Renault R31

[sknguy]

Just to clarify for myself is this correct?

[PlatinumZealot]

Check the FEE thread.. like 50 pages on this car.but yes you are correct. the trajectory changes with speed of the car, rpm, shape of the leading edge of the floor, exhaust pipe direciton and shizzle.

[bot6]

I think he means the exhaust pipe itself, not the gases.

No, they are not routed inside the tub. They go forwards right under the radiators, just outside the tub, then at the end they turn sharply outwards. There's pictures of the car without the sidepod covers in the FEE thread I think.

[sknguy]

Sorry I'll check the other thread. And yes thanks, I was curious about the piping itself actually. Didn't realize they would bend it into sharper turns.

[Lindz]

Exhaust pipe under radiator:

[ringo]

what's interesting is that the pipe diameter narrows showing that the want to accelerate the exhaust gas to increase it's speed.
Looks like it goes from 4 inches or so to 2.5.

[BreezyRacer]

First, we're only seeing this one angle so we don't know that the taper is a fitment thing where the width gets wider. But it may be that they are indeed tapering the pipe volume to keep velocity up as the exhaust gases cool.

[wesley123]

what's interesting is that the pipe diameter narrows showing that the want to accelerate the exhaust gas to increase it's speed.
Looks like it goes from 4 inches or so to 2.5.

I think it is just the transition from the regular circular shape to the shape in which it meets the outside world. Wouldnt such narrowing increase the pressure over the pipe reducing its torque?

[ringo]

It does have a smaller cross section at the tip.
There is a negative effect on the engine, but i guess it's the price they pay for increased gas velocity.

The gases could be bordering on transonic speeds.
crazy stuff happens in that speed regime.

It's also possible the elyptical area is the same as the circular one, but the increased speed idea sounds interesting and would benefit what they are doing.

[BreezyRacer]

Ringo

I've followed your fascination with the Renault exhaust and admit that I see it's design much as you do. It's interesting to me how reliable the performance from it has been thru testing and the first race. Contrast that with McLaren for instance, and all the other teams that have been playing design of the week.

You read some of these posts where they get into thermal mapping of the exhaust gases, etc and people act as if this thing is a mystery or that it cannot work at all. Yet it has proven itself to be not at all finicky.

I'm beginning to think that this exhaust solution is a real game changer and easier to replicate than some of the other exhaust solutions such as the RB one. Ross Brawn seems to think so too. I wonder if we can see it next on a Mercedes? They are unsuccessful enough to need to make a big change early ..

[Owen.C93]

There's alot of heat shielding around the pipe in the sidepods, I'll try and find the unshielded one because it's alot thinner.

[BreezyRacer]

There's alot of heat shielding around the pipe in the sidepods, I'll try and find the unshielded one because it's alot thinner.

Yes, any more pics would be quite welcome!

[raymondu999]

Wow! Apparently the ignition overrun means that the cars use 10% more fuel http://www.racecar-engineering.com/news ... more-fuel/

[PlatinumZealot]

An extra 40 pounds of fuel at the start of the race then. By calculations if the overrun is used constantly, by halfway through the race the cars have 20lbs of fuel more than Non Overrun users.

[PlatinumZealot]

what's interesting is that the pipe diameter narrows showing that the want to accelerate the exhaust gas to increase it's speed.
Looks like it goes from 4 inches or so to 2.5.

No way is that 4 inches..