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Re: Honda Power Unit
Posted: 25 Feb 2018, 01:06
by 63l8qrrfy6
amho wrote: ↑25 Feb 2018, 00:19
Mudflap wrote: ↑25 Feb 2018, 00:13
amho wrote: ↑24 Feb 2018, 23:59
Yes these numbers are too imaginary but I wanted to indicate that having higher thermal efficiency does not neccessarily means less heat ejection. Consider Qh for engine A & B equal to 700 and 500 kj for a given fuel and thermal efficiency of 0.5 and 0.4 respectively then A dumps 350 kj and B does 300 kj. Here in F1 if consider all engine have near the same combustion eff. then the one has better thermal efficiency it dumps less heat.
Not imaginary, they were objectively wrong.
Since we are debating F1 engines what is the point of comparing engines of different fuels or different flow rates ?
DFX's statement was spot on.
I don't want to elongate chat but I didn't say anything about different fuel and flow, read once again carefully. Bye
Why is Qh different (700 vs 500 kJ) if the fuel rate and fuel are identical ?
Re: Honda Power Unit
Posted: 25 Feb 2018, 02:11
by godlameroso
Mudflap wrote: ↑25 Feb 2018, 01:06
amho wrote: ↑25 Feb 2018, 00:19
Mudflap wrote: ↑25 Feb 2018, 00:13
Not imaginary, they were objectively wrong.
Since we are debating F1 engines what is the point of comparing engines of different fuels or different flow rates ?
DFX's statement was spot on.
I don't want to elongate chat but I didn't say anything about different fuel and flow, read once again carefully. Bye
Why is Qh different (700 vs 500 kJ) if the fuel rate and fuel are identical ?
The mechanical process of combusting the fuel. It's not hard to melt pistons with just over eager timing changes.
Re: Honda Power Unit
Posted: 25 Feb 2018, 02:18
by 63l8qrrfy6
godlameroso wrote: ↑25 Feb 2018, 02:11
Mudflap wrote: ↑25 Feb 2018, 01:06
amho wrote: ↑25 Feb 2018, 00:19
I don't want to elongate chat but I didn't say anything about different fuel and flow, read once again carefully. Bye
Why is Qh different (700 vs 500 kJ) if the fuel rate and fuel are identical ?
The mechanical process of combusting the fuel. It's not hard to melt pistons with just over eager timing changes.
Huh ? Qh =heating value x fuel mass. It is completely independent of what happens in the combustion chamber. Qh has the same value regardless of whether you drink it or put it in an engine.
Re: Honda Power Unit
Posted: 25 Feb 2018, 03:57
by PlatinumZealot
He is not talking crazy. He said the total energy from the fuel, not the intensive property of calorific value.
He described two different engines burning the same fuel. Qh is the heat input to the engine from burning the fuel.
One burns 500kJ worth of fuel and the other burns 700kJ.
The first has efficiency 50% and the other 40%.
Then he calculated the heat rejected from both.
Not a direct comparison to formula 1 but i reckon he was illustrating that a more efficient engine can reject more heat if it burns more fuel.
He did not mention this, but a more efficient engine with higher combustion efficiency can reject more heat than a less efficient engine with poor combustion efficiency (since more fuel is unburnt).
I am very rusty here but how do you name these two efficiencies? :
efficency calculated with heat input measured from fuel heating value. ( disregards combustion eff. Using fuel heating values and flow rate only)
Efficiency calculated with heat input from the combustion itself (factoring combustion efficiency to get actual heat input to the engine from burnt fuel)
?
Re: Honda Power Unit
Posted: 25 Feb 2018, 04:04
by techman
He did not mention this, but a more efficient engine with higher combustion efficiency can reject more heat than a less efficient engine with poor combustion efficiency (since more fuel is unburnt).
spot on correct
Re: Honda Power Unit
Posted: 25 Feb 2018, 04:05
by wuzak
The first one - brake specific fuel consumption?
Re: Honda Power Unit
Posted: 25 Feb 2018, 04:23
by techman
didnt honda say last year that there mguh were failing because the bearings were overheating and freezing up? maybe due to lack of proper lubrication and cooling. that why i can understand TR going with big intakes with honda unlike mclaren tiny intakes. looks like TR are listening to honda advice.
Re: Honda Power Unit
Posted: 25 Feb 2018, 05:29
by godlameroso
Bigger roll hoop intake smaller side pod intakes, you need a specific area.
Re: Honda Power Unit
Posted: 25 Feb 2018, 05:49
by 63l8qrrfy6
PlatinumZealot wrote: ↑25 Feb 2018, 03:57
He is not talking crazy. He said the total energy from the fuel, not the intensive property of calorific value.
He described two different engines burning the same fuel. Qh is the heat input to the engine from burning the fuel.
One burns 500kJ worth of fuel and the other burns 700kJ.
The first has efficiency 50% and the other 40%.
Then he calculated the heat rejected from both.
Not a direct comparison to formula 1 but i reckon he was illustrating that a more efficient engine can reject more heat if it burns more fuel.
He did not mention this, but a more efficient engine with higher combustion efficiency can reject more heat than a less efficient engine with poor combustion efficiency (since more fuel is unburnt).
I am very rusty here but how do you name these two efficiencies? :
efficency calculated with heat input measured from fuel heating value. ( disregards combustion eff. Using fuel heating values and flow rate only)
Efficiency calculated with heat input from the combustion itself (factoring combustion efficiency to get actual heat input to the engine from burnt fuel)
?
http://users.sussex.ac.uk/~tafb8/eti/et ... ciency.pdf
It specifically says TE=W/(m*Qhv)
W is work
m is fuel mass
Qhv is the fuel heating value.
I agree that you can burn less fuel at poorer TE and have a lower heat rejection.
If you look at his little math he explicitly states the same quantity of fuel, then goes on to say that there is only 10% difference in TE even though one engine outputs 6 times the work of the other engine. That's bollocks.
Re: Honda Power Unit
Posted: 25 Feb 2018, 12:23
by Andres125sx
DFX wrote: ↑24 Feb 2018, 18:46
techman wrote: ↑24 Feb 2018, 11:32
Completely the opposite. Less effient engines needs more cooling than higher effient ones.
mercedes will disagree. the merc is the most efficient achiveing 50 percent thermal efficiency. and they have the biggest air intakes
They can disagree whatever they want, this is thermodynamics.
I´m sure they don´t disagree at all, only that techman is making false assumptions [...]
Re: Honda Power Unit
Posted: 25 Feb 2018, 12:37
by etusch
j.yank wrote: ↑24 Feb 2018, 22:32
DFX wrote: ↑24 Feb 2018, 10:50
etusch wrote: ↑24 Feb 2018, 09:25
Smaller sidepod inlets make me think that engines will run lesser power and because of this they need lesser cooling and more heat during race. If so Honda automatically catch rivals (if they didn't do same)
Completely the opposite. Less effient engines needs more cooling than higher effient ones.
Actually he doesn't speak about efficiency but about saving power because of the 3 engines per season rule.
Yes I don't speak about efficiency.
I have read that Ferrari firstly concentrated on reliability, now same for renault and from directly Abiteboul. So somehow they choose to make smaller inlets. I am not saying this is for sure because of lower power for race, but I guess.
For example mercedes developed engine for more power but for reliability they decided to use same power of level of last year for the race, than it may need lesser cooling than a PU settled for 4 race and more power.
Re: Honda Power Unit
Posted: 25 Feb 2018, 19:07
by Powerslide
the exhaust collectors should be placed behind the cylinder head for the extractors to give way for better aerodynamic packaging if they dont want to run a log style extractors. those end to end turbo certainly allow for a huge compressor
Re: Honda Power Unit
Posted: 25 Feb 2018, 19:20
by Powerslide
godlameroso wrote: ↑16 Jan 2018, 03:34
hurril wrote: ↑16 Jan 2018, 00:18
I don't get the valve lift talk that long quoted paragraph mentions. Why would both the lower lifting and higher lifting cam use 4mm as intro and outro? That means that they have different accelerations / angles of attack (I am not familiar with the terminology.) Is there a reason why the lower-lifting one could not use the same angle of attack as the longer lifting one uses?
Camshafts are a fascinating subject
here are the camshafts Honda used on their 2006 engine, you can learn a lot about the valve train behavior by looking at the lobe profiles.
http://www.racecar-engineering.com/wp-c ... uphv8e.jpg
minimal friction coatings...two angle valves
Re: Honda Power Unit
Posted: 26 Feb 2018, 09:16
by Thunder
Remember this Thread is about the Honda PU, not Renault. 
Re: Honda Power Unit
Posted: 26 Feb 2018, 10:56
by HPD