I tested my car in Finnish VW-Open 1/4mile competition earlier today. The track ( airfield ) was very slippary and 60ft and 330ft times were really bad ones. The Quaife LSD did not help very much even I started with 1200-1300rpm - it was just wheels spinning first 100-150ft. Best time was 13.868 and best end speed 106.34mph. 60ft 2.56 - 2.64 Based on these times 12.9-13.0 will be possible at good track with street slicks with low air pressure. Today I did not lower my Good Year Eagle F1 255/35/18 pressures from 40-41psi. One more mistake: I drove just with 4 gallon of fuel and removed spare wheel etc from the trunk to save another 50 pounds. Next time I add 200 pounds of sand to the trunk if still the same problems... Maybe it's also reasonable to test without sport mode of transmission not to use first gear.

I go to dyno after two days - so let's see what's really under the bonnet.

 

Adding weight to the trunk is going to slow you even more! and what all is done to your car or is it stock??

 

It's not a stock car( fully stock one can go 13.6-13.7 as it's best ) The car have potential for just under 13sec even the SC is stock and unmodified if the traction problem is fully resolved. First 330ft took 0.8sec too much. It's quite easy to realise that Eaton runs at it's max and can not boost more well over the 5000 rpm's. There is 4.5PSI lower pulley. Massive torque on low revs makes starting more difficult, butfor normal everyday drive it's of course great. Adding 200lbs to the trunk slows time maybe 0.2sec but may give much more advantage because of extra traction.

 

try proper tyres

 

Wheelspin is bad. Even worse with 3.58s. I was messing around with a Gtech the other day trying to see what 0-60 i can muster and regardless if I was in 1st or 2nd starting out the best I could get was 5sec flat with a full tank and a passenger in a car. I think once I resolve the TCM and throw a smaller pulley it will be a beast.

 

Here video of yesterday's dyno pull. There were some problems to get revs up from 5500rpm's with the dyno/transmission. Next time hopefully
up to rev limiter. Torque was very flat and it has been the main target.

Jaguar XJR dyno pull - YouTube

 

I drove today 13.604 / 105.55. Better traction than last time ( 60ft 2.26s ) most probably because I dropped rear tire pressures from 42PSI down to 30PSI - but still quite far away from the target. Air temperature was a bit too high, near 79F (26C ). The major problem is that power is just flat from 5200rpm even it should go up until 6200rpm. Maybe the engine do not get enough air?? ( I use BMC CDA intake ) or Eaton can not provide overboost....

http://kuvia.1g.fi/#/kuvat/Tapahtuma...e/MOP_3560.jpg

 

It's interesting, your time barely came down, and yet your trap speed decreased 1mph. The "jerk" is a calculation I hear can be used for this, but higher trap speeds
don't need to coincide with slower times.

I think your first run, you did something right... just were lacking grip. If you are
confident, and know the 722.6's stall point, you could launch your car, all other variables the same, and get higher trap speeds/ quicker times.

13.6 is great for a daily driver! The quickest Car/Driver could get their
XJR to do (stock was 13.9 @ 103. Motor trend, 13.7 @ 103.8... and they
launch those press-fleet cars hard.

Cheers

Ian

 

I ran a 13.13 1/4 mile ET @ 106.63 mph with a completely stock car.

Just had some weight removed

 

Where did you remove the weight from?

 

Trunk, some interior.
I had some of the interior removed for a different reason and thought I'd see what it would run at the drag strip.

 

What tires are you guys using?

 

Old, bald, stock P Zeros.

 

so what did it dyno??

 

My 98 XJR has ran 12.7 @ 108mph. It's all about grip, boost and plenty of airflow.
Rear tyres were mickey thompson 245/40/18.
16 psi boost on the ported Eaton M112 and shortened pulley.
3.5inch K&N intake and 2.5 inch Magnaflow exhaust.
No spare in the boot.

On the wet, the trick is to create a rolling start in sport mode. This means accelerate off the line but allow the traction control to do its job, then after about 30 metres put the foot flat.

 

Wow, that is a good time!

Are you using anything to control IATs? I am going to install a Snow Stage II meth/water injection kit. I will post my results/review when it is installed.

16 psi-are you using a 4 lb lower puller to get this? What do you mean shortened pully, do you mean smaller upper pulley?

Thank you for the info

 

I already have quite a many modifications done to get higher power output, including 17% bigger lower pulley, high flow cats, EAPJ catback system, Arden additional ECU ( specially designed for 4.0 XJR ), BMC CDA air intake, bigger intercooler and upgraded SC waterpump and Quaife LSD. Heads are machined to the brand new level this year and timing chain job also done a couple months ago. Based on dyno pulls, something do not work well since output is too low and go not increase after 5200rpm.

I run 1/4mile with 1.5 gallon of Shell V-Power ( US 93+ ) spare wheel and all tools removed from the trunk. Sport cats and new catback decrease weight also by 50lbs.

I think not very many have LSD in their cars and when I have tested starts with ESP on, it has really been diffifult to get start with combination of that system and LSD.

Later this year we will analyse where is the bottleneck for high output. I think intake is the major point to start.

I have driven both competitions on very slipery air fields, which are very far away from the grip level of real drag strips.

Adam, your time is really fantastic if the car has been 100% stock since I have not seen any stock car running under 13.6. You can check times from the Dragtimes. There we can see also Jason's 1998 XJR time of 12.77.

 

what was the power on the dyno???? what was the torque

 

Did you rest the adaption values by doing the battery disconnect after all the upgrades?

 

@Xjr-99
Personally I don’t think the CDA is a good choice, maybe for a stock car but not a modified one.

To check if that is the main issue you experience, simply measure your vacuum in the intake. Also check your boost level during the run, that could also reveal some issues. Another value to check is the MAF reading, so with a obdii reader that can log data, do a power run in 3rd, select only engine RPM and MAF, you should see a fairly steady climb unitl redline.

Have you checked with Arden if the tune you have is also right for the increase boost? If their tune is sharp for a stock car, it wouldn't be right for your modified one.

Can you show your dyno slip, with the a/f ratio? I may be able to give you some more hints as to what could be the issue with your car.