F-type V6 S BHP

[300bhp/ton]

Dolittle said:

OK, so how would you explain the F Type V8 putting out the correct figures?

But you don't know it is correct? That's the point, a rolling road dyno simply cannot give you accurate comparable figures to manufacture rated flywheel figures.

All they can do is give you a rwhp figure and then "guess" the drivetrain losses.

There are many ways of doing this, but all are flawed and none can give you an accurate result.

Article here about it:
http://www.superstreetonline.com/how-to/engine/mod...

If you have an interest in this, then I highly advise you click the link and read the article.

If you don't, then here is the important bit:

article said:

In the end, there's no easy way to estimate the drivetrain loss your vehicle experiences on the road or even on the dyno. Coast-down tests are sometimes used on a dyno to attempt to measure frictional losses, but because this test is not dynamic (meaning they're not done while accelerating, but rather while coasting to a stop with the direct drive gear engaged but the clutch depressed so that the engine and transmission aren't linked) it really only captures steady-state drivetrain losses as well as rolling resistance. So rather than attempting to convert your vehicle's dyno-measured wheel horsepower to a SAE net horsepower figure using a percentage or a fixed horsepower value, you're far better off accepting the fact that these two types of horsepower measurements aren't easily correlated and forego any attempt at doing so.

And if the figures you get are close to what the manufacture claims, then it's probably just a lucky guess. Either that or also by a stroke of luck (or operator manipulation), that the figures fed in and the calculations used, produce something that you want. The other highly likely scenario is it was making more. So with all the fudging and guess work, you get something that looks close. Again this isn't uncommon in the motoring world.

Please understand me, I'm not saying either way on the actual power output of the V6S, just that this form of measurement is at best, very imprecise for such a comparison. But it might well be that the V6S is significantly under performing.


As I posted earlier, it's happened many times before, mostly in the USA.

http://www.autonews.com/article/19990816/ANA/90816...

Edited by 300bhp/ton on Tuesday 4th August 12:09

[a8hex]

There are also many reason why the engine might not perform the same on a rolling road and on a real one.
The reason I think this might well be the case here is that the peaks on your graph don't match the published spec, so there is a good chance that the engine management system is backing off early for some reason.
It would be lovely to get a good explanation out of Jaguar.

[bordseye]

300bhp/ton said:

http://www.autonews.com/article/19990816/ANA/90816...

Edited by 300bhp/ton on Tuesday 4th August 12:09

Interesting links but they dont explain why the V8 was on target and the V6 not so. I dont for a minute think that the maker of a sports car would sell a big V8 whilst underclaiming its power output. Thats not life.

At a guess Jaguear will use the same alternator , likely the same back axle, maybe the same gearbox and torque converter on both cars. So the power losses to drive those transmissions will be roughly the same. Yet the dyno graphs are using a percentage for adjustment not a bhp figure. In both cases they are saying about 15%

If the 76 bhp adjustment for the V8 engine is in the right ballpark as suggested by the fact that the estimated engine output ties in with Jaguars measurements and this adjustment is added onto the 290 rear wheel bhp of the v6 then the crank output of the V6 becomes 266. Within the limits of operating accuracy this ties in with Jaguars numbers.

IMO this is a possible scenario. Thanks to the low unit volumes expected, much of the same components are used on both small and big engined car with the same absorption of power before it reaches the wheels. What do you think?

[300bhp/ton]

bordseye said:

Interesting links but they dont explain why the V8 was on target and the V6 not so. I dont for a minute think that the maker of a sports car would sell a big V8 whilst underclaiming its power output. Thats not life.

Oh it certainly happens.

One I cited earlier. It is well know the 4th Generation Camaro/Trans Am's make more power than advertised.

Another example is the 2003/4 Ford Mustang Cobra. It is thought that after the legal action with the 1999 Cobra not making the claimed HP (see my earlier link), that they deliberately underrated the supercharged one. So as that it would always dyno above the official figure.

bordseye said:

At a guess Jaguear will use the same alternator , likely the same back axle, maybe the same gearbox and torque converter on both cars.

No idea, I wouldn't bet on it though. A 4.0 auto p38a Range Rover uses a different gearbox to the 4.6 ones. So it's not uncommon to see quite a number of changes from engine option to engine option.

bordseye said:

So the power losses to drive those transmissions will be roughly the same.

Nope, that's the main point of the article I linked to, they won't be the same. The more power you make, the more losses you'll have.

bordseye said:

Yet the dyno graphs are using a percentage for adjustment not a bhp figure. In both cases they are saying about 15%

Which is a very flawed way of guessing flywheel output. Even more so for automatics. But proves that the dyno can do nothing more than 'guess' when talking flywheel figures.

bordseye said:

If the 76 bhp adjustment for the V8 engine is in the right ballpark as suggested by the fact that the estimated engine output ties in with Jaguars measurements and this adjustment is added onto the 290 rear wheel bhp of the v6 then the crank output of the V6 becomes 266. Within the limits of operating accuracy this ties in with Jaguars numbers.

IMO this is a possible scenario. Thanks to the low unit volumes expected, much of the same components are used on both small and big engined car with the same absorption of power before it reaches the wheels. What do you think?

This is all possible. But I think the actual conditions the car was dyno'd under are more important. The curve profile seems wrong for the V6S pulls, which suggests environmental issues (heat soak, high ambient temp, lack of air flow) and/or operator induced error.

As for the V8, I have not seen any other dyno charts, so I don't know if that is a typical figure or not. But a flywheel figure is still a guess. Comparing RWHP figures with other V8's would give a better indication on the consistency of the numbers. A single car cannot give you this info.

With multiple datasets you'll be able to guess a ball park figure for the flywheel output and if it is near, below or higher than factory rated.


This all said and done, there might well be an issue with the V6S, but you'd need multiple sets of data to see a trend, not just two examples from the same dyno on the same day with the same operator.

Indecently, the V6S pulls all seemed higher than the non-S V6 posted earlier by the op. This would support that they are producing different amounts of power. That and the V6S didn't seem to make PEAK hp at the right rpm (common on a heat soaked engine, even more so ones running boost), then it suggests that under different conditions the V6S's would indeed have made even more power than the non-S.

[ewolg]

The update is - there is no update!!
Despite being promised a result today, I had to call 'yet again' for them to call me back. I just hope that when I get the car back on Friday it is a different beast. Rolling road will be booked for Monday to see.
More info as I get it..... (might be a wait)!

[ewolg]

300bhp/ton said:

This all said and done, there might well be an issue with the V6S, but you'd need multiple sets of data to see a trend, not just two examples from the same dyno on the same day with the same operator.

There have been 4 dyno's in actual fact all reading a similar figure. The most accurate one in Germany was showing 344 on a V6S.

[Dolittle]

Dolittle said:

Is that the same data you were due last Tuesday Geoff? And then last Friday? Whats the betting it gets postponed again.

What did I say last night Geoff.

They never return promised calls. And when you do get in contact with them by having to spend ages chasing, they are oh so apologetic, Also they blatantly lie. Problem is they are not very good liars, if they decide to lie, they should at least make sure that everyone else in their team is aware of the same lie that they are going to tell. I so wish I had recorded some of the conversations I had with them.

[300bhp/ton]

ewolg said:

There have been 4 dyno's in actual fact all reading a similar figure. The most accurate one in Germany was showing 344 on a V6S.

Are the rwhp figures all similar too?

And have any non-S V6's been on these 4 different dyno's? If so, what sort of hp difference is there between them?

[Turkish91]

Who is the problem here? The dealer, Jaguar UK or both?

Also OP; I fail to see how Jaguar buying your car back for more than you paid for it, then charging you a measly £2k to upgrade to a V8 model is an issue? Or have I misread your post? I'd be ecstatic to pay just £2k extra to swap my V6S for a V8!

[Dolittle]

Turkish91 said:

Who is the problem here? The dealer, Jaguar UK or both?

Also OP; I fail to see how Jaguar buying your car back for more than you paid for it, then charging you a measly £2k to upgrade to a V8 model is an issue? Or have I misread your post? I'd be ecstatic to pay just £2k extra to swap my V6S for a V8!

It's a little more long winded than that. After I bought my V6S I found my car to be plagued with problems. Ok the problems weren't major, but the dealership didn't seem able to fix them. My car went back to them on 5 occasions. After getting my car back on the 5th occasion and still finding it had the same problems and a new one I asked for a refund. At the same time as all this, this BHP issue came to light. The dealer refused to give me my money back which really I should have pursued further, but by now I was pissed off with the whole thing, especially as Jaguar UK said that I had to wait until Ewolg got his car back before they would address my issues. I wasn't prepared to wait another month before they took my car for possibly yet another month. Eventually the dealer said that they would swap my car for another V6S, they didn't seem to grasp the fact that one of the reasons I wanted rid of my car was because it and all other V6S' are underpowered to what they advertise. I wanted a V8, as then there would be no question about the power. The next hurdle was that they could only swap my car for one at an Authorised dealership. Most of the dealer cars were way more than what my V6S cost, but I managed to find one car. The dealer had to buy it in from another dealership and paid £52300 for it. My car cost me £52500. The only way I could swap was by giving the dealer another £2000.
Now I was under the impression that I would get £52500 credited for my old car, making the dealer owe me £200. But no, the dealer obviously wanted to make something out of the deal which I thought unfair as I swapped because it was a lemon. The dealer was saying that he had to add on a warranty etc thats what the extra cost was. I have since found that if my warranty on the V6S hadn't been touched, it may have been possible to transfer or refund it. But it was touched, because the dealer claimed on it to try and fix all the faults with the car!

I was dealing with Jaguar UK about the BHP and the dealer about the other issues. They didn't seem capable to work together. In hindsight and after taking advice I should just have dealt with the dealer. Who I should have insisted refunded me.

During this whole process I did not drive the car, I didn't want to add any extra mileage etc until the matter was sorted out. The dealer at the time said we haven't told you not to drive it. But when it came to the crunch, extra mileage came up as another reason why the car wasn't worth much also that I had put it on a rolling road, apparently according to the dealer that would have given the car a hard time. Yet according to experts, a professional rolling road is less stressful on the car than driving normally on a road.

Also when I did the swap, I spoke to Jag UK and expressed my feeling to how I thought I was being shafted and agreed that we would talk again once results were in about the V6S true power. But have now basically stuck up two fingers.

My main gripe is, I would not have bought the car had I known it only had 335 BHP, I'd probably have bought a V8 or something completely different altogether. And the fact that I was forced in effect to buy the V8 from a main dealer, whereas had I got a refund I could have got a better deal buying privately, at the time there were a lot of nicely specced cars for less money.

[Dolittle]

300bhp/ton said:

Are the rwhp figures all similar too?

And have any non-S V6's been on these 4 different dyno's? If so, what sort of hp difference is there between them?

V6 non S has been on one rolling road, the same one I put a V6S and a V8s on.

V6 290BHP Jag quote 340BHP

V6S 335BHP Jag quote 375BHP

V8S 506BHP Jag quote 488BHP

[a8hex]

bordseye said:

Yet the dyno graphs are using a percentage for adjustment not a bhp figure. In both cases they are saying about 15%

They aren't
Look at the numbers, actually sod that just look at the lines. They aren't the same shape and they don't have the same peaks, they aren't using a simple percentage. If they were using a percentage the shape would be the same, just one line would be bigger than the other.

Can someone who's seriously into this game comment on the lambda lines that are shown on some of the plots. Only the non S V6 seems to make any sense here. Even the high performing V8 shows the ECU pulling the plug on the run just below 6000RPM. Why?
This should be easy enough to check on the road, does the same thing happen there?
Actually, what happens when you nail the car on a suitable bit of tarmac? Does the power die below 6000RPM like it does on the graphs or is it still pulling like a train. I must admit I've never pushed my XKR that hard, but when I test drove the early 4.2 XKRs putting it in paddle shift mode I kept hitting the rev limiter before either I noticed a drop in umph or had time to hit the paddles.

[elementad]

a8hex said:

bordseye said:

Yet the dyno graphs are using a percentage for adjustment not a bhp figure. In both cases they are saying about 15%

They aren't
Look at the numbers, actually sod that just look at the lines. They aren't the same shape and they don't have the same peaks, they aren't using a simple percentage. If they were using a percentage the shape would be the same, just one line would be bigger than the other.

Can someone who's seriously into this game comment on the lambda lines that are shown on some of the plots. Only the non S V6 seems to make any sense here. Even the high performing V8 shows the ECU pulling the plug on the run just below 6000RPM. Why?
This should be easy enough to check on the road, does the same thing happen there?
Actually, what happens when you nail the car on a suitable bit of tarmac? Does the power die below 6000RPM like it does on the graphs or is it still pulling like a train. I must admit I've never pushed my XKR that hard, but when I test drove the early 4.2 XKRs putting it in paddle shift mode I kept hitting the rev limiter before either I noticed a drop in umph or had time to hit the paddles.

They pull all the way up to red line

[jamieduff1981]

jamieduff1981 said:

These cars use accelerometers for the Dynamic driving mode and the 8 speed gearbox locks up and unlocks for a whole host of reasons governed by the logic programmed in by the development engineers.

Jaguar charge coolers work fine on real roads but do heatsoak if stood idling or doing repeated dyno runs.

Notwithstanding the fact that rolling road dynos are just a means of making up numbers, the fictional numbers are further invalidated by the run down being corrupted by the intelligent gearbox lock-up logic.

That's before even considering if the ECU is looking for some hint about what the car is doing from the accelerometers which will be reading zero because the car is strapped down stationary.


I really can't take these figures seriously and to be honest think it's crazy that anyone would let a crappy rolling road put them off a great car.

[bordseye]

a8hex said:

They aren't
Look at the numbers, actually sod that just look at the lines. They aren't the same shape and they don't have the same peaks, they aren't using a simple percentage. If they were using a percentage the shape would be the same, just one line would be bigger than the other.

Each dyno graph has two similar shaped bhp lines plus the usual torque line. In the absence of any key saying what the second lower line is, I am assuming that its the uncorrected rear wheel bhp. Its difficult to get really accurate peak numbers off a graph on a monitor but as far as I can see the numbers are:

V6s rear wheel 292 corrected 338 factor 13.6%
loan car rear wheel 263 corrected 310 factor 15.2%
V8 rear wheel 430 corrected 506. factor 15.1%

In percentage terms the correction applied to the measured rear wheel bhp is near enough the same at around 15%. Maybe someone can be bothered to check the parts lists for the V6 and V8 but I'm betting that many of the components causing the loss of power between crank and rear wheel are the same so that the power absorbed in bhp will be the same and not a percentage.

[a8hex]

bordseye said:

a8hex said:

They aren't
Look at the numbers, actually sod that just look at the lines. They aren't the same shape and they don't have the same peaks, they aren't using a simple percentage. If they were using a percentage the shape would be the same, just one line would be bigger than the other.

Each dyno graph has two similar shaped bhp lines plus the usual torque line. In the absence of any key saying what the second lower line is, I am assuming that its the uncorrected rear wheel bhp. Its difficult to get really accurate peak numbers off a graph on a monitor but as far as I can see the numbers are:

V6s rear wheel 292 corrected 338 factor 13.6%
loan car rear wheel 263 corrected 310 factor 15.2%
V8 rear wheel 430 corrected 506. factor 15.1%

In percentage terms the correction applied to the measured rear wheel bhp is near enough the same at around 15%. Maybe someone can be bothered to check the parts lists for the V6 and V8 but I'm betting that many of the components causing the loss of power between crank and rear wheel are the same so that the power absorbed in bhp will be the same and not a percentage.

Take a look at elwogs' graph at the top of page 3 since that's a nice high res picture. You'll need to click on it and possibly click on it again to zoom right in so you can see the details.



The upper line is still going up where the bottom line is going down, the bottom line then drops off much more steeply.
The rear wheel number is peaking at about 5800 and the crank at about 6100.
To my mind the key thing here is that they clearly aren't at 6500 which is where Jaguar say the peak is.
Measuring torque accurately is not straight forward, measure frequency is a piece of piss. The rolling road isn't going to get that number wrong.

The torque line is a guestimated one, someone picked me up on that mistake earlier.
The dyno measures the rear wheel torque and then calculated the rear wheel BHP from those numbers (see the sum above). It then guestimates crank numbers and plots these guesses at the power and torque.
In a posting above somewhere I put the rear wheel torque figures calculated back from the rear wheel BHP numbers.

[300bhp/ton]

Dolittle said:

300bhp/ton said:

Are the rwhp figures all similar too?

And have any non-S V6's been on these 4 different dyno's? If so, what sort of hp difference is there between them?

V6 non S has been on one rolling road, the same one I put a V6S and a V8s on.

V6 290BHP Jag quote 340BHP

V6S 335BHP Jag quote 375BHP

V8S 506BHP Jag quote 488BHP

On face value those figures look fine.

The V6 makes the least, noticeable gap to V6S and noticeable gap to V8S.

The higher the figure, the bigger the fudge factor to "guess" flywheel figures.

And if you read back through my earlier posts, there are plenty of reasons why figures maybe different and why sometimes you might think they are accurate or not.


But look at this logically.

Jag claimed figures:
375 - 340 = 35hp difference.

Your own dyno testing produced:
335 - 290 = 45hp difference.

That would seem about bang on. The fact the total numbers are different likely relates to the myriad of reasons posted already.


The oddball figure is the V8S. But without know what correct factors and how this is being applied as well as how the flywheel guessing figure is produced, the numbers mean little.

Not too mention yet again, heat soak, ambient temp and air flow can all play major roles in rolling road dyno sessions.


But if I sum up.

You are claiming:

-The V6S is underpowered
-But makes 45hp more than a V6

Are you also claiming the V6 is underpowered?


Logically, is it more likely Jag have got two figures wrong, or that your testing approach is maybe not the most accurate and comparable?


I'm not saying the V6S isn't underpowered, only that your "evidence" doesn't support this and is far from conclusive.


__________________________

[300bhp/ton]

a8hex said:

Take a look at elwogs' graph at the top of page 3 since that's a nice high res picture. You'll need to click on it and possibly click on it again to zoom right in so you can see the details.



The upper line is still going up where the bottom line is going down, the bottom line then drops off much more steeply.
The rear wheel number is peaking at about 5800 and the crank at about 6100.
To my mind the key thing here is that they clearly aren't at 6500 which is where Jaguar say the peak is.
Measuring torque accurately is not straight forward, measure frequency is a piece of piss. The rolling road isn't going to get that number wrong.

The torque line is a guestimated one, someone picked me up on that mistake earlier.
The dyno measures the rear wheel torque and then calculated the rear wheel BHP from those numbers (see the sum above). It then guestimates crank numbers and plots these guesses at the power and torque.
In a posting above somewhere I put the rear wheel torque figures calculated back from the rear wheel BHP numbers.

The different in curve profile could be, as I see down to the fudge factor of guessing flywheel hp.

There is the 15% rule, although for automatics often used as an 18% rule (which dramatically changes the flywheel figures it produces).

Again I've also seen dyno's use 12% for manual cars and even extremes of 25% for AWD vehicles.

There are also some that use a fixed value + percentage, such as 10%+12hp or something similar. Which some claim works well on higher output cars, but would obviously be flawed if you dyno's a 60hp city car.

Then other variations of this could be a cost down value + percentage or even a varying cost down value + percentage.


It is odd the curve profiles don't match, but I think it's just a side affect result of how they are buggering about with the rwhp numbers to try and give some kind of flywheel figure.


Personally I'd just stick to the rwhp figures and note the differences between them.


If a V6 makes 30-40hp less rwhp than a V6S, which in turn makes 100+hp less rwhp than a V8S, then they all seem pretty sound and relative to each other.

The only way to fully know how much power the engine makes is to fit it to an engine dyno and test it to the exact same standard and level, using the same equipment as Jaguar did. That would then give you a comparable result. Nothing else will.

[a8hex]

300bhp/ton said:

The different in curve profile could be, as I see down to the fudge factor of guessing flywheel hp.

Exactly, I was just pointing out that these graphs don't show a fixed percentage.
Back when ftypical pointed out my error in assuming the torque was the measured one I actually worked out the variation in difference between the measured rw numbers and the guestimated crank ones, it does increase with revs, which makes sense, but it wasn't linear and wasn't obvious, so I didn't take it any further... I'm not quite that nosy.

300bhp/ton said:

It is odd the curve profiles don't match, but I think it's just a side affect result of how they are buggering about with the rwhp numbers to try and give some kind of flywheel figure.


Personally I'd just stick to the rwhp figures and note the differences between them.

Personally I'd like to see the use of crank figures banned as they are totally useless to anyone. IMHO manufactures who wish to quote engine performance stats should be required to publish the rear wheel numbers which are the only useful ones. Since you can't use the engine sitting on a bench with an ECU which has all the go like stink settings locked permanently on, what's the use of quoting it. You can however use the poke that erupts out of the rear wheels.
I don't think that this would solve this particular problem however since I don't think the engine on the rolling road is running at full chat. It's just a pity that someone from Jaguar's public relations dept won't poke someone technical to give a quick run down on why not.

300bhp/ton said:

The only way to fully know how much power the engine makes is to fit it to an engine dyno and test it to the exact same standard and level, using the same equipment as Jaguar did. That would then give you a comparable result. Nothing else will.

Even for simple engines this is the case, I remember talking to people who prepare classic XK race engines with mechanical points and carburettors and they said that setting the engine up on a rolling road didn't equate to then taking it out on the track at trying for real. Certainly my own XK150 wouldn't behave anything like right on a rolling road since it would overheat the float chamber on the front carb in no time. Even backing off briefly on the track is enough to take her off song.

Edited by a8hex on Wednesday 5th August 18:29

[bordseye]

a8hex said:

Take a look at elwogs' graph at the top of page 3 since that's a nice high res picture. You'll need to click on it and possibly click on it again to zoom right in so you can see the details.



The upper line is still going up where the bottom line is going down, the bottom line then drops off much more steeply.
The rear wheel number is peaking at about 5800 and the crank at about 6100.
To my mind the key thing here is that they clearly aren't at 6500 which is where Jaguar say the peak is.
Measuring torque accurately is not straight forward, measure frequency is a piece of piss. The rolling road isn't going to get that number wrong.

The torque line is a guestimated one, someone picked me up on that mistake earlier.
The dyno measures the rear wheel torque and then calculated the rear wheel BHP from those numbers (see the sum above). It then guestimates crank numbers and plots these guesses at the power and torque.
In a posting above somewhere I put the rear wheel torque figures calculated back from the rear wheel BHP numbers.

I dont disagree with the points you make - it is clear that the dyno adjustment to get crank bhp is weird . And not just in the graph you quote. The second one on Page 1 showas the power absorption staying constant as the revs increase and power drops from the peaklevel. Plus as you point out, they dont show power peaking at the revs quoted by Jaguar. So yes there is something not right. But at the same time I suspect the major difference between the dyno figures and Jaguars is the adjustment from rear wheel to crank output.

Unfortunately only Jaguar can tell us unless some member is willing and able to remove his engine and put it on an engine dyno.