Diesel tuning for LSR attempt.

[SteveM]

OK - since there is not a lot of public information regarding tuning a diesel engine for an LSR application, I thought I'd start a topic.  I only know a little about the subject, and I'm definitely hoping to expand my knowledge base.

I'll just lay out my current plan and solicit opinions.  Hopefully some folks with more knowledge will add to the discussion.

I'm building an H-class engine for a diesel truck.  The engine will be a VW indirect injection diesel (not a TDI).  These IDI engines are 100% mechanically controlled and injected.

I have a 1.6L "turbo" block, which is set up with oil squirters at the bottom of each bore for piston cooling.  The non-turbo blocks do not have this feature.  Knowledgeable people say that the turbo block is a near-necessity for a high-powered VW diesel effort.  The entire rotating assembly for this engine is from a 1.5L VW diesel (the bore of the 1.5 and 1.6 engines is the same). 

The cylinder head is from a 1.9L diesel, which uses larger valves than either the 1.5 or the 1.6.  It should flow Use of the 1.9L head also decreases the static compression from approximately 22.5:1 down to 18:1 or so (depends on final head gasket thickness).  Based on what I have learned about these engines, the lower static compression should be a good thing, as it means I'll be able to run more boost (through an icewater chilled intercooler) to get the cylinder pressures back to the same level.

In terms of the injection pump, I have one on the way that is pretty much stock, but has had the governor circuit modified for additional fueling at all rpms, and also has a more aggressive timing curve than stock.  The thinking here is to provide excess fuel, then use the intercooled turbo pressure and airflow to move back towards an ideal A/F ratio.  An adjustable waste gate and/or blow-off valve will be needed here.  I have a local guy (Turbo Center of St Louis) who has a lot of diesel experience and has been very eager to help with this setup.

I think the limiting factor for fuel and airflow is going to be the exhaust gas temperature (EGT).  This is an area where there isn't much information available with respect to land speed racing.  In terms of drag racing, and even tractor pulling, it seems that the diesel guys are able to get away with higher EGT's, but the duration of their efforts is obviously shorter than in LSR.   A rough rule of thumb might say that 1300F is the maximum EGT that an engine should be allowed to produce, but for how long a period of time?

This question of the maximum sustainable EGT for the duration of an LSR run is one that I am particularly interested in.

I've seen some photos and video footage of diesel 'liners, and they typically show A LOT of black smoke, which indicates heavy fueling.  Can anyone share information regarding typical EGT readings for this type of diesel 'liner or truck effort?

That's all for now.

Steve.

[McRatX]

OK...

Here are the problems with diesels:

Piston crown temps can actually ignite the aluminum if given the chance.  This is the #1 problem for long duration HP.

Timing is GOOD, if you don't burst.  Bursting is when you inject the fuel too quickly, and the air is not hot enough to ignite the fuel.  The engine "unstarts"  the excess fuel cuts the air temp so much it's like turning off the key.

Being able to advance the timing based on boost is critical.  Not like gassers.  I run up to 45° advance at high boost.

Go low compression.  You aren't looking for street torque.  You need to keep the rods and crank alive.  16:1 seems to be a good number.

Once the mixture ignites, pump the living crap out of the fuel.  The fuel will cool the piston.

EGT's are tricky.  1600°F will eventually destroy your turbos, but bursts up to 2000 are common for drag racing.

Nitrous cools this down a lot, but is illegal if you're caught.

Waste gates are useless on diesels that aren't over 45psig boost.  They hurt, not help.

IMO ...

[McRatX]

Note:  With a factory Garrett AVNT GT37 that comes on a Duramax, I can hold 1350°F till the cows come home.  It won't get hurt at 1350.  The turbine is inconel, and the center section is watercooled.  Factory setting is 22PSIG boost.  It took 55PSIG boost and 50% over peak impeller RPM to hurt it.  And I still drove it home 25 miles from the race track.

The typical gas racing chargers will explode way before they reach the stock spec on a modern diesel turbo.  I spin my GT4202R up past 150,000 rpm constantly (yes I have a turbo tach).  I've yet to kill one after 1000+ runs.  It's what I drive on the street as we speak.

[McRatX]

Note, black smoke is fuel shot into the cylinder without enough time to burn.  Droplet size is too big.

Only gases burn.  Liquids do not burn.  You must heat the liquid to a gas for ignition to occur.

Liquid fuel used to cool the pistons.

It is interesting that you can run pretty clean and still kill overfueled engines. There is no AF ratios for diesels.

Video.  White truck is me.  I drove to the track with 2 passengers a 6000lb trailer, and the bed full of tires at Texas:

http://www.youtube.com/watch?v=b6sm0lFKmXU

Single GT42 on truck stop fuel.

http://www.youtube.com/watch?v=IAbgw0w5_gs

Drove to track with 2000lb of sandbags in bed.

http://www.youtube.com/watch?v=_J0CQN5vV0g

Street legal, factory trans, axle and engine.  Single GT42 on truck stop fuel.


All these were done the same year.

[SteveM]

Thank you for weighing in on this topic, Pat.  I was hoping that you would.  You have "been there and done that", so I appreciate the technical help.

I have plenty of learnin' to do.  I was thinking about what types of high-temp materials are available for the hot side of the turbo. Inconel is certainly an excellent choice.

Now I have some more reading to do.

Steve.

[LittleLiner]

Steve
I suspect the answer to this question if "cost."  I was wondering why you didn't consider going with a full TDI engine?

[SteveM]

I researched going with a TDI.  The biggest issue I saw for this application is that there is no easy way to get a TDI with less than 1.5L displacement in the USA. 

I couldn't find a cost-effective way to de-stroke a 1.9L TDI.  There are some 1.3L TDI's available in Europe, but none in the USA (or Canada, I believe).

If I get to the point where I want to run in the G displacement class, then a TDI makes a lot more sense for me.

Steve.

[Tman]

I do not know diesels even tho I direct a couple dozen of them around the country every day but am enjoying watching all of this Steve.

[SteveM]

I chose to build a vehicle for an attempt at the H/DT record, because I thought that I stood a reasonable chance ($$$$-wise) of building a vehicle that could contend for this record.

Like anything else, the costs add up very quickly, but I am committed to completing this project and hopefully being competitive against the existing record. 

When you think about it, there aren't many vehicles that have ever been available in the USA which would meet the 1.5L diesel truck description.   In terms of a marketing niche, I think there's a definite hole there.  If we can get reasonable diesel-friendly legislation on the books, I think there's a big potential market for small trucks with small diesel engines, especially if they are diesel/electric hybrids.

When that time comes, I expect that someone will build a 1.5L diesel truck for LSR racing that will readily beat anything currently on the salt.  The current and previous recordholders in this class were Rabbit Pickups - not exactly known for their aerodynamics, and not exactly "late model".  If Toyota, GM, Ford, Dodge, VW, Isuzu, Subaru, etc. comes out with a sleek, aerodynamic, small diesel-powered pickup truck, it's just a matter of time before somebody shows up with one on the salt.

There are some very cool diesel engines available in Europe which probably have more power potential than the one(s) I have in my garage, but they are in Europe, and I am in Missouri.  My goal for now is to try to use "old school" techniques to boost the power of a 1.5L mechanically injected diesel, and have fun while doing it.

Steve.

[Trouble]

Friday Joke of the Day!

GMC actually made diesel pickups from 1980-1984 "Caballeros".  These are not legally diesel pickups, yet a gasoline Rabbit is.

[Tman]

Friday Joke of the Day!

GMC actually made diesel pickups from 1980-1984 "Caballeros".  These are not legally diesel pickups, yet a gasoline Rabbit is.

Were those the converted gas engines that GM tried in the Elcamino platform?

[Trouble]

Friday Joke of the Day!

GMC actually made diesel pickups from 1980-1984 "Caballeros".  These are not legally diesel pickups, yet a gasoline Rabbit is.

Were those the converted gas engines that GM tried in the Elcamino platform?

It was that POS Old's 350 diesel.  Arguably the dumbest thing the General ever did.

[Tman]

Thats what I thought. Never knew they put them in GMC "elcos"