So how much power does a 720s actually produce
Discussion
We have all read the specs and seen the videos; the 720s appears to be a monster. But questions have been asked how 710hp is able to compete with over 900hp in a P1.
Well according to Fabspeed it appears McLaren have been a little conservative with the power figures. According to their dyno a bone stock 720s produces 698hp at the wheels. This would mean that the car is producing close to 800hp at the crank which is incredible.
Compare that to the 650s on the same dyno that produced 569hp at the wheels. That means the 720s is producing 130hp more than the 650s which is a lot different to the 69hp increase quoted by McLaren.
Why would McLaren do this and to those with these cars does it feel that much faster
Well according to Fabspeed it appears McLaren have been a little conservative with the power figures. According to their dyno a bone stock 720s produces 698hp at the wheels. This would mean that the car is producing close to 800hp at the crank which is incredible.
Compare that to the 650s on the same dyno that produced 569hp at the wheels. That means the 720s is producing 130hp more than the 650s which is a lot different to the 69hp increase quoted by McLaren.
Why would McLaren do this and to those with these cars does it feel that much faster
I thought Dyno figures should always be taken with a large pinch of salt. With estimates of drive-train losses based on the dyno alone, and as McLaren will have tested their engine output on a bench rather in the car, the pure BHP results can't be comparable.
The details that suggest the 720s is getting to P1 speeds will be more due to the weight difference than any doctored BHP figures, but regardless, the 720s is clearly a very swift car indeed.
The details that suggest the 720s is getting to P1 speeds will be more due to the weight difference than any doctored BHP figures, but regardless, the 720s is clearly a very swift car indeed.
What type of dyno do they use?
Yank dynos are notorious for widely overreading (expecially Mustang dynos) to the point that their quoted wheel hp can more or less correspond to our good old euro crank hp.
698 bhp tells me that the new engine will do near or perhaps even a shade more than its quoted figure of 710 bhp when/if it's properly run in. I feel sorry for that engine if it's being thrashed on a dyno without even having been run in at all.
Yank dynos are notorious for widely overreading (expecially Mustang dynos) to the point that their quoted wheel hp can more or less correspond to our good old euro crank hp.
698 bhp tells me that the new engine will do near or perhaps even a shade more than its quoted figure of 710 bhp when/if it's properly run in. I feel sorry for that engine if it's being thrashed on a dyno without even having been run in at all.
Thom said:
What type of dyno do they use?
Yank dynos are notorious for widely overreading (expecially Mustang dynos) to the point that their quoted wheel hp can more or less correspond to our good old euro crank hp.
698 bhp tells me that the new engine will do near or perhaps even a shade more than its quoted figure of 710 bhp when/if it's properly run in. I feel sorry for that engine if it's being thrashed on a dyno without even having been run in at all.
The McLaren engines are run-in on the dyno so that shouldn't be a worry. The 1,000 km running-in period is to allow the brakes to bed-in and for the drive-train. Certainly was for my 570s.Yank dynos are notorious for widely overreading (expecially Mustang dynos) to the point that their quoted wheel hp can more or less correspond to our good old euro crank hp.
698 bhp tells me that the new engine will do near or perhaps even a shade more than its quoted figure of 710 bhp when/if it's properly run in. I feel sorry for that engine if it's being thrashed on a dyno without even having been run in at all.
Thom said:
What type of dyno do they use?
Yank dynos are notorious for widely overreading (expecially Mustang dynos) to the point that their quoted wheel hp can more or less correspond to our good old euro crank hp.
698 bhp tells me that the new engine will do near or perhaps even a shade more than its quoted figure of 710 bhp when/if it's properly run in. I feel sorry for that engine if it's being thrashed on a dyno without even having been run in at all.
If you factor in that in a car like this you should expect 15% - 18% losses through the transmission then you are going to be looking at way more than 710hp at the crank surely.Yank dynos are notorious for widely overreading (expecially Mustang dynos) to the point that their quoted wheel hp can more or less correspond to our good old euro crank hp.
698 bhp tells me that the new engine will do near or perhaps even a shade more than its quoted figure of 710 bhp when/if it's properly run in. I feel sorry for that engine if it's being thrashed on a dyno without even having been run in at all.
Plus again I draw your attention to the 650s power figures on the same dyno, the difference between them is huge which could be explained on different dynos but not the same one or am I missing something here???
Engines being run in on a dyno is a fairy tale to satisfy owners with zero patience to play right away with their new toy.
In the real world an engine is never fully run in until it has seen proper road use at varying engine loads within a certain distance. I would never give a new engine full beans before at least 1k miles of running in.
In the real world an engine is never fully run in until it has seen proper road use at varying engine loads within a certain distance. I would never give a new engine full beans before at least 1k miles of running in.
Streetrod said:
Plus again I draw your attention to the 650s power figures on the same dyno, the difference between them is huge which could be explained on different dynos but not the same one or am I missing something here???
The only published difference between the two engines is that the newer one is 0.2L larger. How about cam profiles, turbos and boost?Thom said:
Engines being run in on a dyno is a fairy tale to satisfy owners with zero patience to play right away with their new toy.
In the real world an engine is never fully run in until it has seen proper road use at varying engine loads within a certain distance. I would never give a new engine full beans before at least 1k miles of running in.
Surely McLaren's Dyno would simulate all of that?In the real world an engine is never fully run in until it has seen proper road use at varying engine loads within a certain distance. I would never give a new engine full beans before at least 1k miles of running in.
Tolerances are so tight these days with ever thinner oil grades that the engines must be given some kind of short essential basic run ins so that they doesn't lunch themselves if abused right away, but nothing will ever replace a proper and timely run in on the road with smooth transitions in thermal exchanges to allow for the moving parts to expand gently at they warm up. The smoother the thermal expansion rate, the better the engine will have been run in and the longer it will perform at or near or even above its quoted figure.
While this could definitely be programmed on an engine bench, there is no turning around the various expansion rates of materials. Sorry guys, it's just physics.
While this could definitely be programmed on an engine bench, there is no turning around the various expansion rates of materials. Sorry guys, it's just physics.
Thom said:
Streetrod said:
Plus again I draw your attention to the 650s power figures on the same dyno, the difference between them is huge which could be explained on different dynos but not the same one or am I missing something here???
The only published difference between the two engines is that the newer one is 0.2L larger. How about cam profiles, turbos and boost?Thom said:
I would say that the figure of 0.2L is the only significant and quantified technical difference I have been able to spot so far.
With the greatest respect you are wrong, a mere increse in the stroke of the engine would not produce the numbers Mclaren are showing. Do a little investigation and you will find out how extensive the changes have been to the engineThom said:
I would say that the figure of 0.2L is the only significant and quantified technical difference I have been able to spot so far.
Using that logic, are you saying there is no significant or quantifiable technical difference between the 3.8 engine in the 540c and the 3.8 engine in the 675LT?Not sure where I would be "wrong". I am talking about quantified changes. Do we know if the cams have changed? If yes what were the old profiles and what are the new ones? What are the specs of the old vs new turbos? How much boost are the new turbo running vs the old ones? Where are the compressor maps? Not the kind of stuff a manufacturer of a new car would publish anyway, but this is where we can tell where the change in performance comes from.
I would bet there is minimal internal differences between all the variants of the 3.8 engine. I believe the 540 is just a detuned 570S. The 675LT probably just has bigger cams and turbos. People don't seem to be aware how much tuning flexibility there is with turbocharged engines. Some companies offer to remap the 570S to near 700bhp already.
I would bet there is minimal internal differences between all the variants of the 3.8 engine. I believe the 540 is just a detuned 570S. The 675LT probably just has bigger cams and turbos. People don't seem to be aware how much tuning flexibility there is with turbocharged engines. Some companies offer to remap the 570S to near 700bhp already.
Edited by Thom on Tuesday 1st August 18:54
Yipper said:
Most credible stats so far point to the P1 remaining much faster in a straight line than the 720s.
Where the 720s is smashing the P1 is on wet tracks. The P1 is a disaster in the wet and McLaren seems to have learnt some lessons there for the 720s.
Hadn't your 'P1 is a disaster in the wet' claim been debunked by owners before Where the 720s is smashing the P1 is on wet tracks. The P1 is a disaster in the wet and McLaren seems to have learnt some lessons there for the 720s.
Test drove a 720S and in reality it didn't seem that much faster than a 650S on normal UK roads TBH.
Always thought the 650S figures were conservative to the competition but there is no way there is a 130 bhp jump to 720S.
I noticed the 25 bhp difference between 12C and 650S and 70 to the 720S seems about right and more realistic. Knowing McLaren they are stickler for details so the figures quoted are accurate if conservative for very good reason
Always thought the 650S figures were conservative to the competition but there is no way there is a 130 bhp jump to 720S.
I noticed the 25 bhp difference between 12C and 650S and 70 to the 720S seems about right and more realistic. Knowing McLaren they are stickler for details so the figures quoted are accurate if conservative for very good reason
The Surveyor said:
Yipper said:
Most credible stats so far point to the P1 remaining much faster in a straight line than the 720s.
Where the 720s is smashing the P1 is on wet tracks. The P1 is a disaster in the wet and McLaren seems to have learnt some lessons there for the 720s.
Hadn't your 'P1 is a disaster in the wet' claim been debunked by owners before Where the 720s is smashing the P1 is on wet tracks. The P1 is a disaster in the wet and McLaren seems to have learnt some lessons there for the 720s.
On a wet track, the 720s is proving up to 10secs faster than the P1. It is like night and day.
I've personally run or been run in a few McLarens against other supercars and the performance figures alone suggest they are all more powerful than they suggest.
A 570S was 5 car lengths ahead of a Huracan after a 1mile drag.
Same 570S was neck and neck with a 488 on the same day.
Now the Huracan supposedly has 40hp more and AWD to help off the line, yet was destroyed. 488 is same weight yet has 90bhp more.
The LT on a Supercar Driver day was 5 car lengths ahead of the Aventador SV.
The numbers simply don't add up, they must be putting down more power, or they just have a staggeringly efficient drivetrain that loses very little power from the crank to the wheels.
A 570S was 5 car lengths ahead of a Huracan after a 1mile drag.
Same 570S was neck and neck with a 488 on the same day.
Now the Huracan supposedly has 40hp more and AWD to help off the line, yet was destroyed. 488 is same weight yet has 90bhp more.
The LT on a Supercar Driver day was 5 car lengths ahead of the Aventador SV.
The numbers simply don't add up, they must be putting down more power, or they just have a staggeringly efficient drivetrain that loses very little power from the crank to the wheels.
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