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I think I have uneven airflow....

carrollcw

carrollcw

Well Known Member
I now have about 90 hours on my RV7. Now that I have worked out the major kinks, I am trying to refine it a little. I have noticed that on all my flights, 1/3 CHT's and EGT's run hotter than 2/4 while ROP, however once LOP, 1/3 are my coolest cylinders. When I say hotter, the CHT's are about 20 deg hotter and the EGT's almost 100 deg hotter. When LOP, the CHT's are 60 deg cooler and EGT's 100 deg cooler.

This tells me that 1/3 are getting better airflow, thus run leaner than 2/4.

Furthermore, my GAMI spread is about 1.5 with 1/3 peaking first.

So, what can I do? Right now I have the standard ECI updraft sump that came with my Titan engine. I have heard that the Superior sump is better balanced than the stock Lycoming or ECI. Does anyone have any real world experience with this?

Another option is to heat wrap my 1/3 induction tubes, but I think this would just be a patch for the real problem.

If a new sump is the best choice, has anyone swapped out their superior updraft for cold air induction and would be willing to sell me their old sump???

Thanks!
 
carrollcw said:
Furthermore, my GAMI spread is about 1.5 with 1/3 peaking first.
Click to expand...

Assuming your 1.5 is 1.5gph difference between first and last peak. If this is the case, fix this first. this will pull the engine cylinders into a closer tolerance in everything.
 
Kahuna said:
Assuming your 1.5 is 1.5gph difference between first and last peak. If this is the case, fix this first. this will pull the engine cylinders into a closer tolerance in everything.
Click to expand...

Absolutely correct, but this is an EFii electronic fuel injection system. Clark can't fix it with a simple nozzle restrictor swap like we can with our constant flow systems. That's why he is hoping to correct an intake mass flow imbalance with a different sump.

I for one would be very interested to hear the results of a swap to a Superior updraft sump.

Clark, the trusty Siemens injectors are supposed to be very closely matched. However, since they are simply o-ringed into the intake tubes, and thus easy to move around, it might be informative to swap the injectors side to side. If the temperature pattern changes, you have an injector flow imbalance in addition to (or rather than) a mass flow imbalance.
 
I agree with Kahuna. If 1/3 are that far leaner than 2/4, 1/3 will run hotter in both EGT and CHT when rich of peak, and cooler in both EGT and CHT when lean of peak. Tune your injectors, assuming you are injected. Do that before changing anything else. If you have 0.028" nozzles in all injectors, I would put 0.027 in 2/4 and run the test again and see how things run.
 
With my experience in working with a SDS equipped Reno racer, Dan is correct, the injectors are not created exactly equal. They are very close so swapping them around may not nake a big difference, but it is worth a try.

There are companies out there that will very accurately flow test the injectors as part of a cleaning process. The one we used gave us before and after flow numbers. Ours had badly fowled due to inactivity over a few months, but the cleaning returned them to specification.

I don't know if 100LL will be a problem over a long time, but EFI users should keep an eye on their EGT numbers and look for long term changes.
 
DanH said:
Absolutely correct, but this is an EFii electronic fuel injection system. Clark can't fix it with a simple nozzle restrictor swap like we can with our constant flow systems. That's why he is hoping to correct an intake mass flow imbalance with a different sump.

I for one would be very interested to hear the results of a swap to a Superior updraft sump.

Clark, the trusty Siemens injectors are supposed to be very closely matched. However, since they are simply o-ringed into the intake tubes, and thus easy to move around, it might be informative to swap the injectors side to side. If the temperature pattern changes, you have an injector flow imbalance in addition to (or rather than) a mass flow imbalance.
Click to expand...

Dan, you are correct, I cannot do a simple injector swap to fix an imbalance. Furthermore, I have swapped the injectors from 1/3 with 2/4 and the temps remained exactly the same. Thus, the injectors are balanced. This is why I think I have an airflow problem, not injector problem. I have heard the superior sump is more balanced.
 
Have you contacted Robert at EFII? I am going with a similar setup and would be interested in his take. I am sure that you are not the first to use the stock sump.
 
carrollcw said:
Dan, you are correct, I cannot do a simple injector swap to fix an imbalance. Furthermore, I have swapped the injectors from 1/3 with 2/4 and the temps remained exactly the same. Thus, the injectors are balanced. This is why I think I have an airflow problem, not injector problem.
Click to expand...

Excellent. You, me, and Bruce all thinking alike. Puts me in good company ;)

I have heard the superior sump is more balanced.
Click to expand...

And I suspect we're going to find out if it is true or not.
 
I saw it was EFII. I assumed that an electronic FI could easily control the amount of fuel dispersed with time open. If this is not the case, then how does one ever control the even distribution of fuel in an EFII setup? Swap sumps until you find the best? Yikes!
 
Sumps

Hi Clark,
The Superior cold air sump is a nice upgrade. I would say close to half our customers order their engines originally with the Superior sump.

Robert
 
Kahuna said:
I saw it was EFII. I assumed that an electronic FI could easily control the amount of fuel dispersed with time open. If this is not the case, then how does one ever control the even distribution of fuel in an EFII setup? Swap sumps until you find the best? Yikes!
Click to expand...

That's pretty much it.

It's a pulse width modulated constant flow system, not a sequential injection system. All injectors open and close at the same time, and they are all supplied at the same fuel pressure, so all cylinders get the same fuel delivery, or better said, the same within the flow tolerance of the injectors. There is no way to modify fuel flow to any particular cylinder, so an owner is left with trying to modify the air delivery, or living with a huge GAMI spread.

rcpaisley said:
The Superior cold air sump is a nice upgrade. I would say close to half our customers order their engines originally with the Superior sump. Robert
Click to expand...

A year and a half of heavily promoted Titan partnership, and nobody saw this on the dyno?
 
This was discussed at length a couple months back on VAF. The core problem is the unequal airflow of certain sumps and perhaps heads. Here's what I said back on June 24th in that thread:

"I'll say it again, low GAMI spread achieved by changing individual injector flow rate is useful but really a partial patch for the actual cause in the first place. Makes people feel good watching that close alignment but all cylinders are not doing equal work which is what we should really be striving for. People have become fixated on low GAMI spread in the aircraft world with only a few companies (mainly on the race and performance side) tackling the actual problem with better designed and produced components."

It'd be very useful if someone could run the same engine (preferably with flow benched balanced heads and injectors) with Lyc, Superior, ACE, Barrett, Sky Dynamics etc. sumps on the dyno and document the GAMI spread of each design.

The Sky Dynamics stuff is used on many Red Bull aircraft: http://www.skydynamics.com/index.php/products/sump/intake This is how I'd design a manifold if I had a Lycoming. I'm not associated with these folks, just like what they've done here.
 
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Fuel delivery

Actually, the fuel balance with electronic injection is light years ahead of any alternative.

Yes the flow balance with a mechanical injection can be balanced at one operating point. But the fuel balance falls apart at every other operating point.
This contributes to the hard starting and rough idle that we see with mechanical systems. We clearly see this on the dyno as well as on planes.
Also, the fuel delivery with mechanical injection is constant flow, not pulsed as with the electronic injection. There is also no atomization through a mechanical injector, it literally looks like a laminar stream coming out of a garden hose. The spray pattern from the electronic injector is nicely dispersed and atomized.

The amazing flow balance of the electronic injection across all operating points is one thing that blew Titan away when they saw it on the dyno. They had never been able to achieve that before. The rest is history!

Robert
 
Kahuna said:
I saw it was EFII. I assumed that an electronic FI could easily control the amount of fuel dispersed with time open. If this is not the case, then how does one ever control the even distribution of fuel in an EFII setup? Swap sumps until you find the best? Yikes!
Click to expand...

I built a custom EFI for my porsche. Obviously I had complete control over each injector and could tune fuel flow. Most EFI's have a TRIM function that allows a +/- 10% constant adjustment in injector flow (separate trim for each bank or injector). You should ask your EFI provider if they have a way to adjust TRIM values on individual installations.

Larry
 
rcpaisley said:
Actually, the fuel balance with electronic injection is light years ahead of any alternative.
Click to expand...

Both constant flow injectors and pulse width modulated injectors are little more than a hole in a fitting. If the holes in a given set of injectors (of either style) are the same size and they all get supplied at the same pressure, they all flow the same volume.

Yes the flow balance with a mechanical injection can be balanced at one operating point. But the fuel balance falls apart at every other operating point.
Click to expand...

What you mean is that EGT relationships shift with changes in mass airflow. It's an airflow change....so both injection styles will respond the same. Balance does not "fall apart", whatever that means, for either style.

This contributes to the hard starting and rough idle that we see with mechanical systems.
Click to expand...

Hot start and hot idle issues with constant flow systems are due to high fuel vapor pressure combined with low line pressure at low flow rates. At idle, line pressure is a little more than ~2 psi from the servo ball valve to the flow divider, and nil from there to the injector, thus fuel can boil in those parts of the system. Under hot start and idle conditions the EFI system has a major advantage, as it maintains relatively high line pressure (typical is 40~50 psi) at all flow rates. The advantage fades to zip at higher flow rates.

None of the above has anything to do with balance.

Also, the fuel delivery with mechanical injection is constant flow, not pulsed as with the electronic injection. There is also no atomization through a mechanical injector, it literally looks like a laminar stream coming out of a garden hose. The spray pattern from the electronic injector is nicely dispersed and atomized.
Click to expand...

Pulsed delivery or constant flow delivery makes no difference.

The flow from a constant flow nozzle is partially atomized, the purpose of the air bleed hole in the side of the nozzle body, under the screen. The degree of atomization is small at cruise and WOT flows, when it is unnecessary, and much larger at idle, when it has value.

The amazing flow balance of the electronic injection across all operating points is one thing that blew Titan away when they saw it on the dyno. They had never been able to achieve that before. The rest is history!
Robert
Click to expand...

Never able to achieve that before? Not a flattering statement for sure. I'm inclined to think everybody at Continental San Antonio knows how to reduce a constant flow system's GAMI spread to zero. It is quite apparent that they were not able to reduce Clark's GAMI spread using your system...which is why he is now forced to consider how to change mass airflow balance, or live with the performance described in the first post.
 
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Whoa. Don't go off on Dan. It's not a vendetta or arrogance. He is making arguments to specific points. This is called discussion. I, for one, do care if he is right or wrong, but only because I wish to learn something. By the way, he's been right about more than a few things in the past.

I find the topic very interesting and I don't yet know enough about it to have a firm opinion. One can learn by listening to all sides of any argument. Once convinced of the validity of one view or another by the preponderance of evidence, you can better decide what to buy into.

Pax,

Ed Holyoke
 
Knowledgeable

Sometimes the difference between being knowledgeable and arrogant is hard to tell. I for one have always found Dan H to be knowledgeable. I appreciate his candor and his inquisitive mind that has resulted in his broad knowledge of airplanes and their systems. I look forward to learning more from Dan's posts.
 
Dan, for the most part, does not argue. He usually posts only facts, and scientific laws.
 
It would seem that one of the main reasons to favor FI over carburation would be ability to run lean of peak for economy, cleanliness, and cooling. With a large GAMI spread, this would be difficult to do. A mechanical FI is fairly straight forward to adjust for near simultaneous peak by swapping injectors. Yes, this can mask basic differences in volumetric efficiency between the cylinders. It would indeed be better to have flow matched cylinders fed by an induction system which provides equal airflow to each. We don't all have this. Perhaps as more folks use Robert's system with various sumps a consensus of which works out the best will reveal itself. In the meantime, it would appear that the inability to adjust individual injectors may be a bit of a liability for running LOP.

Ed Holyoke
 
I hope the moderators delete your post.
Personal attacks like this is what drive the good folks away. I love Dan's posts and even thought much of it goes over my head, I learn something from every one, which is a lot more than I can about your posts (all 17 of them).
Keep up the good work Dan!
 
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Could the position of the throttle plate have a bearing on which cylinders front or rear sets have more flow of air to the cylinders? If so WOT should show the same flow/distribution to front / rear... Partial throttle would favor either the front or the rear depending on the angle of the throttle plate.
 
Boyd Birchler said:
Could the position of the throttle plate have a bearing on which cylinders front or rear sets have more flow of air to the cylinders? If so WOT should show the same flow/distribution to front / rear... Partial throttle would favor either the front or the rear depending on the angle of the throttle plate.
Click to expand...

This is one reason why properly engineered manifolds have a reasonable plenum volume- so throttle angle should have little impact on cylinder to cylinder air distribution. The throttle opening fills the plenum at a more constant rate (instead of a sharp spike) and the plenum feeds the cylinder with the open valve.

The factory Lycoming manifolds have no plenum volume to speak of and accordingly, work rather poorly in this regard. If they were any good, folks like Sky Dynamics probably would not go to the trouble to produce something proper...
 
rv6ejguy said:
This is one reason why properly engineered manifolds have a reasonable plenum volume- so throttle angle should have little impact on cylinder to cylinder air distribution. The throttle opening fills the plenum at a more constant rate (instead of a sharp spike) and the plenum feeds the cylinder with the open valve.

The factory Lycoming manifolds have no plenum volume to speak of and accordingly, work rather poorly in this regard. If they were any good, folks like Sky Dynamics probably would not go to the trouble to produce something proper...
Click to expand...

Ross, is there a full featured (hard and software) EFI system that you like that includes individual injector trim?
 
Stock Lycoming horizontal induction sumps have a large plenum. The vertical induction sumps do not.
 
BillL said:
Ross, is there a full featured (hard and software) EFI system that you like that includes individual injector trim?
Click to expand...

Yup, MoTec. I believe the ECUs alone start at over $4K. These need a cam sensor to identify and synch the injector pulses. Harder to do on a Lycoming due to design but where the mags turn at half crankshaft rpm, an assembly that fits into the mag hole could give that info to the ECU. I'm not keen having electronics mounted inside the engine though unless the components are spec'd to at least 125C.
 
Some random thoughts............

BillL said:
Ross, is there a full featured (hard and software) EFI system that you like that includes individual injector trim?
Click to expand...

The problem with the individual injector "trim" as you call it, is getting a feedback system that accurately and swiftly responds to the change in fuel/air ratio.

In automobiles we can do this with O2 sensors in the exhaust, but our leaded fuel in aircraft will kill the sensor pretty quick. That leaves EGT or CHT.

CHT is too slow-----------so we are left with EGT. Not sure if anyone is using that to drive a cylinder by cylinder feedback EFI system------or if such a system would be feasible.

Considering the fact we spend the vast majority of our engine run time at a constant RPM, the need to have a rapid responding feedback system may be invalid even??????????

Ross---------what say you?
 
Mike S said:
The problem with the individual injector "trim" as you call it, is getting a feedback system that accurately and swiftly responds to the change in fuel/air ratio.

In automobiles we can do this with O2 sensors in the exhaust, but our leaded fuel in aircraft will kill the sensor pretty quick. That leaves EGT or CHT.

CHT is too slow-----------so we are left with EGT. Not sure if anyone is using that to drive a cylinder by cylinder feedback EFI system------or if such a system would be feasible.

Considering the fact we spend the vast majority of our engine run time at a constant RPM, the need to have a rapid responding feedback system may be invalid even??????????

Ross---------what say you?
Click to expand...

Since we generally do not run aviation systems in closed loop and generally lean manually to LOP, we should be able to trim injector pulse width pretty accurately for typical, steady state, cruise configurations. Only with some thorough dyno or instrumented flight testing could we learn whether the same flow rate splits would hold true across the operational rpm range and throttle openings. Since we are mostly in cruise and when not, we are usually running richer, AFR/ EGT spreads in the TO and climb regimes are generally less important and again, this comes down mostly to manifold design.

I should mention that user tuning of something like a MoTec is probably outside the scope of most people's capabilities.
 
do you have ram air intake, could the ram air be contributing to uneven intake pressure?
 
Mike S said:
The problem with the individual injector "trim" as you call it, is getting a feedback system that accurately and swiftly responds to the change in fuel/air ratio.

In automobiles we can do this with O2 sensors in the exhaust, but our leaded fuel in aircraft will kill the sensor pretty quick. That leaves EGT or CHT.

CHT is too slow-----------so we are left with EGT. Not sure if anyone is using that to drive a cylinder by cylinder feedback EFI system------or if such a system would be feasible.

Considering the fact we spend the vast majority of our engine run time at a constant RPM, the need to have a rapid responding feedback system may be invalid even??????????

Ross---------what say you?
Click to expand...

Mike, I was talking about just the trim, or compensating for a standardized AF across the manifold pressure and speed range by cylinder. Trim is typical another lookup table over that 2D (or 3D) map. There is no feedback control for trim, once it is matched to the engine, that's it, it's "fixed". Sometimes it is a simple % on-time shift for the PWM driver signal. It requires individual current drivers in the controller for each injector and is therefore more expensive. If they all fire at once, I don't know if they share a current driver or they are just triggered together. I think the former would cost less.
 
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bret said:
do you have ram air intake, could the ram air be contributing to uneven intake pressure?
Click to expand...

The unequal air/ mixture distribution in stock Lycoming vertical manifold engines is well known and has been for as long as we've had individual EGT probes attached to them. Unequal runner length, almost zero plenum volume, unequal entry angle from "plenum" to runner plus heads which may also have airflow variances within the ports compared to its other brothers, all contribute to this. Ram air would simply change the manifold pressure ever so slightly.

I first heard this from a friend many years ago who built a beautiful 6A back in 2003 with an O-360. "Yeah, 4 one cylinder engines flying in close formation" he remarked after seeing a 190F EGT spread in cruise between coldest and hottest.

People spend $10-$30K on a bunch of glass for a day VFR airplane, $25-$30K on an engine and maybe $8K on a C/S prop but they have trouble coughing up another $2-3K for a proper manifold to get the best performance from their engine? I guess my priorities are different from most...
 
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rv6ejguy said:
...People spend $10-$30K on a bunch of glass for a day VFR airplane, $25-$30K on an engine and maybe $8K on a C/S prop but they have trouble coughing up another $2-3K for a proper manifold to get the best performance from their engine? I guess my priorities are different from most...
Click to expand...

Filing this away for reference when I get to the FWF stage. Thanks! :)
 
Wow, this has become a pretty heated discussion. First of all, I want to make it abundantly clear that the EFII system designed by Robert and Ross is absolutely amazing and I would never go to one of the older antiquated systems. This is the technology of the future. Although I have a fairly large gami spread, I can still run lop much leaner than most RVs (almost a full GPH). That means my cylinders 1/3 are over 100 deg lop when 2/4 are 50 lop and the engine runs smooth and I cruise at about 170 TAS. From talking to others, they can't get anywhere near over 100 lop and the engine runs fine. The fact I can leads me to believe it is due to the superior fuel dispersion of the EFII. Yes, it would be nice to be able to individually tune each injector, but the root cause here is not the EFII, but instead the poor air supply of the Titan sump. So, it seems clear to me that I need to invest in the superior sump. Furthermore, my engine runs smoother and starts easier than any of my friends' RVs.

For those of you considering a Titan engine, just be wary of the updraft sump. I have heard the Titan horizontal cold air sump has much better airflow. However you pay the price of higher oil temps. Living in Houston, I knew I would have oil temp probs with a high horsepower engine, so I elected to go with the vertical induction. So, since I have chosen to stick with vertical imduction, I just need to find a sump with more balanced air flow. Seems the superior sump is the way to go.
 
carrollcw said:
Wow, this has become a pretty heated discussion.
Click to expand...

One guy shows up and blows up. No big deal.

First of all, I want to make it abundantly clear that the EFII system designed by Robert and Ross is absolutely amazing and I would never go to one of the older antiquated systems. This is the technology of the future.
Click to expand...

Actually, a batch fired speed-density EFI system is many generations in the past. At the fundamental level, it is the same as the Bosch system installed on a 1968 Type 3 Volkswagen. The technology of the future? Automotive is switching to GDI (gasoline direct injection) right now.

Yellowed page from a 1971 how-to manual:



Being an old idea doesn't make it a bad idea. Speed-density is simple and adaptable, which is why Ross sticks with it, and he has been building ECUs a long time. (A few readers might be surprised to hear that I have one here, for installation on another project.) As for the EFii branded system, Robert picked pretty good off-the-shelf components. It's all far more reliable than the vintage Bosch parts.

Back in 1968, a fellow could go to the hardware store and buy a pretty good claw hammer. Today a fellow can buy what is arguably a better hammer, with a comfortable rubber and fiberglass handle. It may be more pleasant to use, and harder to break, but it is still a hammer. It will not build a house faster than the 1968 version.

Therein lies the problem with EFii brand hype. It's a simple fuel delivery system, not a Magical Mystery Machine. It will not make your airplane do anything amazing. It will only do what the laws of physics allow, no matter how many exclamation points are added to the advertising. That includes both strong points and compromises, just like any design.

Here, in return for simplicity and price point, one of the compromises is lack of individual injector fuel trim...the equivalent of restrictor insert swapping in a constant flow system. As Ross has stated, it's available with more expensive systems, but not this one. Here a user must accept the compromise, or find a way around it. ((EDIT, 2017...in-flight injector trim is now available from SDS....nice work!

Maybe the Superior sump will even up air delivery. Heck, I hope so; although not directly comparable, being sure about a better sump would be a big plus for the carb guys as well as EFii users. Please do take the time to fly and record a few specific repeatable test flight profiles before the swap.
 
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DanH said:
One guy shows up and blows up. No big deal.



Actually, a batch fired speed-density EFI system is many generations in the past. At the fundamental level, it is the same as the Bosch system installed on a 1968 Type 3 Volkswagen. The technology of the future? Automotive is switching to GDI (gasoline direct injection) right now.

Yellowed page from a 1971 how-to manual:



Being an old idea doesn't make it a bad idea. Speed-density is simple and adaptable, which is why Ross sticks with it, and he has been building ECUs a long time. (A few readers might be surprised to hear that I have one here, for installation on another project.) As for the EFii branded system, Robert picked pretty good off-the-shelf components. It's all far more reliable than the vintage Bosch parts.

Back in 1968, a fellow could go to the hardware store and buy a pretty good claw hammer. Today a fellow can buy what is arguably a better hammer, with a comfortable rubber and fiberglass handle. It may be more pleasant to use, and harder to break, but it is still a hammer. It will not build a house faster than the 1968 version.

Therein lies the problem with EFii brand hype. It's a simple fuel delivery system, not a Magical Mystery Machine. It will not make your airplane do anything amazing. It will only do what the laws of physics allow, no matter how many exclamation points are added to the advertising. That includes both strong points and compromises, just like any design.

Here, in return for simplicity and price point, one of the compromises is lack of individual injector fuel trim...the equivalent of restrictor insert swapping in a constant flow system. As Ross has stated, it's available with more expensive systems, but not this one. Here a user must accept the compromise, or find a way around it.

Maybe the Superior sump will even up air delivery. Heck, I hope so; although not directly comparable, being sure about a better sump would be a big plus for the carb guys as well as EFii users. Please do take the time to fly and record a few specific repeatable test flight profiles before the swap.
Click to expand...

All true but Lycomings won't be adapted to GDI any time soon as it involves very high pressure (hundreds of Bar) injectors mounted into the combustion chamber and high pressure pumps as well. While the demonstrated fuel burn reductions are certainly there as are increased detonation margins (substantial), the jury is still out on long term reliability of the systems compared to port injection. Audi and others had widespread problems initially with severe carboning of the backside of the intake valves since there was no fuel there to wash off deposits. Lexus discovered this problem in long term testing and employed both GDI AND port injection (together) on some of their V6 engines to solve the issue. Not sure where that stands now but GDI is certainly the way for automotive use. Some people found the injectors were not lasting like port injectors due to the high pressures and carbon buildup as well. Like you say, advantages and disadvantages to everything.

One primary focus is not to obsolete previous models or radically change the physical layout. Yes, the 5th generation ECU and software is very advanced from the 1st one but for 18 years, the hardware could be inexpensively upgraded to the latest software and most of the wiring would still plug in. We don't like to create orphan devices like many other electronics firms have if we can help it.

We've installed EFI on a lot of automotive engines and never saw any mileage or power drop with batch fired injectors over "sequential" (timed) types. That technology was developed mainly for emission reasons which we don't care about much in the aircraft or racing world.

In the end, it works pretty well when combined with a proper intake manifold. You get better hot and cold start and should have virtually zero maintenance compared to legacy aircraft fuel and ignition systems just as we saw in the automotive field starting in 1967 with the Bosch D Jetronic, some of which are still running today with original components.

Anyway, it's just another choice in the market. Some people will want it, others won't.

We have some new ideas on how to make the systems even better for aviation applications in the future as we concentrate more energy on that market. Will have to see how the R&D and testing goes first...
 
carrollcw said:
...From talking to others, they can't get anywhere near over 100 lop and the engine runs fine. The fact I can leads me to believe it is due to the superior fuel dispersion of the EFII...
Click to expand...

Just as a data point, I have run the 200 HP 360 in the RV-8 to 100 LOP with standard Bendix injection (and Pmags). This is also with the stock Lycoming horizontal, tuned sump.

At 100 LOP, it ran smooth as glass, but power was way down. No way I got anywhere near your 170 KTAS.
 
Toobuilder said:
Just as a data point, I have run the 200 HP 360 in the RV-8 to 100 LOP with standard Bendix injection (and Pmags). This is also with the stock Lycoming horizontal, tuned sump.

At 100 LOP, it ran smooth as glass, but power was way down. No way I got anywhere near your 170 KTAS.
Click to expand...

I too have an RV-8 with a stock factory Lycoming IO-360A1B6 and Precision Airmotive RSA-5 Injection + Slick Mags. At low altitudes and high manifold pressures, I can easily run 100F LOP (1.3+ gph LOP) and make 170 kts TAS (with 26 or so inches manifold pressure) and the engine runs smooth as glass and very cool even on hot inversion layer SoCal days.

Of course, at normal (for me) cross country cruising altitudes of 8500-12,500 or so, I don't run this lean because you're right...power levels are really low. The point is, 100F LOP and 170 kts is a meaningless data point without knowing the actual manifold pressures...and also the stock mechanical injection system is plenty capable of running smoothly far lean of peak at least with the forward facing Lycoming sump. The real limitation for me is the slick mags will start dropping sparks when the mixture gets too lean.

Skylor
RV-8
 
Here are some numbers from 2 recent flights:

11,500'
167 TAS
20" MP
6.3 GPH
1/3 110 LOP
2/4 35 LOP

7,500'
168 TAS
23.4" MP
7.3 GPH
1/3 170 LOP
2/4 80 LOP

So, as you can see, I can even go to almost 200 LOP and still have a smooth running engine!
 
carrollcw said:
Here are some numbers from 2 recent flights:

11,500'
167 TAS
20" MP
6.3 GPH
1/3 110 LOP
2/4 35 LOP

7,500'
168 TAS
23.4" MP
7.3 GPH
1/3 170 LOP
2/4 80 LOP

So, as you can see, I can even go to almost 200 LOP and still have a smooth running engine!
Click to expand...

Here's a larger engine, with well-worn Slicks and an AFP FM200, at 25~30 LOP, going 10 knots faster on 7.8 gph. I'll be going to electronic ignition in the near future, and expect to pick up the half gallon due to timing advance.

No magic.

Note the GAMI spread...5 degrees F. Given an engine with less than perfect mass airflow balance, an engine with each cylinder's fuel delivery matched to the available air works better than an engine with some cylinders running a little rich or lean.

 
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carrollcw said:
. . . For those of you considering a Titan engine, just be wary of the updraft sump. I have heard the Titan horizontal cold air sump has much better airflow. However you pay the price of higher oil temps. Living in Houston, I knew I would have oil temp probs with a high horsepower engine, so I elected to go with the vertical induction. So, since I have chosen to stick with vertical imduction, I just need to find a sump with more balanced air flow. Seems the superior sump is the way to go.
Click to expand...
I have not heard anyone say the forwared facing cold air induction would result in higher oil temps before your post. I have just such a sump feeding air into my Titan IO340. I have absolutely no oil temp issues in the 5+ years I have been flying this setup. In fact it is the reverse of what you say. I sometimes think my oil temp should be higher than it usually is. Typically my oil temp is around 175 F or so. Even on blistering hot days, of which Oklahoma has been known to have, it may reach 195 F. I would not let this unsubstantiated notion stop you from installing cold air induction. I do not believe it is an accurate statement based upon my first hand experience running it in my plane.
carrollcw said:
Here are some numbers from 2 recent flights:

11,500'
167 TAS
20" MP
6.3 GPH
1/3 110 LOP
2/4 35 LOP

7,500'
168 TAS
23.4" MP
7.3 GPH
1/3 170 LOP
2/4 80 LOP

So, as you can see, I can even go to almost 200 LOP and still have a smooth running engine!
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reality is, it doesn't really matter whether you run 10, 50, 100, 200 LOP. Those EGT readings are not anywhere as important as fuel flow, and even more so CHT readings, when it comes to running succsessfully LOP. Monitoring EGT gets you in the LOP range, then your fuel flow and CHT are what you need to watch to keep things where you want them after the initial Big *** Pull to LOP.
 
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Dan,
You posted just before my previous post. Alhough Dan has an 8 with a larger engine than my 9A the engine performance is very similar. He just flies faster than I do with the same LOP operations. Although to be fair, in this example I am at 12.5K and burning 6.7 gph. I would get a touch closer to his speeds if I were to bump my fuel flow up to the 7.8 gph he was running in his example. But speed isn't the thing to observe in either pic. Look at both Dan and my Oil and CHT temperatures.
IMG_1302.JPG
 
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Temps

RVbySDI said:
Dan,
You posted just before my previous post. Alhough Dan has an 8 with a larger engine than my 9A the engine performance is very similar. He just flies faster than I do with the same LOP operations. Although to be fair, in this example I am at 12.5K and burning 6.7 gph. I would get a touch closer to his speeds if I were to bump my fuel flow up to the 7.8 gph he was running in his example. But speed isn't the thing to observe in either pic. Look at both Dan and my Oil and CHT temperatures.
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Down low, high MAP LOP ops. Also note the engine and oil temps (67 OAT).

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Skylor
RV-8
 
RVbySDI said:
I have not heard anyone say the forwared facing cold air induction would result in higher oil temps before your post. I have just such a sump feeding air into my Titan IO340. I have absolutely no oil temp issues in the 5+ years I have been flying this setup. In fact it is the reverse of what you say. I sometimes think my oil temp should be higher than it usually is. Typically my oil temp is around 175 F or so. Even on blistering hot days, of which Oklahoma has been known to have, it may reach 195 F. I would not let this unsubstantiated notion stop you from installing cold air induction. I do not believe it is an accurate statement based upon my first hand experience running it in my plane.
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Cold air induction does in fact increase oil temps. I spoke with Kevin Eldridge when he was at Titan, Clint at Veterman's exhaust, as numerous others with a lot of engine knowledge. You may not have an issue, but that is most likely due to the lower HP of an IO340. More HP = more heat. The RV7 cowl was never designed to handle the cooling issues of higher HP engines. Once you go past 180 HP, you will have oil temp probs with the standard setup.
 
carrollcw said:
Cold air induction does in fact increase oil temps. I spoke with Kevin Eldridge when he was at Titan, Clint at Veterman's exhaust, as numerous others with a lot of engine knowledge. You may not have an issue, but that is most likely due to the lower HP of an IO340. More HP = more heat. The RV7 cowl was never designed to handle the cooling issues of higher HP engines. Once you go past 180 HP, you will have oil temp probs with the standard setup.
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just so you are aware of one other data point, my IO-340 is rated by ECI at 185 HP. So according to their information I have a 180+ HP engine. Also, not sure what you refer to as a "standard setup". I have a standard Vans IO-360 RV-7 cowl with the Vans RV-7 snorkel on my 185 HP IO-340. So this engine is not as powerful as Dan's IO-390 but I would put it up against any 360 out there.
 
carrollcw said:
Cold air induction does in fact increase oil temps. I spoke with Kevin Eldridge when he was at Titan, Clint at Veterman's exhaust, as numerous others with a lot of engine knowledge. You may not have an issue, but that is most likely due to the lower HP of an IO340. More HP = more heat. The RV7 cowl was never designed to handle the cooling issues of higher HP engines. Once you go past 180 HP, you will have oil temp probs with the standard setup.
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Just to be clear, be sure that you aren't misunderstanding "cold air induction" as the cause of higher oil temperatures vs. engines with oil squirter nozzles. It just so happens that the common 4 cylinder lycomings that have the forward facing induction are the angle valve engines (IO-360A) that also include piston squirter nozzles. The piston squirters are often attributed to increased oil temperatures since the oil is being used to remove some of the combustion heat from the pistons.

Skylor
 
Another data point. Up draft sump, not to bad.

Here is another data point.

We are currently developing a fuel injection kit that will fit in the stock Van?s 320 cowling without modifying the cowling. Our test bed was an RV-6 with a Titan 340 engine. The stock configuration was with an MA-4 carburetor (although the sump looked like a stock 360 sump to me). Data from the GRT down load on previous runs with the carb. gave the following:
T.O. power of 2624 RPM and 29?MAP around 15 GPH with EGT?s of 1445, 1411, 1265, 1223 (cyls. 1-4 respectively in degrees F.). At a cruise power setting of 2600 and 24?and 11.3 GPH with EGT?s at 1215, 1213, 1318, 1305. All data here was full rich

With no changes to the engine other than bolting on a FM-150L with stock injector nozzles we install on a 320 (all the same size) and installing the necessary high pressure engine driven pump, aux pump and a new inlet filter air box we got the following. Take off power 2600 RPM and 28.5? MAP fuel flow was 15.7 GPH with EGT?s at 1274, 1294, 1251, 1298. Cruise power of 2400 and 24? fuel flow 11.4 GPH with EGT?s at 1225, 1268, 1217, 1249. Again all data here was full rich

Checking the full rich to peak EGT at 24 square gave a change of around 230 degrees F. Indicating the fuel control was set plenty rich. This gives a F/A of around .089 (or for you car guys 11.2:1). A quick lean to peak curve was run at 24 square to check the GAMI spread. This was by no means really accurate because the time to lean was only around 45 seconds( normally to get accurate data, EGT needs to sit on a data point for 30 seconds then lean 0.2 GPH etc.), but GAMI spread was 0.3 to 0.1 GPH. This was only run to 50 degrees LOP with smooth operation.

While we are still improving our filter box to get rid of some flow loses this preliminary data shows that the stock up draft sump that many think is the evil for air distribution, really flows air quite well. Can there be improvements; probably. But the gains probably won?t be noticeable in a flight situation. Even with tuning the injector nozzles we probably will not see an improvement in power, with only a slight improvement in fuel economy.

This was a pretty simple install, no programming, no jet changes, just straight up bolt on and set the idle mixture.

So, more to come as we complete this project with the final design of the air box and gather additional real flight data.

Don
 
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