Super V.E. for diesels

[Logic]

I NB much talk about cold air cutoff temperature here.
I also NB that hot water in a swamp cooler, cools just as well as cold water, but more of it evaporates.

"...a 7.3% increase in evaporation rate when increasing water supply temperature from 20°C to 60°C... there was an average loss of 0.26K of cooling when increasing the water supply temperature from 20°C to 60°C..."
https://www.heat-island.jp/web_journ...20evaporating.

The same principle would apply in engines:
The hotter the fuel; the more/faster it will vaporize and the more of it that's vaporized; the more of it will burn at optimal crank angles where it adds to turning the wheels the most.
ie:
The air can remain colder, getting more oxygen into the engine, without losing out on vaporization as much if the fuel is hotter.

As the diesel pipes are at very high pressure AFTER the pump and boiling point increases with pressure, one does not have to worry about vapour lock (fuel boiling/vaporizing) if one heats it after.

But those pipes run pretty close to the hot head and normally close to the exhaust manifold too, so is there anything to be gained by heating the fuel with say hot coolant or hotter exhaust?
Has anyone tried this?

Perhaps copper 'brackets' (or heat pipes?) from somewhere hot like exhaust manifold nuts to 'hold'/heat the pipes close to the injector..?

Perhaps the simplest 'trick' might be to (sand and) paint the pipes matt black to absorb more radiant heat, but who knows if it's even worth the paint!?

[AdrianD]

Originally Posted by oil pan 4

You will definitely see gains. Old Chevy non turbo diesels have long runners like that gasser and the later model with turbos have the simple compat intake like you showed. Do it.

I've been thinking about datalogging AFR before and after.
My engine has a VNT turbo and I tune the ECU myself, so I can also play around with fueling, rail pressure, ignition timing etc to help maximize the benefit.

I already increased rail pressure and added some timing in both cruise and high power areas.

After the swap, should I target the same AFR as before? Being a VNT turbo, boost control is pretty nice and the current boost map is very close to factory in low load conditions.

Cruising conditions are 2000 to 2400rpm, which results in 3.6 to 5 psi of boost and 15 to almost 20mg of actual injection quantity.

[oil pan 4]

Originally Posted by AdrianD

I've been thinking about datalogging AFR before and after.
My engine has a VNT turbo and I tune the ECU myself, so I can also play around with fueling, rail pressure, ignition timing etc to help maximize the benefit.

I already increased rail pressure and added some timing in both cruise and high power areas.

After the swap, should I target the same AFR as before? Being a VNT turbo, boost control is pretty nice and the current boost map is very close to factory in low load conditions.

Cruising conditions are 2000 to 2400rpm, which results in 3.6 to 5 psi of boost and 15 to almost 20mg of actual injection quantity.

I didn't have any of that fancy stuff when I tested the long runner intake vs the short turbo intake.
I could tell that power was way down to the point where I thought something was wrong with my engine and fuel economy was also down 2 to 3mpg when running the turbo intake without a turbo.
That was the only way I could devise a fair test between the two intakes.
I would be surprised if you didn't see fairly dramatic results between the 2 intakes.

[oil pan 4]

Originally Posted by Logic

I NB much talk about cold air cutoff temperature here.
I also NB that hot water in a swamp cooler, cools just as well as cold water, but more of it evaporates.

"...a 7.3% increase in evaporation rate when increasing water supply temperature from 20°C to 60°C... there was an average loss of 0.26K of cooling when increasing the water supply temperature from 20°C to 60°C..."
https://www.heat-island.jp/web_journ...20evaporating.

The same principle would apply in engines:
The hotter the fuel; the more/faster it will vaporize and the more of it that's vaporized; the more of it will burn at optimal crank angles where it adds to turning the wheels the most.
ie:
The air can remain colder, getting more oxygen into the engine, without losing out on vaporization as much if the fuel is hotter.

As the diesel pipes are at very high pressure AFTER the pump and boiling point increases with pressure, one does not have to worry about vapour lock (fuel boiling/vaporizing) if one heats it after.

But those pipes run pretty close to the hot head and normally close to the exhaust manifold too, so is there anything to be gained by heating the fuel with say hot coolant or hotter exhaust?
Has anyone tried this?

Perhaps copper 'brackets' (or heat pipes?) from somewhere hot like exhaust manifold nuts to 'hold'/heat the pipes close to the injector..?

Perhaps the simplest 'trick' might be to (sand and) paint the pipes matt black to absorb more radiant heat, but who knows if it's even worth the paint!?

Cummins tied heating the fuel. It seems to work best with the fuel at 70f. I figured the injectors being screwed into the cylinder head the fuel was normally injected at cylinder head at coolant temperature. The fuel might cool some running maximum power for extended time and the fuel flows through the injectors faster than it can warm up, maybe.

[AdrianD]

Originally Posted by oil pan 4

I didn't have any of that fancy stuff when I tested the long runner intake vs the short turbo intake.
I could tell that power was way down to the point where I thought something was wrong with my engine and fuel economy was also down 2 to 3mpg when running the turbo intake without a turbo.
That was the only way I could devise a fair test between the two intakes.
I would be surprised if you didn't see fairly dramatic results between the 2 intakes.

And that's how I'm getting roped into a ton of work

Just eyeballing, it seems like the plenum of the aluminum manifold might have some interference with an A/C line and even with the throttle potentiometer, so either I "downgrade" to a plastic, 5 cylinder manifold, which has a shorter plenum but also long runners, or I change to a throttle from a mercedes, with the potentiometer next to the pedal, and modify the A/C line.

[Logic]

Originally Posted by oil pan 4

Cummins tied heating the fuel. It seems to work best with the fuel at 70f. I figured the injectors being screwed into the cylinder head the fuel was normally injected at cylinder head at coolant temperature. The fuel might cool some running maximum power for extended time and the fuel flows through the injectors faster than it can warm up, maybe.

Thx oil pan

Naturally I couldn't just leave this alone!
A quick search found that diesel only starts to boil at 175C 350F but starts to freeze at 15C 60F already.
It seems heating with coolant, pre pump, where its much easier is possible and VW uses coolant heating in their filter, pre pump already.
Probably as a means to decrease the load on the pump mostly, but also to get the fuel up to temperature sooner.

See VWRacer's post # 3 here:
https://vwdiesel.net/forum/index.php/

All you guys up in our Great White North Neighbor can probably benefit from somewhat heated fuel. Diesel fuel ranges from a carbon number of C9 to C23, centered on C16 (gasoline ranges from C3-C10, centered on C8 ). All hydrocarbons solidify at a rate proporsional to their carbon number, with the higher diesel compounds solidifying (freezing) as high as 15C (60F). By -5C (~20F) half of diesel compounds are near or below their freezing point, and the fuel can really benefit from external heating.

Conversely, diesel compounds have quite high boiling points, ranging from 175C (~350F) for the lightest compounds to more than 370C (700+F), so even if it's heated to the standard operating temp of a TD (95C or 200F) it is just slightly thinner, but in no danger of boiling. There isn't much change in volume as diesel heats up, so that isn't much of an issue, either. (The coefficient of thermal expansion for diesel is 0.0046 per degree F, so heating a gallon of it from 32F to 212F (0C to 100C) increases its volume to just 1.083 gallons.) Moreover, heated diesel has lower drag in fuel lines and injectors, makes for a better spray pattern, and ignites easier in the cylinder.

In a normally running diesel engine, all the conponents heat up to operating temp eventually, so once the engine is thoroughly warmed up, there is probably little need for additional fuel heating, but it won't hurt any.

Here's a study talking about nozzles and: "...preheating of biodiesel exhibited reduction in rheological properties of biodiesel and that causes improvement in efficiency and reduction in emission due to better spray characteristics..."
https://thermex-systems.com/fluid-fuel-warming-systems/fuel-warming-system/

Here's a company selling heaters:
https://thermex-systems.com/fluid-fu...arming-system/

Then there's this startup talking of using the pressure of compression to super pressurize the fuel (as the pump) and a nozzle with 180 tiny holes. Clever, if it works!
https://www.rklab.com

[Logic]

Originally Posted by AdrianD

And that's how I'm getting roped into a ton of work

Just eyeballing, it seems like the plenum of the aluminum manifold might have some interference with an A/C line and even with the throttle potentiometer, so either I "downgrade" to a plastic, 5 cylinder manifold, which has a shorter plenum but also long runners, or I change to a throttle from a mercedes, with the potentiometer next to the pedal, and modify the A/C line.

Nowadays you can send a CAD design to various places like Send-Cut-Send and they will 3D print the part out of a metal or plastic of your choice, skipping all that extra work.

People are using scanners to scan the engine bays etc so as to get the spacing right before designing the part.

https://www.youtube.com/watch?v=rJtX_xwq_4M

Do check out his other videos on the scanner etc. He is doing really good engineering!

[AdrianD]

Scanning and printing a manifold - not going to happen.

I bought the 6-cylinder manifold for $35 USD, I can get a 5-cylinder manifold for similar money.

[AdrianD]

I found a bit of time and measured the runner length. Counting the length of the ports in the head, it should be right around 20", which is much longer than I expected.
According to the graph in the first post, it will have useful VE gain from 3500rpm up to where I will configure it to shift
Max RPM on my engine can be 5000rpm or more but it depends a lot on the injectors and turbo.

Found an interesting post online but without too much data. Apparently the left side manifold in the attached photo has a 20hp peak gain over the factory manifold. No torque graph, no info about tune differences between manifolds, just a blind number.

[Logic]

Originally Posted by AdrianD

I found a bit of time and measured the runner length. Counting the length of the ports in the head, it should be right around 20", which is much longer than I expected.
According to the graph in the first post, it will have useful VE gain from 3500rpm up to where I will configure it to shift
Max RPM on my engine can be 5000rpm or more but it depends a lot on the injectors and turbo.

Found an interesting post online but without too much data. Apparently the left side manifold in the attached photo has a 20hp peak gain over the factory manifold. No torque graph, no info about tune differences between manifolds, just a blind number.

ye, but here "peak gain " will be at much higher rpm like max power rpm.
Not at the lower max torque rpm range.

Do I have it correct that:
Max torque rpm
at ~75% load
= Max BSFC?

Oh ye:
if you can access your intake runners there's some free power to be had by some careful flap wheel sanding:

The pic shows the ideal elliptical shape (worth 30% IIRC) but any rounding is way better than none.