Why Does Tuning A Diesel Get HP Easier?
Discussion
I understand that a turbocharged engine is going to make HP easier than a NA car...
But why does a turbocharged diesel make more power than a turbocharged petrol when tuned?
EG: 3 series diesel BMW could make an extra 40-80HP from a stage one map... (Intake, Exhaust, Remap)
Where as a turbocharged petrol hatchback like a gold GTI or such can only make 20-50HP from a stage one map.
But why does a turbocharged diesel make more power than a turbocharged petrol when tuned?
EG: 3 series diesel BMW could make an extra 40-80HP from a stage one map... (Intake, Exhaust, Remap)
Where as a turbocharged petrol hatchback like a gold GTI or such can only make 20-50HP from a stage one map.
Just be aware that not all horsepower is the same. A single-turbo on a diesel will ‘tend’ to give a large chunk of its remapped power increase in one lump, say 2-2,500 rpm. A remapped petrol turbo will have a far greater spread of increased power, say 2-6500 rpm.
So when you look at the power graphs, the Petrol might well gain more ‘under the curve’ than the diesel.
However.... don’t try and compare, they’re too different.
So when you look at the power graphs, the Petrol might well gain more ‘under the curve’ than the diesel.
However.... don’t try and compare, they’re too different.
Primarily because the main factor limiting OEM calibrations of diesel engines is the "SMOKE LIMIT". OEMs are necessarily conservative with their smoke limits, because they not only have to make a car that can be legally sold (ie meet certification emissions limits) but also because they don't want people to see their cars spewing great streams of black smoke out the back.
In the world of aftermarket tuning, there are none of those worries, all that matters is making the largest power number, how you do that, or what comes out the back, no one cares (currently, i note that soon, aftermarket diesel tuning is very likely to become illegal). And with a diesel, the smoke limit (the point at which the engine makes excessive and visible soot particulates) might be at say 14:1, but the engine WILL make more and more power right down to AFR's in the single figures.
Check out the american derv drag racers for reference: rolling_coal
By comparison, for gasoline cars, the point of best torque is (typically) mostly leaner than the point at which excessive soot is made, so the manufacturers can run those rich mixtures as standard. (you will see gasoline cars making soot, but it's most usually either a very fine "haze" or a short puff of soot as a result of poor transient mixture control)
In the world of aftermarket tuning, there are none of those worries, all that matters is making the largest power number, how you do that, or what comes out the back, no one cares (currently, i note that soon, aftermarket diesel tuning is very likely to become illegal). And with a diesel, the smoke limit (the point at which the engine makes excessive and visible soot particulates) might be at say 14:1, but the engine WILL make more and more power right down to AFR's in the single figures.
Check out the american derv drag racers for reference: rolling_coal
By comparison, for gasoline cars, the point of best torque is (typically) mostly leaner than the point at which excessive soot is made, so the manufacturers can run those rich mixtures as standard. (you will see gasoline cars making soot, but it's most usually either a very fine "haze" or a short puff of soot as a result of poor transient mixture control)
Max_Torque said:
Primarily because the main factor limiting OEM calibrations of diesel engines is the "SMOKE LIMIT". OEMs are necessarily conservative with their smoke limits, because they not only have to make a car that can be legally sold (ie meet certification emissions limits) but also because they don't want people to see their cars spewing great streams of black smoke out the back.
In the world of aftermarket tuning, there are none of those worries, all that matters is making the largest power number, how you do that, or what comes out the back, no one cares (currently, i note that soon, aftermarket diesel tuning is very likely to become illegal). And with a diesel, the smoke limit (the point at which the engine makes excessive and visible soot particulates) might be at say 14:1, but the engine WILL make more and more power right down to AFR's in the single figures.
Check out the american derv drag racers for reference: rolling_coal
By comparison, for gasoline cars, the point of best torque is (typically) mostly leaner than the point at which excessive soot is made, so the manufacturers can run those rich mixtures as standard. (you will see gasoline cars making soot, but it's most usually either a very fine "haze" or a short puff of soot as a result of poor transient mixture control)
Out of interest, where did you find that little snippet of good news?In the world of aftermarket tuning, there are none of those worries, all that matters is making the largest power number, how you do that, or what comes out the back, no one cares (currently, i note that soon, aftermarket diesel tuning is very likely to become illegal). And with a diesel, the smoke limit (the point at which the engine makes excessive and visible soot particulates) might be at say 14:1, but the engine WILL make more and more power right down to AFR's in the single figures.
Check out the american derv drag racers for reference: rolling_coal
By comparison, for gasoline cars, the point of best torque is (typically) mostly leaner than the point at which excessive soot is made, so the manufacturers can run those rich mixtures as standard. (you will see gasoline cars making soot, but it's most usually either a very fine "haze" or a short puff of soot as a result of poor transient mixture control)
masonZS said:
But why does a turbocharged diesel make more power than a turbocharged petrol when tuned?
Lets see some examples of all these diesel cars winning races ? or dyno reports of them making mower power than petrol ?It would be rather naive to think diesels make more power size for size....because they do not.
227bhp said:
They've won umpteen times at Le mans.
So their wins outnumber petrol ? What sort of ratio ? And did the cars make more power ?Modern diesels are certainly easy to get mild gains from...but petrols do make more power, and size for size, the petrol turbo engine is easier to get more power again.
eg...how many 300hp 2.0 diesel cars are there ? Yet that is basically expected from any 2.0 petrol...before they're tuned these days.
Edited by stevieturbo on Friday 7th December 18:53
227bhp said:
stevieturbo said:
Lets see some examples of all these diesel cars winning races ? or dyno reports of them making mower power than petrol ?
It would be rather naive to think diesels make more power size for size....because they do not.
They've won umpteen times at Le mans.It would be rather naive to think diesels make more power size for size....because they do not.
stevieturbo said:
227bhp said:
They've won umpteen times at Le mans.
So their wins outnumber petrol ? What sort of ratio ? And did the cars make more power ?Modern diesels are certainly easy to get mild gains from...but petrols do make more power, and size for size, the petrol turbo engine is easier to get more power again.
eg...how many 300hp 2.0 diesel cars are there ? Yet that is basically expected from any 2.0 petrol...before they're tuned these days.
Edited by stevieturbo on Friday 7th December 18:53
GreenV8S said:
227bhp said:
They've won umpteen times at Le mans.
Different technical regulations apply to the different fuel types, don't they?227bhp said:
To give them an advantage? I don't honestly know for sure, but AFAIK it's a fair fight between the two. You're right though, they win endurance races due to not having to stop for fuel as often and also being more reliable as the engines are less stressed (redline is 5k).
The rules are changed every year to try and create a balance of performance across the various cars in each class. In other words, Le Mans uses a handicapping system. So, if we take that further, ignoring crashes and reliability issues, the car that wins will be the least handicapped, whether diseasel, petrol or fairy dust powered.Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff