HHO and pilot injection on Diesels

[JojoJaro]

Folks, for those of us who drive Diesel trucks, I may have an explanation why MPG gains are minimal.

On these new Diesel engine design (common rail), there is a pilot injection of minute amounts of diesel before the main injection of the majority of the fuel. Could it be that the pilot injection is completely igniting the HHO before it has a chance to act on the main injection.

We theorize that HHO improves MPG because it burns the fuel charge faster. However, if the pilot injection completely ignites the HHO, there won't be anything left to affect the main injection.

If this is true, no amount of HHO injection will help, because whatever amount you produce, it will be consumed during the pilot injection, leaving no HHO to improve the combustion of the main injection.

What do you think? Any diesel techs here?

[timetowinarace]

I've read many positive results for great gain on small diesel cars.

In short I think the problem is a matter of volume more than anything else.

[JojoJaro]

I've read many positive results for great gain on small diesel cars.

In short I think the problem is a matter of volume more than anything else.

Are the small diesel car of the common rail design. Many older mechanical injectors do not have pilot injection. HHO will benefit these engines.

I am unsure if the Unit Injectors on VW diesels have pilot injection.

The Mercedes Diesel 2005 and newer use common rail and has pilot injection. Have you any feedback on gains on these engines with HHO.

All late model Ford, Dodge and GM diesels have common rail, hence pilot injection.

The concern I have is that the pilot injection will totally consume all the HHO before the main injection is initiated. Hence the HHO will not have the chance to act on the main injected fuel charge to make it burn faster like its supposed to.

Once I have my HHO unit, I'm gonna have to experiment with this and program out the pilot injection and see if it helps

[JojoJaro]

So, I did some math on the Pilot Injection timing.

On my Duramax, the main injection is around 1-11 deg After TDC. The Pilot injection is around 1-1.2 ms ahead of the main injection.

At 2000 RPM, the pilot injection is around 12-14 deg ahead of the main injection. This means that the pilot injection is 1-3 deg before TDC.

Interesting. What this means is that we might probably be igniting all of the HHO before TDC, robbing the engine of power and/or negating the increased power of the injected HHO (if HHO is increasing Power - a Big IF.)

[timetowinarace]

I can't say for sure, but I don't believe pilot injection is a major culprit.

1. Stratous on this board, though he has been absent in recent days, has gotten good gains on his '06 cummins. Check his signature at the bottom of his posts. He is injecting more hho than most of us.

2. Propane systems on diesels use the same method we are using. The theory is the same. Injection into the intake is the same.

3. Before I installed my unit, I went and talked with my local performance diesel mechanic. He is very good and competes in truck pulling competions, works with kids that want to race, transport businesses and people like myself that pull trailers down the highway often. The area I live in is very big on diesel performance. Bullydog was founded and is just a few miles away. In short, I was informed the faster burn rate of hho over propane would be advantagous.

Non-scientific reasons for a conclusion for sure, but it leads me to the opinion that the amount of hho is key.

[smartHHO]

Friend of mine had his on his 08 cummings. At first 2.5 mpg gain. Then it went to nothing. He even put O2 extenders on incase that was the problem. No results. Grant it, his gen was only a measily .4LPM. I am building one of the smack designs this weekend. We are going to install it with another Gen to get more production. I am guessing that with a 6.7L engine, you do need way more production to make it work. Hopefully on Monday we can say YES, it needed more production and that will fix your problem.

[timetowinarace]

I'm going to have to take a look. I don't believe the '06 or older diesels have O2 sencers. I don't remember seeing one. '07 and up have a bunch of new garbage on them.

[JojoJaro]

I don't believe any modern diesel have o2 sensors. The soot simply will clog up the o2 sensors in the exhaust in no time. o2 sensors are not workable on diesels because of this.

Diesels have MAF (mass air flow) sensors for detecting the amount of air in intake, and MAP (Manifold Air Pressure - aka Boost sensor) sensors for detecting amount of air boost by the Turbo (if it has a turbo.)

BTW, all diesels run lean. So, an o2 sensor makes no sense since diesels do not calibrate their fuel feed based on the o2 content in the exhaust. Diesels do not have to maintain stoichoimetric A/F ratios. It is always lean.

My Duramax has .625 Equivalence Ratio. Simply, Stoichoimetric air amount is 38% less than what my diesel is sucking. So, my Duramax is sucking 38% more air than what a stoichoimetric A/F mix needs.

I believe the ECM will aim to try to maintain this ratio. During periods of high fuel feed during high throttle positions, the turbo ramps up and feeds more air to match the increased fuel being injected, always trying to maintain .625 Equivalence Ratio.

That is how I understand it. I suspect it is the same on Cummins.

Also, my Duramax is non-adaptive. This means, it does not learn like how a gasser would learn how much fuel to input based on the o2 sensor reading (called short-term and long-term fuel trim). My Duramax operates based on the calibration tables. The tables tell it how much fuel and air to input based on throttle position, RPM, Speed, etc. (There is also a 'delta' value component that modifies the values on the main tables slightly based on Barometric pressure, Intake Air Temperature, Coolant Temps and Ambient Air Temps. But for the most part, the engine operates based on the values it finds in the calibration tables.) What this means is that the engine has no mechanism to detect if HHO is being injected. (It treats HHO-enriched air as ordinary air). Neither can it act on this fact even if it is able to detect it, because there is no 'delta' component that is based on any o2 sensor reading.

[JojoJaro]

I can't say for sure, but I don't believe pilot injection is a major culprit.

1. Stratous on this board, though he has been absent in recent days, has gotten good gains on his '06 cummins. Check his signature at the bottom of his posts. He is injecting more hho than most of us.

2. Propane systems on diesels use the same method we are using. The theory is the same. Injection into the intake is the same.

3. Before I installed my unit, I went and talked with my local performance diesel mechanic. He is very good and competes in truck pulling competions, works with kids that want to race, transport businesses and people like myself that pull trailers down the highway often. The area I live in is very big on diesel performance. Bullydog was founded and is just a few miles away. In short, I was informed the faster burn rate of hho over propane would be advantagous.

Non-scientific reasons for a conclusion for sure, but it leads me to the opinion that the amount of hho is key.

I hope you are right about the pilot injection not being a problem. I am not looking forward to having to turn off my pilot injection and have to forward my main injection to compensate. This is risky proposition in my eyes.

[precaster1@msn.com]

I don't believe any modern diesel have o2 sensors. The soot simply will clog up the o2 sensors in the exhaust in no time. o2 sensors are not workable on diesels because of this.

Diesels have MAF (mass air flow) sensors for detecting the amount of air in intake, and MAP (Manifold Air Pressure - aka Boost sensor) sensors for detecting amount of air boost by the Turbo (if it has a turbo.)

BTW, all diesels run lean. So, an o2 sensor makes no sense since diesels do not calibrate their fuel feed based on the o2 content in the exhaust. Diesels do not have to maintain stoichoimetric A/F ratios. It is always lean.

My Duramax has .625 Equivalence Ratio. Simply, Stoichoimetric air amount is 38% less than what my diesel is sucking. So, my Duramax is sucking 38% more air than what a stoichoimetric A/F mix needs.

I believe the ECM will aim to try to maintain this ratio. During periods of high fuel feed during high throttle positions, the turbo ramps up and feeds more air to match the increased fuel being injected, always trying to maintain .625 Equivalence Ratio.

That is how I understand it. I suspect it is the same on Cummins.

Also, my Duramax is non-adaptive. This means, it does not learn like how a gasser would learn how much fuel to input based on the o2 sensor reading (called short-term and long-term fuel trim). My Duramax operates based on the calibration tables. The tables tell it how much fuel and air to input based on throttle position, RPM, Speed, etc. (There is also a 'delta' value component that modifies the values on the main tables slightly based on Barometric pressure, Intake Air Temperature, Coolant Temps and Ambient Air Temps. But for the most part, the engine operates based on the values it finds in the calibration tables.) What this means is that the engine has no mechanism to detect if HHO is being injected. (It treats HHO-enriched air as ordinary air). Neither can it act on this fact even if it is able to detect it, because there is no 'delta' component that is based on any o2 sensor reading.
Then why does my 07 duramax check engine light come on sometimes? I think it detected change in air flow from the hho. any thoughts?

[JojoJaro]

Then why does my 07 duramax check engine light come on sometimes? I think it detected change in air flow from the hho. any thoughts?

What is the code? Could be any number of things. I can't help you unless I know the code. It could be you tranny failing for all I know :-)

I doubt its the HHO being detected. According to the Technical Manuals, there is no sensor that can detect the presence of HHO. It is just a Mass Air Flow sensor, it detects the mass of the air flowing.

Sometimes, when people use a better Air filter, the air flow is higher than what the ECM expects, when it detects a higher air flow, it will light up the Excessive Air Flow code. Are you using an Aftermarket Air Box or filter.

Could also be the turbo pushing more or less air than what is expected.

[timetowinarace]

Then why does my 07 duramax check engine light come on sometimes? I think it detected change in air flow from the hho. any thoughts?

From '07 on the emisions changed dramaticly on the diesels. '06 and older basically didn't have much but a cat. I saw the emisions crap removed from a '07 dodge. It was huge and heavy. I know they now have a filter in the exhaust system that has to be changed periodicly. When they first came out they could not use the low sulfur fuel that was still mostly available. It would plug the exhaust. They can only use the ultra low sulfer fuel that is the only fuel available now. I don't personally know but I'm very sure there are sencors of some sort in these new systems. One is for the filter. When it clogs the CEL will light.