WEC (World Endurance Championship) 2014

[machin]

"small capacity turbo vs large NA engine efficiences" may be a good title for a separate discussion? I'd love to hear more views on the subject.... ????

In race conditions i think a big NA engine is more efficient

I did some research into this and I pretty much concur:-

A high compression ratio, large capacity, NA engine is more efficient (lower BSFC) at full throttle, due to the high Expansion Ratio that a high compression gives. However the big capacity high compression NA engine has higher pumping losses, and at part throttle (low load) the pumping losses become much bigger in relation to the output than a small capacity low compression engine, and therefore results in worse efficiency (higher BSFC).

A low compression, small capacity, turbo engine has smaller pumping losses at part throttle than a large capacity, high CR engine, resulting in more efficiency (lower BSFC) during low load running, however, the low compression means it is less efficient (higher BSFC) at full throttle.

Considering that the majority of driving on the road is conducted at part throttle it is not surprising that manufacturers are switching to small capacity turbo engines since these have better fuel economy in "normal" driving conditions, but still have the power for overtaking manoeuvres, even if the economy at full throttle is worse. However in a race situation, where a large proportion of the time is at full throttle, the choice is not so clear cut, which is why we see one manufacturer with a large capacity NA engine competing on pretty much equal terms with another manufacturer having a small capacity turbo engine.

[Cold Fussion]

"small capacity turbo vs large NA engine efficiences" may be a good title for a separate discussion? I'd love to hear more views on the subject.... ????

In race conditions i think a big NA engine is more efficient

However in a race situation, where a large proportion of the time is at full throttle, the choice is not so clear cut, which is why we see one manufacturer with a large capacity NA engine competing on pretty much equal terms with another manufacturer having a small capacity turbo engine.

Isn't this a function of the rules though? If we make the assumption that the turbo engine is inherently more efficiency, then presumably, Porsche would be able to reasonably calculate the BSFC for the Toyota engine, and then proceed to calibrate their engine mapping to achieve this across a larger portion of the rev range. If the Na engine were to be more efficient, then Porsche's engine choice is rather curious, as you would then expect them to run a compounded NA engine rather than a turbo compounded engine (I could be wrong though as my understanding isn't the greatest). I don't think we can draw that many conclusions of the engine efficiency from the way the rules are currently setup.

[machin]

If we make the assumption that the turbo engine is inherently more efficiency....

My research is based on real engines that aren't governed by any race rules;

A small capacity turbo engine has inherently better efficiency at part throttle.

A larger capacity, higher compression, NA engine has inherently better efficiency at full throttle.

Given the fact that racing cars spend a lot of time at full throttle a large capacity NA engine isn't at a disadvantage to a small capacity turbo engine which explains why Toyota stuck with the large NA V8 and are competing admirably against Porsche.

[Cold Fussion]

If we make the assumption that the turbo engine is inherently more efficiency....

My research is based on real engines that aren't governed by any race rules;

A small capacity turbo engine has inherently better efficiency at part throttle.

A larger capacity, higher compression, NA engine has inherently better efficiency at full throttle.

Given the fact that racing cars spend a lot of time at full throttle a large capacity NA engine isn't at a disadvantage to a small capacity turbo engine which explains why Toyota stuck with the large NA V8 and are competing admirably against Porsche.

To be clear, I wasn't saying it was the case, but a hypothetical. I think we have to be careful here when comparing, the Porsche unit is a new car in a new team, and have reported engine troubles since testing, where as the Toyota unit is mature at this point. In comparing performances, I believe the cars are largely aero dominated, so small differences in engine wouldn't show as much.

[PorscheLMp1Fan]

There's going to be an announcement on Saturday pre-race.

Apparently it's a certain Italian brand.

[Ganxxta]

Lets hope that certain Italian brand will be more successful in LMP1 than in a certain other racing series which is currently going downhill.


Joking aside, it looks good for LMP1 if this is true, Audi, Porsche, Toyota, Nissan, "certain Italian brand", I heard BMW was/is thinking about LMP1 again =D>

[Pierce89]

If we make the assumption that the turbo engine is inherently more efficiency....

My research is based on real engines that aren't governed by any race rules;

A small capacity turbo engine has inherently better efficiency at part throttle.

A larger capacity, higher compression, NA engine has inherently better efficiency at full throttle.

Given the fact that racing cars spend a lot of time at full throttle a large capacity NA engine isn't at a disadvantage to a small capacity turbo engine which explains why Toyota stuck with the large NA V8 and are competing admirably against Porsche.

To be clear, I wasn't saying it was the case, but a hypothetical. I think we have to be careful here when comparing, the Porsche unit is a new car in a new team, and have reported engine troubles since testing, where as the Toyota unit is mature at this point. In comparing performances, I believe the cars are largely aero dominated, so small differences in engine wouldn't show as much.

Actually, so far this year, performance is less aero driven. Porsche have a low drag, low DF setup, Audi are high DF with a lot of drag Toyota are roughly in the middle. All three are pushing aero development to full time f1-style year round tunnel/cfd proframs. Previously sports cars just developed a high df package and a low df package, now they push year round like an f1 team. Actually I didn't mean performance is less aero driven but less DF driven. Efficiency has made a big comeback over pure df because of the energy limited regs

[zonk]

http://www.24h-lemans.com/live/en

[Artur Craft]

Audi will provide their usual onboard(with telemetry) streams for the 24h race
http://www.audi-motorsport.com/de/en/ho ... tream.html

[zonk]

Porsche also: http://www.porsche.com/usa/eventsandrac ... streaming/

[machin]

I think we have to be careful here when comparing, the Porsche unit is a new car in a new team, and have reported engine troubles since testing, where as the Toyota unit is mature at this point. In comparing performances, I believe the cars are largely aero dominated, so small differences in engine wouldn't show as much.

My original post was really in response to the question of why one team would choose an NA engine and another a turbo engine....Regardless of the state of development. What I have found is that a small turbo engine is inherently more efficient at part throttle and a large capacity high compression NA engine is more efficient at full throttle. Now, of course, I'm sure a good turbo engine could be more efficient at full throttle than a bad NA engine at full throttle, and a good NA engine could be more efficient at part throttle than a bad turbo... so yes it is up to Porsche and Toyota to make sure that they both have "good" versions of their chosen format. That being the case what I conclude is that it is unlikely that either manufacturer can gain particularly more performance over the other from engine architecture alone; i.e. it would be wrong to claim that a small turbo charged engine is inherently more efficient in all conditions than an NA engine (I'm not saying you have suggested this, however it is a commonly held belief, and I will admit that before I did this research I did not know the relative benefits myself either).

[machin]

They're calling it a GT-R, so maybe it will have GT-R headlights, tail lights and a GT-R grill?
Possible something like the late 90's GT1 cars attempting to look like road cars.

Maybe like this???

[Scania]

They're calling it a GT-R, so maybe it will have GT-R headlights, tail lights and a GT-R grill?
Possible something like the late 90's GT1 cars attempting to look like road cars.

Maybe like this???

http://i90.photobucket.com/albums/k248/ ... 8bc64e.jpg

http://www.gtplanet.net/new-teaser-for- ... ign=buffer
or this?

[kooleracer]

Can somebody maybe elaborate on the difference between the hybrid systems of the 3 manufacturers? Are they only using KERS to charge the battery? What are the benefits and drawbacks off the different systems?

I will be watching the free practice, but I would like to know more about the technical aspects of the cars.

Thanks in advance.

[Pierce89]

Can somebody maybe elaborate on the difference between the hybrid systems of the 3 manufacturers? Are they only using KERS to charge the battery? What are the benefits and drawbacks off the different systems?

I will be watching the free practice, but I would like to know more about the technical aspects of the cars.

Thanks in advance.

Toyota uses Kers on front and rear axle. Their ES is supercaps. Porshe uses kers on the front plus a mgu-h. Their ES is a li-po battery. Au i uses only a front kers. Their ES is the Williams electro-mechanical flywheel.