My mechanic endorsed lower pulley upgrade after he drove other customers car MB SL500 2005 and said my car felt much weaker. I asked if he had the S button on... He was shocked a sc 4l v8 would not have more punch. I asked if 12 years old my car had substantially lost power and he shook his head.

Is the merc really that much more powerful? I found CLK55 amg 2004 not as punchy as 2002 xkr so the comment is a surprise. Now the 5.5 v8 from 2007 on was equal to xkr.

Something I need to check besides ebay for a lower pulley to have Eurotoys work on to swap with mine when done?

 

Ill help you out, send your blower to steigmeyer, have them do the snakebite upgrade and lightened rotors with re-balance.


Then bolt it on your car, the upgrade is almost like? 90rwhp+So screw what the mechanic thinks, he don't own either.


Or put a whipple etc on top.

Whatever you do, you will need a dyno tune, and I have no clue as to how to tune these cars. The Jaguar algorithm is very powerful and no one local has been able to crack it as I have tried taking my Jaguar to a few import tuning shops.

 

These cars are geared high and are not red light warriors, so they don't "feel" fast.

If you really want to know how it's performing, take your car to a dyno and get a baseline done. That will tell you if it's significantly tired or not.

That's not entirely true. You can do quite a lot without getting a tune, as the software is pretty adaptable. The 4.0 cars are actually a little easier as you add an aftermarket fuel pressure regulator and adjust it higher as needed. On the 4.2 it's a little more complicated.

 

I have installed the Eurotoy's lower pulley upgrade and supercharger porting, along with an LSD and rear axle ratio change to a 3.27 and I can honestly say that I don't want more power. When I punch it at a light or on the highway, the pull and acceleration is actually scary. I actually warn people, like mechanics, who drive my car about the "touchy" throttle because several have come to me after pulling my car into an engine bay to tell me the throttle response scared them. I'd say if you actually want more acceleration/power, get one of avos's twin screw systems. All that said, you will never get 3 second 0 to 60 times out of these cars; they're just not made that way. So unless you want to blow the doors off a McLaren, I'd let it go.


I will ask one question though. Have to tightened up the throttle cable? This has been known to occur and does affect the response. I had this done a couple years ago. There are thread on here about this issue.


As for me, I still scare myself sometimes when I step on the gas too hard.


Mark

 

Weisberg,
Your mechanic's full of crap. The base 2005 SL500 had performance times that were much slower than your XKR's. 0-60 time was 6.3 seconds and 1/4 mile was 15 seconds. The 2002 XKR, like yours and mine, had a 0-60 time of 5.2 seconds and a 1/4 mile was 13.8 seconds.

If the Mercedes was the AMG massaged version, those numbers improved but that was not the SL500, it had a bigger engine.
See the articles below:
http://www.automotive.com/mercedes-b...-blower-page-2

 

Between the s/c upgrades and the rear axle ratio change listed above my 0 to 60 times dropped to the mid 4 second range (as per the Torque app on my cell phone). While this is not as accurate as taking it to a track, I am confident that my times are below 5 seconds. I've never determined the 1/4 mile time.


Mark

 

There are several common things that can rob power on a SC 4.0 as it ages. The throttle cable was mentioned.

Also:
-Your #2 fuel pump could be out.
-Your intercooler pump could be out
-Your intercooler air seals could be leaking (there is a TSB on this).
-You should monitor your long term fuel trims and see if your engine is compensating for other issues.

 

The most obvious thing that could be wrong that comes to mind is that the mechanic is full of crap. The 2002 XKRs that you and I, (the two bergs) have were conservatively rated at 370hp with the usual Jaguar factory claims for times very, very conservative. Every instrument tested review of any Jaguar product is always well below factory time claims.

The 2005 Mercedes SL 500 was rated at 302hp, was heavier than the XKR and more comparable to an XK8. Even with "one hand tied behind its back," the 2002 XKR (or any MY XKR), would and does "slaughter" the SL 500.

Weisberg,
Tell you mechanic to prove it with an actual car.

 

Weisberg, it appears that your mechanic called all of our babies ugly!


Mark

 

Based on this thread, I'd say you need a new mechanic. At least one that understands late model Jaguars a bit better.

 

The MB has 302 hp and 339 ft-lbs of torque, the XKR has 370 hp and 372 ft-lbs of torque. Weights are about the same. Specs say 0-60 in the MB takes 6.1, the XKR shows 5.3. There' s no way the MB is quicker.

 

my standard XKR does it in 4,5 seconds, so your upgrades doesn't seem to have that great of an affect. It is quick but not superfast.

The other day i drove a brand new 911 Turbo S and the difference is just unbelievable. It feels like it is about 3 times faster. Just no comparison at all to our XKRs.

 

The Turbo S is 560 HP, the XKR S is 550 HP but the R is $50,000 less expensive! The turbo is only 1.2 sec faster to 60, not quite 3 times as fast! I imagine the 0-60 time of the R is affected by traction, not lack of power.

 

Since the Porsche comparison is there, I hear this every now and then from the car guys. My problem with Porsche cormes from the old days, every time I see a Porsche, it reminds me of a hopped up VW Beetle. When I look at a Jaguar, I see a much sleeker, finer design heritage. Just can't shake that memory. Theres more to a car than fast.

 

maybe the mechanic just says "slow compared to brand x" to every customer
because it generates lots of upgrade work.

anyways, if someone wants a dragster ... Jaguar is the wrong answer.

 

+1


Jaguar never tried to be a street light dragster; its more refined and has way more beautiful lines. However, that doesn't mean it can't hold it's own on the street.


As for stock 0 - 60 times, I can (as can forum member motorcarman who installed the mods) attest to the fact that my XKR is much quicker, and has more torque, now than before the mods and is much quicker than a stock XKR, regardless of what you believe your 0-60 times are; as I said all I used was the simple torque app on my cell phone.


Mark

 

My understanding is this is not true. An SL500 is much heavier than an XKR ... at least through 2002 and I doubt they lost much weight with the newer body style. The SL500 is like around 600lbs heavier than an XKR. The SL600 (which has close to the same HP as the XKR) weighs nearly as much as a Chevy Tahoe.