Problem with performance through turbocharging

[09webbad]

After receiving no reply in the engine sharing forum, I thought i'd bring this issue directly in the developer questions... Ford's Eco-boost engine produces extremely good efficiency and more power than a 1 litre may suggest. So I decided to create something similar to this concept and when I compared this turbocharged engine to my current N.A. engine which is pretty much the same, there was no difference is economy and power. Virtually tiny difference! So, the actual question here is... Is this supposed to happen?

Here's the turbo engine...

[09webbad]

And the N.A. engine...

If you don't want to download click here... viewtopic.php?f=34&t=2647

[Daffyflyer]

Ahh, now Turbo engines aren't greatly more efficient than N/A engines in terms of turning fuel into power when running flat out, in fact the rich fuel mixture they like often makes them worse.

The reason for running a tiny turbo motor like a 1ltr eco boost is as follows.

If you wanted as much power as a 1ltr eco boost you'd usually need a 1.6, when you were cruising at 100kph you might only be using 5kw of power, and to get that small amount of power out of a 1.6 you'd need the throttle almost closed, the 1.6 would be spending a lot of energy trying to suck air past a closed throttle.

The 1ltr, because it has less capacity, and less power (when not on boost) could cruise at a higher throttle setting, working itself harder, spending less energy trying to suck air, and working more efficiently because of it. Then when you DID need to accelerate hard, the ecoboost could just spool up the turbo to make the power that it needed.


The reason you can't see this in the engine designer is that it only shows how effecient the engine is at turning fuel into power at full throttle, once it's in a car you'll be able to find out what kind of economy it actually gets, taking account of gearing, how much power it needs to cruise at 100kph, and what throttle setting and RPM that puts the engine at

[09webbad]

hmm... interesting. Does this mean that the fuel efficiency in my turbocharged engine is meant to be similar to the N.A. engine, but fuel economy is better

[Daffyflyer]

Yeah, the all out efficiency is similar AFAIK, it could be somewhat better due to the engine making use of exhaust energy to help it breathe in new air. But that gain could be lost in tuning it richer to avoid knock under boost. I don't think it's a massive gain in that respect.

Where it IS a massive gain is the ability to run a downsized engine, and then "scale it up" as required, using boost

We did quite a bit of research when setting up this part of the game, and I remember being surprised at how little efficiency difference a turbo made.

[09webbad]

It makes waiting for the full car designer to come out

So when you say the engine becomes richer to avoid knock under boost... is it possible to retart the valve timing during boost using VVT? or would that be less worthwhile...

[Daffyflyer]

VVT would be tuned differently on a turbo engine, typically you'd run it in a much less overlap-y cam timing when it's under boost. I'm not sure if you could do much about knock with VVT, although having control of valve timing would certainly be useful for things like running the best cam timing to spool the turbo up.

Typically turbo engines will retart ignition timing, and add a bunch more fuel as boost rises, though I think modern engines are playing with keeping it somewhat leaner under boost with the aid of direct injection and suchlike

[09webbad]

interesting stuff... Have you got a date on the full car designer btw? Just curious

[Killrob]

It's still the old date: end of the year. Probably there will be two more releases between now and then though. First Multiplayer, then Marriage, then the full Car Designer.

[Wirenfeldt]

It's still the old date: end of the year. Probably there will be two more releases between now and then though. First Multiplayer, then Marriage, then the full Car Designer.

Marriage.. .. i feel like i'm missing something.. feel free to enlighten me good sir..

[Killrob]

That's when engine and car are put together. For the first time you'll be able to put your engine designs into your car designs.

[09webbad]

So about the marriage, what features will and won't be included compared to the full designer? Will we get all the car some of the car stats?

[Daffyflyer]

So about the marriage, what features will and won't be included compared to the full designer? Will we get all the car some of the car stats?

Probably some acceleration stats will be available by then. But nothing like comfort/handling etc. Also weight will be kinda fudged as you won't be able to choose interior stuff etc yet.

[09webbad]

Sounds good to me