Running-in CGTS

[BertBert]

a little bit of googling suggests that correction factors should not be used where the engine/ecu can correct for itself especially turbo engines.
Bert

[TB993tt]

BertBert said:

a little bit of googling suggests that correction factors should not be used where the engine/ecu can correct for itself especially turbo engines.
Bert

Yup, but its a bit more complicated than that with turbo engines since it's about how the measurement is done especially how post turbo intake temps are controlled and at what level they are at when max power is tested (with the engine being braked at full load for a number of seconds until stable). If you look at the detail of the latest EU standard EWG80/1269 which was actually written in 1980 by the looks of it
http://eur-lex.europa.eu/legal-content/EN/ALL/?uri...

Item 5.2.4.2.2.1

There is no provision for the post turbo intake temperature other than testers notes (from what I can see ?) and this is totally key particularly on a 500+hp turbo engine.

Everyone knows Porsche turbo horses are stronger than others and I think the way they measure the power has a lot to do with this, Porsche have their own methods which I do not know but they will conform with the EU directive I know my engine guys match Porsche's numbers using their set up + the (now out dated) DIN 70020 CF which seems weird and highlights the ambiguity. And then we have the 8 second chassis dyno runs which lots of "tuners" like to use

[ORD]

Don't let the engine labour at 1,000 revs as it will in PDK auto mode just because that is how it is programmed. It is programmed to do that for CO2 testing reasons, and (to the decision-makers at Porsche) that takes priority over preventing slowly accumulated wear and a small risk of failure in the early years.

Porsche does not give a crap about the longevity of your engine - it just wants to sell you a car and hit CO2 targets.

[bcr5784]

ORD said:

Don't let the engine labour at 1,000 revs as it will in PDK auto mode just because that is how it is programmed. It is programmed to do that for CO2 testing reasons, and (to the decision-makers at Porsche) that takes priority over preventing slowly accumulated wear and a small risk of failure in the early years.

Porsche does not give a crap about the longevity of your engine - it just wants to sell you a car and hit CO2 targets.

Because some very critical statements from yourself and Mr D, I thought it interesting to ask the question of engineermk, since, from the sound of things he has considerably more experience than any of us in this area. Interesting that he doesn't consider it an issue - or perhaps Porsche are one of his customers and he is reluctant to be critical.

[engineermk]

TB993tt said:

engineermk said:

Yes I agree, I should have said a naturally aspirated engine has these characteristics. Engines with forced induction can compensate with in the limits of their boost control.

Most "dyno" operators still use the various correction factors (DIN/EWG 80/1269) when testing these turbo engines I find it quite fascinating to try get a definitive answer on the rights and wrongs of doing this.

On an engine dyno which uses a water cooled intercooler to control (post turbo) intake temperature at a certain level (water temp can be taken into account by adjusting water flow) then it seems valid to use ambient temperature in a correction factor since the variation should be taken into account. Correction for pressure is a bit more difficult to justify as subject to the turbo running within its efficiency range the ambient pressure should be adjusted for by the ECU....

My engine guys use DIN 70020 and have done for many years it is integrated into their engine dyno software and weather station so they say all their build results are comparable they go on to say that they strive to match the HP readings Porsche quote and their set up replicates these well.

Occasionally a customer who has paid a lot of money for some big hp will insist that the engine is taken up the road to Weissach (in the back of a van) to be power tested by Porsche, they have always been pretty spot on......

DIN70020... great standard to use to get that extra 1, 2 or 3 PS (not BHP or kW) so you can quote a 1000PS from your Bugatti W16.

All test laboratories that quote power outputs have to measure them to known standards on calibrated test equipment independently verified by organisations such as the VCA, TNO or TUV. I'm referring to working in a test laboratory, not a tuning company's dyno. Unless the test measuring equipment is calibrate to traceable standards, such as ISO 17025, the number produced can be very inaccurate.

[TB993tt]

engineermk said:

DIN70020... great standard to use to get that extra 1, 2 or 3 PS (not BHP or kW) so you can quote a 1000PS from your Bugatti W16.

engineermk said:

All test laboratories that quote power outputs have to measure them to known standards on calibrated test equipment independently verified by organisations such as the VCA, TNO or TUV. I'm referring to working in a test laboratory, not a tuning company's dyno. Unless the test measuring equipment is calibrate to traceable standards, such as ISO 17025, the number produced can be very inaccurate.

Could you comment on the intake air temp control on high power turbo petrol engines, is there a standard for the cooling used (which presumably is supposed to replicate maximum power on the road at maximum speed ?) or do they (TUV etc) accept what the manufacturer determines to be the correct IAT for a full power test as long as it seems reasonable ?

[engineermk]

Everything is corrected for an AIT of 25degC

[engineermk]

An insight to my work... http://www.intertek.com/automotive/miltonkeynes/

[TB993tt]

engineermk said:

Everything is corrected for an AIT of 25degC

What does that mean for testing a turbo car in terms of intercooling effectiveness ? How would your (very impressive) facility test max power on a high power turbo gasoline engine how would you control the post turbo intake temp ?

Is it a case of blasting 25C air through the intercooler cores at a given speed (if so what is the given speed) ?

[FrankCayman]

engineermk said:

I work in car engine development, we test engines (without the car) in laboratories that can simulate a granny driving to the shops or a racing driver lapping the nurburgring and anything in between. Typically our clients (manufactures, not private individuals) are from the luxury/super car market.

It usually takes 40-50 hours to run an engine in. We run the engines over a wide range of speeds and loads, gently increasing them from 25-50% load to 100% load over the first 20 hours. Every 10 hours we run a power curve, its takes about 2hours to complete that! When two consecutive power curves match the engine is 'run-in'.

My basic advice to you has to be, drive the car to warm it up (don't sit on the drive way at idle) don't labour the engine or rev it to very high speeds in the first 10-20 hours. Give it the very occasional wide open throttle accel after 15 hours, but most of the time just drive it sensibly following the car in front. Basically; don't be a hooligan, be sensible, and your car will run in OK. If you choose PDK you can pretty much drive and forget (with the exception of using kick down) as the transmission ECU will make sure you neither labour or over rev the engine.

Manufacturing tolerances are so good now that the running in your Dad had to do on his 1978 Cortina is obsolete. Just keep an eye on the oil level (most cars do that for you these days) as it will use some in the first few thousand miles. The oil doesn't need changing at 2,500miles, it will easily cope with 20,000miles

Great post. This is how I've always run my brand new cars in....nice to have it confirmed as being the correct way by a professional!

I remember my old 987.2 2.9 Cayman drank nearly all it's oil in the first 5,000 miles, then proceeded to never need topping up between the 20K services from that point on.

[TB993tt]

I had a quick look at that impressive site and read that you test to ECE regulation 85.

A quick google and near the bottom of this document:
http://www.unece.org/fileadmin/DAM/trans/main/wp29...

One gets the testing requirement for turboed engine's intercooling..... so looks like it's blasting 25C air through the intercoolers or if the manufacturer prefers a water cooled intercooler like my guys use. Still doesn't specify what post turbo IAT can be used (a water cooled intercooler can produce whatever temp the manufacturer wants within reason) and I'd still like to know what the Weissach turbo testing bed uses

9 Charge air cooled engines shall be tested with charge air cooling, whether liquid or air cooled, but if the engine manufacturer prefers, a test bench system may replace the air cooled cooler. In either case, the measurement of power at each speed shall be made
with the same pressure drop and temperature drop of the engine air across the charge air cooler on the test bench system as those
specified by the manufacturer for the system on the complete vehicle.

Edited by TB993tt on Tuesday 23 June 19:00

[TB993tt]

Enjoying reading the Intertek site, came across the blurb below which looks like they have "chilled fluid control" for controlling IATs so looks like they use a water (or some other fluid) type intercooler just like my guys

I still want to know eg what target post intercooler IAT would they aim for on eg a 620PS 997GT2RS engine, Porsche know what numbers they use but this information is the Porsche hp difference

[engineermk]

TB993tt said:

I still want to know eg what target post intercooler IAT would they aim for on eg a 620PS 997GT2RS engine, Porsche know what numbers they use but this information is the Porsche hp difference

The post IAT depends on the manufacturers spec, they will specify what they want us to control it to. The target temp will have been derived from previous on road test data and in in-house test specs and varies from customer to customer. I don't know what temp Porsche specify.

[engineermk]

bcr5784 said:

Because some very critical statements from yourself and Mr D, I thought it interesting to ask the question of engineermk, since, from the sound of things he has considerably more experience than any of us in this area. Interesting that he doesn't consider it an issue - or perhaps Porsche are one of his customers and he is reluctant to be critical.

Confidentiality agreements prevent me from saying who our clients are, confirming or deigning any client that hasn't publically acknowledged us would result in me loosing my job.

I can say our newest labs are capable of testing any road car engine up to approx 800kW (petrol, diesel or hybrid) and we would not have invested in them if we didn't have work for them!

Having worked in vehicle emissions for many years I am very critical of the European drive cycle test that produces the magic CO2 data politicians love so much. I know how to 'cheat' the test to get a good result. And I know how manufactures use every loop hole to get that good result.

[bcr5784]

engineermk said:

Having worked in vehicle emissions for many years I am very critical of the European drive cycle test that produces the magic CO2 data politicians love so much. I know how to 'cheat' the test to get a good result. And I know how manufactures use every loop hole to get that good result.

The argument that is being put forward is that manufacturers of automatics in particular might cause the engine to run at lower revs than is desirable for the durability of the engine JUST to achieve the magic CO2 figures. Some are adamant that this is the case (though I don't think they have facts to back it up)- I have an open mind at the moment. But it sounds like you have some knowledge about how far they are prepared to go.

[engineermk]

bcr5784 said:

The argument that is being put forward is that manufacturers of automatics in particular might cause the engine to run at lower revs than is desirable for the durability of the engine JUST to achieve the magic CO2 figures. Some are adamant that this is the case (though I don't think they have facts to back it up)- I have an open mind at the moment. But it sounds like you have some knowledge about how far they are prepared to go.

I agree, auto transmission cars will be programmed to keep engine revs low, this gives low CO2 results. That's why you have a sport button, to get the car into a more driver friendly mode. But don't assume the low revs damage the engine, the drive cycle test 'hills' (accelerations) are so pedestrian an asthmatic pensioner on a push bike could achieve them. in real life driving the transmission will be programmed to change down if it needs to. The drive cycle speed load sites are well below where most of us drive even in congested traffic. The ECU is calibrated to give a good test result and drive well (without damaging the engine) for how the car is driven on the road.

Manual transmission drivers get the worst deal. The drive cycle says what gear you must be in for the test speeds so the only thing manufactures can do to get low CO2 numbers is fit high gear ratios.

There's new legislation coming to stop this cheat... its called PEMS. Soon cars will be tested on the road to determine their real world emission... google 'PEMS horiba' or 'PEMS AVL' to see more.

[SkinnyPete]

engineermk said:

I agree, auto transmission cars will be programmed to keep engine revs low, this gives low CO2 results. That's why you have a sport button, to get the car into a more driver friendly mode. But don't assume the low revs damage the engine, the drive cycle test 'hills' (accelerations) are so pedestrian an asthmatic pensioner on a push bike could achieve them. in real life driving the transmission will be programmed to change down if it needs to. The drive cycle speed load sites are well below where most of us drive even in congested traffic. The ECU is calibrated to give a good test result and drive well (without damaging the engine) for how the car is driven on the road.

Manual transmission drivers get the worst deal. The drive cycle says what gear you must be in for the test speeds so the only thing manufactures can do to get low CO2 numbers is fit high gear ratios.

There's new legislation coming to stop this cheat... its called PEMS. Soon cars will be tested on the road to determine their real world emission... google 'PEMS horiba' or 'PEMS AVL' to see more.

Thanks for sharing all you have so far.

As has just discussed, engine labouring is what I try and avoid be it manual or automatic.

PDK is adamant about jumping into 7th gear at 1100rpm which then generates a deep reasonace from the engine, I personally can't see how it is healthy for the engine or drivetrain (dual mass flywheel in particular) so I always stick it in sport mode to wake it up a bit.

[BertBert]

Surely that's just self respect. No Porsche engine should be running at those revs unless it's stationary?

[SkinnyPete]

BertBert said:

Surely that's just self respect. No Porsche engine should be running at those revs unless it's stationary?

What do you mean self respect? In automatic the gearbox operates automatically, and it wants to jump into 7th as soon as possible which puts the revs at about 1100.

Porsche are not the only manufacturer to do this, my Ford manual (diesel) has a gearshift indicator and that wants me in 6th @ 1100rpm, of course I ignore it and use 4th instead which is about 1,750rpm.

[bcr5784]

SkinnyPete said:

Thanks for sharing all you have so far.

As has just discussed, engine labouring is what I try and avoid be it manual or automatic.

PDK is adamant about jumping into 7th gear at 1100rpm which then generates a deep reasonace from the engine, I personally can't see how it is healthy for the engine or drivetrain (dual mass flywheel in particular) so I always stick it in sport mode to wake it up a bit.

Thanks from me too mk for sharing.

Only get any resonance when I try to hold speed (in auto) up an incline - and then only briefly as I've said, before it changes down. All that said I find sport mode a pain in the neck. It's a bit like an over-excited puppy revving quite needlessly and over-blipping on down changes (which I suspect slows, rather than speeds, the gearchange). I always choose to go manual over sport (auto). Don't use sport manual either because of the over-blipping.