Hi Steve, I agree with ya...Put up or shut up. Don't worry I'm going to Labanon Valley Race Park (NY) with my mechanic, Joe Murphy. He's ran his car a few times on "Pinks". He suggested I run side by side his car, a 9 second 1989 Mustang LX with a Rousch/Yates 358 cu. in. Ford small block making an est. 1000 hp.). By the time my foot slips off the brake he'll be 1/2 way there. I know some of ya haven't modded yet and may not want to read this due to disbelief, but...Last night my STR took out a 2006 Subaru STI (305 hp @ 300 lb/ft trq. 4.9 sec. 0-60 mph) from soup to nuts. I want you guys to mod your STR's like I and some others and have some fun!

 

Honestly, ET's are really transparent in terms of performance. There are so many different variables that it's really up to the driver/conditions to post a good time. A good indication of true performance is trap speed. This is a much more consistent indication of power.

When it come's to the 4.2L motors in R Jaguar's, I've decided that it is not worth the time or effort to squeeze more power out of them. If you do a pulley mod, you have to compensate for the extra heat. Thermostat keeps coolant temps lower when you are rolling but a fan switch would be much more useful to curb temperatures when you are at a stop. The car puts out so much heat already that it heatsoaks very rapidly by either idling or making a few runs. And no aftermarket modification for our cars even have dyno sheets to back up the gains. It is all done in theory.

Turning a sub 13 second 1/4 mile would be tough for the STR, XJR, and XKR with the 4.2. (Not including the new body XK's with the 4.2) Conditions would need to be near perfect and the driver has to be perfect to even come close. Running 13 second 1/4 miles is a lot easier than running 12's. Breaking 11's is even harder.

The cars are fast enough as is. Great daily drivers with good power to back them up. If you really want to gun for low E.T.'s and high trap speeds, a car with a larger aftermarket is a lot more fun to work with.

 

Not at all.

I ran a 12.996 on my 99 XJR with only exhaust and intake mods. And it's only a 4.0, not the more powerful 4.2
I'm hardly an experienced drag racer, only been to drag strip four times.

 

R compound tires or dedicated drag slicks? If so, then yes, I can see that happening...not at any of my local tracks though. At sea level, maybe...The density elevation around here is ridiculous.

 

Patrick, I'm confortable to speak for many other STR and XJR owners who disagree with you because we're already running in the 12's with stock tires, etc.. Car and Driver, a conservative publication when it comes to making performance claims, admits that the STR will likely run sub 5 second 0-60 and sub 13 sec. 1/4 mile. You mentioned heatsoak as a limiting variable when it comes to performance, agreed, however when replacing the stock cats with hi-flows and opening up the rest of the exhaust...temperatures went way down. After the low temp thermostat...well you understand what happened thereafter. The 1.5 pulley gave the coupe de gra, absolutely making her a boulevard sleeper/bruiser. An ECU or dyno-tune will most certainly land her in "solid" 12 second territory. If anyone here hasn't noticed how I'v been touting the importance of a full exhaust mod...this one change lowers the temperatures and "really" let's her make power.

 

You may have to post some dyno (or other) figures to convince the doubters (not me - I just read and wonder lol).

 

LOL! jagv8. I can def. picture ya laughing in the background; falling all about the place reading up on some cooky dude tryin to convince these guys "It's all good." Admittedly I'd be giggling too. I've nothing to loose (except some credibility if I'm wrong, LOL)...But here I go again...I'ts all good STR owners! You can do a full exhaust mod to unleash the mean cat inside your leashed STR's! No! I don't have dyno or track sheets...yet. For now you'll just have to trust me and others here that we know what wer'e talking about based upon our experiences. I'm a doc that uses both scientific and anecdotal evidence as tools for making decisions then applications. Until all is verified you'll have to choose anecdotal evidence. It is written that a stock STR with a cat back exhaust mod and an ECU tune produced 430 hp @ 488 lb/ft torque. Now think of what a huge flow inducer such as hi-flow cats and a 1.5 pulley, coupled with another temp. lowering device (185 degree low temp thermosat) will do. I can't wait till an ECU tune.... Someone hand jagv8 a tissue, he's not giggling, he's freekin laughing w/tears flowing down his cheeks. LOL! I'm about to bust up myself. LOL!

 

If you are interested in improving the drag times/power output we should follow Matt Moran. He got an old 2001 XJR with the smaller 4.0 L down to 12.41 sec run! Plus he is consistent and has made many runs. Too bad he has disappeared but his website lives on. He is the only guy who has backed up the mods he did with with real facts like 1/4 times. All the other people just wave their hands and mention 500+ HP or 50-70 HP gains or 12 sec 1/4 miles or sub 5 sec 0-60 mph or TWS blower mods with NOTHING behind the claim!!!

Check out his very informative website.

http://www.matmoranmotorsports.com/index.html
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clubairth, It was Matt, along with others here who were the biggest influences to cause me to step over the line and mod. Back in May this year shortly after purchasing my 03 STR, I was reluctant to modding the exhaust, believing the stock set up was adequate. Work by guys like Riski and Matt proved there was way more to be had.

 

Ha Ha, heck no. Ten year old bald Pirelli tires. Had trouble with grip all the time. With drag radials or slicks, the time would certainly drop a few tenths more. Total weight of car was 4,000 lbs.

Only exhaust and intake modified.

 

http://s988.photobucket.com/albums/a...Oct0912996.mp4

Sorry about the bad cameraman.

 

Er... I didn't mean to imply I am or would be laughing at the claims (or counterclaims). Just that I'm aware sometimes people want actual evidence (can't say that's a surprise or unreasonable). I'm happy to wait till some such is readily available for an STR. (I don't see why it would be unable to at least equal what an older XJR did but engine tuning/modding is way beyond what I know about.)

 

JagV8:
Good point!! The STR should be faster than the XJR but so far it has not? The 4.2 L is an improved engine and did provide a small but measurable increase in power. The HP went from 370 to 390 factory rating. Still want to know why they added VVT in 2006 but no power increase? Did hear it was done mainly for emissions?

Great time SteveM but I could not tell from the video that it was even a Jag?? I wish we could use the same rear end as Matt M. did so we could get a locking rear diff and some other ratio's. Since the XF is built on the S Type chassis I wonder if the new E-diff can be swapped into the older S Types??
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How affordable would that be? Any idea on price?

 

Jag claimed 400 HP for the 06-08 STR with VVT 10 HP power increase with my math.

 

I've looked into it a little and I think the problem would be the electronics involved. You would have to get more then just the diff.

 

JagV8, you need to delete some of your private messages in order to recieve new messages.

 

This would be a great mod..
First off we will need to understand how many modes the differential has and how they are activated..
The rest is easy..

 

I want a LSD on my car so badly it makes my jeans tight in the front.

 

They've been arriving faster than I can cope with them!