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Chris, I fly with a Mazda 13B turbo in my Mustang II. On take-off, I regularly pull more than 40 inches of MP. Three pounds of boost equals approximately 6 inches of manifold pressure, so you should be getting approximately 36 inches of MP if the field atmospheric pressure is approximately 30 inches. Houston is close to sea level. It sounds like you have a severe airflow restriction somewhere in your turbo system, because you most certainly should be getting more MP at full throttle than described below. Further evidence of this is the fact that MP goes up when you disconnect the turbo. If you have an intercooler, is it blocking the airflow? Maybe clogged up? Bob -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf 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 the 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 detonation 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 first. Sent from my iPhone 4 On Aug 20, 2012, at 8:42 PM, "Ed Anderson" <eanderson@carolina.rr.com> wrote: > Chris, > > Exactly where are you taking your manifold pressure from- > > I presume it is after the turbocharger compressor - somewhere between the turbo and the intake manifold OR at the manifold. > > The only way I can make sense of your reading based on information provided thus far is that you are taking your manifold pressure reading before the turbocharger compressor inlet. Then the increased airflow caused by the turbocharger could cause the pressure drop before the compressor due to filter or other restriction. > > Even if you have a restrictive filter, the pressure on the compressor outlet side of the turbo, the turbocharger on pressure in your manifold should be higher than without the turbo. > > You are not spinning your turbo backwards are you?{:>) > > 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. > >> 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 >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html >> >> >> ----- >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 2012.0.2197 / Virus Database: 2437/5211 - Release Date: 08/20/12 >> > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html