In reply to mguar:
I was thinking the ECTA's standing mile races in wilmington ohio. No super speed salt flat stuff.
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Dec. 25, 2011 3:43 p.m. BoostedBrandon HalfDork
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Dec. 25, 2011 10:14 p.m. mguar Reader
Rick wrote:
In reply to mguar:
I heard rumors back in the early 80's that corvette gears fit in the rear of the Jag. Anyone know if it is true?
Later 80's used Dana rear ends but the ratios are close to Jaguar.. Dana Is an American company so buy the gears here from Dana.. In fact you'll be surprised just how many American parts are in a Jaguar..
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Dec. 25, 2011 10:24 p.m. mguar Reader
BoostedBrandon wrote:
In reply to mguar:
I was thinking the ECTA's standing mile races in wilmington ohio. No super speed salt flat stuff.
Well as you get over 100MPH frontal area get's really critical.. the XJ-S is about a foot wider and has over 5 sq.ft. more frontal area.. While the CD is actually lower in the XJ-S than that slippery XK-E those additional 5 sq.ft. gulp power.. It's an interesting question. The trade off between greater traction of a wider tire and the loss of top end spreed because of added drag and more frontal area.. It would be cheaper and easier to race a XJ-S than a XK-E If you do it please keep me informed.. I'd really be interested in those numbers..
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Dec. 27, 2011 12:47 a.m. calvindoesntknow New Reader
Okay so I woke up at 2 am to tell you my idea, what about using an electronictronic 4l60e and messing with it to make it paddleshiftes, I mean even I could fabricate a set of cheap paddleshifter like things to mound behind a steering wheel. Just an idea, personally I don't like paddles but they are cheap and give you manual shifting control
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Dec. 27, 2011 1:57 a.m. mguar Reader
In reply to calvindoesntknow: From 1980 on (and a bit earlier in some cases the transmission in XJ-S was a GM turbo 400. You can get a shift kit for that which will make the shifts a lot faster and allow you to hold the engine in gear past when they normally shift automatically. From I think 1992 they switched to the GM 4180 (overdrive) I don't think there is any advantage to a paddle shifter over the floor shifter.. That's one of those things you could spend a great deal of time and effort for no real gain.
The really high powered, High end cars, with paddle shifters use paddle shifters for a different reason.. At the very best an automatic can shift in slightly less than a second the paddle shifters like Ferrari, Aston Martin, etc. shift in less than .010 of a second.. (and really high end versions much faster than that)! My racing transmission with the dog rings where I do clutchless shifts is faster than the NASCAR boys do it, FASTER than NHRA boys do it, but no where near what modern electronic controls allow paddle shifters to do it in..
It's not just where the shifter is, rather it's a whole totally different system. Very specially cut gears to be light enough to move in tiny fractions of a second while the engine is electronically controlled. They don't have syncro's like a manual or bands like an automatic rather more like my dog rings. except where I stir those gears with a lever and the throttle a Paddle shifter is done by computer.. -
Dec. 27, 2011 11:38 p.m. BoostedBrandon HalfDork
mguar, this is EXACTLY what I had in mind.
http://www.youtube.com/watch?v=aUwj3Mp4c90&feature=related
mmmmm that snarl...
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Dec. 28, 2011 5:21 a.m. speedbiu Reader
Not sure if you guys read my posting on the other page but they did make a few 4 speed XJS's.Mguar,Whats your take on those?Theres on on ebay and one in Columbia South Carolina for sale.There a little more price but still well under 10K.As for shifting my auto I installed a shift kit and a B&M hammer shifter.You can ratchet it back and forth thru 1-3 and shifts as soon as you grab it with the shift kit.I like it better than a manual at this point.IMO.
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Dec. 28, 2011 5:34 a.m. mguar Reader
speedbiu wrote:
The Jaguar 4 speed is marginal in racing applications.. the V12 has too much torque for a well developed V12 engine.. That transmission was originally designed for the little six cylinder motor which really had to be well modified to get over 300 horsepower.. Since 700+ is possible with the V12 I think you can see the trouble.. As for an automatic yes putting a shift kit into the Turbo 400 will make the shifts faster and harder.. However it is only a 3 speed. That means the engine cannot be as highly cammed with the result that peak power will be be down in order to make power throughout the rev range. With a 4-5 speed (assuming an non-overdrive 5 speed) the engine can have a cam designed for a more narrow operational band.. the more narrow the band the more powerful the potential..Not sure if you guys read my posting on the other page but they did make a few 4 speed XJS's.Mguar,Whats your take on those?Theres on on ebay and one in Columbia South Carolina for sale.There a little more price but still well under 10K.As for shifting my auto I installed a shift kit and a B&M hammer shifter.You can ratchet it back and forth thru 1-3 and shifts as soon as you grab it with the shift kit.I like it better than a manual at this point.IMO.
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Dec. 28, 2011 5:45 a.m. mguar Reader
BoostedBrandon wrote:
Several points I noticed about that car.. first I didn't see a rollcage.. While it may have had a roll bar I saw no cage.. Second, notice he used 4 throttle bodies? Not 2?mguar, this is EXACTLY what I had in mind.
http://www.youtube.com/watch?v=aUwj3Mp4c90&feature=related
mmmmm that snarl...
He's extremely proud of those even though Experts point out that in back to back comparisons 4 throttle bodies don't make more power.. Aston Martin tried both and settled on 2 as did Ferrari and BMW.. It's an easy enough modification So feel free to do whatever your heart desires.. Notice too that he ran through a 5 speed? Watch his left leg.. I may be wrong but I didn't see it stab the clutch so I suspect he's running a dog rear gearbox.. (clutchless shifting).. Since it's a 95 that means he's got at least 6.0 litres but in our discussions he likes the HE head.. The prime flaw with the HE head is the exhaust valve is deeply recessed and the intake valve too is recessed (Not as much though) Bottom line? there is not the same flow potential that an early flathead has.. -
Jan. 2, 2012 10:12 p.m. calvindoesntknow New Reader
i built my pedal box for my xjs to have a 3 inch clutch throw, there isnt much leg movement involved at all. altho it is pretty tiring after a long while of traffic
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Jan. 2, 2012 11:54 p.m. mguar Reader
calvindoesntknow wrote:
i built my pedal box for my xjs to have a 3 inch clutch throw, there isnt much leg movement involved at all. altho it is pretty tiring after a long while of traffic
That can be fixed by changing the clutch master cylinder to reduce effective leverage..
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Jan. 3, 2012 2:30 p.m. mguar Reader
dyintorace wrote:
Headers? don't add anything.. (sound wise) Cast Iron Manifolds sound identical.. However if you've ever heard a V12 running you'll swear it's at a really fast idle.. sounds like 1500 rpm or so at 600RPM.. It's because you can hear every single cylinder firing unlike a V8Wow. I hope there is some way for you guys to manage headers. That car should sound awesome! Great score!!
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Jan. 3, 2012 2:33 p.m. mguar Reader
hrdlydangerous wrote:
HiTempguy wrote:
Since the auto-x is a big portion of the challenge, and the car is quite long, as soon as I saw this I envisioned a good 6+ inches being chopped out of the middle of it.
You should do that!
Alter the wheelbase like an old A/FX drag car. That should offset all that V-12 weight on the nose.
On a more serious note is it possible to cut a piece of the trunk floor out to make a window to show off those beautiful inboard brakes?
Stock the rear brake system isn't pretty.. to make it pretty involves a lot of chrome. It's also pretty pathetic.. tiny little rotors and single piston calipers.
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Jan. 3, 2012 2:35 p.m. mguar Reader
Dr. Hess wrote:
I thought all the clown type smack talk was supposed to happen before the Challenge?
Hey, if you took a XJ-whatever-12, put a 500 shot of nitrous on it, I bet that would do pretty well in the drag portion, huh?
Top Gear did just that and beat all the worlds supercars in a drag race with theirs.
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Jan. 3, 2012 2:51 p.m. Javelin SuperDork
mguar wrote:
dyintorace wrote:
Headers? don't add anything.. (sound wise) Cast Iron Manifolds sound identical.. However if you've ever heard a V12 running you'll swear it's at a really fast idle.. sounds like 1500 rpm or so at 600RPM.. It's because you can hear every single cylinder firing unlike a V8Wow. I hope there is some way for you guys to manage headers. That car should sound awesome! Great score!!
I dunno about V12's, but that's a patently false statement for every car I've ever put headers on (leaving the rest of the exhaust the same) including a 289 Mustang, a 5.0 Mustang, a 390 AMX, a 13B RX-7, and a GS-R Integra...
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Jan. 3, 2012 10:13 p.m. mguar Reader
Javelin wrote:
V8's need headers to make power.. that's because adjacent cylinders can fire anywhere from 90 degrees to 270 degrees apart. Those uneven pulses are what hurt power.. A V12 has adjacent exhaust pulses 60 degrees apart. (and if you combine both banks it's 30 degrees apart)mguar wrote:
dyintorace wrote:
Headers? don't add anything.. (sound wise) Cast Iron Manifolds sound identical.. However if you've ever heard a V12 running you'll swear it's at a really fast idle.. sounds like 1500 rpm or so at 600RPM.. It's because you can hear every single cylinder firing unlike a V8Wow. I hope there is some way for you guys to manage headers. That car should sound awesome! Great score!!
I dunno about V12's, but that's a patently false statement for every car I've ever put headers on (leaving the rest of the exhaust the same) including a 289 Mustang, a 5.0 Mustang, a 390 AMX, a 13B RX-7, and a GS-R Integra...
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Jan. 3, 2012 10:53 p.m. Javelin SuperDork
mguar wrote:
V8's need headers to make power.. that's because adjacent cylinders can fire anywhere from 90 degrees to 270 degrees apart. Those uneven pulses are what hurt power.. A V12 has adjacent exhaust pulses 60 degrees apart. (and if you combine both banks it's 30 degrees apart)
Then what about the rotary?
It's definitely interesting. Aren't V12's and certain I-6's the only naturally balanced engines because of this?
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Jan. 3, 2012 11:18 p.m. MrJoshua SuperDork
Mguar-From my brief bits of reading I was under the impression that non flat plane crank V8 engines had to suffer a slightly too large collector during header design because of the unbalanced firing order per bank. It was my understanding that any engine with an equal firing order benefited more from headers than a slightly lopsided one.
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Jan. 4, 2012 9:14 a.m. Autolex HalfDork
I like how demented our boardmembers are.
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Jan. 4, 2012 10:36 a.m. mguar Reader
Javelin wrote:
It's one of the reasons they are in balance.. The other has to do with second order harmonics.. Basically a V8 suffers from second order harmonics (rocking motion) that a V12 doesn't because of the counter-firing possible in a V12 that a V8 can manage. In line six's also have that same sequential firing potential which gives a much smoother power potential but lack the V12's ability to counterfire. Make no mistake, Headers can help any engine in full out racing conditions but they must be tuned to the length the engine tune demands.. Key among those requirements is tubing of exactly the same length. Many so called headers fail to meet that basic requirement..mguar wrote:
V8's need headers to make power.. that's because adjacent cylinders can fire anywhere from 90 degrees to 270 degrees apart. Those uneven pulses are what hurt power.. A V12 has adjacent exhaust pulses 60 degrees apart. (and if you combine both banks it's 30 degrees apart)
Then what about the rotary?
It's definitely interesting. Aren't V12's and certain I-6's the only naturally balanced engines because of this?
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Jan. 4, 2012 10:36 a.m. mguar Reader
Oops! A V8 CAN"T manage
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Jan. 4, 2012 10:49 a.m. mguar Reader
MrJoshua wrote:
The whole reason for headers is to isolate the exhaust pulses long enough for the pulses to come out complimentary. That translates to the pipe length tuned to the camshaft. Higher revs equal shorter primary pipes etc.. The unequal nature of a V8's firing order is usually dealt with by length of The Collector. (If I remember those details correctly) or by what has come to be called TRI-Y headers.. If I remember correctly flat plane crankshafts need to use cross over headers to collect complimentary exhaust pulses.. However to be fair it's been decades since I've bothered to look at anything more than the required formula to make the headers compliment the camshaft..Mguar-From my brief bits of reading I was under the impression that non flat plane crank V8 engines had to suffer a slightly too large collector during header design because of the unbalanced firing order per bank. It was my understanding that any engine with an equal firing order benefited more from headers than a slightly lopsided one.
