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Old 3rd November 2010, 20:48   #31
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CPH I will clear what i wanted to say with an example. I am a petrol head and hate it when people compare the diesel engine torques with petrol engine torque which I feel is totally misleading.

If I just quote the figures the two Merc saloon cars E350 petrol and E350 cdi. The 350 petrol produces max 355 Nm torque and 272 bhp.
The E350 cdi produces 540 Nm torque and only 228 bhp. The petrol is a 3.5l engine and diesel is a 3 l engine. So the diesel is awesome on paper producing 540 NM torque even though the max power is much less than the petrol. But here are the figures with the rpms.

E350
Max torque 355 Nm @4500
Max power 272Nm @6300

E350 cdi
Max torque 540 Nm@ 1600-2400 (Agreed good torque spread)
Max power 228 Nm@ 3800

So if do the math the max power rpm of the two vehicles are in the ratio 6300:3800 or 1: 1.66. So if we multiply the max torque of E350 petrol by the ratio we get 585NM which is not bad at all in fact better than the diesel. In all probability the petrol might have better torque on the wheels than the diesel at least in some of its power band. I am not saying that all the gears are matched exactly as I have calculated but surely will be in and around this ratio may be more may be less but surely the diesel will have taller gearing. Correct me if I am wrong. May be the diesel has better torque low down and better torque spread but the point I wanted to stress is that a torque figure in itself can be misleading.

Also can you give me the rpms and max power of the 1.9 liter diesel car which produces 600 nm.
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Old 4th November 2010, 00:40   #32
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@Born2Slow, you seem to be confusing things. Max bhp and Max torque for an engine are just that - max values. So, how can the E350 petrol have a higher torque than what is already stated. E350 has a max torque of 355Nm and that cannot increase due to some ratios you are trying to compute
Practically, the engine which reaches peak torque and peak bhp at lower rpms will fly off the blocks compared to the other one. IIRC, the E350D beats the E350 wrt performance parameters. One point to note is that E350 is a NA V6 engine, while E350D is a Turbo-charged V6 diesel (hence the high torque)
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Old 4th November 2010, 01:55   #33
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Quote:
Originally Posted by lancer_rit View Post
@Born2Slow, you seem to be confusing things. Max bhp and Max torque for an engine are just that - max values. So, how can the E350 petrol have a higher torque than what is already stated. E350 has a max torque of 355Nm and that cannot increase due to some ratios you are trying to compute
Practically, the engine which reaches peak torque and peak bhp at lower rpms will fly off the blocks compared to the other one. IIRC, the E350D beats the E350 wrt performance parameters. One point to note is that E350 is a NA V6 engine, while E350D is a Turbo-charged V6 diesel (hence the high torque)
So by looking at the torque you decided E350D beats E350 wrt to performance parameters. This was exactly my point, More than torque developed at crank what is important is what is transmitted to the wheels.
Power does not change with gear ratios but we can change the torque to whatever we want simply because power is a resultant of torque and rpm.
so when we consider torque we have to do it so keeping the rpm in mind.

Now consider the e350 petrol fitted with a reduction gear on the crank of ratio 1:1.66 and connect it to a crank dyno after the reduction gear. So the readings you will get is

max power 272 bhp @ 3800 rpm
max torque 589 nm @ 2711 rpm (355*1.66 nm @ 4500/1.66 rpm)

What I trying to say here is whatever higher torque produced by the diesel at crank will get offset when it reaches the wheels due to a taller gearing that has to be done because of the lower engine rpm of diesel. I dont have the performance figures of the two vehicles but I can bet the petrol will perform at par or better. May be some in gear acceleration figures at lower rpms the diesel may perform better but that's it. So the big torque figures look good on paper but you never get it at the wheels where it matters the most.
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Old 4th November 2010, 03:37   #34
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Born2Slow - I do understand where you are coming from, but unfortunately you are talking theory. Don't get me wrong I am not trying to patronise you. I rather want you to step back for a moment and look and the values in a different way.

Forget the peak power and the peak torque. These 2 values are meaningless.

On the engine itself the spread of torque is important. You want to have as much torque as possible for the entire rpm range. The only power source to perfectly provide such a requirement is the electric motor.

What makes your car move is the torque per rpm per ton on the wheels.

On the torque front the turbo Diesel is well ahead of the petrol, which is because of the characteristics of the Diesel fuel.

When Alan McNish drove the Audi LMP1 turbo Diesel the first time he made the point that he had to learn driving a race car again. I have seen the Audis and the Peugeots, which are considerably heavier (about 30% mor4e than the petrols) and they were ever so much quicker. In 2008, the Diesel LPM1s were not only hevily restricted from the air intake, but also tank capacity to make sure that they had to re-fuel as often as the petrols and with the extra weight they still made over 8% more distance than the petrols.

We have done a lot of Diesel modification and the cars have beaten beaten on the drag strip many so called superior cars. I do not want to go too deep into things in this thread because we are going off topic, but I am happy to show more details at a meet when I am back in Mumbai.
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Old 4th November 2010, 14:07   #35
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I stand corrected about diesels. I was aware that diesels are wining some endurance races but thought that was because of their fuel economy. Your reference to LMP1 was quite insightful will read about it in detail when I get time.

But I Still maintain if you don't consider rpm the diesel torques can appear higher than what it is from where I come and also in most parts of the world as petrol's usually rev higher than diesel unless you prove me wrong there too . And yes I am talking pure theory that was the whole purpose when I started it.
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Old 4th November 2010, 14:34   #36
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Quote:
Originally Posted by oxyzen View Post
But if any of you had the torque curve before the mod, you could have an idea about the exact gain due to the upgrade.
Well thats whats being done with the civic. The others had to start somewhere!

Quote:
Originally Posted by oxyzen View Post
Min RPM is 4000 in all the cars except VW. Well it should have been from 800 or 1000. Isnt it? Did they check power only after 4000 RPM? I doubt it. I think its a typo.
It starts past ~2500 on most of the graphs.
Also, its not a typo. Just that the dyno is less and less accurate at lower RPMs and therefore it has been set to start reading after it can assure a certain level of accuracy.

Quote:
Originally Posted by oxyzen View Post
In which gear was the test performed? Was it done with the throttle fully pressed (Wide open throttle)?
3rd gear, and probably WOT (+kickdown for autos).

Quote:
Originally Posted by oxyzen View Post
Is proper warm up done so that oil temperature and tyre pressure is OK?
About a 30sec-minute of warm-up (on the dyno) on cars that had been driven about an hour ago. No intentional warm up as such.

Quote:
Originally Posted by GTO View Post
There wouldn't be a difference in the BHP rating, if only the transmission was upgraded.
Yep, but it could be a more efficient transmission, therefore adding the same %age for drivetrain loss could be boosting the figures.

@akshay1234 - Its really no point trying to get to engine HP. Just use the dyno as a comparative tool (ie between your own runs, and not with the stock specified hp).

Quote:
Originally Posted by GTO View Post
Petrols have a wider usable band. However, us regular joes spend 99% of our life <2,500 rpms. That's where diesels rule.
Wider in the sense that they rev higher, sure. But otherwise i'd imagine the diesels generally have a flatter and higher torque curve, or in other words, higher torque per unit rpm.

Quote:
Originally Posted by Born2Slow View Post
...So if do the math the max power rpm of the two vehicles are in the ratio 6300:3800 or 1: 1.66.
If you're looking for "on the road" torque, you should be looking at gear ratios and final drive ratios and wheel size, not this ratio that you have come to above.

cya
R
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Old 6th November 2010, 20:31   #37
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Quote:
Originally Posted by CPH View Post
There is much more to it, but it would lead to far in this topic and possibly would end up being completely off topic. But feel free to raise the problems in a separate topic.
Quote:
Originally Posted by issigonis View Post
>>>

CPH,

Your remarks are insightful.

...

Yes, I'd like to understand the dynamics of the dyno a little better- please start a thread if you can.
+1
CPH, you're the man! It would be great if you would start a thread on dynamometers, and the measurement of torque and power.

Quote:
Originally Posted by Born2Slow View Post
CPH I will clear what i wanted to say with an example. I am a petrol head and hate it when people compare the diesel engine torques with petrol engine torque which I feel is totally misleading.
.....
May be the diesel has better torque low down and better torque spread but the point I wanted to stress is that a torque figure in itself can be misleading.
Quote:
Originally Posted by Born2Slow View Post
...
What I trying to say here is whatever higher torque produced by the diesel at crank will get offset when it reaches the wheels due to a taller gearing that has to be done because of the lower engine rpm of diesel. I dont have the performance figures of the two vehicles but I can bet the petrol will perform at par or better.
I get what you are saying. But let us change the PoV.

Suppose we have two engines: Engine A=our well known NA petrol mill, and Engine B=a theoretical engine which is exactly the same as A, producing exactly the same peak power as A, but at half the rpm. In addition B has an absolutely flat (this is a theoretical discussion!) torque curve going down to 0 rpm.

If these engines are fitted to identical cars with normal gearboxes, and geared for the same topspeed (at their individual peak power rpm), what will be the driving characteristics of each of the two cars?

Regards
Sutripta
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Old 7th November 2010, 15:34   #38
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Quote:
Originally Posted by GTO View Post
Red Rooster allows non-customers to use their dyno? How much do they charge per run? They have two right?
Boys will remain boys
they will allow anyone to dyno. They have one dyno- hub dyno. Charges 3000 + tax for one hour. you can have as many pulls in one hour. Awesome dyno room. I have a feeling that this type of dyno is not putting enough load like a roller dyno. If you dyno on this one, do not compare with results on a roller dyno.
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Old 7th November 2010, 18:22   #39
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Originally Posted by kutlee View Post
they will allow anyone to dyno. They have one dyno- hub dyno. Charges 3000 + tax for one hour. you can have as many pulls in one hour.
That's correct, I had sent them an email a few days back, and got the same info.
http://www.redroosterperformance.com/dynotuning.php

Last edited by lancer_rit : 7th November 2010 at 18:30.
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Old 8th November 2010, 10:15   #40
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This is what redroosters have..
Dynapack
Browser Warning
It looks like a clinical equipment. I think it should be calibrated properly to get some accurate figures.

some more interesting read. This dyno thing is not straight forward as i had thought!
http://forums.hybridz.org/index.php/...ive-dynojet-d/

Last edited by kutlee : 8th November 2010 at 10:17.
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Old 8th November 2010, 14:54   #41
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Originally Posted by kutlee View Post
This is what redroosters have..
Dynapack
Browser Warning
It looks like a clinical equipment. I think it should be calibrated properly to get some accurate figures.

some more interesting read. This dyno thing is not straight forward as i had thought!
New dyno numbers (down with Dynapack, long live Dynojet ) - HybridZ
It isn't as straight forward as most people think. And it can get even worse. The operator can manipulate results very easily in many ways.

Another factor is ignorance. When the car is not properly lined up with before or after and correctly on the other run you will either have a smaller gain showing or a gain to big showing.

Also the weight of the dyno rollers make a difference. Often when people that aren't truly seasoned tuners re-map cars on the dyno (usually turbo petrols) the dyno shows phantastic results> Then when test driving the car is not performning even close to standard...

I don't want to go any deeper into this in this thread. It might make sense to create a thread specifically for problems with dyno graphs.
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Old 8th November 2010, 17:43   #42
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Quote:
Originally Posted by CPH View Post
I don't want to go any deeper into this in this thread. It might make sense to create a thread specifically for problems with dyno graphs.
I think we still can have some valid discussion since this is a 'dyno' thread. I think someone can do two runs of the same car on two different days or two different dynos. I think if someone does it on two different dynos (even of the same type) will show different results. I still stick to my argument that dyno figures are clinical. A seasoned tuner will only need it as a helping hand.
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Old 9th November 2010, 01:13   #43
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Originally Posted by kutlee View Post
I think we still can have some valid discussion since this is a 'dyno' thread. I think someone can do two runs of the same car on two different days or two different dynos. I think if someone does it on two different dynos (even of the same type) will show different results. I still stick to my argument that dyno figures are clinical. A seasoned tuner will only need it as a helping hand.
I absolutely agree. This is why I try to make modifications as quick as possible without the car taken off the rollers. And on the next step I try to make a before and after again.

All longterm test without making ne reference tests in between lose out on precision.
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Old 9th November 2010, 10:45   #44
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Originally Posted by GTO View Post
Great meeting all of you. Next time, lets club an early dinner with the dyno run. The evening anyways ran later than expected.



Thanks! It took some fine-tuning on Automech's part and I'm really happy with the end result.



As I mentioned, the mid-range is violent! The car just shoots forward menacingly. Your cars in even better shape than mine which I thought was as good as new.



There wouldn't be a difference in the BHP rating, if only the transmission was upgraded.



Awesome. Hopefully my K&N Typhoon is in and we'll run the Civic together.
Hi GTO,

Quiet some interesting figures, tells me a lot about what is the real power on the wheels rather than feeling nice about the engine power as specified by the manufacturer.

I plan to do a dyno run on my stock Getz Crdi, i intend to remap my ECU and upgrade the filters, so as suggested in this thread, i would like to have a stock report and then do a 2nd run post the upgrade. This way i can really understand what is the %age difference in my ride after the remap.

Let me know if you guys intend to go there, i would love to join with my ride for the maiden dyno run.
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Old 9th November 2010, 13:49   #45
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After looking at these graphs, and looking at peoples examining them i realised that the scale of things was a bit confusing.

The fact that each run is squeezed or stretched to fit the full width of the graph, and that the HP curve is compressed down to fit in the same box as well.

So i put them all together onto one graph! This more clearly shows how each car is different from the other when producing power...

Note : The length of line along the RPM range is different for every car, since some runs did not cover as much of the RPM range as others. Also i've cut off the inaccurate data that was trailing off on the original graphs.


Accord V6, mapped Linea, Fusion & Jetta on the dyno! UPDATE: Comparo on pg3-all-5-comparo-hp.jpg

Observations :
  • The v6's huge power in comparison to the other cars is much clearer now
  • Notice the jump in HP at ~5300 for the v6 -- i'm assuming this is when the vtec kicks in. Wait till you see the torque!
  • The Jetta (diesel)'s low redline shows. However, note that the power produced all the way from 3k up is roughly more than the ford 1.6 makes till redline. Taller gearing makes this more usable.
  • Why does the Fusion HP dip like that between 5k-7k rpm?
  • Is it possible to see the Linea's slipping clutch post 6k? We'll compare once its re-dyno'd - as the clutch has been changed.

... what else?

Torque coming up next.

cya
R

Last edited by Rehaan : 9th November 2010 at 13:59.
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