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From: "Rogers, Bob J." <BRogers@FDIC.gov>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Re: Turbo question.
Thread-Topic: [FlyRotary] Re: Turbo question.
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Date: Tue, 21 Aug 2012 14:24:59 +0000
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Chris,

I fly with a Mazda 13B turbo in my Mustang II.  On take-off, I regularly pu=
ll more than 40 inches of MP.  Three pounds of boost equals approximately 6=
 inches of manifold pressure, so you should be getting approximately 36 inc=
hes of MP if the field atmospheric pressure is approximately 30 inches.  Ho=
uston is close to sea level.

It sounds like you have a severe airflow restriction somewhere in your turb=
o system, because you most certainly should be getting more MP at full thro=
ttle than described below.  Further evidence of this is the fact that MP go=
es up when you disconnect the turbo.  If you have an intercooler, is it blo=
cking the airflow? Maybe clogged up?

Bob

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh=
alf Of Chris Barber
Sent: Monday, August 20, 2012 8:58 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Turbo question.

I am taking the MP reading from the intake before the injectors but after t=
he turbo, pop off valve and intercooler, in that order. I only have a 3 lb =
spring in the wastegate currently to control boost. Since I had a detonatio=
n issue a while back requiring a teardown to replace apex seals, likely due=
 to too low of octane fuel, I wanted to start with just a little boost at f=
irst.=20


Sent from my iPhone 4

On Aug 20, 2012, at 8:42 PM, "Ed Anderson" <eanderson@carolina.rr.com> wrot=
e:

> Chris,
>=20
> Exactly where are you taking your manifold pressure from-
>=20
> I presume it is after the turbocharger compressor - somewhere  between th=
e turbo and the intake manifold OR  at the manifold.
>=20
> The only way I can make sense of your reading based on information provid=
ed thus far is that you are taking your manifold pressure reading before th=
e turbocharger compressor inlet.  Then the increased airflow caused by the =
turbocharger could cause the pressure drop before the compressor due to fil=
ter or other restriction.
>=20
> Even if you have a restrictive filter, the pressure on the compressor out=
let side of the turbo, the turbocharger on pressure in your manifold should=
 be higher than without the turbo.
>=20
> You are not spinning your turbo backwards are you?{:>)
>=20
> Ed
> --------------------------------------------------
> From: "Chris Barber" <cbarber@texasattorney.net>
> Sent: Monday, August 20, 2012 9:17 PM
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Subject: [FlyRotary] Turbo question.
>=20
>> As I have mentioned I have had what I think are incongruent readings reg=
arding my manifold pressure (mp)and engine rpm. It seems I am getting quite=
 low mp as I add power to higher rpm.
>>=20
>> 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) eve=
ntually my mp should raise a bit more.
>>=20
>> Today I did some static test. I recorded engine RPM with the  turbo hook=
ed 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 con=
fuse me.
>>=20
>> With the turbo hooked up I am getting
>>=20
>> RPM.   MP inches
>> 2000 - 14.0
>> 3000 - 15.5
>> 4000 - 19.3
>> 5000 - 21.6
>> 5700 - 24.5 (topped out)
>>=20
>> With the turbo removed.
>>=20
>> 2000 - 15.8
>> 3000 - 15.3
>> 4000 - 19.7
>> 5000 - 24.8
>> 5833 - 29.8
>>=20
>> Is this indicative of restriction in my plumbing? Perhaps in the inter c=
ooler? A dirty air filter? A bad pop off valve or a leak not allowing the a=
ir pressure getting to the intake. Or????
>>=20
>> I am uncertain what other permitters I need to check and provide. I am j=
ust 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.
>>=20
>> Heck, perhaps this is working properly but it just doesn't seem right/co=
mfortable.
>>=20
>> Thanks folks.
>>=20
>> Chris Barber
>> Houston
>> Velocity SE
>> Rotary 13b turbo (?) :-)
>>=20
>>=20
>>=20
>> Sent from my iPhone 4
>> --
>> Homepage:  http://www.flyrotary.com/
>> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List=
.html
>>=20
>>=20
>> -----
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2
>>=20
>=20
> --
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