Well that didn't go very well! I had a VAP supercharger pulley put on my '10 XKR last week so went back to the dyno yesterday and I seem to have lost up to 100bhp somewhere along the way. The car was dynoed at 502 rwhp after I put the XKR-S tune on it. After putting the supercharger pulley on with no other tune it is now showing 416 bhp and something is pulling it back at around 4,000 rpm's.

Although the management PC has been updated, it is apparently the same dyno and the guy even did a couple of runs on the other dyno to compare results and they were even worse on that one

 

With the pulley installed on the stock XKR-S tune it's throttling back due to airflow (MAF rate) exceeding allowable limits.

Not a surprising result really, there's a very narrow window of what the stock tune "allows" and you've gone past that.

Check you emails, we have a fix for you.

 

It looks like things are moving in the right direction

Last time I visited the drag strip I was just running the XKR-S tune and did a 12.521@118.5mph quarter mile.

It is just coming out of winter here so the track is closed but last week I tested a modified tune and did a 12.41@121 using Dash Command then last night, thanks to a new tune from Cambo, I did an 11.95@126! I appreciate that Dash Command isn't as accurate as proper timing gear but if I can get anywhere near that on the track I will be one happy camper!

I also did a 3.74 second 0-60 last week with the current tune, and that was with summer tyres at 8 deg C on a damp road!

It looks like the car wasn't actually down on power either after my last post as I was still doing mid 4 second 0-60's after putting the smaller pulley on so the car seems to have just been backing off the power on the dyno.

I will hopefully try the dyno again in a week or two and see what results I get with the latest tune. The torque still seems to be reported correctly so worst case is I will get figures for that. I may also try a different dyno if I still have the same issue although I won't be able to compare before and after figures then.

 

 

That sounds a little on the high side although I did runs in opposite directions on the same stretch of road so it should have averaged out if the road wasn't flat but I got almost identical numbers in both directions.

It was around 8 degrees C last night and the supercharger seems to love the cooler temperatures. I had another play tonight and even with my new super sticky tyres the traction control light now flashes madly when I hit kickdown at 60 mph. The front of the car becomes very light as well which makes keeping it in a straight line more interesting.

I am looking forward to going back to the drag strip at the end of the month and would be pretty happy with anything in the 11's and over 120 mph.

 

Lister can get 660hp out of these engines with pulley upgrades don't see why 645hp isn't possible

 

Yeah well 126mph is on the high side too LOL

The fastest tuned/modified V8 F-Type (without nitrous) trapped 125.7mph, so that should tell you something.

If the 126mph is accurate, then the calculated HP is pretty close.

 

I finally got back to the track today. It isn't a huge surprise that Dash Command is a little optimistic but it seems to pretty reliably over read by 2mph so, based on the results from it posted earlier, with idea conditions my car should be able to reach 123/124mph.

Last season and running with just the XKR-S tune and mid pipe my best quarter mile was 12.521@118.5mph. The car is now running with a smaller pulley and tune from Cambo and the best today was 12.100@121.70 but my last run of the day had a trap speed of 121.89 which is quite a nice jump.

I still need to work on the launch though and would hopefully see high 11's with a little work. The best launch setup currently seems to be Snow mode with DSC Trac and Sports Mode. Trying to launch in 1st just seems to provoke too much wheel spin.

The best 0-60 time Dash Command showed today was 4.40 but consistently does 4.1's in the cool evening air on the street so I assume heat soak comes in to play on the track. I also seem to get better traction on the street.

I still haven't managed to get an accurate dyno run though as the car is unfortunately still backing off on the dyno. It is good to know that there definitely has been a jump in power even if I can't get a graph to prove it!

 

Some videos from today

2010 Jaguar XKR v 2010 Mopar 10 Challenger



2010 Jaguar XKR v Ford XR8



My car wasn't the only Jag there



XJ-S Drag Racer

 

Far out.

Although it's disappointing that the 126mph from Dash Command was way optimistic, but we probably should have expected it...

The way this XKR walks away from the XR8 and the Challenger... well, it's awesome to see them disappearing in the rear view mirror.

121.7mph is the fastest trap from any XKR, ever, by a long way.

Your 60ft is still quite slow compared to other XKR's, this guy for example Stock 2010 Jaguar XKR 1/4 mile trap speeds 0-60 - DragTimes.com with a 1.844 60ft

The video tells all to me, you aren't doing anywhere near a big enough burnout to warm the tyres, and you're staying in the water, you have to ride the brakes to get them really spinning, and move it forward out of the water with them still spinning. I didn't see a hint of tyre smoke in your mirror during the burnout... no smoke, not getting warm...

I did some quick calcs and comparisons to your previous runs...

Basically with a "perfect" launch and 1.85 60ft, you'd do at least a 11.87, probably even faster than that since 0.1 in the 60ft is usually worth 0.15 or even 0.2 in the deep end.

It's all in the launch...

But hey, at the moment I don't see any other XKR's trapping better than 120mph.

Result!

 

My best was 121.89

Thanks for your comments (and the tune!). I know from previous runs that the launch is an area I am weak in. My best 60 time today was 2.06 and I was getting 2.2's and 2.3 last time I went so the Michelin's do seem to have helped.

There also seems to be differing views on whether to do a burn out or not with street tyres and I have been advised to avoid the water trap with them as well so I actually reverse up to it but not in to it. There was far too much water in the traps first thing so I couldn't avoid getting my tyres wet on my first run and did the worst run of the day. I guess if I had done a proper burnout though that would have come off.

Today was the first time I actually took the traction control off and did a burn out before staging and it seem to light the tyres up quite easily. Normally I have it in TRAC DSC so it cuts power if I try and do a burn out but it did seem to help today so I will take on board your comments and try doing longer burnouts next time. I usually put it back in to TRAC DSC before launching and find that I can't get away cleanly in 1st.

They have changed the organisation of the meets now so it is much slicker. Even though the track was closed for up to an hour due to oil and antifreeze contamination I still managed to get 9 runs in.

Next meet is 21st October so I will see if I can get in to the 11's then.

 

WooHoo, finally made it in to the 11's!!!!!!

The ambient temperature was in the low 20's so the terminal speed was a little down but at least the track was a stickier which is borne out by my first sub 2 second 60 foot.



Hopefully Cambo is a little happier with the tyre smoke


A couple more runs from today:

2010 XKR v Holden V8 Wagon (the Holden normally does a 12.1)


My old friend, the Ford XR8


As it was a beautiful day and the supercharger was struggling with the heat I decided to spend the afternoon racing my other 'vehicle':

 

Excellent!

First XKR into the 11's, ever.

Well done.

 

Very very impressive!!!

Finally a 11s xkr good job gentleman

 

Congrats Again!!!
But as Cambo above has mentioned, I think you can bring your 60foot times down, into the 1.8's and then you should get even better trap speeds, and overall quartermile run

 

Thanks!

I am not sure if using Snow Mode is a limiting factor because it uses 2nd gear to pull away but I just can't seem to pull away as cleanly or as quickly in Dynamic mode/1st gear.

I will try longer burnouts next time to see if that helps.

 

I managed to do another personal best today 11.925@120.59



I almost gave up to go sailing before that run because my top speed was down a couple of mph due to the heat but I thought I would try one more and am glad I did. I did eleven runs in total of which four were in the 11's. Unfortunately they finished at 3pm, just as it was starting to cool down.

The worst run of the day was in 1st gear so I think I will stick with Snow Mode with Sports Mode for now.

This is what happened when a Honda Civic Type R tried to take me on

 

Wow good job buddy!
I assume that snow mode starts in 2nd?
I wish I can start in second on mine as it feels 1st gear is useless for now so much spin. Although I'm working to dial down 1st gear in the tune that should help somewhat!

 

Thanks. Yes it does and I think that it also dampens the throttle sensitivity which helps with wheel spin.

You could use the paddles on yours to start in 2nd but you would then have to get the changes right manually. It may also still kick down to 1st anyway but might be worth a try.

 

Guys, can I ask a naive question (not being a connoisseur of all things motorsport) but does the RS tune include a transmission control unit upgrade?

Also any pedal sensitivity remapping/fine tuning or software mods in this area?