F1 Exhaust System

[wmm]

I found this article on F1 exhaust systems and I think that it is very interesting especially for those technical F1 fans discussing this subject in another forum named “Exhaust opening” .

‘The moment the outlet valves open, all hell is let loose. One of the 10 cylinders in an f1 engine has just inhaled 300cc of air, laced it with a jet of fuel, compressed the mixture to 10x atmospheric pressure and flung in a spark. At 900 degrees Celsius the gasses produced when the mixture explodes whip past the titanium outlet valves and into the exhaust system at the speed of sound. But far from being a simple means of evacuating hot, high-speed gases, modern exhaust systems have a crucial part to play in determining the power and performance of a racing engine.

Compared with the exhaust of a road-going car, the short but serpentine system in a formula racer looks pretty simple. Each bank of cylinders features a number of artistically twisted steel tubes, with no catalytic converter and no silencer to hinder the flow of the exhaust gases and prevent the engine breathing freely. And yet designing a F1 exhaust system is an extremely complex business that calls for an intimate knowledge of the laws of acoustics if the engineers are to tease the last reserves of power out of the engine. That’s because, like in a trumpet, the exhaust gases vibrate at a specific frequency depending on the speed of the engine. As the valves open and close, they generate a pulsating column of exhaust, with regular peaks and troughs of pressure. To ensure that the 5 cylinders per bank don’t interfere with one another in this respect, all the exhaust pipes must be the same length. And at the end of the collector, the exhaust gasses from each bank exit the car from a single tailpipe.
Racing engines bred for maximum power work with a high degree of valve overlap. That is to say, the inlet valves are opened before the piston reaches top dead center (TDC) while the outlet valves are still open. At this instant, a perfectly tuned exhaust system will ensure that there is already under pressure in the combustion chamber, drawing in the mixture for the next charge. So the induction stroke which is generally triggered by the downward motion of the piston is in this case initiated by the exhaust system . Thus the intake and exhaust system together form an integrated and highly sensitive gas vibration system which influences both maximum power and torque.

At peak revs, a formula engine will blast out exhaust gases 95,000 times a minute. To scavenge maximum power the exhaust pipes need to be as short as possible. Unfortunately , to help generate maximum torque and responsiveness at lower revs, longer splender pipes are called for. As F1 regulations don’t permit variable-geometry exhausts, the answer lies in the best possible compromise.
The current preference for tailpipes that emerge upwards through the rear trim at either side of the car has made life easier for exhaust designers.

Nevertheless, F1 exhausts rarely completes more than 1200km since the need to save weight means they have to be designed close to the limit. The thickness of the heat-resistant steel adopted from the aerospace industry varies but is never more than 1 millimeter. But when eventually kills these waste-gas works of art is not vibration or temperatures of 1000 degrees and more, but stress, The different radii of the various pipes ultimately produce fatigue which leads to cracks where the stress is greatest. Not surprisingly, at this high level of performance even the best exhaust are soon exhausted !!’

[hit_guy]

Sweet Good info

[Monstrobolaxa]

interesting...if anyone finds other articles....post them!

[Becker4]

great article, thanks for sharing

[mikeross]

This is very interesting. I didn't know much about exhaust systems in this type of vehicle. Now i know better..

[autogyro]

This is very interesting. I didn't know much about exhaust systems in this type of vehicle. Now i know better..

When I was building race saloons, rally cross cars and hot rods years ago, there was a guy called mike the pipe who supplied tuned exhaust manifolds and systems.
Does anyone know what happened to him?
There were many articles on the black art of exhaust tuning back then, the knowledge seems to have faded a bit, apart from in F1 of course.

[Giblet]

The Toyota team keeps a mangled but intact exhaust from Timo's huge shunt last year displayed proudly in their shop as a testament to the extreme engineering and craftsmanship of their gear.

[marcush.]

burnsstainless was a long time supplier to me when I build my own headers..some basic info is available on their site:
http://www.burnsstainless.com/weldingarticle1.aspx etc...

http://www.burnsstainless.com/Inconel.aspx


this company claims to supply some f1 teams with exhaust materials:

http://www.sstubetechnology.com/index.htm

[xxChrisxx]

I thought most exhuasts in F1 were made from Inconel (625 iirc), not steel.

Exhaust tuning is becoming easier these days, it's acutally now a fairly simple task to mathemetically model how the exhaust pressure waves behave. They involve calulations that can't be sovled by hand and were traditionally done with a suck it and see approach, so most of the 'black art' has been replaced by science. Getting the best compromise for drivability and power still takes a bit of good judgement, luck and voodoo.

Commercial packages are available such as Ricardo WAVE and lotus engine simulation, allow inlet and exhaust configurations to be tested before they are built.

[autogyro]

Hmmm poppet valve technology.
I bet they have no data bases for proper sleeve valve technology for real power outputs in ic engines. 1941 was the year.

[xxChrisxx]

Hmmm poppet valve technology.
I bet they have no data bases for proper sleeve valve technology for real power outputs in ic engines. 1941 was the year.

I don't understand. What do databases have to do with anything?

[autogyro]

I thought you were refering to an accumulated raft of data that allowed computer simulation of exhaust gas dynamics for the design and manufacture of tuned exhaust systems?
(I used to do it by the suck it and see method on an engine dyno).
Sleeve valves produce different exhaust dynamics to poppet valves and as sleeve valve engines produced more power and efficiency than poppet valves, I was simply interested in the modern computer simulated view on this fact.

[xxChrisxx]

I thought you were refering to an accumulated raft of data that allowed computer simulation of exhaust gas dynamics for the design and manufacture of tuned exhaust systems?

Mathematical models don't use anything but governing equations that you can program in. They require no 'data' to build.

Just like a suspension system can be modelled by a mass-spring-damper system. It doesn't matter what suspension type you are using they all obey the same laws of physics.

This is exactly the same for air flow.

(I used to do it by the suck it and see method on an engine dyno).
Sleeve valves produce different exhaust dynamics to poppet valves and as sleeve valve engines produced more power and efficiency than poppet valves, I was simply interested in the modern computer simulated view on this fact.

Well for exhuast tuning the acutal valve type wouldn't make a difference, air still moves according to the same governing laws. The inital conditions would certainly be different, but that is unlikely to drastically alter the model.

If it was found that a change in valve type made the model invalid, work would be done to get it to match up again. Which isn't that big a task really. Fluid mechanics isn't really an area where I am that strong.

[autogyro]

Point taken Chris.
I should know this of course.
I was just using your posts to bring attention to a long over looked technology.
Sorry.

[xxChrisxx]

Point taken Chris.
I should know this of course.
I was just using your posts to bring attention to a long over looked technology.
Sorry.

You have nowt to be sorry for bud, we just come from very different engineering worlds.

The 'art' aspect of engineering a solution is being eroded and replaced with pure science. Although with modern methods you get much better solutions, quite a lot of the soul and flair are being lost in the process.