"Enhanced" 07 XKR

[SkyUK]

I had a well known company play with my 07 XKR, shorter stiffer springs to sort the handling and laso unexpectedly improved the steering; louder pipes so I can hear her sing; and then sports cats, smaller charger pulley and a remap and she now makes 515 hp and is of course stunningly fast

I don't know how to post the jpg of the dyno run.

[tr7v8]

SkyUK said:

I had a well known company play with my 07 XKR, shorter stiffer springs to sort the handling and laso unexpectedly improved the steering; louder pipes so I can hear her sing; and then sports cats, smaller charger pulley and a remap and she now makes 515 hp and is of course stunningly fast

I don't know how to post the jpg of the dyno run.

A pic of the car would be good!

[SeismicGuy]

Wasn't the "stock" horsepower on these about 420? So you are saying from the relatively minor mods you did you were able to gain almost 100hp??

Doug

[SkyUK]

The before dyno run gave 431 hp so it was a fast car to start with, but yes the increase is substantial.

[SkyUK]

Sorry, been too long since I posted pics to a forum and I can't remember how (alcohol, senility, insanity all play equal parts ;p) do you know?

[SeismicGuy]

Pardon my skepticism but what are the specifics of this upgrade? I have seen some of the pulley conversions claiming maybe a 20hp or 30hp gain and exhaust system replacements rarely gain more than 15hp to 20hp at the wheels. So, specifically what were the details of the components that got you 100hp?

Doug

[NormanD]

SeismicGuy said:

Pardon my skepticism but what are the specifics of this upgrade? I have seen some of the pulley conversions claiming maybe a 20hp or 30hp gain and exhaust system replacements rarely gain more than 15hp to 20hp at the wheels. So, specifically what were the details of the components that got you 100hp?

Doug

I have to agree, someone is using an elastic tape measure.

Possibly 15-20BHP on the pulley although with the Eaton112 mid range extra power but not much extra top end as it will be running out of breath.

I don't think ANY exhaust will give any extra BHP, more of a growl and looks good, thats all
If you want any extra exhaust power the headers will have to be changes as that is the main restriction, I've had a set made for my car, I don't know of anyone else making them.

The ECU will give some gain but NOT a huge increase.

The ONLY way to get 100BHP extra is by fitting a Twin Screw Superchager that saps less power and gives the engine the extra volume of air

[SkyUK]

The pulley runs the blower 8% faster and is claimed to add 30. The cats are claimed at 22-25. The reemap is claimed at 35. The pipes are purely noise. Total increase claimed 87-90.

Actuals: Before dyno 431, after dyno 499, after dyno plus 500 miles 515, total increase achieved 84 (same dyno, different days but conditions similar).

Last time I posted a suppliers name the post got pulled due to breaking advertising rules, but you probably know of the company in Slough who did this work.

Are they lying to me about the dyno run results? I don't know, it's not impossible but I think it's unlikely?

Richard

[G_T]

Richard if you're happy with the results don't worry about it mate.

Dyno's just aren't the most accurate things in the world and they're easily manipulated.

In terms of bragging rights I think you're just being advised by the more knowledgeable members of the forum that 90bhp seems unlikely. It's still hella-quick and undoubtedly sounds a beast!

[SeismicGuy]

I am in the states (California) and have found plenty of independent Jaguar mechanics around my area but frustratingly none who claim to be tuners or tweakers. I have spent years on the various Corvette forums and also considerable time on other car forums and I have rarely seen complaints by the moderators regarding posting the specifics of shops, mechanics, aftermarket manufacturers, etc. Are they that picky on this website that they do not permit posting of those things and, if so, what is the harm, especially if the information can be of benefit to others?

Doug

[SeismicGuy]

Another funny thing purely for the humor of it. At least for my Corvette, there are bunches of improvements, some just bolt-ons on some more serious modifications of engine internals, that are pitched by the various aftermarket suppliers. What is funny especially are the claims of the small bolt-on items--K&N air filter +10hp, throttle body air foil +14hp, open air filter lid +10hp, adjustable fuel pressure regulator +15hp, reprogramming computer +20hp, etc. etc.

The thing is, these measurements might be under some "ideal" measuring situations and are not necessarily additive. So there would always be these guys who just got their Corvette and sprung for these cheap and easy-to-install bolt-ons and then claiming that they just gained 50 or more hp just by spending a few bucks and a few minutes. When an engine is already pretty highly tuned it is no small feat to obtain a real noticeable seat-of-the-pants improvement unless you start doing more drastic things like cam changes, rear end gear changes, head porting or modifying, etc. Even so, where you would see the impact of the changes would be maybe shaving a few 10ths of a second from quarter-mile runs down the dragstrip. How many out there, particularly on the Jaguar forums, are doing quarter-mile runs?

Doug

[SkyUK]

Thanks GT, I'm old enough now not to care too much what others say, but I'm happy to run the car on another dyno if someone wants to suggest one they have faith in and its nearish to kent, heathrow or gloucester

The quoted figures are at the flywheel but we all know the actual measurement is taken at the wheels, so a "correction" factor must be being applied, I don't know how this is calculated, there are many more knowledgeable people than me on this topic.

I think what I really intended to achieve with the post is a personal recommendation of these relatively cheap mods. The springs are transformational to the handling and steering, and the car can be driven MUCH harder while maintaining the same margin of error; with the dampers becoming the limiting factor in tricky corners rather than the too soft standard springs. The noise increase was to allow me to use my ears to know when to change gear on the paddles and I'm currently teaching my ears to match sound to revs. The HP? Well, you can never have too much, and these mods make a significant and very noticeable difference

Although the suppliers haven't printed the torque curve my seat tells me the power delivery is smoother too, and the car is stunningly and deceptively fast. I'm *very* happy with it I'm booked into Palmer on 8th May to get someone skilful to teach me how to drive it faster. And Brands is just down the road, I must get it noise tested to see if I can track it there.

Richard

Edited by SkyUK on Friday 10th April 17:01

[SkyUK]

I just found out the kit car show is at Detling this weekend. I went a couple of years ago and they were doing a run what you brung on a straight piece of tarmac with timing lights. I'll pop down and see if they are doing it again.