Renault Power Unit Hardware & Software

[dren]

So when the waste gates are fully open, they block flow to the turbine and all flow exits the gate? Then partial opening just relieves turbine pressure.

[Brake Horse Power]

They can't block flow to the turbine, turbine would be making a vacuum that way.

If the valve dimensions of Saviour above are scaled down to a 80mm bore, the maximum wastegate tailpipe cross section is just slightly bigger than the total valve sectional area of 1 cylinder.

Can someone explain why you would want to open the waste-gate while spooling up the turbine while accelerating? Seems once accelerating you are in the powerband and you want to use the energy in the exhaust gasses? OR is the rising pressure due to spooling up the turbine having such an impact on properly scavenging the cylinder?

[saviour stivala]

So when the waste gates are fully open, they block flow to the turbine and all flow exits the gate? Then partial opening just relieves turbine pressure.

I did not say that when waste-gates are fully open they block the flow to the turbine, what I was saying was that when the waste-gates are fully open they are meant to bypass exhaust gasses away from the turbine. and when partial open (slightly open/cracked open) they help the H spool the turbo faster with less back prssure.

[saviour stivala]

.... but the F1 waste-gate/s are also used to relieve turbine pressure in race mode out of a corner when they are momentarily cracked open so the MGU-H spooling-up is made faster.....

the Honda telemetry data presumably has shown us what Honda do (or did)
presumably they don't pull the H rpm down any further than is right for the corner exit
you seem to be saying that the corner exit driving is done using wastegating as a substitute throttle
ok it's likely the wastegate actuation has a even smaller response 'time constant' than does the MGU-H
btw there's throttling on the intake side (of the engine - and the compressor ???)

No i was not saying anything of the sort. i do not know what Honda was or is doing, what I know is were Honda was/is re the others. As a reference to the subject proper No I was not saying anything of the sort at all, what I was saying was the waste-gates are cracked open on corner exit (some corners) so as to help the H spool the turbo faster with less back pressure. This mode was arrived at way before the new hybrids even ran on track for the first time. For proper and full explanation refer to “Optimal control theory and FERRARI’s turbo-electric hybrid”.

[saviour stivala]

They can't block flow to the turbine, turbine would be making a vacuum that way.

If the valve dimensions of Saviour above are scaled down to a 80mm bore, the maximum wastegate tailpipe cross section is just slightly bigger than the total valve sectional area of 1 cylinder.

Can someone explain why you would want to open the waste-gate while spooling up the turbine while accelerating? Seems once accelerating you are in the powerband and you want to use the energy in the exhaust gasses? OR is the rising pressure due to spooling up the turbine having such an impact on properly scavenging the cylinder?

The valve sizes that I quoted (41mm intake and 32.65mm exhaust that were used on a 96-98mm diameter bore of the NA engines were the biggest used that I know off and that was giving a valve area to bore area of 37.25%. as I said, I cannot see how such big diameter or even bigger diameter valves and porting can be used on an 80mm diameter bore, BUT I have no doubt that the valve to bore area not only matches that of which I was talking about, but most probably was improved upon.

[hollus]

Just a gentle reminder to everyone that there is a thread on the current generation of 1.6L turbos in general:

viewtopic.php?f=4&t=9259

Discussion on how these engines are designed and controlled would probably be more focused if held in there, as most details are not constructor specific.

[63l8qrrfy6]

As a reference to the subject proper No I was not saying anything of the sort at all, what I was saying was the waste-gates are cracked open on corner exit (some corners) so as to help the H spool the turbo faster with less back pressure. This mode was arrived at way before the new hybrids even ran on track for the first time. For proper and full explanation refer to “Optimal control theory and FERRARI’s turbo-electric hybrid”.

I suppose this is what you are referring to: http://vdol.mae.ufl.edu/JournalPublicat ... covery.pdf

Nowhere does it say about any wastegate cracking to spool up the turbo.

[gruntguru]

So when the waste gates are fully open, they block flow to the turbine and all flow exits the gate? Then partial opening just relieves turbine pressure.

. . . . and when partial open (slightly open/cracked open) they help the H spool the turbo faster with less back prssure.

Very unlikely. The quickest way to spool the turbo would be wastegate closed plus MGUH motoring. The only reason you might open the wastegate during acceleration is to reduce backpressure on the engine and probably not during spooling.

[PlatinumZealot]

They can't block flow to the turbine, turbine would be making a vacuum that way.

If the valve dimensions of Saviour above are scaled down to a 80mm bore, the maximum wastegate tailpipe cross section is just slightly bigger than the total valve sectional area of 1 cylinder.

Can someone explain why you would want to open the waste-gate while spooling up the turbine while accelerating? Seems once accelerating you are in the powerband and you want to use the energy in the exhaust gasses? OR is the rising pressure due to spooling up the turbine having such an impact on properly scavenging the cylinder?

The valve sizes that I quoted (41mm intake and 32.65mm exhaust that were used on a 96-98mm diameter bore of the NA engines were the biggest used that I know off and that was giving a valve area to bore area of 37.25%. as I said, I cannot see how such big diameter or even bigger diameter valves and porting can be used on an 80mm diameter bore, BUT I have no doubt that the valve to bore area not only matches that of which I was talking about, but most probably was improved upon.

Your idea of how the wastegate works is inverted. When wastegates are open there is less flow to turn the compressor and the MGUH has to do all the work by itself. When the wastegates are closed there is more energy going into turning the compressor.


But anyway.. I see you are also talking avout my commeng that the renault exhaust ports looks small.
At no point did i compare them to the NA engines as you said.

It is an interesting topic. For all I know these turbo engine produce over 800horsepower at far leaner mixtures and with far less cylinders.. The air density is higher of course... Maybe three times higher... But i do not expect that the port size would be so much reduced.??

[saviour stivala]

They can't block flow to the turbine, turbine would be making a vacuum that way.

If the valve dimensions of Saviour above are scaled down to a 80mm bore, the maximum wastegate tailpipe cross section is just slightly bigger than the total valve sectional area of 1 cylinder.

Can someone explain why you would want to open the waste-gate while spooling up the turbine while accelerating? Seems once accelerating you are in the powerband and you want to use the energy in the exhaust gasses? OR is the rising pressure due to spooling up the turbine having such an impact on properly scavenging the cylinder?

The valve sizes that I quoted (41mm intake and 32.65mm exhaust that were used on a 96-98mm diameter bore of the NA engines were the biggest used that I know off and that was giving a valve area to bore area of 37.25%. as I said, I cannot see how such big diameter or even bigger diameter valves and porting can be used on an 80mm diameter bore, BUT I have no doubt that the valve to bore area not only matches that of which I was talking about, but most probably was improved upon.

Your idea of how the wastegate works is inverted. When wastegates are open there is less flow to turn the compressor and the MGUH has to do all the work by itself. When the wastegates are closed there is more energy going into turning the compressor.


But anyway.. I see you are also talking avout my commeng that the renault exhaust ports looks small.
At no point did i compare them to the NA engines as you said.

It is an interesting topic. For all I know these turbo engine produce over 800horsepower at far leaner mixtures and with far less cylinders.. The air density is higher of course... Maybe three times higher... But i do not expect that the port size would be so much reduced.??

I did not say that you was compering the exhaust ports to the NA engine, No it was not you.
My idea (opinion) of how the waste-gates work is mine personally and it doesnt make any difference to me if you think it is inverted.
When the waste-gates are fully open and exhaust gasses are bypassing the turbine housing, and the compressor is in electric supercharging mode, the ICE is producing the maximum power possible.

[saviour stivala]

“The turbine is bypassed by a controllable waste-gate,: Closing the waste-gate will increase the power generated by the MGU-H, But will decrease the power generated by the engine”.

[Tommy Cookers]

in a race the car isn't propelled by the (IC) 'engine' artificially helped by previously-accumulated electrical power
it's propelled by the PU

in a race the H will get more power from the exhaust than the power cost to the ICE by the exhaust
some or much of the H power is actually .... free

[hurril]

“The turbine is bypassed by a controllable waste-gate,: Closing the waste-gate will increase the power generated by the MGU-H, But will decrease the power generated by the engine”.

Semantics matter here. The turbine is bypassed by _some_ of the exhaust flow; the way you're wording it, it comes out as though none of the exhaust gasses interacts with the turbine wheel. This is done to reduce engine back pressure (and also to take loading off of the turbine wheel - although this is probably not done to a very large degree what ever.)

[henry]

“The turbine is bypassed by a controllable waste-gate,: Closing the waste-gate will increase the power generated by the MGU-H, But will decrease the power generated by the engine”.

Semantics matter here. The turbine is bypassed by _some_ of the exhaust flow; the way you're wording it, it comes out as though none of the exhaust gasses interacts with the turbine wheel. This is done to reduce engine back pressure (and also to take loading off of the turbine wheel - although this is probably not done to a very large degree what ever.)

@saviour stivala is quoting from the Limebeer paper @mudflap provided above.

That paper was based on Ferrari data. At that point Ferrari had a waste gate arrangement that totally bypassed the turbine. So he was right 5 years ago but your position is almost certainly current state of the art.

[Brake Horse Power]

Your idea of how the wastegate works is inverted. When wastegates are open there is less flow to turn the compressor and the MGUH has to do all the work by itself. When the wastegates are closed there is more energy going into turning the compressor.


But anyway.. I see you are also talking avout my commeng that the renault exhaust ports looks small.
At no point did i compare them to the NA engines as you said.

It is an interesting topic. For all I know these turbo engine produce over 800horsepower at far leaner mixtures and with far less cylinders.. The air density is higher of course... Maybe three times higher... But i do not expect that the port size would be so much reduced.??

Hey don't accuse me I am just trying to figure out Saviours theory.

According to the regulations, with 2 wastegate tailpipes, the diameter of one pipe can be maximum 38.88mm. Judging from pictures they seem smaller in general? Can anyone confirm? How plausible is it that the whole exhaust flow (at max power) exits trough the wastegate at certain times?

I understand the point of SS that an ICE can maybe generate more power with wastegate open. The exhaust pulsation can maybe also be better utilisied as in a NA engine. BUT wasting energy this way doesn't make much sense in Formula 1? Maybe only for an overtake or something..