Drive by cable.

 

Is the floor mat stuck under the pedal? What is the reason it won't go past 75% throttle?

 

Just found this thread didn't know much xjr guys were into drag racing, but looks you guys are more into it than xkr guys
I'm at 12.5 so far with stock supercharger and motor with my 08 4.2 xkr
Anyone running faster with m112 supercharger ?

 

Hey Alex, cool to have you over here, ...you want to see some more in depth guys, ..check this thread... https://www.jaguarforums.com/forum/j...project-52518/

 

Life would be so much easier for us if we could just get something like these machined for our M112 housings. But I’m sure there’s several reasons why we can’t. Just wishful thinking.

 

M. Moran run 12.41 long time ago with his 4.0 XJR ( ported Eaton, drag slicks, high stall speed TC ).
: 9) 12.463 @ 115.36 (115.56) .... street .... Cambo ....... 2009 XKR 4.2L https://www.jaguarforums.com/forum/m...andings-84783/

 

I seen that list , although doesn't look it's been updated in a while . His time 12.46 is at sea level were my at 12.55 is at Density Altitude of over 2k, Plus my car is a convertible so havier and an open differential vs LSD on Cambos.
Per calculations my car should be at low 12s in sea level conditions ,at a minimum of 12.3 so as far as I'm concerned my car is the fastest 4.2 with basic bolt ons out there. My 8th mile time is already faster even at high DA tracks 8.0 vs 8.1 in Cambos car

Anyways I looked into porting, but got mixed results in my research that suggests that 5th gen m112 will not benifit from it. Other option going with smaller pulley , I have 1.5lb pulley now that didn't require snout to be grinded down.
Another option I think it's in the intake system as it looks to be pretty restrictive here's my comparison of 350 horsepower AMG air filter size vs XKR https://www.jaguarforums.com/forum/xk-xkr-x150-33/whats-wrong-picture-350hp-amg-vs-416hp-xkr-air-filter-size-221697/

Slicks of course is an easy fix for a faster time , probably will shave 3 tenths of a second that way, but I'm after more power for now

 

We are upgrading cooling system. The old OEM engine radiator went to upgrading. At the same time transmission oil cooler will be separated from the engine radiator. The SC intercooler radiator has been upgraded model for years as well as the SC water pump. We also change engine oil cooler to more powerfull one. The oil pump is from late 4.2 one. When all these done, the car is quite ready for more serious testing and fine tuning in dyno. The engine master uses simulation software to find out best hardware combos and tunes. At the moment it shows close to 700rwhp @7000rpm with E85 and a bit less with 93/race fuel + water/methanol. Both are possible without any hardware changes. It was good idea too add several failsafe sensors. If oil pressure, fuel pressure, knock or lambda sensors identify any risks - the ECU turns power down by adjusting tune immediately.

 

The fact that the ECM does that is wicked.

 

Following this thread with big interest, I have a Xkr 4.0 coupe that I want to make go faster. Not specifically at the 1/4 mile, but in general, both in a straight line and when the road twists and turns. So far what I have done is rebuilt the front end of the chassis with every single component that wears now replaced. Front brakes upgraded to Brembo four pots with 355 mm drilled rotors and rear brakes replaced with new std calipers and new both grooved and drilled rotors.

Exhaust system is stainless full cat-back Milltek with only the rear silencers, rest is only pipes. The intake air tube is now Mina Gallery aluminium tube and air filter is K&N

1/4 mile is done in around 12.5 at sea level. This coming winter will be focussed at the rear end of the chassis, replacing all bushings. There is still a bit of unrest at high speeds that I want to get rid of.

Love that someone is still working on getting the engine pump out more power, not much of that at the X100 forum.
I will mount a smaller upper pulley this winter, bought it earlier this year but havent found the time to grind the snout of the SC.

When using a standalone engine management system, I guess you must unplug the standard system? Will that throw fault codes at the dash?

 

Any vids on how the exhaust sounds?

 

Will try to record a video within the coming days, stay tuned

 

Sorry your 1/4 mi is at 12.5 with only exhaust and intake on a 4.0 motor is not possible. Maybe you meant 13.5 but even that is a stretch to get ..

 

Nope, around 12.5 every time. But note K&N air filter also, when I changed from stock filter engine pulled a lot harder at high revs and quarter mile time dropped from 13.0 to 12.5. Car is a bit lighter also, removed spare tire, jack and tool kit, together 22 kilos. Exhaust is around 15 kilos lighter than stock also.

I think you confuse the times for Xjr 4.0 and Xkr convertible with the qm times for Xkr coupe, the latter being 100 kg lighter. Xjr 4.0 and Xkr convertible typically do the qm in 13.5

 

Scott in UK with his 07 X358 ran 12.54 @ 111.53 mph. I think he's just exhaust, tune and LSD. There's a video up on Youtube of the run

I think I can manage low 12s maybe break 11s if I spray. Haven't been to the dragstrip since the nitrous install.

 

You're putting out 800 hp on a 4.0 L AJ V8, and reving to 7k rpm? Is this on a stock internal engine, and stock heads/cam, and stock manifolds?

 

No, there have been many stages since 2011 from simlpe lower pulley, cats, catback, ECU tune to the current all custom made 4.2 block based stoker engine with well balanced forged internals.piston, valves and combustion chambers ceramic coated, better bottom end bearing and main studs. Heads are from a GT3 XKR race car, stiffer valve springs, custom made cams, big TB, big MAF, all new fuelling system with big injectors etc, etc. Almost every single part is somehow upgraded. Transmission and TC are enforded and gear changes are very aggressive and fast. All these are after one engine and two heads blowns.One SC damaged as well as orginal, weak diff with Quaife was broken. The forum was more active with performance modes 2011-2016. I just wanted to complete this car project to get it fully back to the road after major engine damage 2014. I was lucky enough to find a guy with huge experince with drag racing, Jaguar cars and all kind of high performance modes including full knowledge tune cars with aftermarket ECUs.

 

Sounds like you've tweaked it quite a bit. I've only put a 3.5" intake and 10% pulley on mine and I have broken my original differential and my second diff is on its way out too. That's been the weakest point for me, even with modest power gains.

I don't do drag racing, but on the street, it can keep up well with modern muscle. I've beat several 392 challengers, and stayed toe to toe with a 2019 Mustang GT.

What's been the weakest point of the car in your case?
What do you think is the next best mod with the most performance gain?

 

I addressed the weak 14HU rear end by using and reinforcing a 15HU. Its not quite as quiet but still acceptable compared to many non Jaguar road cars.

I also went for the Torsen T2R- not necessarily the best choice for drag racing but great for road courses.

 

Yep know Scott he has a 10% pulley as well. I know he has been struggling to come close to those times since nonetheless it's an achievement. I can justify Scott's times for his modifications, but "Higgins" claiming he runs 12.5 on his 4.0 car with exhaust and k n filter is complete BS, it will take a lot more than a k n filter and your exhaust to go from 13.8 to 12.5 , around 100hp more lol