Dynoing my cossie merc

[pentoman]

I have been invited along to a VR6 owners rolling road day this weekend. I am hoping to learn as much about my engine as possible while up there. It's an old fashioned non-catalyst, non-lambda sensor, non-knock sensor car. This may all be unfamiliar to them as they are a subaru tuner (Powerstation in tewkesbury, gloucestershire) !

So what can they do and what should they do?
Can they measure my exhaust mixture through the rev range and will that tell me something? Will they do this by default?
Will they have any idea about the engine and about all the K-jetronic setup, or are they merely trained monkeys?

The car has a flat spot at 3500 rpm. Will anything they do give me pointers as to the cause of this? Is there anything I should be asking for?

It will be interesting to see what power my engine makes. It feels fairly strong in the upper half, and does 7.3s from 0-60 which is 0.1 off Autocar's road test time.

Also what should I do in advance of going? I will fill up with super unleaded from a busy forecourt. Is it worth having an oil/filter change? It is overdue one .

[busa_rush]

Change the oil and filter and check all levels before you go. Use a quality oil for your own sake

Have you checked the water hoses and clips for leaks and the hoses for signs of perishing ? If you've not changed the coolant in the last 2-3 years then do that too with a system flush.

Do you have hydraulic tappets ? If not then having them adjusted if necessary (usually only needed on highish mileage engines) may help too.

Does your gearbox and diff oil need to be changed ? Might be worth doing that too but not necessary.

If an oil service is overdue then some or all of the above may need doing too . . . with such an interesting car it's a shame to neglect these basic tings.

Your rear tyres will take a beating too, make sure they're in good shape. A blow out on the rollers will make you evacuate your bowels

Do you have points and a coil ? Check rotor arm etc. Take it for a good blast first to clear it out then re-check all the levels again.

[stevesingo]

Ask them to plot the Air Fuel Ratio on the graph so you can see if this is the route of your flat spot.

Steve

[agent006]

I'd be surprised if you find Powerstation lacking knowledge. They're not just subaru experts but i believe are very good with ECU mapping of all sorts of stuff. All depends how much you're paying for as to what you get out of them. If it's fairly cheap (£40 ish) then it's likely you'll just get a zip through the gears and a nice pretty graph. If you want more than that i expect they'll want more cash. Can't rememver exactly what they wanted for a detailed run on the Audi but it was £100 ish for a basic fault finding, up to multiples of that for a proper tuning session.

As for preparation, i'd make sure your cooling system is fine but apart from that it's not really any different from a couple of flat out runs on a regular road.

[thong]

pentoman said:

I have been invited along to a VR6 owners rolling road day this weekend. I am hoping to learn as much about my engine as possible while up there. It's an old fashioned non-catalyst, non-lambda sensor, non-knock sensor car. This may all be unfamiliar to them as they are a subaru tuner (Powerstation in tewkesbury, gloucestershire) !

So what can they do and what should they do?
Can they measure my exhaust mixture through the rev range and will that tell me something? Will they do this by default?
Will they have any idea about the engine and about all the K-jetronic setup, or are they merely trained monkeys?

The car has a flat spot at 3500 rpm. Will anything they do give me pointers as to the cause of this? Is there anything I should be asking for?

It will be interesting to see what power my engine makes. It feels fairly strong in the upper half, and does 7.3s from 0-60 which is 0.1 off Autocar's road test time.

this engine is the same as cossie ford except it has chain driven cam's,no turbo and different bore and stroke,k-jet should be no problem to them as its been ues'd for years on all kind's.

Also what should I do in advance of going? I will fill up with super unleaded from a busy forecourt. Is it worth having an oil/filter change? It is overdue one .

this engine is the same as cossie ford except it has chain driven cam's,no turbo and different bore and stroke,k-jet should be no problem to them as it's been use'd for years on all kind's.

Edited by thong on Tuesday 21st November 18:57

[stevieturbo]

thong said:

[quote=pentoman]
this engine is the same as cossie ford except it has chain driven cam's,no turbo and different bore and stroke,k-jet should be no problem to them as it's been use'd for years on all kind's.

So, its quite different lol.


If you are going to a rolling road day, dont expect too much info, as usually that will eat up too much time.
If you are booking time for yourself, then Richard will be able to advise you. Powerstation is a good setup, with some very knowledgable guys.

[slinky]

VIXPY

[pentoman]

Cheers all

thong said:

this engine is the same as cossie ford except it has chain driven cam's,no turbo and different bore and stroke,k-jet should be no problem to them as it's been use'd for years on all kind's.

That's more-or-less as I understand it - standard cosworth design built onto a Mercedes bottom end instead of Ford, with K(E?) jetronic. And being Mercedes, the bottom end and block are tank-like. This apparently makes it a brilliant engine to turbocharge, the cosworth breathing bits meaning it takes to boost incredibly well, and the solid bottom end allowing you to do 400bhp without really trying. Imagine if Mercedes had decided to make it a turbo as Ford did......

agent006 said:

I'd be surprised if you find Powerstation lacking knowledge. They're not just subaru experts but i believe are very good with ECU mapping of all sorts of stuff. All depends how much you're paying for as to what you get out of them. If it's fairly cheap (£40 ish) then it's likely you'll just get a zip through the gears and a nice pretty graph.

It's £30 with 35 cars there... Perhaps I will see if I can speak to them in advance over the phone and ask what they'll do and if they can/will do anything special. Air Fuel ratio sounds like a very good thing to have, especially as the engine has no way of monitoring this itself.

[Marquis_Rex]

From all of that list, changing plugs, changing to a lower viscosity oil, and adjusting the ignition timing (if possible) will give the biggest performance gains.
Adjusting tappet clearances won't give any gains really and in most solid tappet/rocker arm engines, looser clearances usually gives better mid-range because of the way the annoying cam ramps of the cam profile must transition into the cam flanks.

You could check the air filter is not dirty and adjust the throttle stop such that when you're pressing for wide open throttle you're actually getting WOT!

[stevieturbo]

35 cars in one day.....

Each car will be on and off the rollers promptly.

If you want any info on how the car is running, you will need to book time for yourself. they might give you some sort of indication, but there wouldnt be enough time for a proper analysis

[pentoman]

stevieturbo said:

35 cars in one day.....

Each car will be on and off the rollers promptly.

If you want any info on how the car is running, you will need to book time for yourself. they might give you some sort of indication, but there wouldnt be enough time for a proper analysis

Hmm shame oh well, a confirmation of the flat spot, and perhaps a trace of the AFR will give me plenty to work with.

[pentoman]

Comments please:

[pentoman]

To summarize..

218Nm (161 lb ft) at 4975 rpm (should be 177 lb ft)
186 bhp at a ridiculous 7280 rpm!
Why the huge spike at 7000 rpm? It doesn't even feel like it's doing much work once you're past 6200 - I always change up about there.
Oh and obviously there's also the huuuuge flat spot at 3.5k rpm.
Very confused!?

The car has low compression across all cylinders but as far as I know that's all that's wrong with it.

On the same day a standard 204bhp BMW 330Cd made 225bhp! A ferrari 348 tb (tubi exhaust, carbon intake things ) made 315bhp. Both these figures are maybe a bit hight so I don't think it was under-reading.

Edited by pentoman on Saturday 25th November 15:28

Edited by pentoman on Saturday 25th November 15:30

[stevesingo]

Aside from it being a little on the low side throughout the range it looks ok to me. The flat spot is not so big (you should see mine at 2250-2500). It would be of more use if the RPM was on the graph as opposed to road speed.

For what it is worth, I think Powerstations rollers are pretty good in the wheel power but over estimate the drivetrain losses. 70+BHP loss on a 185bhp engine? It is as though they have the correction factors set up four a 4WD.

All in my opinion

Steve

[pentoman]

OK here's a video of the run:
http://video.google.co.uk/videoplay?d
Note to self: make intake louder

stevesingo said:

Aside from it being a little on the low side throughout the range it looks ok to me. The flat spot is not so big (you should see mine at 2250-2500). It would be of more use if the RPM was on the graph as opposed to road speed.

For what it is worth, I think Powerstations rollers are pretty good in the wheel power but over estimate the drivetrain losses. 70+BHP loss on a 185bhp engine? It is as though they have the correction factors set up four a 4WD.

All in my opinion

Steve

Interesting...

I did see them set it up each time for rear/front/four wheel drive.

The 348 tb decat + tubi measured drivetrain losses of 93bhp.

There were loads of 2.8 VR6 golf's there, they all made dead consistently 185bhp. Never saw one under 185bhp - yet standard is 174bhp . So either they are very good, or it was over-reading!!

Never mind, I know the car drives well and it's not really the engine that makes it great :/.

Edited by pentoman on Sunday 26th November 13:57

Edited by pentoman on Sunday 26th November 14:02

Edited by pentoman on Sunday 26th November 14:02

[stevesingo]

My 2.5 M3 with Motec nad I de-cat exhaust made 258bhp at Powerstation which is much more than the claimed 238bhp stock with a 68bhp loss. On Northhampton Motorsports rollers it made 228bhp with a 41bhp loss. At the wheels they were 190 and 187 respectivly lossses were 26% and 18% respectivly.

Draw your own conclusions

Steve

[pentoman]

stevesingo said:

My 2.5 M3 with Motec nad I de-cat exhaust made 258bhp at Powerstation which is much more than the claimed 238bhp stock with a 68bhp loss. On Northhampton Motorsports rollers it made 228bhp with a 41bhp loss. At the wheels they were 190 and 187 respectivly lossses were 26% and 18% respectivly.

Draw your own conclusions

Steve

Very interesting.

There was a E36 M3 3.0 there that had apparently made 295 on some other rollers a few days before, and it made 295bhp again at powerstation. So I thought it must be fairly correct? If they're overestimating then it would mean my car is more like 170bhp!! But I'm sure it's not..

[stevieturbo]

stevesingo said:

My 2.5 M3 with Motec nad I de-cat exhaust made 258bhp at Powerstation which is much more than the claimed 238bhp stock with a 68bhp loss. On Northhampton Motorsports rollers it made 228bhp with a 41bhp loss. At the wheels they were 190 and 187 respectivly lossses were 26% and 18% respectivly.

Draw your own conclusions

Steve

The only conclusions are that it is a waste of time using flywheel guesstimations. Stick with wheel figures.

[stevesingo]

My conclusion exactly

Steve

[GnuBee]

[redacted]