Porsche 919 LMP1 - Why a V4 petrol?

[mollytherocker]

Just curious.

The car did well today at Silverstone and it looks like its quick out of the box.

But why specifically a V4? And could we see it in a road car?

[rossb]

porsche interpret the rules favouring a small engine with big hybrid system (has 2 systems in the 919) - therefore heavily boosted 4 pot. V4 is attractive as it can be used as structural entity - inline4 requires spaceframe - also v4 is also v.short - which is probably good for packaging

[pierslofi]

And I suspect Porsche will introduce a 4 cylinder engine at some point and this gives them a racing pedigree to play on

[Trev450]

I acknowledge rossb's points and they make good sense, but further to Molly's original question, why not a flat 4?

[NJH]

Flat engines tend to have a higher CofG than V engines because the exhaust has to go somewhere and this results in the crank being several inches higher.

[mollytherocker]

NJH said:

Flat engines tend to have a higher CofG than V engines because the exhaust has to go somewhere and this results in the crank being several inches higher.

Good lord, I have never thought of it like that. I had assumed that flat engines always have a lower CofG!

[arcamalpha]

NJH said:

Flat engines tend to have a higher CofG than V engines because the exhaust has to go somewhere and this results in the crank being several inches higher.

Although the exhaust is a factor, I would have thought the main issue on road cars would be the flywheel. I look under my car the exhaust isn' the lowest point - that's the bell housing and the bottom of the crank case. I'd expect this to be the same on most engines, including V engines.

[tr7v8]

arcamalpha said:

NJH said:

Flat engines tend to have a higher CofG than V engines because the exhaust has to go somewhere and this results in the crank being several inches higher.

Although the exhaust is a factor, I would have thought the main issue on road cars would be the flywheel. I look under my car the exhaust isn' the lowest point - that's the bell housing and the bottom of the crank case. I'd expect this to be the same on most engines, including V engines.

With a race clutch & flywheel it will be tiny, probably 5-6" so not on a pure race engine. Also been talk having the "hot" in the V for efficiency, so the turbo & exhaust ports in the V rather than the outside.

[mollytherocker]

Ok, so the V4 is;

Light;
Short, which is great for packaging, especially as theres the turbo and hybrid system to get in there;
Makes it more mid engined, assuming you believe this is a good thing;
Fuel efficient;
Has less moving parts and therefore maybe more reliable?

Perhaps it does make sense afterall.

[Gustavo]

There are a couple of existing renderings that show the engine and installation pretty well:

http://3.bp.blogspot.com/-5kof0gkzJZM/UxWXEP1ezZI/...
http://simanaitissays.files.wordpress.com/2014/03/...

Exhaust ports on the outside of the vee, with turbocharger, wastegate, energy recovery system above the gearbox.
Single, side-mounted, charger air cooler on the right hand side of the car feeding intake air to the middle of the vee.

The whole car rendering also illustrates how the vee configuration forms a back-bone for the car when connected to the gearbox and chassis. Both an inline and a flat / boxer configuration would need additional structure as per a previous comment.

G

[arcamalpha]

mollytherocker said:

Ok, so the V4 is;

Light;
Short, which is great for packaging, especially as theres the turbo and hybrid system to get in there;
Makes it more mid engined, assuming you believe this is a good thing;
Fuel efficient;
Has less moving parts and therefore maybe more reliable?

Perhaps it does make sense afterall.

Sounds about right. One way or another, they're getting the power and torque. The acceleration looked really impressive on Sunday. Perhaps it's mainly handling that's losing them time. Shame they had one car fail. Hopefully something they can identify and resolve for Spa.

[supersport]

I thought that the Toyota looked a lot faster on acceleration than the 919, it was really clear on the slower bends.

[Trev450]

If the new breed of Boxster/Cayman is to be a turbocharged 4 pot as we are led to believe, then maybe that will be a v configuration too.

[Moog72]

Trev450 said:

If the new breed of Boxster/Cayman is to be a turbocharged 4 pot as we are led to believe, then maybe that will be a v configuration too.

Christ I hope not, that will be a sad day indeed - one of the attractions of Porsche to me is the lovely flat 6

[isuk]

Trev450 said:

If the new breed of Boxster/Cayman is to be a turbocharged 4 pot as we are led to believe, then maybe that will be a v configuration too.

Porsche are currently displaying the new 2.0 Macan at Beijing but strangely made no reference to it at the pre show VW group press night where they only revealed the new Boxster and Cayman GTS models. Going by these engine bay shots of the new base model Macan it looks like it could be a V4 engine. The output is said to be 233bhp in this model.

[spyderman8]

isuk said:

Porsche are currently displaying the new 2.0 Macan at Beijing but strangely made no reference to it at the pre show VW group press night where they only revealed the new Boxster and Cayman GTS models. Going by these engine bay shots of the new base model Macan it looks like it could be a V4 engine. The output is said to be 233bhp in this model.

The base model (special order only in the UK) does indeed have a 4-cylinder engine. Specs here:

http://www.porsche.com/uk/models/macan/macan/featu...

[mollytherocker]

spyderman8 said:

The base model (special order only in the UK) does indeed have a 4-cylinder engine. Specs here:

http://www.porsche.com/uk/models/macan/macan/featu...

So, is it the same block then? If so, it will be the only Porsche with a race bred engine!!!!

[burman]

Agree with all above comments, 919 did well on debut and will no doubt improve over the season but I think Toyota will win Le Mans this year, they have 1000BHP and 2 years of development behind them so should be reliable over 24hrs, good drivers, loads of money,and are expected to win in corporate land.
They could still be taken out by an accident or slower car etc etc though.

[arcamalpha]

burman said:

Agree with all above comments, 919 did well on debut and will no doubt improve over the season but I think Toyota will win Le Mans this year, they have 1000BHP and 2 years of development behind them so should be reliable over 24hrs, good drivers, loads of money,and are expected to win in corporate land.
They could still be taken out by an accident or slower car etc etc though.

Yup. I heard the Porsche puts out about 750bhp. Should be more fuel efficient than the Toyota though which would presumably mean it can run at max throttle for longer? (Just guessing; I'm no race engineer!)

[OlberJ]

mollytherocker said:

So, is it the same block then? If so, it will be the only Porsche with a race bred engine!!!!

No, the Macan is an I4 found in all the other VAG cars, Golf GTi etc.

Boxster/Cayman with a V4 would be quite good but would much rather it was SC!