Barbados

Active Member
Just out of curiosity, I wanted to know if anyone was crazy enough to have their 200, 300 or TD5 dyno tested for HP and Torque output.

Would be good to know what losses are in the drive train.

If ever you want to do it, please remember that you have to use an all wheel drive dyno. :D


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Just out of curiosity, I wanted to know if anyone was crazy enough to have their 200, 300 or TD5 dyno tested for HP and Torque output.

Would be good to know what losses are in the drive train.

If ever you want to do it, please remember that you have to use an all wheel drive dyno. :D


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take off the front drive shaft
 
Most motors are rated at the flywheel

True, however real and practical HP of an automobile is what it puts down at its wheels, that's why we wheel dyno test them.

Also rated at the flywheel because it looks better for the car manufactures and marketing.

If they posted HP measured at the wheel, the HP rating will be less than favourable.

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A car can have 200 crank hp, but with all the engine accessories like AC, power steering, alternator, water pump and then drive train, that could drop right down to 150 hp at the wheels.

The best device they have made so far which gives an even more accurate HP and torque reading, by factoring in wind resistance or aerodynamics and road resistance is the G Tech Pro with built in accelerometers. It measures HP and Torque while the car is in motion.

I have to get my G Tech Pro shipped in, one of the best pieces of equipment I like.

http://m.youtube.com/watch?autoplay=1&v=2Tyozgkc7dE

That's a pretty lame Result for that poor guy running 10 psi boost on that car, he needs some Land Rover parts. :D
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I would bet that your average tdi isnt seeing much more than 15/20bhp per wheel!
 
Yup, drivetrain losses can be truly horrendous.

I had a Bentley continental flying spur in the workshop today.
Just blast cleaning and painting the little cosmetic Bentley emblems on the truly huge calipers - part of a bigger service and check over, but it needed doing, as the calipers were looking scruffy.

Simple enough job, also gave the calipers a really good clean, and ground the ridge off the discs all round.

This is a simple enough job on most motors.
I use an angle grinder with an abrasive disc or flap wheel, and either run the car in gear, or get an assistant to turn the disc using a rechargeable drill or similar.

It's a cosmetic job really, but since I am there checking the brakes, it's nice to tidy things up.

On this car, the static transmission drag was truly phenomenal.
I now understand why it uses so much fuel.
None of my power tools could turn the wheel continuously ( remember, all of the wheels were off the ground, and the trans in neutral.)
The drag was amazing !

I had to resort to running the car on the stands to turn the wheels while I dressed the discs, with all manner of weird rattling and knockings coming from the brakes ( even with traction turned off!).

It amazed me how much effort it took to turn the transmission the losses must be immense - never underestimate them.

Anyway, job done, brakes checked, discs re-dressed, calipers cleaned, emblem pieces blaster, painted and refitted, and the wheels cleaned and rotated.
Job done. But by eck - it's a meaty motor!
 
I thought a dyno test normally consisted of a power test and then run down to calculate the drag on the drivetrain and the engine bhp calculated from that.
 
Yup, drivetrain losses can be truly horrendous.

I had a Bentley continental flying spur in the workshop today.
Just blast cleaning and painting the little cosmetic Bentley emblems on the truly huge calipers - part of a bigger service and check over, but it needed doing, as the calipers were looking scruffy.

Simple enough job, also gave the calipers a really good clean, and ground the ridge off the discs all round.

This is a simple enough job on most motors.
I use an angle grinder with an abrasive disc or flap wheel, and either run the car in gear, or get an assistant to turn the disc using a rechargeable drill or similar.

It's a cosmetic job really, but since I am there checking the brakes, it's nice to tidy things up.

On this car, the static transmission drag was truly phenomenal.
I now understand why it uses so much fuel.
None of my power tools could turn the wheel continuously ( remember, all of the wheels were off the ground, and the trans in neutral.)
The drag was amazing !

I had to resort to running the car on the stands to turn the wheels while I dressed the discs, with all manner of weird rattling and knockings coming from the brakes ( even with traction turned off!).

It amazed me how much effort it took to turn the transmission the losses must be immense - never underestimate them.

Anyway, job done, brakes checked, discs re-dressed, calipers cleaned, emblem pieces blaster, painted and refitted, and the wheels cleaned and rotated.
Job done. But by eck - it's a meaty motor!

Surely if the discs have got any lip worth mentioning they need changing regardless of cost?
 
I thought a dyno test normally consisted of a power test and then run down to calculate the drag on the drivetrain and the engine bhp calculated from that.

A wheel dyno test gives you hp and torque measurements delivered to the wheels....that's why it's called a wheel dyno :D

It's that hp and torque which moves you on the road, farm land or track :)

When you see a car ad saying that the car has 200 hp, the bastards are not telling you that the actual hp you have to move might be 50 hp less that 200 :)

They give you the power of the engine not the power to the final drive.

It's like telling a chick you wanna hook up with that you have a million dollar mansion, but fail to tell her the bank owns it because you only paid the 10,000 pound down payment. :D
 
Surely if the discs have got any lip worth mentioning they need changing regardless of cost?

Depends...if it's a slight build with rust, it can be used again especially if you are using a softer compound brake pad.

But yea, if it's a bigger lip, call that Bently back in before the owner give you some lip and have a lot more grinding to do to put back his rad, bumper and bonnet back in place. :D
 
Depends...if it's a slight build with rust, it can be used again especially if you are using a softer compound brake pad.

But yea, if it's a bigger lip, call that Bently back in before the owner give you some lip and have a lot more grinding to do to put back his rad, bumper and bonnet back in place. :D


Whats the wear limit?
On the hgvs new 45mm worn out 39mm, thats an impressive lip I can tell you
 
Yes, that's about right.
Some dynos can actually drive the vehicle wheels to calculate drag too.

In reality though, dyno testing is a bit pointless inkess you have a specific aim.
Just being able to say that you have had it on the dyno does what exactly?

A dyno is a useful too to help diagnose performance issues and maximise power output.

For example, some friends have a 6x6 range rover fire engine that was very slow. Rolling road helped identify a worn out engine, that was only evident while being driven.

I'll be taking my v8 90 to my local 2wd rolling road to optimise the fuelling.
I don't really care about the specific calculation - I just want to get the fuelling and timing as good as I can.

Rolling resistance is more than you would expect on 4wd cars, but not that relevant when you are tuning your engine..
 
Re: the brake disks, it was both cosmetic and for serviceability- removing the lip and rust from the outer edge of the disc.

Discs are well within wear limit, pads about half worn, so removing lip on both faces, and descaling disc outer will prolong the disc and pad life a little, and looks better.

Discs may well get changed with the pads, we will see how much meat is left on them when we get there.
 
There are 4 wheel dynapacks around. My old Skyline GTR was 4 wheel drive and after spending a fair bit on intake, exhaust, upgraded turbos the dynapack reading was same as the factory bhp, which was a bit demoralising, but in reality to get wheel bhp of 340 you're approaching 400 at the flywheel with a 4WD drivetrain.
 
LR90 with 3.5 rover v8 blue printed engine 212bhp stupid torque figures and on twin SU's took many a rolling road session to match needles
 

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