Dyno results debate
Thread Starter
TECH Addict
Joined: Jun 2005
Posts: 2,660
Likes: 14
From: England
Dyno results debate Ok this isn’t LS1, but it is tech. On a different forum there has been some dispute over the claims of a single user. They have an automatic Range Rover Classic with a 4.4 litre Rover V8 (this engine was used in Australia in some British Leyland vehicles).
This is an old school OHV and started life as a 215ci Buick small block. I’m sure some of you are familiar with them.
Not overly powerful, even the last 4.6 EFI units only had 225bhp and ~330lb ft from the factory.
A Range Rover has full time 4wd.
Anyway here’s the problem, they have produced a dyno graph and are claiming PEAK torque @ 1600rpm of 260lb ft to the wheels, they also claim only 50% of the power makes it to the wheels so in essence they are claiming over 500lb ft @ 1600rpm at the flywheel.
So far they will not accept that they may be wrong and that because of the auto the lower section of the torque curve may be inaccurate due to a non lock up converter.
Here is what they have been claiming. I’d appreciate any help or comments you may have as I’m only trying to help them and to discover the truth about their engines performance.
If they are correct and they really do have over 500lb ft @ 1600rpm at the engine could anyone take a stab and explain how?
Cheers.
Ok in an auto Range Rover 3rd gear would be 1:1 not 2nd.
So PEAK torque @ only 1600rpm – eh? Normally these V8’s see PEAK torque above 3000rpm.
Really???
Here are some of their other comments in the discussion:
Not quite sure how making PEAK at higher rpms proves it makes more power at low rpms? Anyone want to take a stab at it?
Thanks for every ones help
This is an old school OHV and started life as a 215ci Buick small block. I’m sure some of you are familiar with them.
Not overly powerful, even the last 4.6 EFI units only had 225bhp and ~330lb ft from the factory.
A Range Rover has full time 4wd.
Anyway here’s the problem, they have produced a dyno graph and are claiming PEAK torque @ 1600rpm of 260lb ft to the wheels, they also claim only 50% of the power makes it to the wheels so in essence they are claiming over 500lb ft @ 1600rpm at the flywheel.
So far they will not accept that they may be wrong and that because of the auto the lower section of the torque curve may be inaccurate due to a non lock up converter.
Here is what they have been claiming. I’d appreciate any help or comments you may have as I’m only trying to help them and to discover the truth about their engines performance.
If they are correct and they really do have over 500lb ft @ 1600rpm at the engine could anyone take a stab and explain how?
Cheers.
Originally Posted by p76rangie
Here is my Dyno graph. It is real and was done in second gear on a 4WD Dyno. The power is measured at the wheels and therefore there is usually a 30% to 40% power drop from ratings at the flywheel.
Originally Posted by p76rangie
The left edge of the graph is about 1,600 RPM. For those that can do the conversions, as the graph is in KW's and Nm's, at the wheels my car was putting out 260 ft lb of torque at 1600 Rpm. The torque then drops off from there.
Originally Posted by p76rangie
No it was at the wheels, so that would be the equivalent of around 400 Fl Lb plus at flywheel. But you have to think about the figures a little more.
Originally Posted by p76rangie
No, it has nothing to do with what gear it is in, you will always lose around 40% of your power through the drive train.
It is an old 1970's 4.4 rover V8
It is an old 1970's 4.4 rover V8
Originally Posted by p76rangie
Based on the gearing, atmosphere, etc, etc, the peak horsepower figure on the graph is less than half that at the actual flywheel.
Originally Posted by p76rangie
I am correct when I have stated that the wheels only generate 50% of the power at the flywheel.
Originally Posted by p76rangie
And in a auto, the torque convertor is the equivalent of the flywheel in a manual.
Originally Posted by p76rangie
you would need a motor putting out around 500 ft lb torque in a manual to have the equivalent torque at the wheels as my motor and auto. I know that this is a difficult concept for some small brains to comprehend, but it does not change the facts.
Here are some of their other comments in the discussion:
Originally Posted by p76rangie
Tdis have around the same torque at 4,000 RPMs as what they do at 1,800 RPM. Even though the 4.0Ltr V8 develops its peak torque at 3,000 RPM, it still has over 200 Ft Lb at 4,750 RPM. So the V8 has more grunt down low than the Tdi's and can deliver it quicker.
Originally Posted by p76rangie
Your problem is that a little knowledge is a bad thing. You read all this stuff and don't understand it, which leads to garbage coming out.
Thanks for every ones help
That graph is a typical graph from an UNLOCKED TC. Which will peak as low as the readings start. Can't get an accurate tq plot with an unlocked converter.
I seriously doubt there is 50% drivetrain loss. Even with an Auto. How in the hell do they explain that. There's no way any modern drivetrain could be so restrictive.
I seriously doubt there is 50% drivetrain loss. Even with an Auto. How in the hell do they explain that. There's no way any modern drivetrain could be so restrictive.
In addition, regardless of drivetrain loss (who knows, maybe they really are 50%), in a graph like that, where there is a single steep line for tq, you are looking at converter FLASH. This is where a converter will FLASH instant tq, which will be a much higher number than the engine is putting out. This is from the converters STR. Check out any big converter dyno unlocked and you will see abnormally high tq numbers due to flash. Almost impossible to calculate real tq from that.
Thread Starter
TECH Addict
Joined: Jun 2005
Posts: 2,660
Likes: 14
From: England
Originally Posted by s10-den
and this is not a diesel right?
WOW. What a load of BS. Think about the economy of a drivetrain that absorbed 50% of the power produced. To the engine that would seem like you were driving around with your e-brake draggin. Not real fuel efficient. Not to mention the fact that the job of a torque converter is to MULTIPLY TORQUE. I think the rangie guy is the one with the small brain. TC does the same job as a flywheel in a manual? What an idiot. To the OP, any chance on a link to that forum/site?
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Originally Posted by shupack
I didn't know that wheels generated power.....
nice....Yeah, that guy sounds like a high school kid that learned a little bit about dynos from talking to his friends / reading stupid people's posts online, then decided that anyone who argues with him obviously didn't do as much "research" as he did and can't comprehend a few simple concepts. His argument might have been a little more persuasive if he had said that this specific vehicle typically sees a 40-50% drivetrain loss, instead of suggesting that ALL automatics see a 40-50% loss.
If he really thinks his vehicle is making that much flywheel horsepower, find a similar vehicle that ACTUALLY makes that much flywheel horsepower and race him. He should lose.
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