Dynoresults From The Xu13j4

[B1ack_Mi16 67]

Better late than never. Today I actually had the XU13J4 in for mapping on a local RR.

 

I'm not 100% sure how to look at the graphs, but it's power at wheels.

 

It was a bitch to map, and we couldn't get the AFR stable, so the humps in the torque curve is due to camshafts, management (too little resolution on speed sites, only each 500rpm), and also probably exhaustmanifold and inlet.

 

It's running a standard!! 309gti16 exhaustmanifold, with a 2.5" home made exhaustsystem.

 

The guy mapping it had recently done two rallycross cars, with volvo 2.4 16v engines, they showed 250bhp at the wheels in the dyno and was supposed to have approx 280bhp in engine.

 

I'm well chuffed, and the beast actoully would wheelspin in 4'th gear with normal road tires!

 

Link to powercurve:

http://folk.ntnu.no/satertro/bil/powercurve.jpg

 

Two videos:

http://folk.ntnu.no/satertro/bil/CIMG0368.divx

http://folk.ntnu.no/satertro/bil/CIMG0371.divx

 

I need to upgrade the Emerald to the K3 software so I can choose speed sites myself..

[KRISKARRERA 2 1 Cars]

I wonder what results one would get with a standard mi16 manifold?

[Baz 421]

Very nice! Be interesting to see it all ironed out torque-curve wise! But i'd be well chuffed with that!

[engine killer 5]

Amazing result! A horrible machine on street.

 

249bhp at wheel? using my friend's dyno's menu suggestion, @wheel Bhp divided by 0.7 which is about the power at flywheel >>> 249/0.7=355BHP!!!!

 

WOW

 

congratulation!

[petert 554]

Are you sure it wasn't power at the flywheel?

[KRISKARRERA 2 1 Cars]

Engine killer - your formula is wrong.

If it is road wheel figure with 15% transmission losses Kristian would be getting 286bhp.

You've also got about 190lbs of torque there - that must be at the fly surely??

[Sandy 189]

That's a great result!

[smckeown 1]

190 lb/ft...jesus that's a lot of shove in the back of the seat I bet it's scary at those revs

[mos 1]

great result

 

with the makings of a decent torque curve across the entire rev range once the low end resolution is sorted

 

congratulations

[Alastairh 47]

Sounds awesome! That'll be an animal

[B1ack_Mi16 67]

Are you sure it wasn't power at the flywheel?

 

Yes it's power at wheels, the dyno didn't have any coastdown funcion, and we just plotted power at wheels with weather correction enabled.

 

I timed the camshafts to 3.65mm lift @TDC (inlet) and 3.25mm lift @TDC exhaust.

 

I still think the results are too good to be true, so I'm not sure what to believe.

 

Kris:

The torque is wheel torque in 4'th gear with 205/50/16 wheels.

So it must be corrected regarding gearboxratio and wheel size.

The powercurve is correct though as the dyno measures it by taking into account speed of the rollers and the applied torque.

[B1ack_Mi16 67]

Looking closer on the graph, I was just so exhausted yesterday so didn't notice.

But it says Engine power.. Although we never did any coastdown runs on it, and they guy claimed it was power at wheels that was measured.

 

He'd done lots of cars for reference and all was far under the claimed factory spec.

The Audi A8 W12 engine was 120bhp under spec, so he was sure it was a power @wheel figure the bench showed.

[VisaGTi16v 1]

"so he was sure it was a power @wheel figure the bench showed."

 

how can he not know exactly what figure HIS rolling road is measuring?

 

wheel or flywheel, still a nice power figure

Edited June 14, 2007 by VisaGTi16v

[PumaRacing 1]

Looking closer on the graph, I was just so exhausted yesterday so didn't notice.

But it says Engine power.. Although we never did any coastdown runs on it, and they guy claimed it was power at wheels that was measured.

 

He'd done lots of cars for reference and all was far under the claimed factory spec.

The Audi A8 W12 engine was 120bhp under spec, so he was sure it was a power @wheel figure the bench showed.

 

If you divide by 0.85 to account for transmission losses you end up with a torque per litre figure that is far too high to be believable at 97 ft lbs/litre. Even at the wheels, if that is what the curves are meant to be, it's 82 ft lbs/litre so I think all you can do is conclude it's an optimistic set of readings and wait until you can compare to another set of rollers.

[KRISKARRERA 2 1 Cars]

Surely 82 pound a litre is about right on an engine of this spec?

[DrSarty 90 1 Cars]

It sounds amazing, and whilst the results do seem a little high for at the wheels, I reckon a second run elsewhere will produce mightily impressive results regardless. You should be pleased, even with 200 ATW!

 

Remember my engine's modelled in most ways on yours, so I'm drooling with excitement now

 

 

Well done.

 

Rich

[Hilgie 16 2 Cars]

Very good results Kristian. Be proud of it!

[PumaRacing 1]

Surely 82 pound a litre is about right on an engine of this spec?

 

It's far too high for a wheel figure and a bit less than you'd hope for from a flywheel figure. If you assume mid to high 80's ft lbs per litre at the flywheel, say 85 to 88, then you could perhaps scale the 249 bhp up in proportion to be in the mid 260's true flywheel bhp. That seems entirely reasonable for a 2.3 litre with the mods it has. It's notoriously difficult getting high powered fwd cars to read properly on rollers so not surprising the wheel figures are well on the high side. They always seem to end up that way if any wheelslip is taking place.

 

Other than the Dastek rollers (possibly also the Dyno Dynamics ones with serrated rollers for grip) which seem to be rock solid and very conservative under all conditions I think more and more these days that it's a fool's errand trying to make any sense of rolling road figures or predict true flywheel figures from wheel ones. You can do as well by predicting the expected figure in advance from the modifications and first principles. You'll at worst be within the 10% to 15% error band which you get from different rollers anyway. It's just a shame that rolling roads are so variable and unreliable that little they claim can be taken as having any validity.

 

There's something of a rash of rather unbelievable torque per litre figures being touted about recently from rolling road data but it probably pays not to get too excited about it all. It's only pub bulls*it bragging rights at the end of the day.

[B1ack_Mi16 67]

I must say I agree the figure is higher than I ever would have expected.

 

The torque though is the torque that the rollers see from the wheels, which is geared through the gearbox, so depending on ratios and size on the wheels.

 

I'm at least pretty confident the engine has got more than 250bhp, which have been the goal all the time.

I reckon it's in the region of 260-270bhp somewhere.

 

The engine has performed very nice, nothing wrong with it mechanically at all. Although the camshafts seem to chip off the nitrided layer so I might need new ones if the keep getting worse.

 

The headwork surely couln't have been that bad either Dave, but I'm sure it's possible to make it better..

[B1ack_Mi16 67]

BTW. Just downloaded the user manual for the Dyno software:

http://www.mustangdyne.com/pdfs/7K%20manualv238.pdf

 

It says the power is calculated by the torque applied to the rollers and the speed of the rollers.

Then corrected to wheel torque is given by: EngineTorque = ((DynoShaftTorque * DynoShaftRPM) / EngineRPM)

 

The engine RPM compared to dynoshaftRPM was calibrated before we started the test.

 

DrSarty: I know your's are based on mine in very many ways, so I'm really curious about your results.

[petert 554]

I've just got around to watching the videos. Sounds awesome. A very impressive result you can be proud of.

[B1ack_Mi16 67]

I've just got around to watching the videos. Sounds awesome. A very impressive result you can be proud of.

 

Thanks.

 

Anyone got an idea of why there's so many humps in the torque curve?

It certainly is the VE that changes very much in a short rpm band.

 

Anyone seen such humps before and know anything about what can be done to get a smoother curve?

[deadcatdave 0]

Thanks.

 

Anyone got an idea of why there's so many humps in the torque curve?

It certainly is the VE that changes very much in a short rpm band.

 

Anyone seen such humps before and know anything about what can be done to get a smoother curve?

 

I have experienced something similar recently.

 

In my experience it was due to slow gas speed due to too large ports/inlet tract diameter.

[B1ack_Mi16 67]

I have experienced something similar recently.

 

In my experience it was due to slow gas speed due to too large ports/inlet tract diameter.

 

I'm wondering if it can be down to the exhaust manifold.

 

Maybe I'll get a 4-2-1 later on, I know some for sale made by Peugeot Sport Denmark, probably going to be able to fit it if I just change the flange.

 

The inlet is 45mm jenveys and can't see that beeing too big on 2.3 litre displacement.

[niklas 1]

I'm wondering if it can be down to the exhaust manifold.

 

Maybe I'll get a 4-2-1 later on, I know some for sale made by Peugeot Sport Denmark, probably going to be able to fit it if I just change the flange.

 

The inlet is 45mm jenveys and can't see that beeing too big on 2.3 litre displacement.

 

Have you modified the inlet ports (ie valve throat) a lot?