>>> 
>>>>> As I have mentioned I have had what I think are incongruent readings
>>>>> regarding my manifold pressure (mp)and engine rpm. It seems I am
>>>>> getting quite low mp as I add power to higher rpm.
>>>>> 
>>>>> I am not well versed in this area but my thought is that as I add
>>>>> power, even with slight boost (currently using a 3 lb spring in my
>>>>> wastegate) eventually my mp should raise a bit more.
>>>>> 
>>>>> Today I did some static test. I recorded engine RPM with the  turbo
>>>>> hooked up and recorded the mp at 1000 rpm increments. Then I removed
>>>>> the turbo plumbing from my intake and recorded the same info My
>>>>> results currently confuse me.
>>>>> 
>>>>> With the turbo hooked up I am getting
>>>>> 
>>>>> RPM.   MP inches
>>>>> 2000 - 14.0
>>>>> 3000 - 15.5
>>>>> 4000 - 19.3
>>>>> 5000 - 21.6
>>>>> 5700 - 24.5 (topped out)
>>>>> 
>>>>> With the turbo removed.
>>>>> 
>>>>> 2000 - 15.8
>>>>> 3000 - 15.3
>>>>> 4000 - 19.7
>>>>> 5000 - 24.8
>>>>> 5833 - 29.8
>>>>> 
>>>>> Is this indicative of restriction in my plumbing? Perhaps in the
>>>>> inter cooler? A dirty air filter? A bad pop off valve or a leak not
>>>>> allowing the air pressure getting to the intake. Or????
>>>>> 
>>>>> I am uncertain what other permitters I need to check and provide. I
>>>>> am just starting my diagnosis in my Phase One testing. I only have
>>>>> 1.6 hours in the air so far. I value ya'll's direction and input.
>>>>> 
>>>>> Heck, perhaps this is working properly but it just doesn't seem
>>>>> right/comfortable.
>>>>> 
>>>>> Thanks folks.
>>>>> 
>>>>> Chris Barber
>>>>> Houston
>>>>> Velocity SE
>>>>> Rotary 13b turbo (?) :-)
>>>>> 
>>>>> Sent from my iPhone 4
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>>>> 
>>>> --
>>>> Man must evolve for all human conflict a method which rejects
>>>> revenge, aggression and retaliation. The foundation of such a method
>>>> is love.
>>>> Martin Luther King Jr.
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> 
> -- 
> Better to remain silent and be thought a fool than to speak out and remove all doubt.
> Abraham Lincoln
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