VC-T - New Type of Engine for F1?

[GrandAxe]

Here's an excerpt about a new type of super petrol engine that Nissan is announcing, do the guru's in the house consider that its principles would make it into F1?

ATSUGI, Japan -- Nissan Motor Co. has come up with a new type of gasoline engine it says may make some of today's advanced diesel engines obsolete.

The new engine uses variable compression technology, which Nissan engineers say allows it at any given moment to choose an optimal compression ratio for combustion -- a key factor in the trade-off between power and efficiency in all gasoline-fueled engines.

The technology gives the new engine the performance of turbo-charged gasoline engines while matching the power and fuel economy of today's diesel and hybrid powertrains -- a level of performance and efficiency the conventional gasoline engine has so far struggled to achieve...

More here:
http://www.autonews.com/article/2016081 ... ged-engine

How would such an engine work? I wonder if it has a sort of "gearbox" for a crankshaft with varied offsets that can be shifted in an out beneath the cylinders? The engineers talked about vibration being one of the problems to be overcome.

[gruntguru]

It just uses a rocker beam between the crankshaft and the connecting rod - move the third pivot on the rocker beam and you change the TDC piston position.

Too bulky, complicated, extra friction, extra reciprocating mass etc. I much prefer Manolis' VCR concept.

Of course VCR is not legal in F1.

[Brian Coat]

In some ways, VCR looks unfavourable compared to an advanced combustion system, which allows high CR all the time.

[godlameroso]

I think the combustion concepts and the MGU-H they're developing in F1 have the highest realistic probability of ending up in road cars. More and more manufacturers are moving towards forced induction and direct injection so introducing it into a hybrid makes sense. Leave it to Nissan to make some other "innovation" that makes a car harder to work on.

[Cold Fussion]

What is the benefit of a variable compression ratio? Is the idea behind this to reduce knocking under high load or something?

[dans79]

What is the benefit of a variable compression ratio? Is the idea behind this to reduce knocking under high load or something?

Fuel saving!

[DiogoBrand]

Can't you do some sort of variable compression just by using variable boost?

[Brian Coat]

Can't you do some sort of variable compression just by using variable boost?

Yes. But ...

Boost can be used to raise the overall pressure ratio of the engine but to get the best efficiency from this you need a way to maximise the use of the extra heat generated - the MGU-H is a great example.

Moreover, If the knock limit is not improved, more boost will require lower static CR so it's not all roses.

And ... in a road car engines, boost has one big diasadvantage as a pure "CR increaser": it does not work at light loads (ie off boost).

The big efficiency advantage of boost in a road engine is it allows you to make the engine smaller.

[Brian Coat]

What is the benefit of a variable compression ratio? Is the idea behind this to reduce knocking under high load or something?

That's right, with an associated reduction in higher load efficiency.

Not great for F1 then, even if it were legal.

[Brian Coat]

I think the combustion concepts and the MGU-H they're developing in F1 have the highest realistic probability of ending up in road cars. More and more manufacturers are moving towards forced induction and direct injection so introducing it into a hybrid makes sense. Leave it to Nissan to make some other "innovation" that makes a car harder to work on.

Too right.

E.g. MAHLE TJI was developed with road cars in mind but a combination of development cycle time and risk appetite has it showing up (?) on race cars first.

I thought about this some more - what becomes a performance limiting factor once an SI engine can run CR and combustion temperatures as high as a Diesel??

Well for a road car it could it be the spark plug itself??

Step forward the clever spark plug R&D team with a plug which will not hole the piston due to thermal run-away induced pre-ignition (not knock) at 15-20:1 CR boosted at full load AND won't fry the catalyst due to plug foul misfire during -10 dec C repeat starts ...

[gruntguru]

The TJI spark plug in its own little pre-chamber with richer mixture is somewhat protected.

[Brian Coat]

The TJI spark plug in its own little pre-chamber with richer mixture is somewhat protected.

For that particular solution, this is a good point. I wonder to what extent this is a benefit?

[Tim.Wright]

Of course VCR is not legal in F1.

Give it time. If it starts being used on production cars the technology will eventually trickle down to F1.

Amirite?

[Brian Coat]

Regardless of trickle-down & legality, I am still wondering what the benefit would be in an F1 race engine.

Ideas?

[PhillipM]

Way too bulky and heavy to be useful tbh, plus a lot more sources of friction losses.