0-60 4.4!
#21
02-03-2012, 10:46 AM
Senior Member
2 things
The 2 things missing for better 0-60 are 4 wheel drive and launch control.
Sorry but the numbers tell me the 2010+ XKR is a 4.4 second car.
My comparison point: 2011 Ford Shelby Mustang GT500 which has
550 HP (more than the XKR)
510 lbs/foot (more than the XKR)
3820 lbs weight (less than the XKR)
0-60, 4.4 sec (same as the XKR)
So the XKR is doing more with less performance numbers.
My source is Inside Line which I believe do the most accurate and TRUE tests (no rollout or fudging the numbes)
http://www.insideline.com/ford/shelb...full-test.html
Sorry but the numbers tell me the 2010+ XKR is a 4.4 second car.
My comparison point: 2011 Ford Shelby Mustang GT500 which has
550 HP (more than the XKR)
510 lbs/foot (more than the XKR)
3820 lbs weight (less than the XKR)
0-60, 4.4 sec (same as the XKR)
So the XKR is doing more with less performance numbers.
My source is Inside Line which I believe do the most accurate and TRUE tests (no rollout or fudging the numbes)
http://www.insideline.com/ford/shelb...full-test.html
Last edited by Mike V; 02-03-2012 at 10:50 AM. Reason: Link mistake
#22
02-03-2012, 12:29 PM
Skeeter,
GT-R and others with AWD and/or launch control can't be compared. Cars with much wider rear tire like the Z-06 can't be compared. Engine weight over the drive wheels like the 911 can't be compared. Actual engine power vs. marketing numbers as mentioned, test conditions including altitude, air temps, road surface grip. Different tires with different grip characteristics, tire profile/sidewall/inflation pressure all affecting launch grip. Octane of fuel used can affect power. Preheating of tires to optimize grip. Power/weight ratio obviously....assuming you can get comparable numbers.
What cars are making you think the XKR isn't measuring up? I can't think of one, but I definitely haven't been giving the issue the same amount of thought...and may have considered more factors. If there is a better performer that can't be easily explained by the above, then that leaves launch technique, stability/traction control setup, and a whack of suspension related factors that could make the difference.
Bruce
GT-R and others with AWD and/or launch control can't be compared. Cars with much wider rear tire like the Z-06 can't be compared. Engine weight over the drive wheels like the 911 can't be compared. Actual engine power vs. marketing numbers as mentioned, test conditions including altitude, air temps, road surface grip. Different tires with different grip characteristics, tire profile/sidewall/inflation pressure all affecting launch grip. Octane of fuel used can affect power. Preheating of tires to optimize grip. Power/weight ratio obviously....assuming you can get comparable numbers.
What cars are making you think the XKR isn't measuring up? I can't think of one, but I definitely haven't been giving the issue the same amount of thought...and may have considered more factors. If there is a better performer that can't be easily explained by the above, then that leaves launch technique, stability/traction control setup, and a whack of suspension related factors that could make the difference.
Bruce
#23
02-03-2012, 12:58 PM
#24
02-03-2012, 06:43 PM
Wrote a long-*** response and lost it when the Siamese decided to step on the "back" key on my keyboard. Ouch. Well, I saved you all a long winded response, the gist of which was that the suggestion to do a dyno and get real RWHP data is a good one. Bruce, I'm thinking of cars like the M3, which matches our 4.4 with less HP and WAY less torque. Or the previously mentioned mustang 302, 60 or so less HP, 80 less lb.ft., only 200 lbs lighter, but flat 4's on a solid rear axle. The GT500 shows 4.2's, even from Ford, and also has a primitive rear end that should advantage the XKR. Problem with the GT500 is traction, impossible to launch. So THEY have an answer to 'why not faster': too much torque, shreds the rear tires, can't put the power down with the suspension/diff/tire setup. I'm looking for a similar answer. Power? Tire size? Suspension? Differential? Gearing? One factor or several? Or no factor at all, 4.4 is what you'd expect given our spec? This last answer doesn't sit well.
The M3: Way less HP and WAY less torque, couple hundred pounds lighter but still inferior power/weight (and torque of 295 at ~4,000rpm alone should put the XKR way ahead), and yet the M3 produces a 4.4 second 0-60.
Powerband doesn't seem a likely culprit: Torque is huge and comes on at 2,500. HP is high and not peaky. Car pulls like a freight train at low RPM. Yet traction isn't as big an issue as it was, say in my old E55, which put out 50 or so lb.ft. more at slightly higher RPM than the XKR.
The torque in the Jag seems perfect. Too much is a problem (as with the GT500). My 2005 E55 would just bake the tires if you fed it an inch too much of the go pedal, too much torque, ~50 more than the Jag. The Jag can certainly be made to light up the tires, but not as eagerly as the E in my experience. Seems like the perfect combo, good but not overwhelming torque down low, over 500hp at 6k, awesome transmission, supposedly state of the art differential and IRS...
I'm not comparing the XKR to a Z06 or GTR! Those are low 3/high 2 cars! Crazy! Our specs don't line up with theirs. I'll go through some other cars and find more examples of cars with less numbers and faster 0-60 times, I'm confident it'll be more the rule than the exception that lesser endowed cars out-match the XKR in this one measure. I feel like something is holding back the XKR. If the answer is power, I'm cool with that.
But 510hp/461lbft@2500rmp is serious power. Not supercar power, and yes, the car isn't super light, but it isn't bloated. I guess I need to see a power/torque to weight ranking of various cars and see what they do 0-60 and the quarter mile in to make my case. But based on what I see cars do, cars I've owned, friend's cars, cars I've driven, that 4.4 isn't right.
Bruce, you are right that launch technique may be a big issue. I suspect I'm under-skilled in the XKR for 0-60 runs. I've had enough track time/cart racing time to feel competent in most driving skills, no expert but certainly enthusiast level skills. But no drag-racing experience. No training, not enough practice, no research or advice regarding techniques, etc. I was hoping for some advice from board members who have broken through to better times and proper technique, but so far little advice and no better results posted.
Suspension is, I'll say again, an area I suspect is part of the problem. In my E55, at launch the suspension could be set to 'soft', and I could feel the car lean back and put more weight on the rear suspension. The Jag, on the other hand, feels tight and stiff at launch, more of a cornering shock rate and less softness to allow weight transfer to the back of the car. Probably no way for me to experiment on this factor, since the shocks are controlled by the 'puter. I wonder if an ECU tuning shop could experiment with these settings, allow for the rear to soften up in a launch scenario. Probably not.
Gearing is another good possibility. Don't know much about gearing and rear end ratios. Are our cars optimized for better performance from higher speeds? When I was on a closed road with no legal repercussions or danger to others, I was BLOWN AWAY at how hard the XKR pulled from ~50 up to the limiter ~155mph. A missile. Seat of the pants dyno was more than satisfied. From a roll, the car digs in her claws, shifts gear with psychic prescience, and takes off like an aluminum missile. No disconnect between results and specs, at least not by the subjective sense since I haven't measured it.
But 0-60, still a bit of a mystery to me, if no one else.
Sorry to
. Imagine how long my original post was if this is a summary! I'll stop with the extended posts and apologize to Kelly for hijacking her thread. Promise
.
Skeeter
The M3: Way less HP and WAY less torque, couple hundred pounds lighter but still inferior power/weight (and torque of 295 at ~4,000rpm alone should put the XKR way ahead), and yet the M3 produces a 4.4 second 0-60.
Powerband doesn't seem a likely culprit: Torque is huge and comes on at 2,500. HP is high and not peaky. Car pulls like a freight train at low RPM. Yet traction isn't as big an issue as it was, say in my old E55, which put out 50 or so lb.ft. more at slightly higher RPM than the XKR.
The torque in the Jag seems perfect. Too much is a problem (as with the GT500). My 2005 E55 would just bake the tires if you fed it an inch too much of the go pedal, too much torque, ~50 more than the Jag. The Jag can certainly be made to light up the tires, but not as eagerly as the E in my experience. Seems like the perfect combo, good but not overwhelming torque down low, over 500hp at 6k, awesome transmission, supposedly state of the art differential and IRS...
I'm not comparing the XKR to a Z06 or GTR! Those are low 3/high 2 cars! Crazy! Our specs don't line up with theirs. I'll go through some other cars and find more examples of cars with less numbers and faster 0-60 times, I'm confident it'll be more the rule than the exception that lesser endowed cars out-match the XKR in this one measure. I feel like something is holding back the XKR. If the answer is power, I'm cool with that.
But 510hp/461lbft@2500rmp is serious power. Not supercar power, and yes, the car isn't super light, but it isn't bloated. I guess I need to see a power/torque to weight ranking of various cars and see what they do 0-60 and the quarter mile in to make my case. But based on what I see cars do, cars I've owned, friend's cars, cars I've driven, that 4.4 isn't right.
Bruce, you are right that launch technique may be a big issue. I suspect I'm under-skilled in the XKR for 0-60 runs. I've had enough track time/cart racing time to feel competent in most driving skills, no expert but certainly enthusiast level skills. But no drag-racing experience. No training, not enough practice, no research or advice regarding techniques, etc. I was hoping for some advice from board members who have broken through to better times and proper technique, but so far little advice and no better results posted.
Suspension is, I'll say again, an area I suspect is part of the problem. In my E55, at launch the suspension could be set to 'soft', and I could feel the car lean back and put more weight on the rear suspension. The Jag, on the other hand, feels tight and stiff at launch, more of a cornering shock rate and less softness to allow weight transfer to the back of the car. Probably no way for me to experiment on this factor, since the shocks are controlled by the 'puter. I wonder if an ECU tuning shop could experiment with these settings, allow for the rear to soften up in a launch scenario. Probably not.
Gearing is another good possibility. Don't know much about gearing and rear end ratios. Are our cars optimized for better performance from higher speeds? When I was on a closed road with no legal repercussions or danger to others, I was BLOWN AWAY at how hard the XKR pulled from ~50 up to the limiter ~155mph. A missile. Seat of the pants dyno was more than satisfied. From a roll, the car digs in her claws, shifts gear with psychic prescience, and takes off like an aluminum missile. No disconnect between results and specs, at least not by the subjective sense since I haven't measured it.
But 0-60, still a bit of a mystery to me, if no one else.
Sorry to
. Imagine how long my original post was if this is a summary! I'll stop with the extended posts and apologize to Kelly for hijacking her thread. Promise.Skeeter
The following users liked this post:
resident_fng (11-07-2021)
#26
02-04-2012, 10:57 AM
I stopped trying to "drag race" my Z06 and focus on it's intended environment - the road course after getting my head handed to me by a Mustang GT500 during a weekly Test and Tune event held at my local track.
It's all in the driver and I finally had to admit I couldn't launch my Z06 with any consistency.
So it's the road course for me
A man has to know his limitations and what his car does best and then extract it.
Tom
It's all in the driver and I finally had to admit I couldn't launch my Z06 with any consistency.
So it's the road course for me
A man has to know his limitations and what his car does best and then extract it.
Tom
Last edited by TomServo; 02-04-2012 at 11:00 AM. Reason: added photos
#27
02-04-2012, 11:40 AM
Skeeter,
For acceleration, the only power number that matters is what it makes at high rpm, not 2500 or 5500 rpm. If it makes peak power at 6000 rpm that's not nearly as useful as at 8000 rpm. Engine torque is multiplied as it's fed through the transmission and differential and becomes the "wheel torque" that propells the car...if the tires can cope with it. First gear multiplies engine power much more than 2nd, and 2nd much more than 3rd. That means a lot more power is driving the rear wheels in lower gears, and every time you upshift you're throwing away power to the wheels.
The most desirable powerband is one where the horsepower as seen on a dynograph continues to rise to a high redline, or maybe only levels or falls off a tiny bit at redline. This shape of power band will always produce the best accelleration when shifted at redline, or darn close. The "optimum shift point" for each gear can be calculated mathematically using engine power and gear ratios.
The XKR powerband and gear ratios selection have been chosen to provide effortless cruising at low rpms, and those for the M3 would have been optimized for the track junkie who is going to wind it out to 8000 with the understanding that that's how you go fast. We like the grunt of XKR in every gear and every rpm, and would probably dislike having to rev the M3, or other "higher strung" powerband cars.
So peak power numbers really don't tell you much when it comes to accelleration, and using them to calculate power to weight ratios leads to further confusion. The effect of addition weight on acceleration is significant, and more than what comparing misleading power to weight ratios would reveal.
But let's talk rear tire grip for a second. It's pretty obvious that the XKR's has a huge lower rpm torque explosion, intensely multiplied by such a low gear that starting in 2nd is all but mandatory, and the use of direct injection and operating in dynamic mode is the response equivalent of a hair trigger, and it's little wonder it's so hard to launch the thing without excessive wheel spin. The vehicle traction control electronics are working overtime to reduce the wheel torque, and siphoning off much of that 461 ft-lbs of torque. The M3 isn't going to have these issues, and it probably has launch control to guarantee it.
I could spin the tires at almost 60 mph when flooring it while driving along the highways this fall when temps were getting cool. Traction control was kicking in. I can't imagine trying to launch effectively from 1st or 2nd.
Maximum tire grip for acceleration is achieved with some slippage, and varies from one tire to another. Optimizing acceleration would require a launch control that maximizes the powerband and gear ratios used for 0-60, the 1/4 mile, etc, and a traction/stability control system that allows just the right amount of wheel spin.
I imagine Jaguar had different priorities in mind for their upscale GT cruiser than designers of hardcore sports cars and sedans did, and you can see there are far too many factors that explain differences in performance to try to predict anything based on a few isolated ones. What you can hopefully predict is that the car will accelerate as advertised and tested...at least under some conditions!
Bruce
For acceleration, the only power number that matters is what it makes at high rpm, not 2500 or 5500 rpm. If it makes peak power at 6000 rpm that's not nearly as useful as at 8000 rpm. Engine torque is multiplied as it's fed through the transmission and differential and becomes the "wheel torque" that propells the car...if the tires can cope with it. First gear multiplies engine power much more than 2nd, and 2nd much more than 3rd. That means a lot more power is driving the rear wheels in lower gears, and every time you upshift you're throwing away power to the wheels.
The most desirable powerband is one where the horsepower as seen on a dynograph continues to rise to a high redline, or maybe only levels or falls off a tiny bit at redline. This shape of power band will always produce the best accelleration when shifted at redline, or darn close. The "optimum shift point" for each gear can be calculated mathematically using engine power and gear ratios.
The XKR powerband and gear ratios selection have been chosen to provide effortless cruising at low rpms, and those for the M3 would have been optimized for the track junkie who is going to wind it out to 8000 with the understanding that that's how you go fast. We like the grunt of XKR in every gear and every rpm, and would probably dislike having to rev the M3, or other "higher strung" powerband cars.
So peak power numbers really don't tell you much when it comes to accelleration, and using them to calculate power to weight ratios leads to further confusion. The effect of addition weight on acceleration is significant, and more than what comparing misleading power to weight ratios would reveal.
But let's talk rear tire grip for a second. It's pretty obvious that the XKR's has a huge lower rpm torque explosion, intensely multiplied by such a low gear that starting in 2nd is all but mandatory, and the use of direct injection and operating in dynamic mode is the response equivalent of a hair trigger, and it's little wonder it's so hard to launch the thing without excessive wheel spin. The vehicle traction control electronics are working overtime to reduce the wheel torque, and siphoning off much of that 461 ft-lbs of torque. The M3 isn't going to have these issues, and it probably has launch control to guarantee it.
I could spin the tires at almost 60 mph when flooring it while driving along the highways this fall when temps were getting cool. Traction control was kicking in. I can't imagine trying to launch effectively from 1st or 2nd.
Maximum tire grip for acceleration is achieved with some slippage, and varies from one tire to another. Optimizing acceleration would require a launch control that maximizes the powerband and gear ratios used for 0-60, the 1/4 mile, etc, and a traction/stability control system that allows just the right amount of wheel spin.
I imagine Jaguar had different priorities in mind for their upscale GT cruiser than designers of hardcore sports cars and sedans did, and you can see there are far too many factors that explain differences in performance to try to predict anything based on a few isolated ones. What you can hopefully predict is that the car will accelerate as advertised and tested...at least under some conditions!
Bruce
#28
02-04-2012, 12:53 PM
Veteran Member
I may be wandering into a forum section where I don't belong but the thread title caught my eye. The hand-wringing going one about whether the car will run 4.4 or 4.2 or 4.0 0-60 is amusing. In real-life day-to-day driving are you going to be driving around disappointed that, on paper, your car might be 0.2 sec less fast? If your life revolves around your ability to go from 0-60 in some specified time, go buy one of those super light super fast Subaru WRX or similar for a few thousand dollars and be happy.
Just sayin'
Doug
Just sayin'
Doug
#29
02-04-2012, 02:11 PM
Veteran Member
Nice pictures, Tom, nice day, nice cars and looks to be a well behaved field.
Street cars on tracks have come a long ways in past 8 years since I quit racing. I noticed from the Skeeter-attached Boss 302 road-test in this thread that it ran pretty much identical lap times at Laguna Seca (1:40) that I used to run in my full race, slicks-equipped 2100lbs race GT-3 car and win the race. I'm impressed for a 3600lbs street car, with assumed street tires, to be able to do that. I would expect your ZO6 with 400 lbs less and 60HP more to have even more potential for the track. Impressive!
Albert
Street cars on tracks have come a long ways in past 8 years since I quit racing. I noticed from the Skeeter-attached Boss 302 road-test in this thread that it ran pretty much identical lap times at Laguna Seca (1:40) that I used to run in my full race, slicks-equipped 2100lbs race GT-3 car and win the race. I'm impressed for a 3600lbs street car, with assumed street tires, to be able to do that. I would expect your ZO6 with 400 lbs less and 60HP more to have even more potential for the track. Impressive!
Albert
I stopped trying to "drag race" my Z06 and focus on it's intended environment - the road course after getting my head handed to me by a Mustang GT500 during a weekly Test and Tune event held at my local track.
It's all in the driver and I finally had to admit I couldn't launch my Z06 with any consistency.
So it's the road course for me
A man has to know his limitations and what his car does best and then extract it.
Tom
It's all in the driver and I finally had to admit I couldn't launch my Z06 with any consistency.
So it's the road course for me
A man has to know his limitations and what his car does best and then extract it.
Tom
#30
02-04-2012, 04:15 PM
I may be wandering into a forum section where I don't belong but the thread title caught my eye. The hand-wringing going one about whether the car will run 4.4 or 4.2 or 4.0 0-60 is amusing. In real-life day-to-day driving are you going to be driving around disappointed that, on paper, your car might be 0.2 sec less fast? If your life revolves around your ability to go from 0-60 in some specified time, go buy one of those super light super fast Subaru WRX or similar for a few thousand dollars and be happy.
Just sayin'
Doug
Just sayin'
Doug
If your not interested in tracking your car the numbers are meaningless.
Tom
#31
02-05-2012, 03:33 PM
Seismic, I'm not sure what I wrote that you are reading as 'hand-wringing'.
I've been curious about this aspect of the car and asked questions, no more. Maybe you missed all the posts about how in love with the car I am and how I'd like to solve what looks like a riddle to me. I look forward to playing around with this, I'm having a good time with it and hope to produce results. And there is a BIG difference between running a 4.4 (which is not easily repeated and the BEST I've turned), and a flat 4. Huge difference, 4 tenths in a short run to sixty is a major diff, many many car lengths lost in only 4 seconds. Hell, .4 in the quarter mile is a huge difference. .4 difference in 0-60 is another planet!
If anything, you should see that I'm a major proponent of my XKR by feeling that it is capable of more and wondering how. Telling me to buy a different car if I expect performance in this arena is grounds we've already covered and misses the point of the question. PLEASE enough with the 'if you want to go fast 0-60, buy a Subaru/Z06/GTR'... No, I'll drive the Jag, with pleasure, and will do what I can to figure out how get best performance out of it. I've posted tons of posts with similar questions related to other aspects of performance, handling, etc., so this is one of many things I'm trying to learn and optimize.
But seriously, we went over this many many posts ago. Crazy IMO to say that if you also want good acceleration numbers, numbers that seem attainable given the specs and overall feel of the car, that somehow that is wrong and I need to buy a different car.
Let's stick to Kelly's original question and not dismiss it, or say that if 0-60 times are of interest that one's life 'revolves around it'... If my life revolved around it, I'd be modding the cr*p out of the car, putting bigger rear tires on it, spending every spare moment launching and practicing, or I'd trade it in for a XKR-S. I love the car as is, just feel like it has more in it than I am extracting and wondering why.
On the board I participated in for my E55, these kinds of topics (how to launch for better 0-60, why can't I put up numbers that seem attainable, etc) were met with suggestions, launch techniques, times other owners were producing, power mods, cooling mods, tire swaps, suggested tire pressure and suspension settings, etc. Not these posts about what heresy it is to suggest that the 510 HP XKR feels like more of a beast than the 4.4 best time we see, or that trying to turn good 0-60 times is below the aristocratic Jaguar brand, and to buy another car if I care at all about 0-60 times. What gives?
Bruce, huge thanks for the informative post. Not sure I understand that a car will produce faster 0-60 times with peak HP at a much higher RPM, I would think that the lower it comes on the better, likewise with torque. Unless (like the E55), it puts down so much torque that you can't hook up. The torque and HP curves for the Jag look ideal for launch, but clearly you are more of an expert to me, so I'll re read your post and try to wrap my head around it and see what actions/mods/launch techniques might help. With traction control off, a skilled driver should be able to spool maximum torque to the rear wheels without overwhelming the tires, and produce a result in line with the big low RPM torque #s and the high HP at lower (and more easily tapped into) RPM, unlike the M3. Gotta say, massive wheel spin has been less of an issue in the Jag. If too much power is the problem, your post suggests that launch technique may be the answer, so you've given me something to work on next time I can practice. If the answer were as simple as larger/stickier rear tires, we'd be on to something... This is where I was hoping the thread would go
The car is plenty fast my friends, more than enough to frighten even brave passengers who ask to see how fast she'll go in a safe setting. I'm in no way any less in love, nor am I interested in a Subaru WRX... So much done so well in the Jag. But I don't treat mine like a fancy car that isn't meant to be pushed in the right setting. Life is for the living and if I wanted a car to be driven gently, I'd have bought some luxury boat and gone from point A to point B without looking for a visceral thrill along the way.
Thanks,
Skeeter
I've been curious about this aspect of the car and asked questions, no more. Maybe you missed all the posts about how in love with the car I am and how I'd like to solve what looks like a riddle to me. I look forward to playing around with this, I'm having a good time with it and hope to produce results. And there is a BIG difference between running a 4.4 (which is not easily repeated and the BEST I've turned), and a flat 4. Huge difference, 4 tenths in a short run to sixty is a major diff, many many car lengths lost in only 4 seconds. Hell, .4 in the quarter mile is a huge difference. .4 difference in 0-60 is another planet!
If anything, you should see that I'm a major proponent of my XKR by feeling that it is capable of more and wondering how. Telling me to buy a different car if I expect performance in this arena is grounds we've already covered and misses the point of the question. PLEASE enough with the 'if you want to go fast 0-60, buy a Subaru/Z06/GTR'... No, I'll drive the Jag, with pleasure, and will do what I can to figure out how get best performance out of it. I've posted tons of posts with similar questions related to other aspects of performance, handling, etc., so this is one of many things I'm trying to learn and optimize.
But seriously, we went over this many many posts ago. Crazy IMO to say that if you also want good acceleration numbers, numbers that seem attainable given the specs and overall feel of the car, that somehow that is wrong and I need to buy a different car.
Let's stick to Kelly's original question and not dismiss it, or say that if 0-60 times are of interest that one's life 'revolves around it'... If my life revolved around it, I'd be modding the cr*p out of the car, putting bigger rear tires on it, spending every spare moment launching and practicing, or I'd trade it in for a XKR-S. I love the car as is, just feel like it has more in it than I am extracting and wondering why.
On the board I participated in for my E55, these kinds of topics (how to launch for better 0-60, why can't I put up numbers that seem attainable, etc) were met with suggestions, launch techniques, times other owners were producing, power mods, cooling mods, tire swaps, suggested tire pressure and suspension settings, etc. Not these posts about what heresy it is to suggest that the 510 HP XKR feels like more of a beast than the 4.4 best time we see, or that trying to turn good 0-60 times is below the aristocratic Jaguar brand, and to buy another car if I care at all about 0-60 times. What gives?
Bruce, huge thanks for the informative post. Not sure I understand that a car will produce faster 0-60 times with peak HP at a much higher RPM, I would think that the lower it comes on the better, likewise with torque. Unless (like the E55), it puts down so much torque that you can't hook up. The torque and HP curves for the Jag look ideal for launch, but clearly you are more of an expert to me, so I'll re read your post and try to wrap my head around it and see what actions/mods/launch techniques might help. With traction control off, a skilled driver should be able to spool maximum torque to the rear wheels without overwhelming the tires, and produce a result in line with the big low RPM torque #s and the high HP at lower (and more easily tapped into) RPM, unlike the M3. Gotta say, massive wheel spin has been less of an issue in the Jag. If too much power is the problem, your post suggests that launch technique may be the answer, so you've given me something to work on next time I can practice. If the answer were as simple as larger/stickier rear tires, we'd be on to something... This is where I was hoping the thread would go
The car is plenty fast my friends, more than enough to frighten even brave passengers who ask to see how fast she'll go in a safe setting. I'm in no way any less in love, nor am I interested in a Subaru WRX... So much done so well in the Jag. But I don't treat mine like a fancy car that isn't meant to be pushed in the right setting. Life is for the living and if I wanted a car to be driven gently, I'd have bought some luxury boat and gone from point A to point B without looking for a visceral thrill along the way.
Thanks,
Skeeter
Last edited by Skeeter; 02-05-2012 at 03:37 PM.
The following users liked this post:
resident_fng (11-07-2021)
#32
02-05-2012, 06:26 PM
Veteran Member
#33
02-05-2012, 06:27 PM
Skeeter,
The "ideal shift point" would be worth a google to maybe better see how hp peak and torque peak are combined with gear ratios to provide maximum power to the wheels for acceleration. The way I described it may seem counter-intuitive, it certainly did to me when I first tried to understand it, but once you understand the concept you may find my description makes perfect sense!
The key concept is that an engine that makes it's peak power as close to redline as possible will have its ideal shift point close to redline, and this will more effectively take advantage of the torque multiplication factor of the gear ratios to accelerate as fast as possible...and the higher the redline the greater the gains. I'm losing internet access in a few minutes until next weekend, but we can pick it up then if you have questions after looking into it more.
I didn't suggest a tire upgrade as I was addressing "numbers that seem attainable given the specs", but tires with more grip is 100% the way to go. 285's are par for an OEM tire on this sort of vehicle, but waaaay under-sized for turning righteous burnouts into impressive strip times. It's not really practical for most, but mounting a "drag radial" on your rear rims (if available in right size) would make a big difference, as would a wider tire on stock rim if it would physically fit. Wider rims could also be used if wider tires required them, and if they'd fit under the fenders. Check Tire Rack reviews for grippier tires, or even consider R Compound tires that are much stickier still, but aren't as good in the rain and wear out more quickly.
If you're changing wheels go with a 19" for the rears, or an 18" if they'll fit over the brake rotors and calipers. This will allow you to choose a higher profile tire, while maintaining the original overall tire diameter, with the high sidewalls flexing more to increase tire contact patch area upon launch for more grip. Lower inflation pressures promote the effect also. Warm up your tires before launch to soften the rubber, but over-cook them! The 3rd lap around a race track on a Toyo R compound tire will be the fastest because the first two warm the tires up to maximum grip temp, and after that grip starts to fall off due to hotter temps. Same goes for street tires.
Hope that helps,
Bruce
The "ideal shift point" would be worth a google to maybe better see how hp peak and torque peak are combined with gear ratios to provide maximum power to the wheels for acceleration. The way I described it may seem counter-intuitive, it certainly did to me when I first tried to understand it, but once you understand the concept you may find my description makes perfect sense!
The key concept is that an engine that makes it's peak power as close to redline as possible will have its ideal shift point close to redline, and this will more effectively take advantage of the torque multiplication factor of the gear ratios to accelerate as fast as possible...and the higher the redline the greater the gains. I'm losing internet access in a few minutes until next weekend, but we can pick it up then if you have questions after looking into it more.
I didn't suggest a tire upgrade as I was addressing "numbers that seem attainable given the specs", but tires with more grip is 100% the way to go. 285's are par for an OEM tire on this sort of vehicle, but waaaay under-sized for turning righteous burnouts into impressive strip times. It's not really practical for most, but mounting a "drag radial" on your rear rims (if available in right size) would make a big difference, as would a wider tire on stock rim if it would physically fit. Wider rims could also be used if wider tires required them, and if they'd fit under the fenders. Check Tire Rack reviews for grippier tires, or even consider R Compound tires that are much stickier still, but aren't as good in the rain and wear out more quickly.
If you're changing wheels go with a 19" for the rears, or an 18" if they'll fit over the brake rotors and calipers. This will allow you to choose a higher profile tire, while maintaining the original overall tire diameter, with the high sidewalls flexing more to increase tire contact patch area upon launch for more grip. Lower inflation pressures promote the effect also. Warm up your tires before launch to soften the rubber, but over-cook them! The 3rd lap around a race track on a Toyo R compound tire will be the fastest because the first two warm the tires up to maximum grip temp, and after that grip starts to fall off due to hotter temps. Same goes for street tires.
Hope that helps,
Bruce
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Skeeter (02-05-2012)
#34
02-05-2012, 09:40 PM
Veteran Member
Skeeter
Do pay atttention also to the transmission and rear end ratios. They make a substantial difference in acceleratiom. Note that the Boss 302 comes with a 3.73 rear, optimised for quick spool-up. Our XK(R)s are tuned for much wider ratios that favors relaxed cruising, instead of max. acceleration. That is an obvious design difference between a true GT car and one with track performance priorities.
Albert
Do pay atttention also to the transmission and rear end ratios. They make a substantial difference in acceleratiom. Note that the Boss 302 comes with a 3.73 rear, optimised for quick spool-up. Our XK(R)s are tuned for much wider ratios that favors relaxed cruising, instead of max. acceleration. That is an obvious design difference between a true GT car and one with track performance priorities.
Albert
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tommyd (02-06-2012)
#35
02-05-2012, 11:49 PM
The "hand-wringing" are the 30+ posts debating the issue over a couple of tenths of seconds. Really?
Doug
So discussion=hand wringing. Ok. With 1,488 posts, your hands must be in bad shape!
No, all in good spirits here, enthusiast questions about an enthusiast's car. Youve had your car a while, I'm a relatively new owner of a relatively new motor, and curious about its capacity and limits. All part of the thrill of a new car to me. I won't be asking or wondering when my car is six years old, so I guess I see why you might not relate to those of us who are curious about less reviewed cars.
And we are talking about a couple of tenths... Right.
Feel free to tune the thread out if not of interest, or if the subject beneath you. 'hand ringing', 'Buy a Subaru', got it...
Bruce: bigger/stickier rear tires, potentially 18" rims, sounds like sound advice. If I had access to a track I'd invest in a set of slicks to sort out the tire traction side of the equation. But you've got me thinking traction is an issue, maybe bigger rear tires on the stock rims? Is there enough rim to upgrade to a meaningfully wider tire? Possible? I did notice that the rear tires aren't as extreme as those on some of the other cars brought up in this thread (Subaru's not withstanding). Maybe part of the GT goal, with a much fatter tire producing more noise and harder ride, thus we have a thinner car an optimal for launch? THat would make sense. Interesting...
Thanks,
Skeeter
Doug
So discussion=hand wringing. Ok. With 1,488 posts, your hands must be in bad shape!
No, all in good spirits here, enthusiast questions about an enthusiast's car. Youve had your car a while, I'm a relatively new owner of a relatively new motor, and curious about its capacity and limits. All part of the thrill of a new car to me. I won't be asking or wondering when my car is six years old, so I guess I see why you might not relate to those of us who are curious about less reviewed cars.
And we are talking about a couple of tenths... Right.
Feel free to tune the thread out if not of interest, or if the subject beneath you. 'hand ringing', 'Buy a Subaru', got it...
Bruce: bigger/stickier rear tires, potentially 18" rims, sounds like sound advice. If I had access to a track I'd invest in a set of slicks to sort out the tire traction side of the equation. But you've got me thinking traction is an issue, maybe bigger rear tires on the stock rims? Is there enough rim to upgrade to a meaningfully wider tire? Possible? I did notice that the rear tires aren't as extreme as those on some of the other cars brought up in this thread (Subaru's not withstanding). Maybe part of the GT goal, with a much fatter tire producing more noise and harder ride, thus we have a thinner car an optimal for launch? THat would make sense. Interesting...
Thanks,
Skeeter
Last edited by Skeeter; 02-06-2012 at 12:12 AM.
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resident_fng (11-07-2021)
#36
02-06-2012, 10:18 AM
Veteran Member
Yeah--I have a lot of posts mostly about more mundane things like about how to fix a headrest that doesn't work or how to deal with the convertible top hydraulic problems. I have also been interested with tweaking more power out of whatever cars I have owned--not sure why as I have never taken a car to the track nor ever done any street racing. But still if you could easily do something that resulted in more oomph that was always nice.
But the only times I have seen threads getting down to the nitty gritty of how to get another tenth of a second in the quarter mile are either folks that routinely went to the drag strip and seriously competed (plenty of those on the Corvette forums I was a member of) or the boy/girl racers you find on the ricer forums where you find endless discussions of adding nitrous, or swapping body parts for carbon fiber to save a pound or two here or there.
I guess those types of discussions just seem incongruous on a Jaguar forum as I doubt whether there are many here that spend time at the drag strip or track. I guess it might be some important ego thing to be able to tell BMW or Mercedes acquaintances that your car is spec'd at 4 second 0-60 rather than (God-forbid) 4.2 seconds but other than that, what is the point?
Doug
But the only times I have seen threads getting down to the nitty gritty of how to get another tenth of a second in the quarter mile are either folks that routinely went to the drag strip and seriously competed (plenty of those on the Corvette forums I was a member of) or the boy/girl racers you find on the ricer forums where you find endless discussions of adding nitrous, or swapping body parts for carbon fiber to save a pound or two here or there.
I guess those types of discussions just seem incongruous on a Jaguar forum as I doubt whether there are many here that spend time at the drag strip or track. I guess it might be some important ego thing to be able to tell BMW or Mercedes acquaintances that your car is spec'd at 4 second 0-60 rather than (God-forbid) 4.2 seconds but other than that, what is the point?
Doug
#37
02-06-2012, 09:50 PM
Doug,
When you are talking about current model, 500+ horsepower cars costing >$100k new, the difference between a flat 4 and a 4.4 second 0-60 matters to many customers in that market. And YES, bet your *** that those numbers sell cars.
I see that you've even contemplated swapping out your catalytic converters to a high flow set if you can get a performance gain. Frankly, THAT seems odd, as it is not a cheap mod, and will in no reality give you close to a half second lift 0-60.
And you continue to equivocate... Who is talking about a tenth in the quarter mile? Not a single post by anyone, yet that's how you continue to dismissively frame the topic here. A .4 second lift to 60 is NOT a small difference, not just a mental thing, and something that any half way tuned in driver would notice. Discussing the possible limits of a newer model with a paucity of data is what forums are all about.
If the conversation isn't relevant to you and your 2005, why bother telling us that it shouldn't be to us? Maybe you tell to much in saying that the difference is 'some ego thing'; maybe it is (or would be) to you. I don't talk performance numbers of my car with anyone outside this board. Not an ego thing for me, I just want to see what a newly bought car is capable of.
The age of your car clearly puts you out of the quest of this thread. We Jaguar owners come in all shapes, we have different cars capable of different results, and I've been clear that I love my XKR for many reasons, performance being high on the list. I'm quite sure I drive my car harder than yours when the conditions allow. So performance matters to me.
I must be honest when I say that it perpetuates all the negative stereotypes about the Jaguar brand when 'buy a Subaru' is the response to curiosity about how to put down better performance numbers... That it's an old man car with a fancy wood interior made to drive sedately to the golf course on Sunday, not capable of sizing up to modern cars. That may be fine for some, but Jaguar made a serious statement in putting in the new 5.0S, and it (AND the class brand reputation and design) brought me back to the mark as a consumer as a result (among other things).
So embrace the differences Doug, be delighted that people have varied interests in their Jaguar, and recognize that the sustainability of the brand DOES include things like how fast they go. No, not hand wringing and misplaced and endless fixation over '1 tenth in the 1/4', give the thread another read and you'll see that the only one talking about that is you.
Later,
Skeeter
When you are talking about current model, 500+ horsepower cars costing >$100k new, the difference between a flat 4 and a 4.4 second 0-60 matters to many customers in that market. And YES, bet your *** that those numbers sell cars.
I see that you've even contemplated swapping out your catalytic converters to a high flow set if you can get a performance gain. Frankly, THAT seems odd, as it is not a cheap mod, and will in no reality give you close to a half second lift 0-60.
And you continue to equivocate... Who is talking about a tenth in the quarter mile? Not a single post by anyone, yet that's how you continue to dismissively frame the topic here. A .4 second lift to 60 is NOT a small difference, not just a mental thing, and something that any half way tuned in driver would notice. Discussing the possible limits of a newer model with a paucity of data is what forums are all about.
If the conversation isn't relevant to you and your 2005, why bother telling us that it shouldn't be to us? Maybe you tell to much in saying that the difference is 'some ego thing'; maybe it is (or would be) to you. I don't talk performance numbers of my car with anyone outside this board. Not an ego thing for me, I just want to see what a newly bought car is capable of.
The age of your car clearly puts you out of the quest of this thread. We Jaguar owners come in all shapes, we have different cars capable of different results, and I've been clear that I love my XKR for many reasons, performance being high on the list. I'm quite sure I drive my car harder than yours when the conditions allow. So performance matters to me.
I must be honest when I say that it perpetuates all the negative stereotypes about the Jaguar brand when 'buy a Subaru' is the response to curiosity about how to put down better performance numbers... That it's an old man car with a fancy wood interior made to drive sedately to the golf course on Sunday, not capable of sizing up to modern cars. That may be fine for some, but Jaguar made a serious statement in putting in the new 5.0S, and it (AND the class brand reputation and design) brought me back to the mark as a consumer as a result (among other things).
So embrace the differences Doug, be delighted that people have varied interests in their Jaguar, and recognize that the sustainability of the brand DOES include things like how fast they go. No, not hand wringing and misplaced and endless fixation over '1 tenth in the 1/4', give the thread another read and you'll see that the only one talking about that is you.
Later,
Skeeter
Last edited by Skeeter; 02-06-2012 at 09:58 PM.
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resident_fng (11-07-2021)
#38
02-06-2012, 10:32 PM
Veteran Member
#39
02-06-2012, 11:23 PM
Veteran Member
So sorry Skeeter..but as an attorney I'm sure you would want the facts of the case to be laid in order:
You've actually got Doug bracketed; 1st and last in references to the 1/4, and in totals you've doubled him up, 2:1. (unless you want to count actual "mentions" rather than # posts - hint: you don't) By the careful reading you advise, one may even draw the conclusion you baited Doug into his one reference to it then he plainly tried to refocus the discussion on the 0-60 IAW the OP's post.
OBJECTION! (your honor) "the attorney is projectiing on the plaintive..."
You've actually got Doug bracketed; 1st and last in references to the 1/4, and in totals you've doubled him up, 2:1. (unless you want to count actual "mentions" rather than # posts - hint: you don't) By the careful reading you advise, one may even draw the conclusion you baited Doug into his one reference to it then he plainly tried to refocus the discussion on the 0-60 IAW the OP's post.
Yeah--...
But the only times I have seen threads getting down to the nitty gritty of how to get another tenth of a second in the quarter mile are either folks that routinely went to the drag strip and seriously competed ...here or there.
...at 4 second 0-60 rather than (God-forbid) 4.2 seconds but other than that, what is the point?
Doug
But the only times I have seen threads getting down to the nitty gritty of how to get another tenth of a second in the quarter mile are either folks that routinely went to the drag strip and seriously competed ...here or there.
...at 4 second 0-60 rather than (God-forbid) 4.2 seconds but other than that, what is the point?
Doug
Doug,
....
And you continue to equivocate... Who is talking about a tenth in the quarter mile? Not a single post by anyone, yet that's how you continue to dismissively frame the topic here. A .4 second lift to 60 is NOT a small difference, not just a mental thing, and something that any half way tuned in driver would notice. ..
....
... No, not hand wringing and misplaced and endless fixation over '1 tenth in the 1/4', give the thread another read and you'll see that the only one talking about that is you.
Later,
Skeeter
....
And you continue to equivocate... Who is talking about a tenth in the quarter mile? Not a single post by anyone, yet that's how you continue to dismissively frame the topic here. A .4 second lift to 60 is NOT a small difference, not just a mental thing, and something that any half way tuned in driver would notice. ..
....
... No, not hand wringing and misplaced and endless fixation over '1 tenth in the 1/4', give the thread another read and you'll see that the only one talking about that is you.
Later,
Skeeter
OBJECTION! (your honor) "the attorney is projectiing on the plaintive..."
Last edited by aholbro1; 02-06-2012 at 11:35 PM.
#40
02-07-2012, 12:27 AM
Veteran Member
However, the last 0.05 seconds will only be found on the track, on a good day, with the best driver on his best day.
The "possibility" that brand "X' will do 0-60 in n.nn seconds might sell cars to a select few. How many times they actually get to see 0-60 in n.nn seconds is infinitesimally small. Especially if they want to keep their licence.
Want to know if a specific car can do 0-60 in 4.xx seconds? Take it to the track and get it timed.
Be prepared to get spanked by those who have better reaction times.