F-type V6 S BHP

[Dolittle]

Has anyone with a V6 S ever had their car on a Rolling road? The reason I ask is that both myself and a friend with another V6 S recently did this and the results were quite surprising. My runs showed that my car had 335 BHP at the flywheel and my friends had 340 BHP. Considering the cars are supposed to have 375 BHP thats quite a difference. Its the level of power you might expect from a non S version of the car. Jaguar are on the case and have checked that the dyno run was done correctly. Which they have confirmed it was. It would be interesting to see if anyone had seen the full 375. My cars a late 2013 and my friends an early 2014 car. I find it hard to believe that All F types were sold grossly underpowered like this, perhaps one or two of the S versions got the non S map in error?

[a8hex]

How did you measure the crank BHP on a rolling road?
Surely they measure the BHP at the rear wheels and then subtract some random numbers and percentages, there is no way to know what the actual losses are in the car. Different rolling roads can use different figures, maybe it depends on whether they are taking a before or after measurement
Maybe the rolling road you used assume bigger in car losses than are really happening.
I've had 2 dynos return figures 60BHP apart. I think the numbers you get are really only useful for comparing before and after numbers for some work, and then only if you trust the person doing the test not to skew the figures.

[Dolittle]

a8hex said:

How did you measure the crank BHP on a rolling road?
Surely they measure the BHP at the rear wheels and then subtract some random numbers and percentages, there is no way to know what the actual losses are in the car. Different rolling roads can use different figures, maybe it depends on whether they are taking a before or after measurement
Maybe the rolling road you used assume bigger in car losses than are really happening.
I've had 2 dynos return figures 60BHP apart. I think the numbers you get are really only useful for comparing before and after numbers for some work, and then only if you trust the person doing the test not to skew the figures.

Im afraid I cant answer that, my friend who is also a member here might be able to, hes more technical. But the chart was enough to alarm Jaguar. My cars going into them for a diagnosis. Im hoping its somthing silly. I should add that my friends car has been dyno'ed twice by two seperate companies. It seems odd that the figures are what you would expect the non s to produce.

[jamieduff1981]

With a supercharged and intercooled engine the amount of heatsoak is very important.

Even a 2nd run will be down on power noticably compared to a first as everything is hot 2nd time around.

Tyre pressures, ambient temperature, density etc all make big differences as of course does the algorythm in the rolling road software to estimate flywheel power from measured driving wheel torque.

[ewolg]

I'm the other person Pete is referring to. I've had lots of cars on a RR so know a little about this and that.
Mine was tested at two reputable dyno's and yes, all things that previous posters mention were taken into consideration (not repeating it all).
We just want to see if any other F-Type 'S' owners have had theirs on a power run - would be interesting to see the results.

[Dolittle]

Im surprised that there is not more interest in this. Doesnt anyone care if their F-Type S has only got 335 BHP? Jaguar HQ seem very concerned, they are doing diagnostics on my car as I type. My car is not an isolated case either. No coincidence that Geoffs car is the same. He put his car on a dyno for the third time yesterday and still got less than 335 BHP. Would be really helpful if a few others tested their cars to add to the evidence.

[CarbonXKR]

This sort of thread went on and on for ages on the HSV and Monaro forum with many a heated discussion re RWHP to FWHP and how such huge power losses were calculated. Bear in mind that the machine is working out RWHP i.e. power being put down on the road. As with any engine, this can vary greatly depending on how much power is being used/lost to the supercharger, aircon, electrics etc. etc. If you're happy with the way that the car drives (I am as I had a full day test in one on Tuesday!), then why worry about what the bragging rights are as seemed to happen on the other forum. As has been said though, it is a great tool for comparing before and after figures. Jaguars hp figures are measured with the engine on a bench btw.

[Dolittle]

CarbonXKR said:

This sort of thread went on and on for ages on the HSV and Monaro forum with many a heated discussion re RWHP to FWHP and how such huge power losses were calculated. Bear in mind that the machine is working out RWHP i.e. power being put down on the road. As with any engine, this can vary greatly depending on how much power is being used/lost to the supercharger, aircon, electrics etc. etc. If you're happy with the way that the car drives (I am as I had a full day test in one on Tuesday!), then why worry about what the bragging rights are as seemed to happen on the other forum. As has been said though, it is a great tool for comparing before and after figures. Jaguars hp figures are measured with the engine on a bench btw.

I'm not bothered by bragging rights, if that were the case I would have kept my 580BHP Murcielago. All I want is the 375BHP that I paid for when I bought a V6 S, not the 335BHP that you get with a non S. Jaguar HQ seem to be just as concerned from what I gather. There seem to be rumours of incorrect ECU's being put into some of the cars Prior to mid 2014. As from what I can gather it's the map that makes most of the difference between S and non S models where power is concerned.

[ewolg]

Dolittle said:

I'm not bothered by bragging rights, if that were the case I would have kept my 580BHP Murcielago. All I want is the 375BHP that I paid for when I bought a V6 S, not the 335BHP that you get with a non S. Jaguar HQ seem to be just as concerned from what I gather. There seem to be rumours of incorrect ECU's being put into some of the cars Prior to mid 2014. As from what I can gather it's the map that makes most of the difference between S and non S models where power is concerned.

I agree, having had a few much more powerful cars too.
So if they are tested on a bench its flywheel BHP, yes? That is exactly what the manufactures quote so we have 335/8 and we are meant to have 375. At least Jag are now taking it on board and will hopefully do something about it.

[ftypical]

Dolittle said:

Has anyone with a V6 S ever had their car on a Rolling road? The reason I ask is that both myself and a friend with another V6 S recently did this and the results were quite surprising. My runs showed that my car had 335 BHP at the flywheel and my friends had 340 BHP. Considering the cars are supposed to have 375 BHP thats quite a difference. Its the level of power you might expect from a non S version of the car. Jaguar are on the case and have checked that the dyno run was done correctly. Which they have confirmed it was. It would be interesting to see if anyone had seen the full 375. My cars a late 2013 and my friends an early 2014 car. I find it hard to believe that All F types were sold grossly underpowered like this, perhaps one or two of the S versions got the non S map in error?

Which gear did the technician use for the power run? Higher gears give lower readings as the rolling road measures Torque at the wheels, which is a product of engine Torque as multiplied by the overall gear ratio, minus losses.

This leads on to what the torque curve actually looked like. First, what was the peak figure and over what range of engine speeds did it achieve it? Second, what were the torque figures at 5000rpm and 6000rpm?

It's always possible that the car is loaded with the wrong engine map, but the ECU has a number of different ones to cope with things like altitude, temperature and fuel octane, in addition to specific fault conditions.

HTH

[Dolittle]

4th gear I believe, Jaguar did actually speak to the rolling road company to check it was all measured correctly. They were satisfied.

Edited by Dolittle on Saturday 20th June 10:21

[ftypical]

Dolittle said:

4th gear I believe, Jaguar did actually speak to the rolling road company to check it was all measured correctly. They were satisfied.

Edited by Dolittle on Saturday 20th June 10:21

That looks like it's got a problem between ~4,000 and 5,000rpm rather than being a 340hp map. The gradient on the power curve should be constant up to 5,000rpm.

[a8hex]

ftypical said:

That looks like it's got a problem between ~4,000 and 5,000rpm rather than being a 340hp map. The gradient on the power curve should be constant up to 5,000rpm.

The torque curve is coming down from about 4300. Jaguar's figures suggest it should be flat between 3500 and 5000, but the torque figure you're seeing is well below the quoted figure even for the lower output engine. You are seeing a peak torque figure of 316, Jaguar are quoting in Nm 450 for the base engine and 460 for the S version, in lbft that's 332 and 340.

[ftypical]

It's also dropping off sharply from a little over 6,000rpm - which would explain why peak power is where it is rather than at Jaguar's quoted figure of 6,500rpm.

Anyone else think the kink at 5,250rpm and shape of the Torque curve either side suggests a switch over point in the intake system.?

[a8hex]

Yes it's off a cliff edge by 6200, so there's no way it could be making peak poke at 6500.

Thanks for posting the graph, I can understand your concern now. You can argue about the accuracy of guessing flywheel BHP figures, but measure revs accurately isn't rocket science and seeing the shapes of the torque graph it clearly isn't doing what the specs say.

[Dolittle]

a8hex said:

Yes it's off a cliff edge by 6200, so there's no way it could be making peak poke at 6500.

Thanks for posting the graph, I can understand your concern now. You can argue about the accuracy of guessing flywheel BHP figures, but measure revs accurately isn't rocket science and seeing the shapes of the torque graph it clearly isn't doing what the specs say.

Thanks for that, i dont understand anything on that graph, it may as well be in chinese, I have been relying on what the rolling road company have said. I have a feeling that a high percentage if not all V6S cars are like this. So far there are including mine 2, would be very helpful if more owners would check their cars to find out if any are actually putting out the correct figures.

[a8hex]

If you look at the Jag spec on

http://www.jaguar.co.uk/jaguar-range/f-type/pricin...

The simple thing is that on your graph the peak power (top of the graph) is at 6100RPM, and the spec says the peak is at 6500. If the graph kept going up to there you'd probably be looking at over 360BHP. Instead the operator of the rolling road has stopped measuring at 6550RPM because it's clear the show is well and truly over by this point. Even if you had the non S engine the graph is still wrong the top of the graph is still in the wrong place. For some reason the engine isn't working where it should be making peak power.

I don't know how to read the Lambda 2 line but it does something weird at the end. It the air/fuel ratio and I presume it should be fairly constant (flat on the graph), it's going down from 5200RPM and then jumps at about 6200RPM.

The guy on the rolling road would be able to talk you through the graph far better than me. Probably someone here will be along to explain things better soon.
About 30 years ago I made my living measuring things and plotting graphs, I like the look of that brown line at the bottom below 5200RPM, it looks like real measurements of something near constant when someone isn't bullstting. Really straight lines of graphs aren't normally the results of people taking real world measurements.

[ewolg]

Going on from Pete's post, here is my graph done at the same place, same conditions etc.

Edited by ewolg on Saturday 20th June 23:14

[a8hex]

So yours looks very similar. The power peak is between 6000 and about 6100, and by 6500 where the spec says the peak is, you're down to about 12%, the change is the more important thing here rather than the absolute power figures, without knowing a lot more that I do about the test.

[ewolg]

a8hex said:

So yours looks very similar. The power peak is between 6000 and about 6100, and by 6500 where the spec says the peak is, you're down to about 12%, the change is the more important thing here rather than the absolute power figures, without knowing a lot more that I do about the test.

Indeed it does. We'll leave it to Jaguar to assess the problem and come up with a solution.