Extreme/expensive mods to gain milage in (turbo)diesels

[TimV]

Hi

I was thinking of the following mods. And need some advise/user expirience.

- Installing LPG injection in a turbo diesel.
Costs is around 2000 to 2500 euro's.
Payback time is somewhere between 100 000km and 250 000km

- waterinjection: injectin water under high pressure trough nozzle in the intake air stream.
Cost???
Wear of the engine?
How much injectin?
How big of a tank?

- I drive a lot on highway. And went from 6l/100km with constant trotle. Tot 5,5l/100km with puls and glide.
Now i was thinking. If we design some sort of electronic circuit that would change the combustion cycle.

Normal cycle of the engine is 2 revolutions for each combustion. If we design it this way. It would be 4 revolutions 1 combistion. So we hack in to the injectir signal with elecronics to block 1 combustion cycle and let the next one trough.
Expecting to drive on 2 cilinders on the highway wen the revs are high (above 2000rpm) and continiuesly change the cilinders that are inactive. So the entire engine keeps balanced in heath.

And so on

Other mods to do?

[oil pan 4]

$2500 euros is obscenely expensive. Only way I could see it being cost effective is if the propane were nearly free.
If the buying power of the euro is what I think it is then about 200 of them should put together a nice water injection setup.

[TimV]

Current prizes are:
1,1€ /l diesel
1,4€/l super 95
1,5€/l super 98

0, 45€/l LPG

Our goverment decoded that the taks on diesel must go up. And that it would cost at the beginning of 2018. Diesel cost equal as super 95. Within a few months the first rise of the taks is real.

Therefore i aim willing to invest some monney. But payback time needs to be reasonable.

[oil pan 4]

Just remember when you burn LPG in a diesel you are mostly just replacing Diesel fuel with LPG.
Then when replacing diesel with LPG its not a 1 for 1 swap. If I remember correctly LPG only has about 2/3 the energy content per gallon that diesel has.
So right now burning some LPG to save some diesel will save you very little.

If the government is going to arbitrary raise the price of diesel to equal that of top grade gasoline for no reason and you say it will take 100,000 to 250,000 km for pay back, does that include the future price increase?
Also, how long do you think it will take you to drive 100,000 to 250,000 km?

Have you considered aerodynamic mods?

[TimV]

Ive got an offer of 2700 euro installation all in.
At the fuel prices of the moment, it will be arround 300 000km to have a pay back.
But the prices are going up the comming few years, so payback arround 150 000 a 250 000km. (depending on fuel prices)

When the fuel prices of diesel is equal of benzine, then it would be somewhere arround 100 000 to 150 000km

I drive arround 21 000km a year.
So payback time is little to long when the installation is this expensive!

[TimV]

Yes. I aim fully buzzy with aerodinamic mods. But most mods are not allowed on the road where i live. So need to be careful with the things i do.

Something that realy works is changing gear ratio's.
I run 2350rpm at 100km/h.
With is high for a 2l turbo diesel.

I was planning on changing gear ratios.
Placing the 5th gear where the 4th gear is. And then let someone make a new 2end, 3th and 5th gear.

The only problem is that the person who i contacted can only make straith cut gears.
Those make that wind you hear in rally and race cars. But is this also this loud in a normal car? In a diesel that does not run 7000rpm or higher?

I do run sometimes 3500rpm or 4000rpm... On the german autobahn! But with a higher 5th gear. Those rpms are going to be lower

Price: 1100 a 1200 euro.

Gain in milage: 4 to 20% (wiki reported)
so lets say a 8% increase.
With prices now and a bump in the future: 150 000 a 200 000km
I realy think the gain can be bigger then this. My highway consumption is higher at 100km/h then when i drive the backroads at 70km/h ( 1650rpm). Even 50km/h (1150rpm) i drive in biggest gear.

If i gain 12%: 100 000 a 150 000km payback

The car has 120 000km on it.
I drive 25 000 to 30 000km a year.
I plan to drive it until 300 000km.
So another big 6 years

I should do this. But i dont know if the sound is to loud for me or not...
Lucky i may drive with the car of his sun. A big jeep with has a strait cut final gear change for lower consumption.

I keep you updated!

[cRiPpLe_rOoStEr]

Straight-cut gears are usually a little noisier, as you can perceive when you're using the reverse gear (which is usually straight-cut), but it also tends to last longer. If the noise wouldn't annoy you so much, it sounds like a reasonable mod.

But you should forget that cylinder deactivation trick, it's not a good idea for a Diesel at all.

BTW is your turbocharger a VGT or a fixed-geometry?

[TimV]

Can you explain why cilinder deactivation is not good?

I have a vgt turbo.

[cRiPpLe_rOoStEr]

Originally Posted by TimV

Can you explain why cilinder deactivation is not good?

Because thermal management in a Diesel is more critical than in a spark-ignited engine, and switching alternately from one cylinder to another as you were initially considering to try wouldn't really add any efficiency gain.

I have a vgt turbo.

If you had a non-variable turbo I'd suggest you to try a different turbo setup, maybe a twin-stage.

[RustyLugNut]

Originally Posted by TimV

Can you explain why cilinder deactivation is not good?

I have a vgt turbo.

A diesel always operates at "full throttle" simply because it has none. Fuel control is how you moderate power production.

A spark ignited gasoline engine uses a throttle. This causes the pumping losses talked about in depth on this and other forums. Cylinder deactivation results in larger throttle opening and a decrease in the pumping losses. Diesels do not have this pumping loss to begin with.