with effect from August 21st 2016, avos has decided to stop making Twin-Screw kits for the coming time. See post #358 for details - GGG


With great pleasure I can announce that after many months (ok years…); I have finally finished my Twin-Screw kits in 2010.

In the meantime more kits have become available to suit different models, please see below the list of cars for which a kit is currently available or in the makes

Kits available:
Supercharged 4.0 (AJ26) XKR and XJR's (with stock bored out 82mm TB)
Supercharged 4.0 (AJ27) XKR and XJR's (versions with Stage II 90mm TB)
Supercharged 4.2 XKRs up to 2006 (steel bodied versions, Stage II 90mm TB)

Kits close to be finished (expected soon now!)
Supercharged 4.2 S-Type (with stock Bored out 82mm TB)
Supercharged 4.2 XJR models until 2008 (with stock Bored out 82mm TB)
(Possibly the supercharged 4.2 XFR)

Next in the line (hope around summer 2014)
Supercharged 4.2 XKR from 2006 (aluminum bodied).

Also note that the mentioned power output is based on normal fuel (premium/super of course). Once you choose higher octane fuel, or methanol kits, you can increase the boost further and thus also the power, the kit will not be the limiting factor. The Stage II kit provides the most power, but that one is only available for the XKRs from 2000 till 2006, and later for the aluminium bodied version.

Please find below in the post more info about what a twin-screw supercharger is, and also more about how the project started.

Here are some details of the Kit for XKR 4.0 and 4.2 Kits (STR and 4.2 XJR will be detailed once finished)
The primary supercharger I use is the Kenne bell designed 2.6 Large Bore High Compression twin-screw version that has proven itself as the best type for our 4.0 (AJ27) and 4.2 engines, for several reasons. Amongst others the low noise levels (compared to the smaller 2.1L version, which I tried before) and the high compression for even more efficient operation and thus more power to the wheels.
For all superchargers, being it the Eaton or Twin-screw, the airflow from the filter to the intake of the supercharger should be as smooth as possible, preferably no bends and no obstructions. I have designed the kit now in such a way, that this criterion is met as good as possible and the slight bends left are very carefully rounded to ensure the air to flow with the least possible resistance/turbulence. This directly aids in higher efficiencies, and thus more power to the wheels. The Stage II kit provides a 90mm throttle body over the stock 75mm that improves the airflow even more again.

The Stage I KIT for AJ26 (82mm intake) Includes:
- 2.6LH Large Bore High Compression Twin-Screw
- Custom CNC front cover
- Custom Snout & Coupler
- CNC Supercharger Outlet Adapter
- CNC Inlet elbow system with 82mm TB Adapter
- All fittings needed to bolt on the supercharger
- 3.0" Pulley with Belt (Single sided)
- New Bypass valve (Old one needed as core)
- 1 year warranty on Twin-Screw unit
- Needless to say all my support where possible, ranging from pre-checks of your car, to after checks.
- Extra power range about 120 HP to 180 HP

(Stock TB needs to be bored out to 82mm, Maxbore can perform this work)

The Stage II kit (90mm intake) for AJ27 and 4.2 XKR includes:
- All of the above, but with a new 90mm Throttle Body.
- Extra power range about 140 HP to 220 HP (and more pending other mods)


Additional info for both Kits
- It is not needed to tune your ECU (haven’t tuned mine even), however it might provide you even more power in the end.
- The kit can be used for both street as track (please notify me if it is for the latter, extra care is needed there).
- You will need to do some work yourself on the car to make the kit fit, which is why I call it a DIY kit. These modifications are relatively easy for anyone that is comfortable working on our cars, and easy for any Jaguar dealer/indy. Of course instructions will also be included.

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For interest/price info please PM me on info@tsjag.eu , I can then provide more details for your specific car and answer questions. There is so much to tell, and there is so much possible, just look at the www.kennebell.net or www.modularfords.com websites, am more than happy to talk about .


Here is a dyno run, 506 and 512 rwhp (609HP and 616HP using 17% drive train loss), that is 237 HP more than I started with.



Here is a dyno run with racefuel that gave 524rwhp, and the numbers below are based on a 17% drive train loss so max 631 HP, which means 251 HP more than I originaly had stock

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What is a twin-screw?
The standard supercharger (Eaton) on the Jaguar is of the roots type. In short, this one pushes air with large flat blades into the engine, somewhat similar to the old Mississippi paddlewheel boats.

A twin-screw supercharger is more advanced and works more similar to the modern screw driven boats. It also does something extra, and that is compress the air already in the supercharger case via 2 different size screws, which is much more efficient than trying to push air into the engine via the paddle mechanism of the Eaton.

With a proper twin-screw setup, gains are easily starting from 100 (bone stock car) or more than 220 extra horses, where the latter would depend on other mods like ecu tune, exhaust etc, and with higher octane fuel of methanol kits you can even push it further.

There is a place for the roots type supercharger, it is cheap to manufacture, and relatively ok with boost no going over 11 psi (for comparison, in an older TS setup I tested with about 12/12.5 psi gave me already 60-70 horses more to the wheels!).

The drawback of the twin-screw type superchargers is that they are more expensive to manufacture.

Here is some more information about the 2 different superchargers:
http://www.kennebell.net/techinfo/general-info/twinscrew-vs-roots-fromcatalog.pdf


Some background:
I have started this (ad)venture about 5 years ago when I wanted some extra performance from my 4.0 XKR. The standard items like lower pulleys to speed up the supercharger etc didn’t give me the power I was looking for, actually dyno tests showed that my top end power was almost similar as stock. After some thorough investigations I found that the current Eaton is already at is maximum efficiency, and spinning it faster will at some point will cost even more power from the engine than that it can bring. Several studies/tests have been made proving this, and this was consistent with my findings on my own car. Early 2006 I stumbled over the aj6enginering website as they were speaking about twin-screw superchargers, and after contacting them I got the confidence that a twin-screw could be an option, and of I went.

My XKR is my daily driver and have driven already 170.000 miles with it. So for me it is important that with the extra performance, the car should also stay drivable, provide good comfort levels (low noise) for normal cruising and last but not least not loose reliability. It all has taken considerable amount of time & miles to develop handmade kits and test out different setups/twin-screws until I was completely satisfied. This proved to be a tough task and has taken lots of time and investments (am not easy satisfied ;-). In the back of my mind I was always keeping an eye on making the kit in such a way that it could also be reproduced, so the last steps where making professional 3d CAD drawings of the best design I came up with for CNCing the final parts for the highest possible precision.

One of the early handmade versions I have made in 2008 has also been covered in a story about Norman’s (exceptional) car in the Jaguar World Monthly magazine May 2010:



Important to note that I am NOT doing this for a business, it is purely a (quite possibly out of control maybe) hobby of mine, which I do with great pleasure, and I hope even to develop (or help others) over time with more improvement items for our cars (and a TS kit for the STRs).

 

good luck Andre!

Thread stickied for a month or two with moderator & admin permission to conduct this offer to our members.

 

nice! congrats, do you mind posting some videos for us of drive by's and what not so we can hear the whine?

 

how's the response so far Andre? besides brutal's apparent interest.

 

@Jaggyx,
Haven't made any vidoes, will see if I can do something, as I need both hands on the steering wheel...

@h2oboy,
Just solde the 500th kit

Just kidding, I think the interest is as expected for a conversion like this. With some enthusiasts I already had contact for a longer time, as I haven't made it a secret that I was working on something. This is also ok for me, as I provide also all the help in putting everything together, I couldn't sustain large numbers. I want already to thank you that you allowed me to post here (and fixed some typos), especially as this is not a profit making venture, so I appreciate this very much.

 

Andre,

Sent an email yesterday. Can you post some pics of your setup?

Thanks,
Kevin

 

haha true well pics video, whatever you can get!

 

The videos have to wait, I feel not so comfortable with the amount of power to floor it, and only 1 hand on the steering whell...

For the pictures wanted to wait as I haven't yet worked on cleaning up underwood (painting/powdercoating all the parts nicely), and the intake part. For the latter I just use some silicone tubing fitted in a way I can quickly remove it. But I am working now on a new intake with a larger MAF sensor and new air filter, but that will take some time before I finish that.
But to give you already an idea, here is a picture

 

I have read that you said that you the kit ready for the 4.2 XKR but do you have a kit for the 4.2 XJR.

Thanks

 

Hi SergeXJR,

Not for the moment, however the STR kit which I am working on will also fit the 4.2 XJR, but that will still take some time to finish unfortunately.

 

Awesome stuff you are doing. I look forward to reading more.

 

Im tuned in to see the video...

 

video!

 

Freakin Awesome Man. Just read about it and am I stoked. I just bought my car, a 2000 XKR with 67k mi, and I'm obsessed with it! I also just replaced all chains, tensioners etc. (myself) and am elated to hear you have 170k mi on your 2000; so mine should last my lifetime. Guess nikasil can be a good thing huh? And to hear you've added all this power without hurting it...sooo cool. Also, I was thinking of getting the smaller SC pulley; thanks for educating me that it is a waste of money (like $300 plus), or at least very little gain. Besides the cost which I will inquire about; what about adding all that torque to the stock transmission and rear end...can they handle it; long term reliability still paramount with me. So the TS is not physically bigger or higher..still fits under the hood? WOW you're the man.

 

Hi! Avos how is the STR kit coming I am very interested. thanks Paul

 

@Fla Steve,
Well if you can change your tensioners yourself, you can install the kit with ease if you ever decide to go for it. The extra amount of power is really what the car should have gotten originaly imho (Jaguar did teh right thing with the 5.0 SC, juts to late), it has blown new life into my car, as it does give a new dimension when you need to be careful with the throttle. One of the things I really like is when you cruise, and you want to speed up quickly (i.e. to overtake or so), you only need to press the pedal down a bit and you already feel a large amount of torque without the gearbox having to shift down. It makes the car less nervous, and more a joy to cruise. Of course all h..l breaks lose if you open the taps. Will send you a PM with more details.

@uropnm6
Sorry, but it will take some more time; I do hope to make some good progress in December/early January. I can’t guarantee any time yet though, at least I know what to do and it is just getting the 3d drawings made (the hardest part…).

@Video
Will see what I can do, but for those that want a loud supercharger whine I have to disappoint you. However it will depend on the pulley chosen, but in the recommended setting the sc wine might be just the same as with the stock Eaton. I can remember that when I had the faster spinning Eaton it was very loud, especially when it was ported (too loud imo).

I know some really like a loud whine, and when I experimented with the first kits (the 1.7L and later the 2.1L), the noise was somewhat intoxicating, you just wanted to hear it scream. But I didn’t liked that in the long run, I just drive to much, I want to have a GT quality car so that was one of the reasons I went with the 2.6LH twin-screw.

Hopefully in December I can do some dyno runs as I will also have the 3.5” MAF setup ready then, maybe I can make a video on the dyno.

 

What would I be looking at in term of cost? I run an 01 XJR 4.0

 

i too am working on a twin screw setup but for the 6 cylinder

 

Good choice ;-)

Am more than happy to help if needed, you can pm me on my mail address mentioned.

PS If needed I know an almost unused KB 2.1L secondhand unit, but not sure if that one could fit.

 

In what country are you located at avos. UK or US?