Renault Power Unit Hardware & Software

[FPV GTHO]

Renault must be losing alot of performance through the turbo through the year, if even at so much lower than the max RPM theyre having reliability issues. I expected Renault to be the ones running at max RPM

[noname]

Renault must be losing alot of performance through the turbo through the year, if even at so much lower than the max RPM theyre having reliability issues. I expected Renault to be the ones running at max RPM

108.000 RPM is reasonable good result for them. Their turbo from the very beginning (2014) was running slow. It (was) not necessary bad thing considering its sizing.

Quantifying the gap can be tricky, however 2 years without major developments for sure does not help. Especially when both Merc and Ferrari put significant efforts into their turbos.

[hurril]

Renault must be losing alot of performance through the turbo through the year, if even at so much lower than the max RPM theyre having reliability issues. I expected Renault to be the ones running at max RPM

108.000 RPM is reasonable good result for them. Their turbo from the very beginning (2014) was running slow. It (was) not necessary bad thing considering its sizing.

Quantifying the gap can be tricky, however 2 years without major developments for sure does not help. Especially when both Merc and Ferrari put significant efforts into their turbos.

This is certainly true. How do we know about the Mercedes and Ferrari RPM:s though?

[noname]

This is certainly true. How do we know about the Mercedes and Ferrari RPM:s though?

People in F1 are moving around all the time. And there are plenty of partners and suppliers involved.

[wonk123]

Renault’s woes were track-specific

http://www.f1technical.net/news/21434

Renault let its turbochargers run at 108.000/min at the beginning of the weekend. As the engineers found out after the early issues experienced during the practice sessions that this running value it too high, the rev speed was decreased to 102.000/min for the race. This decrease meant a loss of 0.15 of a second in pure lap time.

Interestingly, Ferrari could run its turbochargers at the maximum of 125.000/min while Mercedes was only a tiny bit below that limit.

Why would Mexico cause problems? The circuit seems to be reasonably smooth so it probably has nothing to do with the bumpiness. Ambient temperature might have been problematic, or the altitude?

I assumed that the turbo was run at higher rpm to make up for `the higher altitude. More rpm would keep the engines at approximately the same HP as at sea level. However they did not cope with the forces involved

[godlameroso]

That is actually very interesting, I was curious for a long time as to what turbo RPM manufacturers ran.

[MHR650]

In the turbo industry nobody uses RPM, what is important is tip speed of the compressor wheel in meters per second. A turbo spinning 108,000 rpm can have a much higher tip speed than one running 125,000 depending on the size of the wheels. For reference a really small turbo like from a 3 cylinder Smart car spins more like 300,000.

[63l8qrrfy6]

In the turbo industry nobody uses RPM, what is important is tip speed of the compressor wheel in meters per second. A turbo spinning 108,000 rpm can have a much higher tip speed than one running 125,000 depending on the size of the wheels. For reference a really small turbo like from a 3 cylinder Smart car spins more like 300,000.

Nonsense, shaft speed drives mechanical loads. What do turbo speed sensors measure in the turbo industry ?

[noname]

Nonsense, shaft speed drives mechanical loads. What do turbo speed sensors measure in the turbo industry ?

MHR650 is right in saying tip speed matters. Although it is much easier to measure RPM, but you do need to know what wheels are inside. Quite often compressor maps are showing tip speed, not RPM.

Good luck in trying to spin this beauty to 100.000 RPM
http://www.motorship.com/__data/assets/ ... harger.jpg

BTW, also in this department Renault falls behind.

[63l8qrrfy6]

Nonsense, shaft speed drives mechanical loads. What do turbo speed sensors measure in the turbo industry ?

MHR650 is right in saying tip speed matters. Although it is much easier to measure RPM, but you do need to know what wheels are inside. Quite often compressor maps are showing tip speed, not RPM.

Good luck in trying to spin this beauty to 100.000 RPM
http://www.motorship.com/__data/assets/ ... harger.jpg

BTW, also in this department Renault falls behind.

I've not said it does not matter. Also, most compressor maps I've seen plot shaft speed rather than tip speed.

Secondly the point of the conversation was the effect of turbo speed on reliability. In that respect tip speed is almost meaningless (particularly when the wheel diameter is unknown) while shaft speed is much more relevant as unbalance loads increase with the square of angular velocity.

[noname]

(...) the point of the conversation was the effect of turbo speed on reliability. In that respect tip speed is almost meaningless (...)

"Almost" makes a difference
https://www.youtube.com/watch?v=7Y01Ed4Sg3U

[FPV GTHO]

In the turbo industry nobody uses RPM, what is important is tip speed of the compressor wheel in meters per second. A turbo spinning 108,000 rpm can have a much higher tip speed than one running 125,000 depending on the size of the wheels. For reference a really small turbo like from a 3 cylinder Smart car spins more like 300,000.

The regulations stipulate max rpm though, so its relevant for that fact alone.

And if there's a suggestion Renault dont need to match Mercedes and Ferrari's rpm as they possibly have a larger turbo, i think you're dreaming.

[63l8qrrfy6]

(...) the point of the conversation was the effect of turbo speed on reliability. In that respect tip speed is almost meaningless (...)

"Almost" makes a difference
https://www.youtube.com/watch?v=7Y01Ed4Sg3U

Rotational energy dissipated in the impact is 0.5 x inertia x shaft speed ^ 2. Where is the tip speed in that ?

[Tommy Cookers]

additional to these various difficulties of the (unplanned ?) need to race at 2200m altitude by raising the turbo rpm ......
there would be electrical difficulties as the H generation and motor action requires at least a correspondingly raised excitation frequency

[wuzak]

In the turbo industry nobody uses RPM, what is important is tip speed of the compressor wheel in meters per second. A turbo spinning 108,000 rpm can have a much higher tip speed than one running 125,000 depending on the size of the wheels. For reference a really small turbo like from a 3 cylinder Smart car spins more like 300,000.

The regulations stipulate max rpm though, so its relevant for that fact alone.

The regulations stipulate the maximum rpm of the MGUH, not the turbo. The MGUH can be geared up or geared down from the turbo.