water-meth in itself doesn't add any power, it simply allows you to take advantage of more boost/timing safely, or supplement fueling requirements,

I think with the boost/pulley Jeff is running, he can't take any meth out of the equation right now without running lean,

 

The twin-screw indeed has a lower heat output than the Eaton, however at 20 psi and higher it isn't cold either...

By increasing boost you will speed up the combustion, taking up the reserve build into the ECU (based on ignition timing start before TDC and optimal peak pressure at about 17 degrees after TDC), and at a certain point you need to slow that down again to still stay within the optimal range for peak power (so about 17 degrees after TDC, if more before or after you lose power).

Another risk with increasing boost is the increased chance on detonation. I guess that around 20 psi with the twin-screw kit is about the max I would go with street fuel, after that higher octane fuel or water/meth would be needed.

As Jeff is going above 20 psi the water/meth kit is a good option as that will help in slowing down the combustion speed via cooling down the air/charge and the methanol (fuel) enriches the mixture both lowering the combustion speed and in addition it also adds more protection against detonation.

It can also work against you if you slow down the combustion speed too much (by spraying to much), so you need to carefully set the right amount. Am only recently experimenting with water/meth, and the amount to spray will depend on how much boost you run, so my best guess for Jeff’s setup would be around 400/500 cc.

Best is to test this on the dyno, and also check the air/fuel ratio so you don’t to go rich. I am now at about 600 cc (3 x CM2 nozzles, with 50/50 mix), that I hope to be right for about 24/25 psi which I would like to test.

Last but not least I do apreciate the cleaning capabilities of water/meth kits. last year I passed the emission testing only barly with my sport cats, and this years one was an easy pass because of the cleaning.

Dislike is the re-filling part, and if there is a dependancy on the water/meth kit to work, as that could fail. Make sure you choose a system that will let you know if it is not working properly (ie lower flow for instance or blockage of nozzle). I choose the coolingmist one with the failsafe, but there others as well.

 

There's a fellow in Tucson that has a Mercedes SLS AMG... ahem, I think that he's suped it up a bit, too! I had my video camera on, but the street was headed due West into the setting sun and I wasn't about to add risk by one-handing the smart phone. It wasn't very safe but the road was open. He pulled up on me after I went through an intersection where he was waiting his turn to pull out. As he got alongside my XKR we both floored the throttles. His exhaust was insanely loud. We had fun, but he pulled away from me like he had about 300 more horsepower... REALLY! He must have paid $200,000 for it, PLUS another $100,000 making it even faster. That thing was a dragster. =) I feel honored to have been able to have fun with him. He even rolled his window down for a bit so he could hear my supercharger. He seemed to be a having fun, too.

 

That seems to be the karma thing when you get what you think is the fastest car. Sure enough you end up finding yourself next to the guy that has the hotter car and you get spanked.

Doug

 

Lighter cars are always faster...and his wallet couldn't have weighed much anymore. Sounds like you had fun anyway.

 

I am still amazed how at fast my XKR is with its new supercharger. This thing is amazing to drive. What is REALLY amazing is that I can have a car this fun to drive and NOT have spent twice the price of a house to own it.

 

Sometimes the karma thing goes both ways. A few years ago when I still had my 1995 Corvette I was on surface streets on the way home. The car looked real sharp (red coupe and in pristine condition) but it was obviously an "older" model compared with the latest and greatest. Also the car originally had only a "paltry" 300hp which I goosed up a bit with a few mods.

I rarely punched the car since that is not the way I choose to drive. But anyway these guys pull next to me at a stop light in some newish Mercedes CLS or whatever the larger coupe is called. It was black and obviously some souped up model (maybe AMG). I was in the right lane at the light and I could see ahead that the lane ended requiring a merge left. Well the guy in the Merc obviously noticed that as well and punched it hard when the light turned green. So I punched it also expecting to have to slow down and cut behind him but, to my surprise (and likely his annoyance) with his engine screaming I still zoomed by him. I suppose if there had been more distance he would have eventually passed me by. But this really drove home the point that the lighter car with "meager" horsepower will show pretty well against the behemoths with ridiculous horsepower, at least for the stop light to stop light type contests that most will encounter.

Doug

 

Lol karma, kinda like back in the 80's when i drove my elcamino with a 427 in it, a 11sec street car. Late one night pulled up next to a nice hopped up early camaro i reved the engine alittle and he did. Light turns green i punch it and.........he didnt what the hell i thought for sure he was game. Then i realised he saw the cop behind me with his lights now on...

 

SLS AMG's trap over 125mph in the quarter... no surprise it left the XKR behind, no shame in that though!

Unfortunately, even with the twin-screw, these 4.2 cars are still not that fast... but certainly quick enough!

 

But I love it when the AMG guy will get blown away by the street ricer with a blown Subaru WRX with nos (or another similar tin can rice wagon).

It amazes me when I see the endless threads on some of the car aficionado sites where some guys will research specs and pore over 1/4-mile drag times or lap times around the Nurburgring in deciding whether or not they should be considering this car or that one. As if they will be doing anything more in real life than going from stop light to stop light. This is not made up as I still lurk around the Corvette forum and have to laugh about all of the boy racers discussing the new C7 and how it compares to Porsche, etc. and found some arguments regarding Nurburgring times.

Doug

 

Come on Jeff, Get it on the Dyno and give us the figures!

 

It rarely rains in our desert. I got to drive this monster for the very first time in the rain today. WOW! The O.S. Giken limited slip differential is amazing. I can hit the gas and take off from a stop rather quickly! Sure, it's not AWD, but this thing takes OFF on wet roads. The differential is a worthwhile addition.

 

Definately agree. Right before attending a slalom event with the Jag club here in Phoenix I had a Quaife LSD fitted. OMG my car was totally controllable when I was breaking the tail loose to get round some tight corners fast. Best upgrade I've ever done to a car. I hardly ever see the TC light now even under full throttle starts its amazing.

 

OMG...

The Jag had a weird issue. It stalled out and wouldn't restart, as if it was flooded. It turned out that the fuel pumps were D-E-A-D, DEAD. I had 2 new units put in. The others were the originals.

The car is now even FASTER. WTH? I suppose that they couldn't keep up with the demand previously. The XKR is so fast now that I can take off from a light at about half throttle, getting about 30 feet away from the stop light, and if I floor it at that point it STILL spins the tires. JEEZ.

If I keep it floored as it shifts into 2nd it continues to spin the tires for a little bit.

I'm thinking that I'll get a dyno run put in after the holidays.

Y'all be safe out there!

 

Of course, the possibility exists that only 1 pump was working previously or 1 or both were not providing adequate Volume for your High Load requirements.

 

"The Jag had a weird issue. It stalled out and wouldn't restart, as if it was flooded. It turned out that the fuel pumps were D-E-A-D, DEAD. I had 2 new units put in. The others were the originals.

The old orginal pumps do not like higher fuel pressure. They just die. Happened to me also.

 

Greetings from an STR owner from Scottsdale. Can you send me the link to your Jag club? I might be interested in joining. Thanks

 

Jeff do you have some news for us?
Maybe a dyno run?
Regards from Munich
Maxi

 

Rasputin sorry for not getting back to you earlier, I only just now saw your post.

Yes, the club I'm talking about is the Jaguar club of Central Arizona (JCCA), we are the local chapter of the JCNA, which is the (only) officially sanctioned Jaguar club in the US.

sw02 Home Page
(Please note that we are far more active than the event tab on our page on that link would suggest, as those are just the sanctioned events at national level. We schedule all our local events on a page on meetup.com that is visible to members only).

We currently have about 80-90 members and more are always welcomed.

Neil.

 

Sorry for not being very active lately. In December my pinion gear decided to
disintegrate. Hah!

The car will be back together in about another week.

We didn't shot peen the gears prior to the installation of the OS Giken differential, like AVos had recommended.

Lots of research lead us to determine the best way to put things back together. Falconworks found a specialty shop in Los Angeles that does exactly what we needed. We paid $1,000 to have an analysis of the metal done. We sent them chunks of the broken stock Dana pinion gear for vaporization. With those results, they have determined the correct way to harden a new set using heat treating and shot peen techniques. Prior to sending the new set to the vendor, Falconworks took off all sharp corners from a brand new set of gears.

We'll see how this one holds up... they say that I should be able to beat on it pretty hard without grenading it again. When it popped, I had just come out of a corner and was laying down 2 patches of rubber as I accelerated. The XKR has become quite a rubber patch laying machine. Someone has to seal the roads around here!

I got bored while waiting for the XKR gear work, so, on my Land Rover, I cut the fenders and added flares, over sized tires, and heavy duty high-clearance bumpers with a winch. I've been going places that I'd never point the Jag at. This rig has a locking rear diffy, too. The rocks that it can go over are huge!