Putting the "turbo" back in turbodiesel

Well, unless you like full-size pickups, the only diesels on the open market in the USA are Volkswagens. And their TDI engines are pretty unspectacular; 90 hp and 155 lb/ft of torque. There's worse out there, but there's also a lot better.

I'm not yet a real tuner, seeing I don't want to waste good cash on the minivan I'm driving now. Any of you know of some aftermarket magic for a diesel engine that might soup up one of those VWs enough to take on stock Hondas without fear?

Does this sound like the sort of thing you're looking for?

http://formen.ign.com/news/23047.html

"the bored and stroked TDI beetle now squeals the wheels to the tune of 295 horsepower and 210 lb/ft of torque through a stock block bored from 1.9 to 2.6 liters."

or this?

http://www.bb-automobiltechnik.de/english/mvw_v_beetletdi.html

Two stage turbocharging should be nice... but probably expensive.

Wow. They managed to make a TDI more powerful than torquey. Doesn't that kinda defeat the purpose??

um, what purpose are you referring to? It's not like they lowered the torque output.

Oh, i know, but diesels rarely have more power than torque from what i've seen. Could be wrong though, seeing your reaction.

That's really just a matter of the shape of the torque curve and the operating speed range. An engine that reaches peak torque at a fairly low rpm will have high torque relative to power.

For ANY engine, if peak power happens at less than 5252 rpm, peak power in hp will be less than peak torque in ft*lbf. The converse is not necessarily true.

(correct me if I'm wrong on the above, but it sure seems right to me.)

Yep, you're right on that one. Even with a 4000 lb-ft torque peak at 5251 rpm, your hp is 3999.2 hp.

And I see that I may have caused confusion earlier. I wasn't insulting the fact that they got more power than torque, i was just surprised. You usually don't see too many diesels turboed or not get more power than torque. I guess that with a higher CR characteristic with diesels, the engines can't rev too high.

Must've lowered the CR by quite a bit.

Not necessarily. If they messed with the compression ratio at all, it was probably just to keep peak cylinder pressure reasonable with the increased boost.

Yeah, you can't run huge boost with 13:1 compression or higher even.

I had a question, and it seems like it might get an answer in this thread.

Why can't diesels rev as high as petrol engines?

Originally posted by 911GT2
Yeah, you can't run huge boost with 13:1 compression or higher even.

well, maybe not huge, but I've worked on a diesel engine design that ran 55psi boost @ 18:1 compression...

Originally posted by 454Casull
I had a question, and it seems like it might get an answer in this thread.

Why can't diesels rev as high as petrol engines?

In general, because they're built to run more slowly. There are diesels in the works that will run at 4500-5500rpm, but nothing that I'm aware of that will run much faster than that.

Part of the problem is probably that the peak cylinder pressure in a diesel requires heavy reciprocating components, while high speed operation favors lighter components. The gas force balances the inertia force when the piston is at the top on the compression stroke, but there's no such balance on the exhaust stroke, and BDC acceleration can be just as bad.

Search for HSDI online and see if you come up with anything interesting.

Originally posted by ivymike1031


well, maybe not huge, but I've worked on a diesel engine design that ran 55psi boost @ 18:1 compression...

Wow....18 wheeler turbodiesel??

I worked at a moving company for the last 2 summers so i've seen and heard a whole lot of turbodiesels. They run some crazy boost in comparison to high boost DSMs and such.

But you worked for a trucking company at one time didn't you?

At one point I worked for a semi truck OEM. I currently work at a consulting firm that does a great deal of engine design.

The 55psi/18:1 engine was based on a truck engine design, but was not intended to go back to that application.

The highest boost I've seen used on a semi truck in stock configuration was 27psi, if I remember correctly.