McLarens strange exhaust note at Spa.

[Zico]

Most noticable coming down through the gears in the braking zones, to me It sounded like they were also throttling while on the brakes.
Martin Brundle iirc commented that was it to do with their blown diffuser but could anyone elaborate on what he might have meant?

Could it be the Ignition timing on the overrun changed to create more airflow while throttle not 'on load' to reduce twitchiness ?

...and/or position/outlet aspect/shape of exhausts is causing such strange acoustics?

[Stefvh]

i was there, and i heard that. Don't how it works

[Sodemo]

I would have thought being on the throttle a lot whilst on the brakes would use up a lot of fuel, but perhaps the benefits are worth it? Who knows, it did sound strange though.

[wnut]

Originally Posted by Sodemo

I would have thought being on the throttle a lot whilst on the brakes would use up a lot of fuel, but perhaps the benefits are worth it? Who knows, it did sound strange though.

Was it the same throughout the race or just in qualifying and early in the race maybe. I have not heard it at all but noted Brundle's remarks.

[1200Datto27]

From my understanding, this is a bit like anti lag on rally cars, where the throttle is kept partially open and the ignition timing and fuelling is changed to create airflow through the exhausts, but not much power, in the same manner that if you rev a car with the gearbox in neutral, then you get the airflow through the engine, but as there isn't any real load on the engine, it isn't creating a lot of power.

[wnut]

Originally Posted by 1200Datto27

From my understanding, this is a bit like anti lag on rally cars, where the throttle is kept partially open and the ignition timing and fuelling is changed to create airflow through the exhausts, but not much power, in the same manner that if you rev a car with the gearbox in neutral, then you get the airflow through the engine, but as there isn't any real load on the engine, it isn't creating a lot of power.

That is what I was thinking Datto, but I would have thought it would consume too much fuel to run the whole race. Which is why I was interested to see if it was a quali and 1st lap phenomenon or consistently for the whole race.
You are right though it would certainly increase what was available for the diffuser! Good thinking McLaren!

[E.B]

I think it was not so much a McLaren technology, but is their 'me too' version of what was developed initially by Newey and RBR in their trendsetting 'blown' diffuser. In much the same way as all the teams now seem to have their 'me too' version of the McLaren inspired F Duct technology.

[wnut]

Originally Posted by E.B

I think it was not so much a McLaren technology, but is their 'me too' version of what was developed initially by Newey and RBR in their trendsetting 'blown' diffuser.

Why does the Red Bull not have the same exhaust note, anti-lag is very very noticable and quite specific?



Are they running it (anti-lag, blown diffuser) for the whole race or just a few banzai laps?



It will be a total must have item either way - given the importance of quali.

[bjohnsonsmith]

Was this 'happening' with both cars?

[broadrun96]

Thought Renault had said the reving of the engine that Red Bull was using to keep air over the diffuser was most likely to blame for the damages to their engines earlier this season. Red Bull was supposedly running the engine hotter and harder than Renault had designed.

[Zico]

Originally Posted by wnut

Why does the Red Bull not have the same exhaust note, anti-lag is very very noticable and quite specific?



Are they running it (anti-lag, blown diffuser) for the whole race or just a few banzai laps?



It will be a total must have item either way - given the importance of quali.

Modern ALS sytems usually have additional fuel injectors which are used as air valves which bypass the throttle butterflies, they occilate while aditional fuel is injected on the overrun to keep boost levels up controlled by the ECU as is the timing/fuelling, to the best of my knowledge such engine modifications would probably not be possible to do due to the engine development freeze so at the most Im thinking just basic ignition timing on the overrun.

I remember hearing it on Lewis's car due to most the camera work being on the leader, maybe someone else remembers it from Jenson's?

It was being used in qualy and I remember still hearing it between half and two thirds of way through the race, could have been more.

[bdwoody]

it kind of sounded like a broken header pipe ...

[Zico]

If McLaren are retarding ignition to blow their diffusers during off-throttle moments it doesn't make sense that we could hear it later on during the race due to the additional fuel it would use not to mention the huge amounts of heat it would generate unless of course the bennefits outweigh the additional fuel weight penalty and they have somehow found a way to manage the additional heat over a long period.
It also turns out that it's an idea originally developed by Red Bull and used maybe also Renault themselves as explained in Scarbs F1 blog..

http://scarbsf1.wordpress.com/2010/0...teams-q3-pace/


"Of course this gain doesn’t come for free, the heat of combustion now takes place in the exhaust port, so that the exhaust valve, cylinder head and exhaust pipe all suffer excessive heat. This will affect them, as they cannot withstand this sort of thermal load for long periods. Equally the process burns additional fuel, in the race this is a negative thing as fuel is limited and no refuelling is allowed.
This ignition retard mapping would be controlled via the SECU via the driver selecting a steering wheel control, using quite normal tuning parameters and not some clever workaround. Of course this is all quite legal.
If the overheating issues can be contained, this would be a relatively simple mapping to introduce for another EBD team. As mentioned Renault Sport, Red Bulls engine supplier would have to know about this. Copying the concept, but not the actual SECU code would be quite easy."


This could well explain why Red Bulls qualifying pace has generally been far superior to their race pace.. they could be using the retarded ignition mapping sparingly ie, only in qualifying.. to limit the damage this excessive heat will do to their exhaust and engine.


What do you think?