JPI 830 w or w/o Gami's

[WAFI]

Hey guys-- I would like some feed back on if I should go ahead and purchase Gami fuel injectors for my IO-360-A3B6D because I'm getting the JPI 830 installed next week? Does anyone have a JPI installed without Gami Injectors? I ask this because from what I've herd their a must have if I want to fully benefit from the JPI functions. 

Any and all feed back is welcome.

FYI - My motor runs great with the stock injectors, so that's my only hesitation. 

[ArtVandelay]

No, get the JPI first, then do some lean tests to see what kind of fuel flow spread you have, if it’s 1/2 gallon or better…then get the gamis.
Edit: by better I meant larger.

[Aerodon]

22 minutes ago, ArtVandelay said:

No, get the JPI first, then do some lean tests to see what kind of fuel flow spread you have, if it’s 1/2 gallon or better…then get the gamis.

1/2G or WORSE, then get the Game's.

 

Aerodon

[PT20J]

Most IO-360s do fine with stock injectors. If not, I would make sure that there are no issues with the engine such as intake leaks before installing GAMIjectors. You need the JPI first anyway to get data to order the GAMIs

[jaylw314]

36 minutes ago, WAFI said:

Hey guys-- I would like some feed back on if I should go ahead and purchase Gami fuel injectors for my IO-360-A3B6D because I'm getting the JPI 830 installed next week? Does anyone have a JPI installed without Gami Injectors? I ask this because from what I've herd their a must have if I want to fully benefit from the JPI functions. 

Any and all feed back is welcome.

FYI - My motor runs great with the stock injectors, so that's my only hesitation. 

GAMI injectors aren't as much help for Lycomings, and the IO-360 is usually pretty good.  I installed an 830.  My gph spread is only about 0.2-0.4 gph so GAMI's would be trivial to minimal help, but I already knew that because I had a JPI 700 beforehand.

What made you decide on the 830?  EI makes a comparable monitor that is easier to fit on a panel, the rectangular display is just big enough it's tricky positioning it in the instrument panel.  The EI fits in a standard 3" hole. I only went with the 830 because it's an easy upgrade from the 700, since I just reused the sensors (well, I had to add the MP and RPM sensors))

Edited December 9, 2021 by jaylw314

[WAFI]

3 minutes ago, jaylw314 said:

GAMI injectors aren't as much help for Lycomings, and the IO-360 is usually pretty good.  I installed an 830.  My gph spread is only about 0.2-0.4 gph so GAMI's would be trivial to minimal help, but I already knew that because I had a JPI 700 beforehand.

What made you decide on the 830?  EI makes a comparable monitor that is easier to fit on a panel, the rectangular display is just big enough it's tricky positioning it in the instrument panel.  The EI fits in a standard 3" hole. I only went with the 830 because it's an easy upgrade from the 700, since I just reused the sensors (well, I had to add the MP and RPM sensors))

I looked at the EI and Garmin 275 but I have friends with the JPI and they swear by them. I've never heard anything bad about JPI. Also, I have the panel room for the 830. 

[WAFI]

38 minutes ago, ArtVandelay said:

No, get the JPI first, then do some lean tests to see what kind of fuel flow spread you have, if it’s 1/2 gallon or better…then get the gamis.
Edit: by better I meant larger.

Ok, so I'm not that familiar with the JPI functions yet but I'm assuming 1/2gal spread means I can some how check the GPH on each cylinder with the JPI? 

[WAFI]

12 minutes ago, PT20J said:

Most IO-360s do fine with stock injectors. If not, I would make sure that there are no issues with the engine such as intake leaks before installing GAMIjectors. You need the JPI first anyway to get data to order the GAMIs

Motor runs great!!! Not to get off topic but I'm curious as to why you brought up intake leaks since I've heard this before? Is IO-360 prone to having intake leaks? If so where?

[jaylw314]

2 minutes ago, WAFI said:

I looked at the EI and Garmin 275 but I have friends with the JPI and they swear by them. I've never heard anything bad about JPI. Also, I have the panel room for the 830. 

There have been comments on customer service and communications issues with some shops I remember reading about (I never had issues with them, though).  I REALLY like the look of the EI display, but that may be just a preference thing, and they do have someone on this board.  If you have the extra panel space for the 830, though, it's been a good piece of kit.  Some people here will argue if you're going to spend the money on wiring for the 830, why not spend a little more to get the primary 900 and ditch the factory instrumentation.  It's a reasonable argument, but didn't apply to me since I had minimal rewiring to do.

[Aerodon]

4 minutes ago, WAFI said:

Ok, so I'm not that familiar with the JPI functions yet but I'm assuming 1/2gal spread means I can some how check the GPH on each cylinder with the JPI? 

Sort of, the famous GAMI test is to note the FF when the first cylinder reaches peak EGT, then keep leaning until the last cylinder reaches peak.  The difference between them is the 'GAMI Spread'.  If the spread is low, it means that all the cylinders are operating at very similar air to fuel ratios and efficiency.  If the spread is high, it can be corrected with GAMI's

Aerodon

 

[WAFI]

6 minutes ago, Aerodon said:

Sort of, the famous GAMI test is to note the FF when the first cylinder reaches peak EGT, then keep leaning until the last cylinder reaches peak.  The difference between them is the 'GAMI Spread'.  If the spread is low, it means that all the cylinders are operating at very similar air to fuel ratios and efficiency.  If the spread is high, it can be corrected with GAMI's

Aerodon

 

Great, thanks for clarifying. I'm sure there's some YouTube videos I need to watch. 

[Vance Harral]

5 minutes ago, Aerodon said:

If the spread is low, it means that all the cylinders are operating at very similar air to fuel ratios and efficiency.  If the spread is high, it can be corrected with GAMI's

Some additional info: the basic reason for wanting closely matched fuel flow from each injector is to allow the engine to run smoothly when all cylinders are operating lean-of-peak (LOP).  If you want to operate in this regime, (more efficient, cleaner, but always slower in a normally-aspirated airplane), then you *might* want GAMI injectors.  If you don't care about operating LOP (value speed over efficiency, don't have problems with plug fouling, etc), there is little reason to invest in them.

As a data point, the famous "GAMI spread" in my IO-360-A1A is not particularly good - about 1.0 GPH difference in fuel flow between the points across which the four cylinders hit peak EGT.  But I'm still able to operate with the last cylinder to peak running at 10-20 degrees LOP.  The engine runs a little rough at that setting.  Not "OMG it sounds like it's going to quit" rough, just a little fatiguing.  I don't particularly care about that, because I rarely choose to run LOP.  Therefore, I'm not especially interested in GAMI injectors.  If I had problems with plug fouling, was more concerned about CO poisoning, or just really enjoyed the efficiency vs. speed tradeoff, I'd run LOP and likely invest in GAMI injectors.

 

[Greg Ellis]

1 hour ago, WAFI said:

Great, thanks for clarifying. I'm sure there's some YouTube videos I need to watch. 

Here's a place where you can get started on your quest for the perfectly balanced engine.

General Aviation Modifications, Inc. (gami.com)

[PT20J]

2 hours ago, WAFI said:

Motor runs great!!! Not to get off topic but I'm curious as to why you brought up intake leaks since I've heard this before? Is IO-360 prone to having intake leaks? If so where?

The seals where the intake tubes enter the sump can be damaged if not installed properly after removal for cylinder work. The gaskets at the cylinder end of the tubes can leak if the bolts loosen. I always check all the intake bolts and exhaust bolts for tightness during annual. A significant intake leak will make the engine  idle poorly.

Skip

[Aerodon]

4 hours ago, Vance Harral said:

Some additional info: the basic reason for wanting closely matched fuel flow from each injector is to allow the engine to run smoothly when all cylinders are operating lean-of-peak (LOP).  If you want to operate in this regime, (more efficient, cleaner, but always slower in a normally-aspirated airplane), then you *might* want GAMI injectors.  If you don't care about operating LOP (value speed over efficiency, don't have problems with plug fouling, etc), there is little reason to invest in them.

As a data point, the famous "GAMI spread" in my IO-360-A1A is not particularly good - about 1.0 GPH difference in fuel flow between the points across which the four cylinders hit peak EGT.  But I'm still able to operate with the last cylinder to peak running at 10-20 degrees LOP.  The engine runs a little rough at that setting.  Not "OMG it sounds like it's going to quit" rough, just a little fatiguing.  I don't particularly care about that, because I rarely choose to run LOP.  Therefore, I'm not especially interested in GAMI injectors.  If I had problems with plug fouling, was more concerned about CO poisoning, or just really enjoyed the efficiency vs. speed tradeoff, I'd run LOP and likely invest in GAMI injectors.

 

Vance, close but not completely correct.  The idea is to get the cylinders running at very similar air to fuel ratios, then they will be operating at the same efficiency and power, the by-product is the engine will be smooth.  If you want to run at 'best power', you still have the advantage of one cylinder not running lean, another one running very rich, and it's smooth.  And you will have less problems with that rich cylinder fouling the plugs.  If your 'spread' is 1GPH, that extra GPH is effectively going into 1 or 2 cylinders and they are way rich.

 

Aerodon

[Vance Harral]

4 hours ago, Aerodon said:

The idea is to get the cylinders running at very similar air to fuel ratios, then they will be operating at the same efficiency and power, the by-product is the engine will be smooth

If we're going to get into details, let's get it exactly correct.

Balanced fuel flows across all cylinders increase engine smoothness at stoichiometric mixtures, and mixtures lean of stoichiometric.  Producing the same amount of power under these conditions requires injecting the same amount of fuel, because fuel is the governing input to the combustion equation.  Unequal amounts of fuel -> unequal amounts of power developed -> engine roughness.

But unbalanced fuel flows across all cylinders in rich-of-peak operations have (almost) no effect on power developed, and therefore no effect on engine smoothness.  The reason is that the excess fuel in a rich mixture is simply unused, and blows out the exhaust unburned.  It doesn't matter whether you have "a little" more fuel than the stoichiometric ratio, or "a lot" more.  The power developed is the same (well, aside from the effects of small differences in additional cooling, and the density of the material exiting the exhaust system, which explains the less-than-flat power/mixture graph on the rich side).

If your point is that unbalanced fuel flows across cylinders can allow some cylinders to be ROP while others are LOP, sure, that's true.  But that is not "best power", which is the point you are emphasizing:

4 hours ago, Aerodon said:

If you want to run at 'best power', you still have the advantage of one cylinder not running lean, another one running very rich, and it's smooth.

Best power in an aircraft cylinder is always rich of peak (100-200 degrees ROP for the typical Lycoming, see graph below).  If the mixture crosses over into lean-of-peak operation, the cylinder is not running at best power.  Furthermore, as the graph shows power decreases more quickly on the LOP side than on the ROP side.  So in an engine with less than perfectly matched fuel flows, best power is achieved when one cylinder is around 150 degrees ROP, and all other cylinders are still ROP.  Again, if any cylinder actually crosses into LOP operation - where fuel flow does affect the power developed - that is by definition not best power.

 

 

4 hours ago, Aerodon said:

And you will have less problems with that rich cylinder fouling the plugs.

LOP operations tend to produce plug that look nice when pulled for inspection and gapping.  But let's be careful with the word "fouling", and distinguish cosmetics from actual mis-firing of the plug.  As a primarily ROP-in-cruise flyer, I have zero problems with misbehaving spark plugs.  This is almost certainly because I aggressively lean during low power ground operations, which is where essentially all plug-fouling-of-the-type-that-causes-misfire occurs.  Barring very extreme cold weather operations, any power setting actually used in flight produces sufficient cylinder combustion chamber temperatures for the lead scavaging agents in the fuel to do their trick, and it's generally lead contamination that causes poor spark.

Again, the plugs from a primarily-LOP-flown engine will tend to have just a hint of light brown residue on the plugs, while a primarily-ROP-flown engine will have a heavier, blacker residue.  So LOP is "cleaner" for the plugs, no argument there.  But not cleaner in a sense that actually matters.  I'm not finding huge balls of lead down in the plug well when I pull my plugs for inspection and gapping, and I don't have problems with mis-firing plugs.

 

4 hours ago, Aerodon said:

If your 'spread' is 1GPH, that extra GPH is effectively going into 1 or 2 cylinders and they are way rich.

Concur, no argument.  If I had GAMI injectors, then instead of flying with one cylinder at 150-ish ROP and some of the other cylinders even richer, all the cylinders would operate right at 150-ish ROP at the best power setting.  There would be no difference in the power developed or the speed I traveled at vs. without GAMIs, but fuel flow would be a few tenths of a GPH less.

[PT20J]

It’s good to remember that GAMIs only balance out cylinder to cylinder power variations. All internal combustion engines have cycle to cycle variations in the combustion event in each cylinder that affect power output, and cycle to cycle variations are greater LOP. This is why the engine is smoother ROP than LOP.

Skip

[Aerodon]

14 hours ago, Vance Harral said:

Concur, no argument.  If I had GAMI injectors, then instead of flying with one cylinder at 150-ish ROP and some of the other cylinders even richer, all the cylinders would operate right at 150-ish ROP at the best power setting.  There would be no difference in the power developed or the speed I traveled at vs. without GAMIs, but fuel flow would be a few tenths of a GPH less.

I'm not sure I agree with this statement.  If the spread is 1GPH before GAMI's and .2GPH after GAMI's, and you lean the first cylinder to 150 ROP, the other cylinders will be just behind this (slightly richer) and you will be burning 0.8GPH less?  And if you lean the engine so that the average of the cylinders are 150 ROP, you could still save 0.4GPH?  At $5/g and $700 for the GAMI's, thats a 175 hour payback.

I was an early adopter of GAMI's for my Seneca, and we went from 12GPH / side to 11GPH /side with no speed loss or CHT issues.  We also installed the Merlyn wastegate.  I have not flown my 252 enough to fully appreciate the intercooler and tuned induction system, but if I have more than 1/2GPH GAMI spread, I would install GAMI's.

I do not have any direct experience with 4 cylinder GAMI's, I seem to recall that it is not as easy to get a balance FF with a Lycoming 4 cylinder than with a  6 cylinder Conti.  I think the spread can be somewhat dependant on power setting.  The spread in a Continental is a direct function of the continuous flow injection and the sequential induction system.

Aerodon

 

[kortopates]

As others of said, just install the EDM-830 for now. Or better yet, if not upgrading from a older 700, go directly to a TSO'd for primary EDM-900 so you can eliminate airframe dependence on factory gauges.

Once you have your new monitor installed created a free SavvyAnalysis Account on SavvyAviation.com to upload and analyse your data. https://www.savvyaviation.com/free-stuff/ 

Then fly the Savvy Analysis Test Profile https://resources.savvyaviation.com/resources/other-documents/flight-test-profile/

If you do want to fly LOP, the gami spread size is only half of what is needed. Its just as important to evaluate your ignition and ensure its in good enough health to fire LOP without premature misfire. LOP stresses the ignition system much more than ROP and many find eventhough they have the gami spread to support LOP, that their ignition system is in need of maintenance.  Its also typically the first to get out of tolerance.

After you fly the Savvy Test profile of sweeps and LOP Mag test, you can use Savvy's free online tools to evaluate your data and see what size spread you have as well as evaluate your ignition. But make sure you first change the EDM data sampling rate from its default of every 6 sec to every 1 or 2 sec. (I recommend every 1 sec). Odds are that you won't need gami injectors, only very few Lyc IO-360's ever due (~10%) but almost every 6 cyl engine needs tuned injectors to keep the spread within 0.5 GPH.

Edited December 10, 2021 by kortopates

[Vance Harral]

1 hour ago, Aerodon said:

If the spread is 1GPH before GAMI's and .2GPH after GAMI's, and you lean the first cylinder to 150 ROP, the other cylinders will be just behind this (slightly richer) and you will be burning 0.8GPH less?  And if you lean the engine so that the average of the cylinders are 150 ROP, you could still save 0.4GPH?  At $5/g and $700 for the GAMI's, thats a 175 hour payback.

That sounds about right to me.  Labor adds to the $700 kit cost if you're not your own A & P, but swapping injectors is not a labor-intensive job.  Maybe a couple hours worst case (sometimes you need to go multiple rounds of swapping with GAMI to get the absolute best result).  Call it $1000 all-in, and a 200 hour payback worst case.

This is a theoretical argument that assumes one meticulously manages the mixture at all times.  If you're a little lazier like most of us, and/or spend a lot of time flying around the pattern, doing IFR training, etc., you're not going to save the full 0.8gph during every hour of operation.  Regardless of those quibbles, though, there is always going to be a break even point within a few years.  Up to each pilot to decide if that's the best use of their dollars compared with additional training or other alternatives.

 

1 hour ago, Aerodon said:

I was an early adopter of GAMI's for my Seneca, and we went from 12GPH / side to 11GPH /side with no speed loss or CHT issues.  We also installed the Merlyn wastegate.  I have not flown my 252 enough to fully appreciate the intercooler and tuned induction system, but if I have more than 1/2GPH GAMI spread, I would install GAMI's.

Let's try not to confuse the original poster, who has a normally aspirated engine (as do I).  Turbocharged Senecas and 252s have the option to run LOP in cruise while still maintaining "rated" cruise power (60%, 65%, 70%, 75%, whatever - take your pick based on desired engine longevity).  One can simply push the throttle forward, increase manifold pressure, and maintain rated power up to the critical altitude of the turbo.  That ability to maintain rated cruise power and run LOP without slowing down is attractive.  If I had the privilege of operating a turbo'd bird, I'd likely fly LOP in cruise.

At optimum cruise altitudes in a normally aspirated engine, however, it's a tougher sell.  Running LOP and also making rated cruise power requires staying low, where additional drag is working against you.  Climb up to optimum NA density altitudes of around 8K and you're likely below max rated cruise power even at the best power mixture.  Going LOP there slows you down.  Still a great tool in the tool bag for increasing range when needed.  But a lot of us normally-aspirated drivers just can't stand to give up the knots it costs to get the benefit, even though that's an emotional argument that has little impact on real-world, door-to-door enroute times.

[A64Pilot]

You don’t even need to do a “gami spread”, set the aircraft up at a normal cruise of 75% or less, then start leaning, if she will continue to run smooth well after there is a a noticeable power loss. I mean one that when you go back to rich will be very. very noticeable, then the engine is running smooth well lean of peak 

Try this run 22 squared, and lean to 7 GPH, that will be way LOP. but then go down to 6.5, which is so lean of peak I doubt anyone will run that lean 

If she is still relatively smooth way down at 6.5. you don’t need to do anything

 

Edited December 10, 2021 by A64Pilot

[WAFI]

Thanks guys for all the info… 

Definitely learned a bunch of random stuff too.

[John Mininger]

On 12/9/2021 at 12:04 PM, jaylw314 said:

There have been comments on customer service and communications issues with some shops I remember reading about (I never had issues with them, though).  I REALLY like the look of the EI display, but that may be just a preference thing, and they do have someone on this board.  If you have the extra panel space for the 830, though, it's been a good piece of kit.  Some people here will argue if you're going to spend the money on wiring for the 830, why not spend a little more to get the primary 900 and ditch the factory instrumentation.  It's a reasonable argument, but didn't apply to me since I had minimal rewiring to do.

I’m going to be one of the people arguing for the EDM 900. If you can fit an 830 in your panel, you can in all likelihood fit a 900. I made a big mistake when I decided to go with the 830. I cut out a template from heavy card stock to what I thought were the dimensions of the 900 and set about trying to find a place in the panel where it would fit. It wouldn’t. And the reason it wouldn’t fit was because I had cut it out to the wrong dimensions! I mistakenly used the 930’s dimensions, not the 900.

Anyway, if I had to make the decision again, I would go with the 900.

The 900 will certainly cost more. Not only for the unit itself, but you will probably want to upgrade your fuel tank senders to Cies; two per tank. That will add at least another $2000 just for the senders, plus the extra labor for both installing the senders and doing fuel quantity calibration. But I would recommend you at least consider the EDM 900

As far as I know, Air Parts of Lock Haven is the only place where that primary engine gauge cluster at the top can be repaired anymore.

I will say though that I like the 830 a lot, and the only problem that I’ve had with it was fluctuating RPM that would swing up and down by about 200. That turned out to be not the fault of the 830. I asked JPI about it at Oshkosh and they said the problem was probably caused by “noise”. But they had no guidance on where it might be coming from, or where one might begin to look for it. I then talked to a very experienced MSC A&P. He told me that whenever they had “funky” issues with avionics, they would relocate the ground cable coming off the battery, from the shelf that runs between the stringers, to the stringer itself. He said that that generally solved the problem 80% of the time. That was done, and the problem went away.

[John Mininger]

20 hours ago, kortopates said:

Odds are that you won't need gami injectors, only very few Lyc IO-360's ever due (~10%) but almost every 6 cyl engine needs tuned injectors to keep the spread within 0.5 GPH.

Very interesting. I never knew that. GAMI injectors were about halfway down on my capital improvement list.

[Austintatious]

28 minutes ago, John Mininger said:

I’m going to be one of the people arguing for the EDM 900. If you can fit an 830 in your panel, you can in all likelihood fit a 900. I made a big mistake when I decided to go with the 830. I cut out a template from heavy card stock to what I thought were the dimensions of the 900 and set about trying to find a place in the panel where it would fit. It wouldn’t. And the reason it wouldn’t fit was because I had cut it out to the wrong dimensions! I mistakenly used the 930’s dimensions, not the 900.

Anyway, if I had to make the decision again, I would go with the 900.

The 900 will certainly cost more. Not only for the unit itself, but you will probably want to upgrade your fuel tank senders to Cies; two per tank. That will add at least another $2000 just for the senders, plus the extra labor for both installing the senders and doing fuel quantity calibration. But I would recommend you at least consider the EDM 900

As far as I know, Air Parts of Lock Haven is the only place where that primary engine gauge cluster at the top can be repaired anymore.

I will say though that I like the 830 a lot, and the only problem that I’ve had with it was fluctuating RPM that would swing up and down by about 200. That turned out to be not the fault of the 830. I asked JPI about it at Oshkosh and they said the problem was probably caused by “noise”. But they had no guidance on where it might be coming from, or where one might begin to look for it. I then talked to a very experienced MSC A&P. He told me that whenever they had “funky” issues with avionics, they would relocate the ground cable coming off the battery, from the shelf that runs between the stringers, to the stringer itself. He said that that generally solved the problem 80% of the time. That was done, and the problem went away.

I agree with this... the added cost is not all that much, but you get a large benifit of being able to get rid of a lot of stock gauges that are more prone to failure and inaccuracy and getting more expensive and difficult to find.