[Shan2nu]

The bottom end torque delivery is quite good, which looks to me because of the improvement of the air intake even if it can be improved. But I am not convinced that the reading at the bottom is correct.

Japanese normally aspirated engines are known to be not great on torque. Under 70lb ft per litre is nothing great. An just above average European n/a engine does reach at least 80lb ft per litre. Achieving between 85 and 90 lb ft is quite good. Above 90 is very hard and 100 hasn't been reached yet.

I dont think so. The 5ltr V10 M5 does 384lbft at the crank which equates to 76lbft/ltr. If we consider 15% loss for a RWD, that comes down to 326lbft at the wheels (65lbft/ltr).

The Mclaren F1 does 480lbft (78lbft/ltr) at the crank from a 6.1ltr V12, torque at the wheels should be around 408lbft (66lbft/ltr)

Getting 85-90lbft/ltr at the wheels is almost impossible for a NA engine, unless you're mixing up lbft with nm.

Shan2nu

[Rehaan]

A quick post before i get around to replying to the rest:

Originally Posted by CPH

....I won't tell what site this is because this would be unfair to admin me not being approved so please don't ask) and there should be no reason for the slipping not to stop....

There is a "Homepage" field in your User Profile for your website. We encourage you to use it
(Your profile can be edited via the User CP link on the top left).

Originally Posted by avinash_m

BTW, could you please elaborate a bit more on the 'dynolicious' software

Heres a TBHP thread on that : Dynolicious : Want to Dyno your car? Get an iPhone.

There are a few free alternatives listed in that thread / on the app store as well.

cya
R

[CPH]

Originally Posted by pranavt

Even the diameter and shape of the intake setup (manifold, runners, intake pipe, etc) decide the level of improvement or dictate the optimum powerband. It's a complete system and everything affects the power produced at X rpms.

Quite right.

Combined intake length an exhasut length determine optimal torque readings (peak).

With different set ups on the exhaust you can shift the peak power point up and down the rpm range. Of course the primary, secondary and collector pipe diameters and lengths have to be calculated and be accurately built.

On a four cylinder engine it makes a differenc whether you use a 4 in 1 or 4 in 2 in 1 exhaust manifold. The 4 in 1 is good for more peak power. The latter one is better on torque.

Torque can be spread by un even primary lengths and stepped primaries. But this will go on the expensive of some peak power.

On the air intake you will gain torque with longer air intakes. For peak power you want to have rather short in take lengths.

You can get quite some peak power with fairly long intake lengths, but you need to get the balance right between length and gas speed.

Originally Posted by Shan2nu

I dont think so. The 5ltr V10 M5 does 384lbft at the crank which equates to 76lbft/ltr. If we consider 15% loss for a RWD, that comes down to 326lbft at the wheels (65lbft/ltr).

The Mclaren F1 does 480lbft (78lbft/ltr) at the crank from a 6.1ltr V12, torque at the wheels should be around 408lbft (66lbft/ltr)

Getting 85-90lbft/ltr at the wheels is almost impossible for a NA engine, unless you're mixing up lbft with nm.

Shan2nu

When we talk about power per litre or torque per litre it is always referenced to the crank output.

The loss on a RWD is generally considerably higher than 15%.

The M5 and the McLasren F1 aren't designed to the capabilities of the M division.

The F1 is heavily dow powered even from the first test engine suplied as this was requested by McLaren at the time when it was designed.

[KSM-Vtec]

Hi Guys,

I think this is a very interesting issue which has not been discussed in detail on our forum in a long time. It would be a great idea to have all our tbhpians come ahead and share the knowledge they have on this subject.

To start off let me post a few links that i found on the net -

Dynamometer - Wikipedia, the free encyclopedia

Dynamometers | Engine Dyno & Chassis Dyno | Engine Testing | Dynamometer Manufacturer


Rgds
K

[KSM-Vtec]

Guys i dont think that this thread has been started to discuss about how dyno's/engines work. I think it will be a good idea to have a dedicated thread to discuss the same and create wealth for our forum.

First i would like to Welcome CPH !!!! onto the forum and would like to create a thread on his behalf(since he is not familiar with the process) to discuss this interesting issue before the steam dies down.

Link to the dedicated thread- http://www.team-bhp.com/forum/techni...ters-dyno.html

[Shan2nu]

When we talk about power per litre or torque per litre it is always referenced to the crank output.

Even so, how many just above average euro NA cars produce above 80lbft/ltr at the crank?

Especially when performance cars like BMW M5 and Mclaren F1 manage under 80lbft/ltr at the crank.

The M5 and the McLasren F1 aren't designed to the capabilities of the M division.

The F1 is heavily dow powered even from the first test engine suplied as this was requested by McLaren at the time when it was designed.

So in other words you're saying that these are average euro engines?

Shan2nu

[megazoid]

Originally Posted by pranavt

Is your OHC a pre-2002 model? Perhaps that would explain the torque hump/dip as the fuel/timing maps were changed in the 2002+ OHC VTECs. Could even be a fault in the dyno or tyre-slip. Can you post the graph here?

It is a 2002 car. I have a feeling that it is the headers or the FFE thats the issue. Am not too sure whether this thread is the one where I can post my graphs or create a separate one. Don't want mix all graphs into this thread.

[mooza]

Wow, are there any automobile service centres that use these? I am sure these will be useful to diagnose our engine and powertrain problems during servicing, without subjecting the vehicle to the road tests on our already traffic choked roads! And the problem solving would be more scientific too.

I guess automobile R & D centres should be using them.

[Ford Rocam]

Originally Posted by megazoid

It is a 2002 car. I have a feeling that it is the headers or the FFE thats the issue. Am not too sure whether this thread is the one where I can post my graphs or create a separate one. Don't want mix all graphs into this thread.

Start a separate thread, Did you dynoed it at Red Rooster?


@ Mods How about an separate Dyno Section ?

[KSM-Vtec]

@ Jitu - dont know about a new section, but have started a new thread for now. Need a good download from you bro!!!

http://www.team-bhp.com/forum/techni...ters-dyno.html

[CPH]

Originally Posted by mooza

Wow, are there any automobile service centres that use these? I am sure these will be useful to diagnose our engine and powertrain problems during servicing, without subjecting the vehicle to the road tests on our already traffic choked roads! And the problem solving would be more scientific too.

I guess automobile R & D centres should be using them.

They do and some incorporate even a wind tunnel, but they nearly is rare as moon dust on earth.

I do all my testing on a number of dynos. And I would never do it without. But road testing has got its points too, which brings up certain design flaws that can't be seen on a dyno.

Reason why they are not to be found very often is the price.

You won't get one under 35,000 pounds new. My favourite one, which can meaure extremely accurately the drive train losses is even 120,000 pounds.

[CPH]

I posted this on another forum, which was more not only for showing the difficulties of getting results for comparison, but also how some people fake results on rolling roads like the DD, which can't measure drive train losses as well as the very advanced TAT, where you can bump up drive train losses:

This can be done on all rolling raods, which includes the Dyno Dynamics one despite the claims of some operators (see article in Redline Feb. 2009 page 21).

Ambient/intake air temperature probe

Every 3 degrees Celsius inlet air temprature increase decreases the by around 1% or 10 degrees by nearly 4%.

This is due to fact that the volumetric weight decreases with increasing ambient temperature. If the temperature where the inlet is located is deliberatedly high an engine with a specific power output can loose a substantial amount of power.

If for example the temperature probe is placed in a very warm environment in of about 20C higher than the actual ambient temperature on an engine with a specific power output of 190bhp the print out would show anything between 205 and 210bhp.

If the very same engine would be operated in a very confined space without the heat dissapating even blowing air onto the engine would not give correct results if the probe is in a much cooler spot. The results can be as low as 175bhp at 20C lower probe temp reading.

Wheel alignment

If the wheels aren't properly aligned the reading on the graph will not be a true reading. This can give wrong results of in excess of even 10%

The operator can influence this by ignorance as well as creating varying results when changing the wheel angle in relation to the rolling road wheels when doing several runs.

Applying brakes

When applying brakes on the run up some of the wheel power will be absorbed by the brakes. The same applies when transmission losses are measured on the run down.

On the run up it would show lower wheel power than the real figures and on run down it would add up to the losses, which would give an inflated flywheel figure.

Throttle position on power runs

Any power run will be different on full throttle or part throttle. Generally the full throttle run will provide a graph with more power than a part throttle run or a run with varying throttle position.

Altering transmission loss data input

This can be done on the Dyno Dynamics too (see above mentioned Redline article). By giving in different runs different transmission loss codes the corrected flywheel graph actually becomes incorrect.

Loading the rollers

Different loads on the rollers will affect the printout on the graphs as well. This can be done in a number of ways (which I am not going into as it is possible to do this in a number of ways), which can be intentional as well as ignorance.

Other factors

The following factors can influence the readings too but are difficult to create intentionally before the audience on a rolling road day.

Tyre pressure differences.

Tyre profiles.

Tyre compounds.

Tyre temperature.

Engine temperature.

Tracking. Especially towing in or towing out.

Transmission fluids. Especially when their properties aredifferent then the ones normally used.

State of gearbox/Diff.

State of clutch.

Brake bind.

Malfunctioning Lambda sensor(s)/MAPsensor(S). Both types of sensors when not in proper working condition can vary results dramatically, which can be from run to run different but also consistently show poor results.

Other factors that can affect the runs especially when the runs are over a longer period apart

Exhaust condition

Air filter condition

Fuel differences

Variations on different rolling roads.

Different operators.

Maintenance.

[CPH]

Originally Posted by Shan2nu

Even so, how many just above average euro NA cars produce above 80lbft/ltr at the crank?

Especially when performance cars like BMW M5 and Mclaren F1 manage under 80lbft/ltr at the crank.

The engine that was tested by the original poster has a torque per litre output of just over 71lb ft per litre with some modifications.

The data that is quoted for the McLaren and the M5 is with a not fully run in engine, which means in real terms it is higher. At least this are the experience I have from having spent thousands of hours on different dynos. The experience from associates is no different.

Originally Posted by Shan2nu

So in other words you're saying that these are average euro engines?

There is a number of engines that exceed 80lb ft per litre.

One of the most impressive engines on the market is the latest Aprilia 999cc engine. 187bhp and 85lb ft of torque.

[CPH]

This is 2 examples of real drive train losses on cars that us folk can afford.

Example 1
Transmission loss
@ 2500rpm = 11%
@ 3000rpm = 11%
@ 3500rpm = 11%
@ 4000rpm = 12%
@ 4500rpm = 12%
@ 5000rpm = 12%
@ 5500rpm = 14%
@ 6000rpm = 16%
@ 6500rpm = 19%
@ 6750rpm = 24%

@ peak power 17%

The car was a modified Punto FIRE with 6 speed gearbox.

Example 2
Transmission loss
@ 2500rpm = 17%
@ 3000rpm = 17%
@ 3500rpm = 18%
@ 4000rpm = 20%
@ 4500rpm = 21%
@ 5000rpm = 23%
@ 5500rpm = 26%
@ 6000rpm = 29%
@ 6500rpm = 34%
@ 7000rpm = 39%

@ peak power 29%

The car was a FIRE engined Seicento with a 5 speed gearbox. The gearbox was fairly new. The tyres had a very soft compound and were wider than standard. The car was lowered by 30mm.

Both vehicles were tested on the same rolling road. This particular rolling road is known to be accurate within 1bhp! The rolling road has got a single wheel.

[Shan2nu]

The data that is quoted for the McLaren and the M5 is with a not fully run in engine, which means in real terms it is higher. At least this are the experience I have from having spent thousands of hours on different dynos. The experience from associates is no different.

Il be waiting for the dyno results of the run in engines.

The engine that was tested by the original poster has a torque per litre output of just over 71lb ft per litre with some modifications.

One of the most impressive engines on the market is the latest Aprilia 999cc engine. 187bhp and 85lb ft of torque.

Exactly, just the fact that you had to go and search for a highly tuned superbike to achieve 85lbft/ltr (just scraping your quite good range) shows how difficult it is to produce torque.

Even the track tuned Enzo FXX just about manages 80lbft/ltr. So how can you say 80lfbt/ltr is just above average. 80-85lbft/ltr is actually fanastic torque output.

71lbft/ltr for a stock car running 9.6:1 compression, 0.88:1 bore/stroke ratio, no lightning of parts, with just a filter and exhaust upgrade is pretty good. Plus this car is running a clutch which has done 70K odd kms.

Shan2nu