XKR 5-Speed Manual Gearbox

[dadofbud]

As the title, has anyone yet managed to install a manual 5-speed gearbox ( as DB7 ) into pre 07 XKR's, with success and then offer the conversion as a turnkey product. ?

Thanks

[Jaguar steve]

The DB7 and XKR use a completely different engine. The DB7 is essentially a revamped Jaguar XJS, but is fitted with either a supercharged version of the AJ16 3.2 litre 6 cylinder engine which was also available in both manual and automatic versions of the XJ6 and XJS from the mid 1980's or a 6 litre V12 that was only available as an automatic in the XJS or XJ12
The XK and XKR were fitted with a completely different V8 engine that was only ever avilable as an 5 speed automatic. Jaguar have never produced a manual V8, but there are aftermarket options for a conversion.

[Triple7]

NormD is fitting a manual g/box in his, is he not?

[XKRacer]

I have done it in my track car.......not a problem if you throw a lot of stuff away and I used a 6 speed T56.

I looked into doing it as a turn key item 10years ago......too much money...I dropped the XKR engine with the 6 speed into an XJS Monaco that was a lot cheaper!

But for an XK you have to change the diff and if you do it to anything over 350bhp (XKR) forget using an XJ LSD they wont take it which means one of Normans and Toms Quaifes and getting a new crown wheel and pinion made top that with the gearbox, twin plate clutch to take the power beacuse of the small bell housing.

New instrument binacle, I binned the ECU and used a stand alone system much more user friendly then again I lost the inlet manifold and throttle body and fitted 8 of them not so user friendly!

If you talk Elite into one of there little boxes to fool the ECU and do all the leg work yourself you might be able to do it for 6K

Jaguar obviously produced the XKRR which was shown on TopGear but none of the elctrics worked properly the little screen on the speedo was having a total head fit when I drove in it. Jaguar used a Vanquish diff with an S Type rear setup shortened drive shafts and a whole host of nightmares to make it work but they did it just to say they could! They also used a T56 and twin plate semi organic clutch.
A very similar set up to my own I just did it a year before them.

Edited by XKRacer on Sunday 23 August 00:31

[dadofbud]

Thanks, looks like a Non-Starter as a buy-in turnkey option, which is a real shame because if you want same-ish performance and good looks but a hell of a lot more money it's a DB7 Vantage if you want a manual box in your grand tourer.

Anyone have any views on the "Button on the steering wheel" gear change for the auto box that you can get retro fitted to XKR, is it an "ashtray on a motorbike" ?

[jgaxkr]

I have fitted a 3.58 LSD from a 6 cyl XJR to my XKR. I had to have the TCM reprogrammed to do this which was quite expensive. The car is also fitted with Racing Greens Speedshift with the buttons on the back of the steering wheel. I could have gone to a 3.77 rear axle but opted for 3.58, the increase in acceleration is quite noticable & the update is quite straight forward. I no longer have to worry about breaking the rear wheels loose every time I pull away from a light, prior to this the car was fitted with a 3.27 ratio diff non pozi. The LSD has solved all my traction issues & should be fitted to any XKR that has been modified. My car is highly modified running 20 psi of peak boost {I have seen 22 psi in very cold weather with water methanol injection on} free flow exhaust modified cooling system, custom 3.5" cold air intake including custom made 3.5" air meter etc etc. I would love to have a manual transmission but have to say the buttons are just as much fun, in my opinion.

[NormanD]

Triple7 said:

NormD is fitting a manual g/box in his, is he not?

I'm quite advanced in making the Manual conversion available.

I have found a gearbox that will take the power AND with the correct ratios so no change to the Diff etc although I would reccommend a LSD that we can supply
Also there was the problem of getting hold of a road going clutch that would also take the power having consideration that most owners would have or will be trying to get more power from their cars, this we have also found one that will do the job

I'm looking to get the conversion available at sensible money that can be fitted by any compitant Jaguar specialist although the first few would be done buy Tom and myself to check there are no problems

Edited by NormanD on Sunday 23 August 17:02

[RW774]

Interesting. All the jag IRS diffs are manufactured by Dana UK, they manufacture and assemble both the current Aston and Jaguar IRS diffs. Crown wheel and pinion are fine up to 500bhp, probably 600. It`s the IRS output shafts that are marginal.I speak from experience having supplied numerous ratios and shafts to an Aston Racer locally, his car is putting out around 550 .Its always the outputs that fail.Last I heard he was having some made.
I see alot of seriously dream BHP figures mentioned, unless they are full blown race cars I find it difficult to believe the achievements . I`m open to debate though.

[XKRacer]

Until someone puts there car on a rolling road everything is going to be superstition.

From what I have been told you can assume 20-25% increase in BHP from losing the torque converter everything after will depend on other mods, twin screw super chargers smaller/larger pulleys and if you have a modest 8 like myself, then you have to go really crazy


Like me!

The original Jaguar ECU is a waste of time in my opinion for a manual as it was geared up for an auto but for a moderate road going car it will do its job fine.

I will also stick a 150 shot of NOS on this engine just to see how quick I can blow it up.
I already have my eye on a 5litre and have made everything so it can be interchangeable (hopefully )

I have also decreased the weight of my car drastically, cut as much metal out as possible, carbon fibre bonnet, removed glass, only 1 seat, no carpets, lost a shedload of trim panels, I lost 25 kilo from each door( motor,glass,trim, metal), I even cut the boot floor out!I reckon I have reduced the car by a possible 250kilos plus.
I have also lost the ABS, aircon, water pump (pump is now electric digitally controlled). Should make an interesting car.....Will drive terrible on the road but with all my designed fully adjustable shocks and coilovers, using 6 pot Alcons for stopping on 2 piece discs should all be good for giggles on the track!

.

Edited by XKRacer on Monday 24th August 14:05

[dadofbud]

XKRacer, that's engineering porn, steady there may be learner drivers viewing, or heaven help us Jaguar Anoraks.

[avos]

@RW774
550 BHP on a car that probably has a manual gear box, would be close to 500 rwhp. That in combination with good traction tires, and racing all the time, not something coming close (yet) to (some) of our modified road XKRs.
I usually drive with 430 rwhp, and so far so good (at least for more than 70Kmiles), but no racing here. Good to hear that the crown/pinion should be able to handle 500 to 600 bhp (based on a manual gearbox. This in combination with normal tires, and tire slippage (even with LSD) will more or less hopefully be the insurance for the rear axles ;-). But the supercharger cars provide somewhat more low end torque…
Besides NormanD’s XKR (and probably next XKRacer) I am not aware yet of other XKRs coming even close to our rwhp output, nonetheless would look forward to others with the same or more as we can all learn from that. NormanD’s car will be something special when he is ready and with manual gearing.

@XKRacer
Great stuff, must be fun going this far ;-). Have you also changed the internals of the engine? And what is your expected output? Regarding the automatic gearbox losses, it might be too optimistic imho, it would be closer to about 6%, nevertheless very considerable gain when going to a manual at for instance 550 BHP…
I agree with the ECU, would have ripped it out myself, but I like my car to be a GT with all the goodies including the automatic, which you loose with a custom ECU.

[XKRacer]

avos said:

@XKRacer
Great stuff, must be fun going this far ;-). Have you also changed the internals of the engine? And what is your expected output? Regarding the automatic gearbox losses, it might be too optimistic imho, it would be closer to about 6%, nevertheless very considerable gain when going to a manual at for instance 550 BHP…
I agree with the ECU, would have ripped it out myself, but I like my car to be a GT with all the goodies including the automatic, which you loose with a custom ECU.

I have left the engine internals standard for now (one reason why I think I will blow it up). I am hoping to get 500BHP, my throttle body set up should gain me a substantial power hike as my injectors are in the throttle body and not in the manifold. Car companies put the injectors as close to the port as possible to reduce emmisions but this does cause a major loss in power. Having the injectors high allows the fuel to mix much better, more power which is also determined by the length of your horns and mine taper from the front and go up 40mm, 50mm, 60mm and 70mm. Having alternate length horns does give you less power at top and bottom end but a much wider mid range power band, which I am happy with. I had to do it that way to clear the bonnet which will also be the 'lid' to my air box. Air will be fed via the front air scoop I have fitted straight into the box giving me a ram air style intake

With the NOS maybe 650BHP but I am not counting chickens until I see the figures, I will scan and post up the magic piece of paper when I have it done




I have told this story many times but I will repeat it here!

I use to have a young guy working with me who went to univertisity to study race technology. On one of there field trips they went to the Ford testing facility. They had an AJV8 on a test bed and the guy testing the engine told him the block can take upto 750BHP before it started to dismantle itself and they achieved that by cold air intake and ECU only. I asked him if the supercharger was different but he said he couldn't tell and didn't ask? But 750BHP on standard internal is 'alot'....One reason I think I want to try and blow mine up

[RW774]

Beam me up Scotty, excellent development work XK racer. What ECU are you using? Is it compatible with the existing Jag harness and dash layout or do you bin the lot.I`d thought about the Landrover 4.4 block to use as the 5 litre.I`m talking to a cranshaft manufacturer regarding a stroker on the old XK motor. The same company said they are working with Jaguar developing a 6 litre V8 crank!

[DrDeAtH]

XKRACER i hope you will be looking to use a Wizards of NOS system on that vehicle... i am sure it will give you better power and reliability over an american single hit system. check them out at: www.noswizard.com or the forums: http://forums.nitrous-sdvice.org some useful stuff on there to read up on


HTH

[avos]

I think Rocketsports have gotten about 650 bhp from a 4.5 liter AJV8 engine (was 4.2). They achieved that not only with similar carburetors you use, but probably also with different camshaft timing and more important revving the engine 1500 rpm or so more. Of course internals where different/stronger, but with some luck, proper fuel management/timing and the scoop it looks promising ;-).

Have you considered to use the Evans NPG coolant? Might be of interest in your setup, as I assume you do not necessarily want to blow the engine up to quickly or?

Never heard that story you told, but could you please tell it again ;-)

It sounds great to my ears that the 4.0 (or was it the 4.2?) block could hold 750 bhp, as I am working to 500rwhp, which means with a modest 15% drive train loss and added the power to drive the SC it will be in the 670 BHP region.

[drummerboyXJR]

Am humbled by you guys and your amazing conversions and upgrades, theres me wondering how i'm going to fit my new fat tailpipes!
Keep up the good work, gives us small time mechanics and tinkerers inspiration!

[NormanD]

avos said:

I am working to 500rwhp
which means with a modest 15% drive train loss and added the power to drive the SC it will be in the 670 BHP region.

That is interesting, haven't looked at it that way.
15% on a Auto I think is low, but when you consider the power to drive the Supercharger as well the bottom end is taking some power.

[avos]

Please note that the figurs are for dynos that have the big drum per wheel, not the small dual drums as they add more friction. The single drum ones come closest to real world wheel HP figures. I think that it will probably be closest to 17%, but 15% is just a bit more modest. You can easily calculate yourself rich by choosing the drive train loss you like ;-). This is stll why I am only interested in what you get at the wheels.

Here is a table (can't get the formatting right, but you should get the picture). On average I have seen 4.0 cars have about 315 rwhp and 4.2 cars about 335, then you see actually that 15% drive train losses comes closest to the advertised BHP values from Jaguar.

Engine rwhp 15% 17% 20% 22%
4.0 315 371 380 394 404
4.2 335 394 404 419 429

Target 500 588 602 625 641

For the 500 rwhp I added also roughly 80 bhp for the SC, but that might be on the high side, but then you come in the close in the 670 bhp.

[XKRacer]

@RW477 I have had to bin most of the original Jaguar stuff, main thing the instrument binacle. I am using an Emerald K3 to run the engine, very simple to use and comes with 3 switchable maps loaded into the ECU. You can switch between a standard road map into a race map at the twist of a switch even on the move! I have lost so much of the original loom it is not funny but changing to the stand alone system is major work and not for the faint hearted but will allow me to play with the engine properly instead of tweeking very slightly to get as much HP as poss with the OE system.
Very interesting about the 6ltr crank that would be excellent.

@DrDeAtH Have already been in touch with Wizards of NOS needed to know the thread rate of the injectors Have heard good things about them.

@avos You are right Rocketsport did exactly what you said, very impressive to. The story I told was on a 4ltr. I also know the engine was originally designed for a race series by Cosworth and TWR hence the nikasil and plastic parts, it was done for lightness then Jaguar decided to drop it into the XK without changing anything, which is why there was so many problems. I can also tell you they had to de-tune it because they considered it far too powerful for your average Jag owner?
Interesting dyno figures but I agree with you RWHP is what matters (of course torque as well) Inflated '@ the flywheel' figures don't mean squat until you put the power on the ground, which then takes you onto 'power to weight ratios' which are even more important!
I will weigh my XK once I am done will be interesting to see what I get per tonne

[a8hex]

If you want to take the power to weight argument to the extreme, then it isn't ever really the rear wheel power you are interested in, but plotting the torque multiplied by gear ratio curves against road speed. This is the best way to get an idea of how well the car will perform. A really peaky engine, with the wrong gear ratios can have a great power to weight ratio but not return good performance.
Problem is, it doesn't give a good simple number to brag about down the pub :-(