Article: adding a turbo to improve efficiency

[boxchain]

Originally Posted by Coyote X

Adding a turbo to a car and not changing gearing or going to a smaller motor is not going to help anything but acceleration really. Kind of a similar problem of doing aero mods and not changing gearing. The engine load decreases but the rpms are high enough you are still using a lot more gas than you really need to.

I guess i'm looking at this from the point of my mostly street level commute, where I don't have a problem with high revs, but I would like more torque at low revs. My D16 tq curve has a very steep climb between 1800 and 2500 where it reaches a tq plateau, so in order to stay producing high tq values, I have to shift at 3000. I'm at 2000 at 45mph in 5th, which makes for slow response on pulses.
if a LPT can shift that plateau to where I'm reaching near max tq at 2000, acceleration would benefit greatly, and I can shift at 2500 to stay in the torque band.
On the short highway portion of my commute, I'd love a 6th gear, I'm at 3000+ doing 60-70. Aero would give a huge benefit here.

I agree with the aero + gearing idea, but all most of us can do is the aero

[zjrog]

I've spent some time with the 80s Chrysler turbo cars and they CAN return some decent mileage. I had a 86 Daytona Turbo with automatic. I could keep an average of 24 with mostly city driving, no freeway. But I also had to resolve all the vacuum line issues and ignored maintenance of the previous owner. The first tank of gas after I could keep it running was only 10 MPG...

I've considered adding a turbo to my Jeep, usually just to make it easier to drive in the mountains. But even at only 6 psi it will provide enough extra torque to make it worth while. The hard part is matching the turbo to the application. I don't want or need to make killer power, but being able to keep a higher gear as mentioned will have an effect. Especially since I do drive a mountain pass to work...

[zjrog]

And of course the main caveat... Absolute power corrupts absolutely.

It is easy to say one wouldn't go beyond a certain boost level, but I have seen it get out of hand... And dragracing is completely different...

[Fuzzy]

Originally Posted by MetroMPG

Yet another good AutoSpeed article: Turbo'd for Fuel Economy - The way of the near future

A good overview of the issues around turbocharging.

Yeah, I took about two weeks away from ecomodder to read through as many of the autospeed tech articles as I could.

"Overview" is good description of the article. It'd be nice to have a more information on how to correlate common turbo specifications to an engine size in order to accomplish these kind of goals.

[metroschultz]

If I turbo my electric lawn mower will it allow me to mow my lawn twice on one battery charge as opposed to 1.3 X right now?
Just playin
I had thought of turboing the Metro once a long time ago.
Plumbing issues beat me up.
I looked & i looked but couldn't find one of the turbometro's anywhere. i even looked for a turbo Subaru Justy.
Oh Well.
now i just need to fix what i have and make it as efficient as possible.
S.
HI HO HI HO
Off To Werk
I GO

[wumpus]

During cruising, the turboed car will have worse efficiency than the NA due to the lowering of the compression ratio by about a point. You will certainly need the improved gearing. Of course, you could get away with the same gearing without the turbo, and just be willing to shift the car a lot.

Me, I'd take an even taller gearbox, a bigger turbo (with good horsepower gains for when I want them), and a methanol injector to keep the compression ratio up. Actually, a DTI would make a lot more sense...

[diesel_john]

wumpus, welcome

if the turbo'd engine were of much smaller displacement, wouldn't it be up on the boost even at cruise? turboing doesn't help economy much unless the displacement is reduced proportionately.

gearing is good, but I can only lug the engine so low before i need a bigger flywheel.

[wumpus]

The article specifically mentioned a pair of 2.0l engines. In practice, I'm not sure the small turbos are more efficient than bigger NA engines, but the engine in the article was different from the turbo=sports car that marketeers seem to think is required.

[trebuchet03]

Originally Posted by wumpus

In practice, I'm not sure the small turbos are more efficient than bigger NA engines...

Yes, in practice they can be. And when designed for it, they are. This is the case for power generation (when turbines aren't used) etc. Unfortunately, for us, auto mfrs like to use fuel for it's heat capacitance rather than it's combustible characteristics - but that doesn't mean things have to be that way...

[diesel_john]

"Unfortunately, for us, auto mfrs like to use fuel for it's heat capacitance rather than it's combustible characteristics "

could you explain, i don't understand what heat capacitance is.

Thanks, trebuchet03, i can google it from there.