Nope, 100 more hp is about a full second faster. And I go few times a year, mostly to test upgrades. Not lately because of something that may be a foreign subject to some; snow and winter.

 

Theoretically perhaps. But it would depend on the rest of the drivetrain being able to hook-up correctly and put the power to the pavement. Not to mention the skill of the driver in also being able to do so. So now in addition to laying out $thousands to get the extra power, if you were serious you would then start laying out big bucks for other improvements (beefed up suspension, other drivetrain components, tires, etc.) and still hope that the car remained relatively driveable for the rest of the time it will actually be driven (unless this is strictly a strip car).


Doug

 

Performance is a mix of compromises and of balancing. Mostly people talk in terms of acceleration, though a road course car is a very different creature.

For acceleration, what range are you seeking matters greatly. 0-70? 1/8th mile? 1/4th mile? 30-70? 0-100? 0 - to absolute top speed?

Gearing obviously factors in to this in those regards. 1/8th mile track bracket racers typically have gearing lower than 5.00. A 180mph track car will have gearing in the 3.0ish, depending on tranny gearing. Gearing factors in for redline limitations and maximizing usage of the horsepower for the application.

There also is the issue of hooking up to the ground - particularly in regards to tires. The old late 60s muscles cars putting out up to 500 horsepower and gobs of torque in stock form rarely could do much better than a 14 second quarter mile et because of severe tire traction limitations. Cars in the 350-450 horsepower range will pick up a second or more in the 1/4th ET just by a rear tire swap. However, racing tires don't last long and drag racing tires are nearly exactly what you don't want for cornering or the street.

Once you hit the 500 hp range, depending on gearing, tires and traction becomes more critical than more horsepower in terms of standing start acceleration. Crappy tires and all your doing is making smoke - you can't use the horsepower.

The horsepower average across the operating rpm range means more than peak horsepower in terms of acceleration - why a supercharged car is superior for acceleration but a turbo car better on a road course. Turbos are all but unheard of in drag racing. Superchargers are rare on a road course track.

So if performance is a goal, the specific needs have to be decided as do the endless compromises you have to make for contradicting priorities. This isn't just about horsepower, but suspension, gearing, and tires all have to be balanced out in terms of usage. Most of us interested in performance also want to keep our Jags street cars with all the comforts and luxuries too. That takes a lot of compromising - from slippery street tires to a quarter ton of luxury weight to gearing that allows us to travel the Interstate at under 4000 rpm.

We also really don't want our cars to break. Put 4.10 gears and 10 inch wide drag slicks at 12 psi on an XKR and you'll shave 2 seconds off your quarter mile ET even on a stock motor. That is unless the hammer/torque effect blows your transmission, a driveshaft or a U-joint. That is the other challenge. How much can the drivetrain, not just the motor, take? Manufacturers often are allowing little extra margins for torque in relation to drivetrains. The near impossible challenge for 928 owners was no transmission alternatives. They could take 600 HP on street tires - but no more. I suspect the Jag drivetrains start protesting around 600 hp too.

 

So, dfwx, let me see if I can summarize here. You want to turn your XKR into a vehicle in which you can ride up and down the street and race with other guys in Vettes, Porsche's, Hemi Challengers, Ferrari's, Lambo's and so forth and be able to best them at various speed ranges from a standing start to 70+ mph, or various running starts. At the same time, you want it to retain the luxury characteristics that it was engineered to have and look about the same as it does now, not with wide drag racing slicks or other obvious modifications to make it faster. You also want it to retain a level of reliability, insofar as the performance upgrades will not damage other parts of the vehicle, such as the transmission, suspension and so forth. Lastly, you want to accomplish this with a fairly modest budget, not an all out expense. Have I missed anything?

 

Yes, you missed quite a bit.
First, I don't see it done on a modest budget. I figure 200-300% more than identical mods on a Chevy or Ford. In other words, $20-25K and that is with some scrouging such as second hand for the second set of wheels, fabing rather than buy an exhaust kit etc.

Second, overbuilding a motor for the drivetrain makes no sense, even in a race car. But knowing where that break-point is not easy for a car that little is known about in that regards.

Third, actually I'm think in terms of a dual profile car, specifically in terms of wheel/tire combos. I have a warehouse that was a repair shop with 5 empty bays and in-floor car hoists. Swap out tires/wheels are not expensive or that time consuming to do.

Finally, ALL those goals you name don't seem that difficult or contradictory at all in principle. I could have that in a Challenger, Mustang, Chrsyler 300C, Cad CVS-C, Camero etc all in less than 30 days off-the-shelf.

For an XRK the challenge is finding the parts and experts, not the theory behind it. 500 bhp out of a supercharged, fuel injected 4.2, 3.73 gears on 3900 pound actual rolling weight with DOT legal "racing" tires isn't all that radical a concept. So, yeah, I want my O5 to do all those things and think it is an excellent platform for it - superior to it's mass produced counter parts.

(Actually, I THOUGHT that is what having a Jaguar performance model was all about - at least that's the legacy.)

I don't see the Jag as a contender against Ferraris, Lambos or ZR1s. Rather, it is annoying to think someone can go drive a new Chrysler Hemi or Mustang off the lot and blow away my XKR - for which there isn't anything I can do about because the XRK isn't modifiable. I just don't think that is true. Rather, there aren't the over-the-counter parts to do it with because the potential market is so small. But the rewards so great if accomplished.

A 12 second Mustang is nothing as a street car. A low 12 second Jag XKR is awesome as a street car. Can you understand that distinction?

What I was balking at was the notion that merely pouring in horsepower by itself - how most people see it - in only part of the picture in terms of performance theory - why I so dwell on rear differential ratios so much.

I believe the XKR has far more potential than has been developed out of them - and in their luxurious street form.

 

Shorter answer...

The numbers are easy enough (though it always cost more than planned for any project)

(BUT FOR THE DAMN TRANS COMPUTER): $10K for 3.73 gears/Q differential, second sway bar, deaden a row of coils ($50), used 18 inch wheels and street/strip DOT tires

$15K for the motor and exhaust: (exhaust built myself, electric cutoffs after foward Borla racing mufflers for duality in loudness v performance) around $600. The motor work would be a lower temp thermostat (cheap), twin-screw (around $7K), Intercooler/pump swap ($1.5K), probably hi-flow CATS ($1K), water/alcohol injection ($1.5K). Still leaves a couple thousand $$ to spare.

Figure the overrun would be $5K for an ECU remapping.

Toss out the spare tire, jack and half a tank of gas.

The result would be a mid 12s to low 12s depending on rear tire selection and psi of those tires. Then pull it into the shop, put the 20 inchers back on and its exactly no more or less civilized than now - even a little better gas mileage and less heat/wear on the motor too as twin screws run cooler.

The "value" is not in the performance, it is in the exclusiveness. If I wanted speed only, I'd just buy a fast generic car off someone who took the cost-hit of building it up. The performance upgrading would not produce a race car. Rather, it would mean my Jag couldn't be shamed by a new off-the-lot generic "pony car" as they used to call them. I'd rather have a 12 second Jag than an 1o second Vette or hotrod - because the Jag is sophisticated and elegant.

 

...sounds to me like you want to create a transvestite Draguar...

I'm interested to see how you make out with it!

 

OK then, distilling it to its finest point, you want to be able to race your XKR up and down the street to prove some level of superiority versus the guy in the other car, and you find the need to tell all of us about this quest. I am not dense, mind you, I have a genius level IQ, and I used to be into drag racing and so forth, and racing people on the street, when I was a young and foolish kid. Most of us have outgrown that foolishness, because it is illegal, dangerous and stupid. I told you about Euroteck twice, and you totally ignored me, until someone else told you about them. OK, I am not trying to get into a never ending back and forth with you. GO FOR IT! When you have a video for all of us to see, please post it. We all could have a Hemi Challenger, etc. off the shelf, if we wanted to be street racers. Jaguar owners are usually a little more discerning and looking to make more of a statement of class and refinement than trying to be street racers. Certainly, many Jaguar owners are into racing and performance on the track, and that is a different concept entirely. You see, here is the thing, you are trying to do, on this forum, exactly what you try to do on the street. You are trying to out talk and overcome everyone, and demonstrate your superiority over everyone. OK, I have outgrown such foolishness. You can continue on in your quest, and, good luck to you.

 

The point of the "pony car" was and still is to shame cars like these for half the price.

They are drag strip warriors. Period.

 

Eurotek's website states promos about itself, but no details in terms of components or prices. They have not replied to my inquiries. You certainly must oppose their business as they promo increasing performance for street cars, not race cars.
I suppose you appreciate that Jaguar had abandoned it's shameful past of such as the XK120 and XK140 and that the board should have been imprisoned for the XJ220, but then were enraged when Jaguar announced it's 520 hp XKR and increasing the top speed limiter. Anything over 75 mph is "illegal, dangerous and stupid."

I am a very competitive person and your defining that as attempting to both "overcome and be superior to others" by actions and results is accurate. I have done so all my adult life and I usually succeed through deliberate - often intense - effort.

Whether my goal is possible with my XKR is still unknown. The quest matters more than the result in terms of cars. The quest is to make the car more than it is as a personal challenge. In performance this also then is relation to other cars and owners. I don't see any benefit or result from a "genius IQ" in buying a car off the lot and keeping it as it is - whether a Prius or a Jaguar. That takes no intelligence.

I gather many Jag owners share your view. That is likely why there are virtually no resources for parts, discount aftermarket parts or information sources.

Some people want to be old. Some don't.

The real question is why did you decide to flame me because I have a different set of goals for my Jaguar than your goal of doing nothing? I didn't flame you for being a frumpy old man - regardless of your age (well, guess I just did, huh?)

(BTW, it's always a mistake for a person to declare they have a "genius level IQ" on a forum because doing so is an oxymoron.

Most true "genius IQ" people I have known generally are relatively socially dysfunctional and tend to not have very successful lives. They also tend to have unjustified arrogance. I truly don't mean that as an insult and is just an observation I often made in the past.)

 

I agree. That also, therefore, is the challenge of it.
The historic change is that it used to take modifying low cost cars to succeed at doing so.
I also fully concede that a Jaguar as they are now can never rule a drag strip.

 

This is getting good


Doug

 

dfwx, get back to me if you ever become a mature adult. In the meantime, good luck with street racing all of the fools.

 

I actually never did drag racing - that is a money contest and I didn't have it. I did "rat racing" - which is playing chase. I did it a lot. For many years. In the city. In the country.

That is what I see as "street racing." It's TOO illegal now to do. Too costly too if caught. And the world is more crowded.

Accordingly I haven't just addressed acceleration, but also tires and suspension. Tires are VERY important in "street racing." A slower car with superior tires and a superior driver will prevail in "street racing" because it is a contest of 90 degree turns.

I don't see going 0-70/80 coming off a redlight leading into four lane divided 60 mph highway leading out to nothingness as "racing" for how most people see it. At 75-80 if they then keep coming they "win." I suppose it's illegal along the lines of speeding. My only care about that is not wanting a ticket, not some ethical "don't do anything illegal" stance.

In most states, merely changing your exhaust regardless of emissions or increasing sound is far more illegal than "street racing."

On the par of "street racing," I have done more "illegal, dangerous and stupid" things in my life than I can possibly count. Among those are my deepest regrets and fondest memories. Street racing is among those fond memories. It also was a developed skill that came in decisively handy a couple times years later.

I have yet to find a solution to the 3.03 rear gear, so I don't know if anything of any significance will happen or not. That limitation truly annoys me. But if so, I'll certainly post (and gloat) about it here on this forum.

Isn't that why people here post photos of their new wheels, polishing jobs, custom parts, new acquisition... gloating? I call it like it is nor deny my motives either of such things.

There is a difference between becoming mature and becoming old. We define those terms differently.

I'll give you one thing as a solid victory on your side of this. Your way with cars is much easier and certainly cost much less. Many people do think that keeping interest in cars beyond utility purposes is juvenile. Greenies would claim your having a Jaguar is immature. There is a rationality in that. Pleasure is not a matter of rationality. Neither is sex. It's about complusions.

Maserati had a slogan they used to put on their brochures years ago that most defined what it's all about: "The seduction of speed."

The best to you. I enjoyed the exchange.

 

Wow, I was looking for wheel info and found this thread. Dfwx I completely agree with you, I hate losing at the light to AMGs etc. So I took the wife's Mustang (pony car)
added everything you could get (cost $12,000) and have an 11 second street racer.
I can kill most of the posers in AMG's BMWs, corvettes etc with a car that is still a daily driver. I use the jag for long distance driving and its a steath mobile that will hit 135-140 in the desert straights. PS 52 years old, but love racing.

 

Excellent!
Long ago I had a '71 Mustang convertible I redid in pearl white with charcoal boss strips with a a 351C 4 barrel motor in it - the big port/value version (it was originally maroon and had been hit in the rear parked at about 40 mph - the way I bought it and then redid it) and His & Her's early vintage 5.0 Mustang convertibles (red and white - both left stock but for the tires. Both with manual trannies).
A Mustang is a fine car for the street. What'd you do your "wife's" Mustang to build it up? (Guys aren't the only ones who like driving swift cars).

 

AND here I "THOUGHT" this thread was about 1 persons individual search for a more personalized/faster Jaguar.
DFWX is searching to make his XKR at the same level as the newer '10 510hp XKR and is brought to task....Should Jaguar be done the same for doing the same!
Personally I do believe there are more people killed every year as the reasult of cell phone useage while driving, than so called street racing. Not condoning, but geez my ex wife was plowed into sitting stopped in traffic in her XJ8 4 yrs ago by a woman doing 70mph(5less than DFWX claims to fun) and she didnt even brake. Why? She was on the phone, thank God no one was seriously hurt, but three cars were totalled. Cell phone useage is worse when driving in my opinion cause you just dont pay attention to what your doing. At least most, when driving fast, have a heightened sense of attetiveness.

 

I agree on the cell phone and I'm personally guilty of it. I had bought a new (used) El Dorado for the Mrs,a very pretty green one, and was on the cell phone in semi-rush hour traffic talking to her when the cars in front suddenly stopped. I reacted too late and hit the car in front of me, the car behind then slamming into me. Fortunately it was just bumper benders, no one hurt and cars still drivable.
I could have blamed the car behind me of course, but why lie? On the spot I wrote both drivers a handwritten note that it was my fault. (My insurance company didn't like that note and canceled.)
They showed a test on TV that demonstrated that people talking on a cell phone have the same reaction times and observation skills as someone who is legally drunk. A person mentally zones out when on a cell phone. I now pull over (safely) to talk unless truly on the open highway with no one around.

Generally when "racing" a person is at their maximum level of focus and (unless stupid) where the road is clear and open. There is a difference between racing and stupidly/dangerously driving fast or darting around through traffic like they are fixed objects (particularly if on a cell phone).

 

For the record.

There is NOTHING wrong with him wanting to make HIS car faster. Furthermore, his reasoning behind it is his alone and none of anyone elses business. Stop putting him down for what he wants to do with HIS car. If it offends your delicate sensibilities, remember the golden rule.

That said I fully support his intentions. What I don't is support is whining, especially without action. If you want something bad enough go make it happen, then stick it to the naysayers. -Shaun

 

I think the complaint may not be so much that he wants to trick out his car, but rather the fact that he was so shocked and surprised that these types of tweaks are not readily available at "affordable" prices. However, even the most casual bit of research prior to purchasing would have revealed this fact.

Before I finally decided to move on from the Corvette, the cars I had been most interested in were the recently introduced Infiniti G37 and the BMW 335i. So the first thing I did was browse around the various Infiniti and BMW forums to see what folks were discussing. This was a very worthwhile exercise. I had thought that the Infiniti marque was somewhat upscale and more "mature" (i.e., suitable to the age that I was approaching). Instead what I found on those forums were a bunch of boy-racers. When they were not talking endlessly about the ways to trick out their cars, they were bragging about the various red-light races where they blew away this car or that car, bringing about a bunch of "attaboys" from the other forum members. I knew then that this was not a "club" I wished to join.

Moving over the the BMW forum I found a bunch of guys that spent time bashing anything that was not the "Ultimate Driving Machine". These guys even bashed owners of other "lesser" BMW models. Quite a snobbish group.

When I (unintentionally) decided to explore used XK8/XKR, I found this and other forums where the emphasis seemed to be quite a pride in the heritage of Jaguar. The lack of red-light kill stories and trick-out talk was somewhat refreshing. I quickly also noticed the absence of the type of performance tweak discussions that I participated in on the Corvette forum for 14 years but quickly learned that the Jaguars are more about the heritage and touring experience rather than being a gearhead car.

So, with the little research I had done, it would have been hypocritical of me to get the Jaguar and immediately start complaining that this was not some street racer.

Just saying.

Doug