Happy to announce 3 offical runs at.WSID all were consistent 13.7 e.t

I have no doubt with 3.58 diff gears and opening up the headers (better flow) I can get this down to 13.4/13.5

 

Sounds like those mods are going to be expensive for not much gain, no? Could you gain more with different tires?

 

Well its already pulling some impressive results for a naturally aspirated 4.2 XK...

To go from stock 14.5 @ 96mph to 13.7 @ 101mph with just cats, exhaust and tune, it's now getting to the expensive end of town...

 

60ft times were pretty consistent 2.0's, traction didn't seem to be too big an issue, my XJR with the Quaife in it does the same 2.0 60ft times consistently.

 

I thought the ECU fought different gears. Impressive numbers for a NA car.

I'd probably redo the intake tract from air filter to throttle body and see if there's anything there. Otherwise, car diet time.

 

Thanks Ranch

Unsure how much I could gain out of intake systen they don't seem to be too restrictive and flow nicely .

Throttle body - maxbore are willing to upgrade 75mms to 78mm.. not really worth it

Diet time yes !!
There isn't a huge amount I can do however I was thinking lighter wheels and shedding the large style rear muffler would help .

 

226 square mm Vs. 245 square mm is almost ten percent more flow. But, would the rest of the system be able to use it?

 

So has anyone tried to put a turbo on one of these cars.

 

It would be better IMHO to install an Eaton. Oh wait...

 

Jag toes I have thought about turbo charging but in honesty if going down that path you are better off starting with a s/c short block and using that as you build up

 

When you look at it that way it does sound a little more impressive.

See how the diff and header/manifold project go first and put this back up on my maybe list

 

That was my weak point last time so, as I am hoping to get back to the track soon, what is the best setup for a clean launch for those of us without an LSD?

DSC, TRAC-DSC or no DSC?

Raise the revs while holding the car on the brake pedal or just boot it when the lights go green?

Foot flat to the floor or ease the revs in gently?

Let down the tyres or run at the normal pressure?

Any other tips?

 

Well, I ran my XKR on the same night as Steve.

DSC off completely, big smokey burnout to warm up the tyres, boot it on the last yellow.

Actually launched OK, even without the LSD, I also did a couple of 2.0 60ft's, a 1.9x once too.

Mind you I had brand new Michelin Pilot Sport 4S 295's on the back, which would have also helped.

Tyres are very important for traction...

 

I launch right off idle and let the tires shock the suspension.

 

Thanks guys. I forgot to add the gear lever to my list so would you recommend D, DS or using the paddles?

 

DS, of course.

 

Which ever lets you launch without slippage. I don't think it'll matter much for drag racing. Only real trick will be getting it to launch clean in first vs second.

 

-Put shifter in DS .

-Hold down dsc button for approx 8-10 sec a chime will indicate it's turned off .

-Paddle shift down to first so you can heat up the tyres with a lengthly burnout

-After heating up the tyres the transmission would have shifted up to 3rd so put back into 1st via paddle shifter

-At the line dial up the revs just before you break traction then release brake pedal and depress accelerate (I went approx 50% throttle for approx half second then fully depressed)

 

Yes your exactly correct the ecu/tcm do 'fight' different gears hence we are working on the software component so the vehicle doesn't go into limp mode when we install the shorter ratio.

 

Also I never heated street tires. They tended to just get slicker. Quick bunny hop after the water to rub anything off the tread and pull up to the line. 'No water' on the windshield keeps the tires from getting too wet. I had a set of cheap meaty Fulda's on my '93 stang that would launch like ET streets. My 60' times were never great but the car pulled hard in the top end, 11.73 @ 119 mpg with a 400 hp torque built 302. 10-1 comp with a very mild cam and 5 psi of Paxton helping.

Single track is just asking for the right tire to break loose easier. Again, clean get away so you can get on the throttle hard. Top end speed says HP, Low ET equal efficiency. Our combos will not be efficient.