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Modern O2 sensors have a heater circuit inside them, as the sensor response is inaccurate at lower temperature. Being able to reliably read Air/Fuel mixture as soon as possible after startup allows the OEM's (whose sensors are used by the aftermarket) to put the ECM into closed loop tuning mode sooner, (i.e make mixture adjustments based on feedback from a sensor instead of relying on a static fueling map). This reduces emissions and is overall healthier for the engine resulting in lower warranty claims. Modern V6's and V8's have 4 O2 sensors, 2 on each bank, pre and post cat. The post cat O2's are only to verify the catalyst efficiency. Most electric heaters, are essentially direct shorts and can consume a fair bit of energy. This installation has 8 so I am sure there was a fair bit of current being drawn.

Edit: This was in response to post #76, for some reason the forum didn't quote it, even though I asked it to.
 

TXFlyGuy

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Modern O2 sensors have a heater circuit inside them, as the sensor response is inaccurate at lower temperature. Being able to reliably read Air/Fuel mixture as soon as possible after startup allows the OEM's (whose sensors are used by the aftermarket) to put the ECM into closed loop tuning mode sooner, (i.e make mixture adjustments based on feedback from a sensor instead of relying on a static fueling map). This reduces emissions and is overall healthier for the engine resulting in lower warranty claims. Modern V6's and V8's have 4 O2 sensors, 2 on each bank, pre and post cat. The post cat O2's are only to verify the catalyst efficiency. Most electric heaters, are essentially direct shorts and can consume a fair bit of energy. This installation has 8 so I am sure there was a fair bit of current being drawn.

Edit: This was in response to post #76, for some reason the forum didn't quote it, even though I asked it to.
Yes, we are in agreement.
Factor in the sensors were out in the open, no cowling installed, being subjected to extreme propeller blast. I would think that may have been a major contributing factor in the current draw.
 

wsimpso1

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What is the purpose for the "8 heaters"?
Exhaust gas oxygen sensors (EGOs) make fine tuning fuel injection possible and self tuning as you drive. It also allows the engine to adapt to varying fuels, etc. Lead in the fuel kills the things, so lead went away in road fuels. Now for a simplified history. The original EGOs were only warmed by exhaust gases and had a number of drawbacks like narrow operating ranges. Later on the automotive industry needed to cover fuels that varied in use - winter vs summer fuels, varying octane improvers and detergents, and varying ethanol content - and needed wider operating ranges to do it. They also needed the system to converge on stoic faster after cold starts. They went with heated EGOs, HEGOs, for quicker warmup and wider operating ranges.

To refine and settle on fueling of airplanes, even with leaded fuels, HEGOs make the process easier and more precise. Once tuning is done, our airplanes have no need for closed loop mixture tuning in flight, and the HEGOs are just dead weight. Out they come.

Billski
 

AdrianS

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Exhaust gas oxygen sensors (EGOs) make fine tuning fuel injection possible and self tuning as you drive. It also allows the engine to adapt to varying fuels, etc. Lead in the fuel kills the things, so lead went away in road fuels. Now for a simplified history. The original EGOs were only warmed by exhaust gases and had a number of drawbacks like narrow operating ranges. Later on the automotive industry needed to cover fuels that varied in use - winter vs summer fuels, varying octane improvers and detergents, and varying ethanol content - and needed wider operating ranges to do it. They also needed the system to converge on stoic faster after cold starts. They went with heated EGOs, HEGOs, for quicker warmup and wider operating ranges.

To refine and settle on fueling of airplanes, even with leaded fuels, HEGOs make the process easier and more precise. Once tuning is done, our airplanes have no need for closed loop mixture tuning in flight, and the HEGOs are just dead weight. Out they come.

Billski
When I was helping a mate with a turbo bike build, we ran one O2 sensor, and 4 egt's.
The O2 sensor gave the average mixture, but we used the egt's for trimming the individual cylinders.
O2 sensor was only fitted while tuning.
 

TXFlyGuy

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When I was helping a mate with a turbo bike build, we ran one O2 sensor, and 4 egt's.
The O2 sensor gave the average mixture, but we used the egt's for trimming the individual cylinders.
O2 sensor was only fitted while tuning.
And my engine will do likewise, O2's only installed for tuning during ground testing. Never for inflight testing. My LS376-495 was perfectly tuned on the final flight.

Takeoff power was 18 inches and 4000 rpm.

We will go through the tuning process again as Hutter Performance has a new custom cam for us. A cam designed for max rpm of 4500. My engine now has the GM Factory Hot Cam. It makes a small improvement, but it is designed for high rpm operation, higher than we can go.
 
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Hey I am curious, is the 4500RPM limit imposed due to engine longevity concerns, available redrive gearing, or airframe safety? LS3 style heads are just starting to party at 4500RPM. They have a lot of runner volume, which tends to bias performance towards the higher end of the rev range. A cam can certainly shift that powerband up and down the RPM band but where they really shine is up top.
 

TXFlyGuy

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Hey I am curious, is the 4500RPM limit imposed due to engine longevity concerns, available redrive gearing, or airframe safety? LS3 style heads are just starting to party at 4500RPM. They have a lot of runner volume, which tends to bias performance towards the higher end of the rev range. A cam can certainly shift that powerband up and down the RPM band but where they really shine is up top.
Yes, the limitation is the PSRU, max continuous 4500 rpm. The Gearbox is rated for 600 hp, but we will never get that much power below 4500.

The dyno showed my engine with the new Hutter exhaust stack doing 412 hp @ 4500 rpm. This was a significant increase over the Titan headers.

With standard long tube headers installed, the engine output was 525 hp at 6000 rpm.

But wait...there are those that claim the BMW V12 is a vastly superior engine to the small block Chevy. Maybe I should just make the switch.

With the new cam, I think from Comp Cams, Hutter estimates another 20 - 25 hp. So that would get us to 435 hp, with the Hutter short stack headers.

My propeller was designed by Jim Rust. Both the prop and the hub were designed to handle no less than 600 hp.

So we have a huge safety margin in both the gearbox and the prop.
 
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Dana

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Doesn't seem like you should need the heaters at all, you're not concerned with emissions and an aircraft is normally operating at a power setting that will keep them hot without extra heat.
 

Vigilant1

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A suggestion: If the intent is to ask Elliot Seguin to test fly this aircraft after the modifications and repairs, it may make sense to bring him in now to do a system review on the plane. Somebody on the old team thought putting 16 amps of resistance heater load onto the 15 amp ECU circuit breaker was a good idea, there may be other surprises in there. Pantdino's plane had the hydraulic pump on the ECU breaker. If he is going to agree to test fly another T-51, I'd think he'd want to take a hard look at everything. Might as well pay to have him do the studying and analysis now (when it is cheaper to make fixes) rather than present him with a fait accompli when he comes to do the test flying.
Other than >perhaps< the aircraft owner, nobody has a greater vested interest in finding bugs than the guy who will be flying. I bet he'll suggest some redundancy/reliability and human factors improvements (e.g don't have one CB placed away from all the others) that might escape a team of experts that specialize in cars.
It probably won't be cheap, but it could be money well spent. It would not be a bad idea to get him started with the most meaty posts on HBA from folks who have taken the time to give suggestions.
 
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Saville

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A suggestion: If the intent is to ask Elliot Seguin to test fly this aircraft after the modifications and repairs, it may make sense to bring him in now to do a system review on the plane. Somebody on the old team thought putting 16 amps of resistance heater load onto the 15 amp ECU circuit breaker was a good idea, there may be other surprises in there. Pantdino's plane had the hydraulic pump on the ECU breaker. If he is going to agree to test fly another T-51, I'd think he'd want to take a hard look at everything. Might as well pay to have him do the studying and analysis now (when it is cheaper to make fixes) rather than present him with a fait accompli when he comes to do the test flying.
Other than >perhaps< the aircraft owner, nobody has a greater vested interest in finding bugs than the guy who will be flying. I bet he'll suggest some redundancy/reliability and human factors improvements that might escape a team of experts that specialize in cars.
It probably won't be cheap, but it could be money well spent. It would not be a bad idea to get him started with the most meaty posts on HBA from folks who have taken the time to give suggestions.

Probably a good idea.

And I realize I'm being - perhaps annoyingly - pedantic about it but this isn't really a T-51 issue.

"If he's going to test fly another home built with a non-certified electrical design and implementation, I'd think he'd want to take a hard look at everything."

I think your idea is a good one because I'll bet anything Mr. Seguin is far more alert to, and keen to detect, possible electrical design flaws after that Pantdino flight.,
 
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TXFlyGuy

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Yes, those are good ideas. Elliot and I remain in very close communication.
In addition, my avionics experts will go over the setup with a fine toothed come.
 

speedracer

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The most successful auto engined homebuilt I've personally seen is Gary Spencer's (250 MPH) Ford V8 powered Long EZ. It didn't have an ECU..... but it did have a 4 barrel carburetor.
 

dwalker

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The most successful auto engined homebuilt I've personally seen is Gary Spencer's (250 MPH) Ford V8 powered Long EZ. It didn't have an ECU..... but it did have a 4 barrel carburetor.
Why do you consider it the most successful? Dan Atkins and Tracy Crook are in the decade plus years of continuous operation on efi rotaries. Shirl Dickeys E Racer used an injected aluminum "Buick" v8. There are literally hundreds of VW powered aircraft, some of them injected.
Ross at SDS has customers with thousands of hours of fight using his ecus.

Just curious what yardstick your using or if you're simply biased against efi.
 

TXFlyGuy

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And we are all aware of the thousands of hours safely flown in T-51 Mustangs, powered by V6's, V8's and V12's.
All of these have ECU's from various manufacturers.

And the Thunder Mustang using MoTeC exclusively, powering the V12.
 

Appowner

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This was the Factory Test Pilot. More hours in a T-51D Mustang than anyone on the planet.
No...I did not know about his number of crashes. But that is not the issue.
He chose to fly an airplane that was clearly not airworthy or in safe condition for flight.
And he did this against the orders of my mechanic.
Don't get me wrong, I'm not trying to fault you. Just such a sad situation IMHO.
 

Marc Zeitlin

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And we are all aware of the thousands of hours safely flown in T-51 Mustangs, powered by V6's, V8's and V12's. All of these have ECU's from various manufacturers...
So this is slightly off topic, but I need to point out some logical issues with this type of argument.

In failure safety analysis (SSA, FMEA, etc.), the number of SUCCESSFUL (non-failure) hours flown is almost immaterial - what matters is the number of failures. Why? Because if you're trying to obtain a MTBF of (let's say) 10^6 hours per catastrophic failure (which a full engine outage most certainly is), then you need 10^6 successful hours for each failure that occurs. And even 10^6 is low - commercial airliners shoot for 10^9 hours between catastrophic failures - we were shooting for 10^6 hours on SS2/WK2/RM2.

So quoting a few thousand hours of flight without failure, while the number of failures hovers in the ~10 range (I'm estimating from the previous posts - I have no idea what the actual # of failures is), then you've actually got a DOCUMENTED failure rate in the 10^2 - 10^3 hour range. Which, let's be fair, is a completely miserable failure rate, and one that would not be acceptable in children's toys, much less a safety critical component that can cause a catastrophic failure in an airplane.

"Bob has flown 1500 hours without a failure" in his <XXX> airplane, in and of itself, means exactly zero with respect to failure rate evaluation.
 

rv7charlie

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It's good to pay attention to overall failure rate, but given the very low number of hours being accumulated on the various engines, I'd think that it's much more important to look at the *causes* of the failures, and even more important to look at the FMEA ('effects' being the critical term). In traditional terms, if a mag quits, the motor continues to run on the other mag. If the carb quits for any reason, the motor stops. Fortunately, hard failures of carbs are extremely rare, so we live without a backup.

Electronic injection is harder to analyse. If the controller quits, there may or may not be a backup. If an injector clogs, it's unlikely that it will stop the engine. If a coil dies, it's unlikely that it will stop the engine. If the fuel pump fails, is there a backup? etc etc etc.

And it makes no sense to call, for instance, a cooling system failure, a failure of an electronically controlled engine, just because the electronics are there. Is the failure of an oil line on a mags/carb engine a failure of a mags/carb engine, or a failure of an oil line?
 
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