Warm Air Intake With Steam

[cRiPpLe_rOoStEr]

Originally Posted by gumby79

Chip Foose was talking about building a custom small block engine that would have liquid propane direct injection the plan was to use the expansion to create false boost.

It would need a considerable volume of fuel to create that so-called false boost, but then, how would it keep the air-fuel ratio?

[teoman]

I think because it is direct injection, it cools the intake charge and has the equivalent effect of more boost.

If it is still spark ignited, i do not think that the LPG's evaporation and expansion can be used for extra power because the spark is before tdc and such a scheme requires at tdc or after injection.

[cRiPpLe_rOoStEr]

Originally Posted by teoman

I think because it is direct injection, it cools the intake charge and has the equivalent effect of more boost.

Had it been injected on the manifold, could eventually cool down the charge air and increase the oxygen concentration allowing a larger mass of air at the same volume, but the manifold absolute pressure doesn't seem to change at that condition.

[teoman]

I am examining the OBD2 info and trying to decide which data to use for my injection algorithm.

I thought i should share my way of thinking so some one can catch my brainfarts.

Objective: bring input air temp to 85 deg C. After maf so engine does not retard timing. (A good one??)

Intake air sensor says 4.5 g/s while idling. 100g/s full throttle.

Intake air temp about +5-10 deg C higher than ambient temp. It was 8.5 deg C outside and i saw 11-16 deg C on the sensor.

So
delta_t = 85-intake_temp
Injection_rate = delta_t * maf * k

Where k is a coefficient for injection that i kind of started calculating in previous posts.



Then the engineer in me started pondering and making things more complicated. Should i be looking at rpm and throttle position and/or fuel per minute (torque doesnt give a more precise fuel consumption figure) to predict the intake requirements an compensate for the time for the steam to reach the combustion chamber.

Right now the injection place will be after the maf. But i could go for egr valve aswell if some one says it will yield better results.

[teoman]

I am still pondering where to do the steam injection.

Is before the throttle body better than after the throttle body? I am starting to think now that after the throttle body would be better.

Also, EGR is routed after the throttle body right? So the EGR input location is starting to appear as a better location.

What do you guys think?

[cRiPpLe_rOoStEr]

I'll have to agree with you on that. After the throttle body seems to be the best option.

[teoman]

Thanks for the reply.

As i have basically no idea what i am doing, it is good to feel i am not the only brain pondering on the matter.


Ill go with the egr, with the assumption that the engineers at MB have thought about the egr as a fuel saving conception instead of just an emissions implementation, i.e. They have done their homework on the flow dynamics so the gasses reach all cylinders equally.

[teoman]

Incidentally, i also have a blocked EGR valve that I will try to fix or get fixed.

Could some one with excess time have a look at this video. It is for removing and fixing the EGR valve on my car.

https://www.youtube.com/watch?v=6H0brGynBBE

Now, what does the EGR actually do to fuel economy. I am not entirely convinced that it has any unburned fuel left in it. It seems to me that it is just a means to stuff an uncombustible gas in there to make the relative engine size smaller.

Now if you look at the video, the guy connects to the ECU and looks at some parameters before and after the EGR fix. What if i were to use my steam injection and completely get rid of the EGR?

I was thinking of tapping in to that solenoid feed and boost the steam injection up when the computer called for EGR.

What do you think of this? Waste of water? Keep engine cleaner? Loose economy?

I could be completely wrong about this so please correct me if my mind has wondered down a wrong path.

[cRiPpLe_rOoStEr]

Not sure if it would be a good idea to get totally rid of the EGR. Even though it would be supposed to keep the engine cleaner, removing it would eventually require a higher fuel volume to keep the air/fuel ratio to avoid knocking. Adding steam either to complement or totally replace the EGR is still likely to provide some benefits and keep the engine cleaner, eventually decreasing the amount of sticky oil residues from the PCV on the intake manifold.

[teoman]

I will try to source another egr pipe and weld my input there.

Any benefit to monitoring the EGR valve actuation and adding a bit of steam to it?