GAMIjectors for Lycomings

[Shadrach]

Quote: danb35

If you're not already familiar with them, I'd recommend a review of many of the Pelican's Perch articles at AvWeb, here: http://www.avweb.com/news/pelican/list.html.  In particular, the "Where should I run my engine" and "Those fire-breathing turbos" series are very relevant.

For advanced study, take the course from Advanced Pilot--$400 online or 1 AMU in person, but given that your engine is around $50k I'd think it's worth it (I'm trying to make the time to take it myself).

[TLSDriver]

Quote: Shadrach

If you're not already familiar with them, I'd recommend a review of many of the Pelican's Perch articles at AvWeb, here: http://www.avweb.com/news/pelican/list.html.  In particular, the "Where should I run my engine" and "Those fire-breathing turbos" series are very relevant.

For advanced study, take the course from Advanced Pilot--$400 online or 1 AMU in person, but given that your engine is around $50k I'd think it's worth it (I'm trying to make the time to take it myself).

[Shadrach]

Quote: TLSDriver

I think I have put the cart ahead of the horse.  I called GAMI today.  Had a great conversation.  He told me they have had 3 engines that didn't like to run LOP.  Unfortunatly, the Bravo was one of them.

I have about a 1.5-2.0gph difference between richest and leanest cylinder.  He said with the GAMI I should be around .5gph.

I asked what could cause such a gap and he said to check for :

1) Induciton leak

2) Exhaust leak.

3) Plugs\Wiring harness(ingition issue.)

4) Make sure that gami injectors are in the correct cylinders.  I guess I must have laughed when he said that and he responded by saying it happens way more than anyone would think.

 

In any event unless the above is as it should be LOP isn't even on the table.

There was two other things that I found intersting.  He claims at 65% power the little red knob will not hurt the engine regardless of where it is set.  Secondly, At or above 20k in altitude LOP was not likely.  I didn't completly understand it but it had to do with the fuel being harder to ignite at altitude and LOP only made it worse.

I have an oil change scheduled for tomorrow so I will bring the above list up with the shop and see what they say.

[Magnum]

Quote: danb35

...Below 60-65% power, it's virtually impossible to hurt your engine with the mixture control ...

[Cruiser]

Quote

4) Make sure that gami injectors are in the correct cylinders.  I guess I must have laughed when he said that and he responded by saying it happens way more than anyone would think.

 I have an oil change scheduled for tomorrow so I will bring the above list up with the shop and see what they say.

 

[TLSDriver]

Quote: Cruiser

 I suspect #4 if you already have GAMIs installed they probably were mixed between cylinders somewhere along the line. This is somethng you MUST let the maintenance shop know about when ever you have service.

Did GAMI tell you how they are marked and how you know which ones go in which cylinder?

 

I watched the tech do the oil change today.  Each fuel line had a metal stamp on it with a letter.  Each injector also had a letter.  I verified each was matched correctly.

We did an exhaust leak and induction.   Some very small bubbles on the exhaust around a few joints.  Sure didn't look like anything serious.  Tech said that is was fine.

The only thing GAMI told me is that they were orginally sent a gami lean test.  They sent out the injectors. There records say they were never contacted again by the previous owner.  So my guess is the owner was happy or just lost interest in it.  Of course if he never looked into LOP then he probaly didn't notice the condition.

I did see somethng a little weird in log books.  At the annual AFTER the GAMIs were installed the paperwork was done for the STC.  It is almost as if they were cleaning up someone sloppy paperwork. 

The plane has 800 hours on it.    I went through the log books twice and don't see a mag replaced.  Eithier I am blind or they are the originals. The plugs were replaced 500 hours ago.  

I dont have a ton of confidence in this shop.

Does anyone know of somewhere that I can bring the plane and really get this figured out?

 

[KLRDMD]

Quote: TLSDriver

[TLSDriver]

I have see Don Maxwell's name dropped a few times.  Sounds like a top notch player.  

[TLSDriver]

Doesn't look like Don Maxwell is a GAMI dealer.  Wonder if that matters.

[Parker_Woodruff]

Quote: TLSDriver

I have see Don Maxwell's name dropped a few times.  Sounds like a top notch player.  

[fantom]

Quote: Parker_Woodruff

If I was you, I'd fly my airplane to Don every year from Florida for an annual.  There's one A&P on this board I'd probably trust, but about 95% of what I hear out of Florida and Mooneys is bad.

[TLSDriver]

Where can I find a power chart for this engine?  The POH doesn't show this info.  For instance, If I wanted to run the engine at 75% power (ROP) what MP and RPM would be set?  60% power?  etc.

 

 

[FAST FLIGHT OPTIONS LLC]

Quote: KLRDMD

LOP, % power is determined exclusively by fuel flow. MP and RPM are irrelevant.

According to a Lycoming, your engine is an 8:1 compression ratio. Therefore 65% power when LOP is 12.2 GPH (64% is 12 GPH) and 75% power is 14.2 GPH (74% power is 14 GPH). Cirrus runs their turbo 550s at 87% power when LOP.

[TLSDriver]

What about ROP?  Where can I get power settings in %?

[KLRDMD]

Quote: 201-FLYER

[jetdriven]

Actually it depends on BSFC, and BSFC depends on where rich or lean of peak you are.  Full rich BSFC is .5-.8.   Best power is in the .45-.5 range.   LOP can be as low as .38.

so, 65% power on, say a lycoming IO-360, LOP, (BSFC of .39 lb/hr/hp (@ 30 degrees LOP)) =  130HP x .39= 50.7 LB/hr

which translates to  8.42 gal/hr.   So, at 30 degrees LOP, lean the engine to a fuel flow of 8.42 GPH, manifold pressure and RPM are irrelevant, but as a starter, around 2" higher MP when LOP is going to be close.

this can get really technical, or ity can be as easy as leaning to a target FF when running LOP and monitoring CHT and EGT for any anomalies.

Quote: KLRDMD

[Kwixdraw]

Regarding the fuel being harder to burn at higher alt., It's a combination of things. It gets harder for the magneto to distribute the spark at high altitudes due to the low air density. You probably have pressurized mags on the Bravo but that can be a problem too as you have a constant flow of air+ whatever is in it through your mag. Everything can get pretty cruddy in those conditions. As you lean your mixture below stoichiometric balance you end up with more air space between the fuel molecules and it gets harder for the flame to burn from one molecule to the next. This slows the flame front and causes the rise in egt because the FA charge is still activly burning when the exhaust valve is opening for the exhaust stroke. This is when the exhaust valve gets good and hot and starts cooking the oil back to carbon on the stem and decides to stick when it cools down. The Bravo heads are supposed to cool the valve guide by having oil passages around the guide to help channel the heat away from the valve and guide. Clean oil is your engines Best Friend since a plugged oil passage is going to cause you a big repair bill. The lycoming I worked on at school had been run hot enough that the holes through the center of the rocker shafts on the exhaust side were completely filled with coked up oil. That was just an O-320.

[KLRDMD]

Quote: jetdriven

[jetdriven]

Then 8.8 GPH, if operated at the LOP setting that will yield a 0.39 BSFC, around 30-50 degrees LOP.  If you go much leaner than that, BSFC actually gets worse and you end up slowing down more than the fuel flow decreases.    I think 10.0 GPH for 65% power and 11 for 75% power are 50 degrees ROP power fuel flows.

[KLRDMD]

Quote: jetdriven

Then 8.8 GPH, if operated at the LOP setting that will yield a 0.39 BSFC, around 30-50 degrees LOP.  If you go much leaner than that, BSFC actually gets worse and you end up slowing down more than the fuel flow decreases.    I think 10.0 GPH for 65% power and 11 for 75% power are 50 degrees ROP power fuel flows.

[jetdriven]

thats news to me, I figured the TSIO-360 had the same BSFC, but it actually quite worse.   APS is the expert in these matters, and yes, I'm with them that FF  is the only way to determine % of power when LOP.