I'm broke, but plane is OK

azure

azure

Final Approach
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azure
Okay I'm not quite broke, but my mechanic just finished spending umpteen hours chasing EGT gremlins and a stubborn gear downlock issue, verifying that I didn't have the original failure-prone gear actuator rod end, and now everything seems to be working fine and stable. I'm sure I'll be closer to broke after my next major expenditure, which will be my first real upgrade since buying the plane:

GAMIjectors.

$699 plus shipping and labor to install. The math I did says they should pay for themselves in 50-100 hours, assuming I can actually run LOP smoothly at 75% power and depending on how consistently I lean for efficiency.

Before I order, are there any pitfalls I should know about? My main concern is that since the injectors are custom made for a specific engine based on operator data, what happens if I have a fuel system problem where the fix would change the fuel/air distribution (say needing a new servo)? Do I then need new injectors (or send back to GAMI for tweaking)?

Of course, there might be other issues too, that I haven't thought of.

Next step may be a digital fuel flow gauge/fuel totalizer.
 
Unless something is blocked up going to an individual cylinder the relationship of the cylinders to each other will remain constant, even if say the servo is screwed up
 
At $1,000 for the injectors the next question is if you have an eight probe engine monitor.

Otherwise, the fuel savings- say 1.5 gph, @$5.50 is going to take some number of hours to pay off.....say 200 hours.

That being said, I enjoy running LOP, but my fuel denominator is quite a bit larger.....

B.
 
Welcome to the club. Mine is in annual right now, needed to open the fuel tanks and discovered that someone in the past used the wrong kind of sealant, which has been impossible to remove, leading to a very expensive labor bill to clean the old crap out of there & rework the nutplates.

Had to replace the ELT this year, too, with a 406 unit.
 
Engine monitors can be a PITA, specifically EGT probes constantly dying, which may or may not be installation related (installing them too close to the exhaust ports of cylinders which gets them too hot).

At $89+ a pop for EGT probes, any fuel savings can easily evaporate from MX cost of an additional system.
 
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bnt83 said:
At $89+ a pop for EGT probes, any fuel savings can easily evaporate from MX cost of an additional system.
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In 1500 hours of flying planes with 12 probes per plane my experience has been that the probes are very reliable overall. No failures there. The Insight probes I had 3-4 fail. The Insight was installed by A&P students, the JPI by fully certified A&Ps.

Definitely saved more, but my fuel bill, like Bruce's, is a lot higher.
 
Ted DuPuis said:
In 1500 hours of flying planes with 12 probes per plane my experience has been that the probes are very reliable overall. No failures there. The Insight probes I had 3-4 fail. The Insight was installed by A&P students, the JPI by fully certified A&Ps.

Definitely saved more, but my fuel bill, like Bruce's, is a lot higher.
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I seem to go through one JPI EGT/TIT probe every 150-200 hours or so.
 
Ted DuPuis said:
In 1500 hours of flying planes with 12 probes per plane my experience has been that the probes are very reliable overall. No failures there. The Insight probes I had 3-4 fail. The Insight was installed by A&P students, the JPI by fully certified A&Ps.

Definitely saved more, but my fuel bill, like Bruce's, is a lot higher.
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I've heard some are worse than others. I didn't know it at the time but the ones in this C177 were used when my brother installed the entire EI EGT&CHT System. No idea how many hours were on it, but I replaced 2/4 EGT's this year.
 
Get mine out of annual (condition) tomorrow. Looking at around $4,700. The other thread was about addiction or passionate about aviation. I think the word might be insanity to continue shelling out cash to own and fly.
 
Sounds like mine were either installed better or I'm just lucky. 310 had its JPI installed 3 years ago, Aztec had the Insight installed 4.
 
Ted DuPuis said:
Sounds like mine were either installed better or I'm just lucky. 310 had its JPI installed 3 years ago, Aztec had the Insight installed 4.
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Our one failure physically broke off, I did spend some time chasing some connection issues though.
 
azure said:
Before I order, are there any pitfalls I should know about? My main concern is that since the injectors are custom made for a specific engine based on operator data, what happens if I have a fuel system problem where the fix would change the fuel/air distribution (say needing a new servo)? Do I then need new injectors (or send back to GAMI for tweaking)?
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I had similar concerns but the reality is pretty simple. You send in your data and money and they send you injectors. The injectors really aren't custom made but they are selected for your engine model. It appears to me that the data really isn't used other than to say yea or nay on their injectors helping.

Give them a call if you like, they are really helpful and knowledgeable folks. They do know their business - I had some concerns because my A&P read the wrong injector number so I thought GAMI had possibly sent me the wrong injectors. I have a TSIO-360-FB with a -K model fuel system so I was wary of some sort of error. It turned out that GAMI sent the correct injectors and was able to clearly and quickly explain why they knew the injectors were correct.
 
bbchien said:
At $1,000 for the injectors the next question is if you have an eight probe engine monitor.
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If by eight probe you mean 4 EGT + 4 CHT, then yes. But if GAMI's labor time estimates are correct, the total installed cost will be somewhere around $770 ($699 for a 4-cylinder NA Lycoming).

Otherwise, the fuel savings- say 1.5 gph, @$5.50 is going to take some number of hours to pay off.....say 200 hours.
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Well I burn about 11 gph now and figure that at peak EGT I should be burning about 9 gph, based on where my first to peak cylinder (#3) peaks now. I think $5.50 100LL is history, we'll be paying between $6 and $7 for the next year or so, and then who knows... but based on $7/gal, that's a $14/hr savings, which means just north of 50 to break even. But I wouldn't run LOP on climbout anyway, and probably not when fighting a headwind, so that's why I figure close to, maybe a little under 100 hours to break even.

It's basically going to cost me a month and a half's worth of gas (present rate of consumption) to do it. If I think of it that way, it doesn't sound too bad. ;)
 
Thanks, I wondered if they might be less "custom" than I thought. But I've also read that they will use data taken after installation to tweak the injectors if they don't get your spread under 0.5 gph on the first try.

I've tried calling them but their tech support person (John Paul) is out of the office. He does seem to answer emails though, so I'll probably follow up that way.

BTW folks, my JPI was already installed when I bought the plane and I've yet to have a probe actually fail. I've had transient "bad probe" messages from the unit once in a blue moon on startup in a winter cold snap, but that's all. Fingers crossed, but so far they've been rock solid reliable.

Clark1961 said:
I had similar concerns but the reality is pretty simple. You send in your data and money and they send you injectors. The injectors really aren't custom made but they are selected for your engine model. It appears to me that the data really isn't used other than to say yea or nay on their injectors helping.

Give them a call if you like, they are really helpful and knowledgeable folks. They do know their business - I had some concerns because my A&P read the wrong injector number so I thought GAMI had possibly sent me the wrong injectors. I have a TSIO-360-FB with a -K model fuel system so I was wary of some sort of error. It turned out that GAMI sent the correct injectors and was able to clearly and quickly explain why they knew the injectors were correct.
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What engine are you running?

In my 172 with IO360 I routinely run WOTLOP trueing 120KTAS at 8.0 gph and 2500 rpm using Gamijectors. I can pull the power back with mixture (wide open throttle) all the way back to about 2100 rpm before it starts to get rough and stumble, my set of injectors is very well balanced. Of course I have full engine monitoring (pretty much a MUST-HAVE for good safe LOP ops), and a fuel totalizer is coming soon.
 
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so if youre WOTLOP and pulled back to a power setting that puts you out of red box and the engine is running smooth, why is engine monitoring required?
 
AirGuy: Liz's engine is a 200 HP IO-360 and yours is 180 HP.

Tony: I tend to advocate it because on some airframes the CHTs can really get high, even with everything else good. I never fixed the EGTs on the Aztec that broke because the EGTs never got hot enough to represent a problem. Meanwhile the CHTs would easily hit the mid-400s if I wasn't careful.
 
your opinion on a 172 w/O-320 at 75% or less power?
 
airguy said:
What engine are you running?
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It's a Lycoming IO-360-A1B6 at 200hp.

In my 172 with IO360 I routinely run WOTLOP trueing 120KTAS at 8.0 gph and 2500 rpm using Gamijectors. I can pull the power back with mixture (wide open throttle) all the way back to about 2100 rpm before it starts to get rough and stumble, my set of injectors is very well balanced. Of course I have full engine monitoring (pretty much a MUST-HAVE for good safe LOP ops), and a fuel totalizer is coming soon.
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For a 172, that is pretty good performance. I assume your IO-360 is either 160hp or 180hp, probably 180.

I cannot really run my engine much LOP right now. I get best performance with #3 around peak EGT, but then #1 and #2 are right in that 25-100 ROP zone that I don't like to operate in at high power even if detonation is unlikely, just because the high ICPs can't be good for engine longevity. If I lean until all of my cylinders are at peak or LOP, it usually runs rough because #3 and #4 are so lean they aren't making power. I prefer to cruise with #3 25-50 LOP, but only if I'm high enough that 65% power gives me decent TAS (>120 kts). That basically limits my LOP flying to DAs of 8000 and above, and it's why I want GAMIs.
 
tonycondon said:
your opinion on a 172 w/O-320 at 75% or less power?
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It wouldn't detonate at 100% power. At 75% you're fine.

As for CHTs, I've never flown one with an engine monitor. So I have no idea.
 
Data point.

I've had my UBG-16 for 8 or 9 years and haven't lost a probe yet.
 
I don't have gamijectors in the mooney and it will run LOP just fine around 9-9.7 gph. 200HP IO360A3B6D - I usually mooney along around 160 knots.
 
wsuffa said:
I seem to go through one JPI EGT/TIT probe every 150-200 hours or so.
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I think I replaced one JPI probe in something like 3000 engine hours on two different airplanes.
 
Liz, in 1995 I bought the first set of GAMI's the company produced for turbo'd engines, and shortly after got the second set as no-cost replacements because the first set was crap.

Having now been involved with more than a dozen injector upgrade sets, I've yet to see anything from the company other than whatever is necessary to provide excellent products and customer service. I think you'll like them.
 
azure said:
Thanks, I wondered if they might be less "custom" than I thought. But I've also read that they will use data taken after installation to tweak the injectors if they don't get your spread under 0.5 gph on the first try.

I've tried calling them but their tech support person (John Paul) is out of the office. He does seem to answer emails though, so I'll probably follow up that way.

BTW folks, my JPI was already installed when I bought the plane and I've yet to have a probe actually fail. I've had transient "bad probe" messages from the unit once in a blue moon on startup in a winter cold snap, but that's all. Fingers crossed, but so far they've been rock solid reliable.
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John Paul has been fairly responsive to me in the past and he's generally very intent on tweaking your injectors until you're satisfied.

BTW, installing injectors has to be the easiest upgrade task ever, especially if access to the top of the cylinders is easy (unfortunately not the case with your C177RG). If I were you I'd ask if I could perform the work myself under the supervision of your A&P to keep your total cost down. The only caveat is that you must take care to not overtighten the injectors. Use a low range torque wrench and tighten to the lower specified limit (something like 25 in-lbs IIRC). This is less torque than I can apply with a screwdriver and with a ratchet it's easy to overdo it. The threads on the injectors are tapered and with excessive torque you can generate a lot of radial pressure in the cylinder which is a known cause of cylinder cracking. About the only other issue is to avoid cross threading the fuel line's compression nut onto the top of the injector.
 
Isn't the purpose of the Gamijectors to narrow the delta in fuel flow between the first cylinder to go lean and the last? The JPI monitor gives you that number. I just wondered what his was.
 
tmyers said:
Isn't the purpose of the Gamijectors to narrow the delta in fuel flow between the first cylinder to go lean and the last? The JPI monitor gives you that number. I just wondered what his was.
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That's their story, but they also know that a substantial drop in fuel flow will occur. The spreads in my first engine in the T-210 were almost perfect out of the box, but the replacement reman was horribly mismatched. Hence the GAMI install.
 
I am seeing a spread of 1.2 GPH and have heard it should be more like .75!or less.. I still have my stock injectors.
 
gismo said:
John Paul has been fairly responsive to me in the past and he's generally very intent on tweaking your injectors until you're satisfied.
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I found him easy to deal with as well for the 520s in the 310. Although the ones they sent us out of the box were perfect, so it didn't require any call backs.
 
Are they custom made for each cylinder, and if so what is that based on?
 
tmyers said:
Are they custom made for each cylinder, and if so what is that based on?
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For Continentals they start with a "standard" set that reduces the FF to the front pair of cylinders slightly and increases the flow to the rear pair by about the same amount. This is an attempt to compensate for the fact that a portion of the fuel from the rear injectors ends up going into the cylinders further forward on the same side, carried by the air flowing forward in the intake manifolds. If that doesn't balance the mixtures adequately GAMI will have you record the FF at peak EGT for each cylinder and send you one or more injectors that have been tweaked to bring the peaks closer together.
 
tmyers said:
Isn't the purpose of the Gamijectors to narrow the delta in fuel flow between the first cylinder to go lean and the last? The JPI monitor gives you that number. I just wondered what his was.
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That is the "GAMI spread" but since this is recorded by definition at each cylinder's peak EGT, it's not "at LOP".
 
Hmmmm. All I know is that when using LOP on the JPI each cylinder EGT bar flashes when the monitor sees a peak temp followed by a slight drop in temp. When that cylinders starts flashing it is by definition lean of peak. By the time the last cylinder flashes three are more on the lean side of peak and the last cylinder is just lean of peak. When that happens I push the LF button and the display indicates a fuel flow that JPI defines as the GAMI spread.

This is not my interpretation, but is what the JPI manual states. All I am asking is if 1.2 is bad, ok, good, or great.

If someone answered this alreadt, sorry for the length of time, I am not the fastest Typer on an iPad
 
I just read through the website and understand the operation better. The data from the JPI would probably give them what they are looking for.
 
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