Neil,

Do you have a wideband O2?  I have to run in the low 11’s at full power and under boost for takeoff. 7000 rpm / 30-48” MP to keep egt’s around 1600F. Typical cruise between 4800 – 5200 rpm  / <30 “ MP with F/A 15.8:1 brings EGT’s into the 1500’s. With an intercooler I would expect F/A in the 12’s will keep egt’s below 1600 but that’s just a guess. I have seen EGT’s at or below 1475F on cold days at altitude. The only time I run stoichiometric is in the pattern and low MP.

Information from Pro Formula Mazda

Engine Vitals: Exhaust Gas Temperatures Exhaust Gas Temperatures (EGTs) are the second most important tuning and troubleshooting channel next to Lambda. EGTs reflect on the injector balance between the front and rear rotor Reflects misfires through high readings accompanied by normal lambda Decline in engine performance can be evidenced by the rate of temperature acceleration between the rotors during a long pull – gapping Emphasis needs put on the condition of the EGTs – low reading sensors are beginning to fail. In order to have an accurate assessment of the performance, EGT sensors must be replaced often. Generally, one EGT sensor is used per rotor. One sensor bung should be welded on the each the outer exhaust pipes 3” from the header flange (the center pipe usually does not receive a sensor). The sensor depth should be enough to where the tip of the sensor is in the centerline of the exhaust flow. Operational Range: Front Rotor: 1450F – 1600F, Rear Rotor: 1400F – 1550F

Engine Vitals: Lambda

Lambda is the measure of the amount of oxygen in the exhaust stream. The value expressed is a percentage of the stoichiometric air/fuel ratio 14.7:1.

Air/fuel ratio can be calculated by multiplying the lambda value monitored by data system by 14.7

(ex: .90 Lambda translates as (.9 x 14.7 = )13.23 Air/fuel ratio

Operating Range = .87 - .91, aim for .90

Bobby

Ok, interesting stuff, but how do you keep the exhaust temp below 1600 degrees without losing a lot of power?  I no longer have an EGT as it just worried me with 1800 degrees and the cost of burnt off egt probes.  From memory 1600 degrees goes out the window at about 6000 rpm or less? 

Neil.

Hi Andrew, I know next to nothing about turbo technology so have stayed clear of them; IIRC this is the first time I’ve heard of using a turbo from the agricultural industry and advice to stay clear of the automotive type ... seems to make sense – tractors use turbos that last for decades.

Jeff (13B, RD1-C, 144 hrs)

 

From:
Sent: December-03-18 5:14 AM
Subject: Re: [FlyRotary] Re: Hey Neil,

 

Neil, Type    Turbo selection     Into search of flyrotary archives, you’ll get about 30 posts from 2002 to 13 that are worth reading, other searches will give more.

 

Basically you want something the size of a T04 60-1, keep the A/R >1, something like 1.15 or 1.30

T04’s are plentiful from all the older diesels like 2wd tractors from last century. you probably got a few parked up around you that will still be servicable. If you can find one without a intercooler on it, chances are that it might have the right compressor. Otherwise they are easy to change.

Steer clear of automotive turbo’s, they will overspeed at altitude & disintegrate, need waste gates & blow off valves. Stuff thats not required on an aeroplane.

 

When installing. Put a normally open solonoid valve in the oil supply line. Allows you to close the oil supply if the turbo blows its seal.

 

Always bugged me why turbo shops charge so much for such a simple part.

 

Andrew