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      07-02-2013, 03:16 AM   #101
Boss330
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Quote:
Originally Posted by NISFAN View Post
No they know exactly what turbo lag is. What they are trying to achieve is a lower boost threshold, extending the operating range of the turbo without resorting to in-efficient twin or tri turbo systems. F1 is all about efficiency.

A turbo below 'boost threshold' and therefore not producing boost, cannot be labelled in any kind of 'turbo lag' situation, as it is physically outside of it's operating range.
The single turbo is there by regulation, not by engineering choices... The previous gen F1 Turbo V6 engines used twin turbos, as that was (is) the preferred choice on a V engine layout. Nowhere in the Renault F1 statement is boost treshold mentioned, even though the MGU-H might be used for that purpose as well. The MGU-H unit is there to "reduce turbo-lag to near zero" (and regenerate energy from the turbo when used to slow down the turbo). They have even defined the delay in torque delivery on a turbo engine as being caused by the turbochargers need to vary it's speed to match the requirement of the engine, which means that the turbo might be spooling down when you start accelerating. The turbo then first needs to stop decelerating (spooling down) before it can start accelerating (spooling up) and create the needed boost. It doesn't take long on a moder engine, but it's not instant. If your argument is that the torque delivery on a turbo engine is just as constant as on a NA engine you are arguing against what is the accepted knowledge (and Renault's F1 engine department...). Even in a situation where you are accelerating (making boost) and then giving the engine full throttle, the turbo will have a short delay before it has reached it's full rpm and boost level for that engine rpm. It's shorter than in the previous scenario, but it's not instant as in a NA engine. Yes, a turbo engine will give you more torque than a similar size NA engine, but it doesn't give 100% of the available torque instantly when depressing the throttle. BTW, I love the torque of a turbo'd engine and have had several turbo'd cars


Not sure why you call a twin turbo "in-efficient"? Are you saying that the BMW M5/M6 engine uses in-efficient turbo design? A smaller turbo has lower inertia, quicker spool up etc. It's also easier to keep exhaust gas speed higher with smaller diameter tubing and inlet (can be done on a big turbo as well with advanced interior design of exhaust tubing).

Regardless, a F1 engine that operates between 10-15000rpm during a lap (might not go as low as 10 grand either) does not need the same low rev driveability characteristics as a street car engine.

And I feel that this quote from Renault's F1 department sums up the difference between a traditionally turbo'd engine and a NA engine:

Quote:
As the turbocharger speed must vary to match the requirement of the engine, there may be a delay in torque response, often known as turbo-lag. One of the great challenges of the new Power Unit is to reduce this to near zero to match the instant torque delivery of the current V8 engines.
So, even with the new technology, the turbo lag is "only" reduced to near zero. Not the instant torque delivery that todays NA engine deliver.

By definition a turbo engine must have turbo lag under certain conditions, because "the turbocharger speed must vary to match the requirement of the engine". That's why rally cars have anti-lag devices and Renault's new F1 engine has the electric generator/motor unit to decrease lag to "near zero". Even with this tech, it won't be instantaneous. I guess there is a limit to how fast the system can react and spool up the turbo

Last edited by Boss330; 07-02-2013 at 03:34 AM..