Hi Andre,

I'm interested in a stage 2 kit for my 2008 XKR.
I know the 2007+ XKR kits aren't ready yet but would be grateful if you could please pm me with at least a guess on pricing and availability date.

I live in Phoenix so only a 2 hours away from Jeff in Tucson. I'm already in touch with him about seeing his car some time soon hopefully.

Thanks,
Neil.

 

Very exciting stuff.. I'd be interested in knowing the cost for 2000 XKR 4.0l and the 2003 XJR kits. I'm also curious of price stage 1 vs. stage 2 kits. I'm in Colorado Springs, CO USA. You can email me at vwerre@hotmail.com

Thanks again.

 

Hi Avos;
Any update on the STR version?

I was the guy who did a bit of underhood measurment for you on my 2005 STR.
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.
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Sorry for the delay with the STR setup. I just didn’t have any time to spend on the project the last months, but that is changing now, and am starting it up again.

 

How is the STR setup coming? Need more test cars?

 

Not yet, but there is one being prepared now, and if all goes well the install will start in 3 to 4 weeks.

 

When you're ready to work with a 4.2L XKR (2008), let me know!

Thanks!

 

Apologies for the delay in updates, but here is one:

The Stype install goes very well, the good news is that mechanically it is more or less sorted now. That was a big step as the STR required some extra changes compared to the 4.2 XJR which was done earlier as there is much less room on the STR to work with. The install is with this new setup much easier, once some modifications are done it will be easier than installing a stock eaton.

Now some electronical ones left to tackle (ie the torque limiter), but that will be sorted very soon as well, am working on it as we speak.


@kcaz007,
Everything learnt now from the 4.2 STR/XJR was actually needed as well for the 2007 and up XKR, but you need to have some more patience, sorry.

 

 

Avos this is great news!

I am still very interested in your stage 2 twin-srew kit for my 2008 XKR.

Jag say the 2008 XKR makes 412 lb.ft of torque at 6000 RPM. The current 510Hp XKR claims 461 ft.lbs so HP->torque increase doesn't seem linear but it still seems likely your kit will make well over 500 lb.ft.

I believe (though not 100% sure) that Jaguar used the ZF 6HP26 transmission for the 2006-2009 XKR. I can't find out if it is a special variant or pretty much just a generic one.

The spec from the ZF website for a generic ZF 6HP26 says it is rated for a maximum input torque of 600 newton metres (440 lb.ft). It therefore seems that a stock XKR (412 lb-ft) is already not so far from the transmission's limit.

Do you think the increase in maximum torque from your twin-screw upgrade would damage the stock 4.2 XKR transmission? Or does the ZF 6HP26 spec just mean those of us with 2006+ 4.2's would just need to upgrade the torque converter?

Thanks,
Neil.

 

very good news avos, thank you for the update!

I am very interested in your STR kit when it becomes available!

How did you overcome the throttlebody elbow design issue with the STR?

Is it going to significantly effect performance over the XKR version you think?

 

Do you have a general ballpark cost for 2003 str ts? And when avail?

 

The thing to keep in mind is that HP = (Torque * RPM) / 5252 so HP and TQ will be equal at 5252 RPM. That means that if the peak TQ is equal to HP at 6000 RPM then the torque curve is falling off at higher RPM. It's not surprising that the new 5.0L makes somewhat more HP than peak torque as it is a more efficient supercharger and more similar to the twin screw in the way the torque will behave.

500 lb-ft from a 4.2L would be a lot to ask. Not impossible probably but still a lot of effort and pushing the limits of reliability.

I can say that from an otherwise stock 4.2L with the Stage II kit I got 454/390 at the wheels, which assuming 15% loss, is about 535HP/460TQ, so pretty similar to the 5.0L XKR.

The thing I would add is that the torque curve with the twin screw is dead flat, and I mean so flat that it makes you wonder if it's real when you see a dyno plot. Just mash the throttle and you will know it's real though, I have a stupid grin every time I drive the car now.

The 6HP26 is actually a pretty reliable transmission and I would be surprised if you manged to break it. The 6HP28 that is used in the 5.0L, including the XKR-S is not very different mechanically and a twin screw on a 4.2L shouldn't really be pushing it much beyond it's published limits anyway, which are undoubtedly German conservative.

Ford builds the 6HP26 under license from ZF and calls it a 6R80, so there are upgrade options, including new clutches and indestructible intermediate shafts that you could put in if you wanted to. These are the sort of things that the 1000HP Mustang guys use.

 

@Justnitz,

I can't comment yet on the power levels you can achieve on your specific model year, although your ECU is easier to play with (needed as there are more restrictions there). Electronical wise your ECU model is easier to work with than with the pre 2007 4.2 models, but for instance the air intake system is more challenging again.

My sentiment is the same as ccfulton's posted, the ZF has some build in margin to play with, similar to the MB version. A lot also depends on how you want to use the power, ie street or track or prolonged German autobahn speed mileage (There is a TS kit on a 4.2 car running there for 2 years now with no failures already).

The ZF unit has proven to be very strong so far, no failures known to me at least, but that doesn't guarantee it will be safe for life either, and I can't give any there.

The torque as ccfulton mentions (as you can also see in my power pulls with above 530 lb/ft), is just flat, and makes you wonder why people speak about torque curves ;-)


@Bradparins,
Once the kit is fully ready I will know the price, but don’t count on anything below $5000 though, thats just not possible with the (extreme) low volumes.

 

I forgot to take a picture when it was done on the 4.2 XJR, but here a quick shot just before with full 3.5" piping, MAF and appropriate filter and a hint of how the new elbow could look ;-)

Don’t know yet what the power levels will be for the recommended setting, and for settings beyond that (remember the TS kit will not be the limiting factor, with more mods more levels are possible).

 

+1. This kit is very far from being generic. All the custom CNC bits and r&d that went into this kit is worth every penny. Not to mention, despite the fact this kit is going to sell in such small numbers, the price isn't too out of line with what a 2.6L KB kit for a mustang/camaro goes for. I'm grateful someone is even offering this product!

Avos, yes I realize the 2.6L TS itself will not be a limited factor,

I want to run the largest throttlebody possible on my STR, 21lbs of boost, fuel fully supplemented through methanol injection. 450whp should be possible even on a stock throttlebody.

 

Avos, a few questions...
1.. For something like $6000, a Stage 1 kit can add maybe 120 HP to a bone-stock STR?
2.. Can I achieve that 120 HP with OEM cats and air box, but just add a K&N?
3.. For Stage 2, a tune, hi-flow cats and 90mm throttle body might give another 100 HP, or are the tune and cats part of Stage 1?
4.. Anything else? Fuel pump, injectors, more cooling, synthetic oil, LSD?
5.. A good indie could do all the work, including your pre-inspection?

 

1 Don't know the price until all is finished. For now there will be only Stage I, where you have to bore out your stock TB to 82mm with Maxbore.

2 The bigger MAF and Filter are a requirement to get there, and higher

3 Don't know yet how far you can go and what is required for that. You can go to smaller pulleys to up the boost, but I have no idea yet how much the stock fuel pumps are able to handle, so more adjustments may be required there for instance.

4 Am currently checking out injectors and may make it part of the kit as well. M1 0W40 is recommended, and an lsd will help a stock car even, so although not a requirement it will give better traction in lower gears.

5 Yes, although I prefer one that knows the Jaguars already.

 

posted wrongly...

 

Avos, excuse my ignorance - my indie is a Jag specialist, but:

Isn't there some special lining material that would have to be replaced after the TB is bored? Does Maxbore do that and also replace the butterfly valve?
If Stage 2 is going to be available later, would it make sense to just fit the 90 mm TB right away?