Hi All,
If I removed the air pump and replaced it with a pully system.
Removed Cats and inserted straight pipes in their place.
How would it effect 0-60 and gas consumption when doing regular
driving lets say 70mph?
Would I have to alter the ECU screw?
Chris
So I can do this to my 1988 XJS.–
Chris, 1988 1/2 XJS with ABS
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// please trim quoted text to context only
In reply to a message from Chris111 sent Thu 17 Nov 2005:
Uhhh…Chris? Didn’t you just give a big ‘‘Woo Woo!’’ in the last few
days because you finally passed emissions? I don’t know Canadian
emission laws, but I’m assuming you didn’t spend a fortune trying
to pass emissions just to impress some cute female
environmentalist. In some markets, it is illegal to remove the air
pump and removing the cats will definately be an emissions no-no.
Having said that, the air pump and rail removal will make little
difference in how your car performs. There would be a (very) slight
power increase from removing a belt driven drag. It mainly cleans
up the engine bay. Looks better, easier to get to some things.
Removal of cats will help power some. On some cars, the cats have
little effect on performance, but by all accounts, these are pretty
restrictive. Removing them does increase horsepower some. But
again, I don’t see how you can do that. Does your area have a
visual inspection along with the emissions testing?
Regards,
Tony Evans Omaha, NE
91 V-12 XJ-S Convertible–
The original message included these comments:
- If I removed the air pump and replaced it with a pully system.
- Removed Cats and inserted straight pipes in their place.
How would it effect 0-60 and gas consumption when doing regular
driving lets say 70mph?
Chris
–
tonysxjs
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In reply to a message from tonysxjs sent Thu 17 Nov 2005:
The car is 17 years old. I will have to do one more emissions test
next year because it failed this year. If a car gets a conditional
pass, you have to re test it the following year. If it passes, you
get 2 years between tests. I eventually got it to pass this year,
but because I originally got a conditional pass it means next year
I will have to retest it for the last time. The test that says I
passed is no good because I got my stickers based on the failed
emissions test. They only make you spend $450.00 here towards a
pass before you get a conditional pass.
After a car reaches 20 years, you no longer have to do emissions
test here in Ontario. So no one will be looking at it again after
next year. I am ready for next years test because I already have
the results. I’m just getting thing going in my head.
Cheers,
Chris
Hope this isn’t to confusing.–
Chris, 1988 1/2 XJS with ABS
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If you open up the intakes and exhaust you will see a significant
performance gain. In addition to the cats, there is a very
tight/restrictive mesh in the down pipes at the exhaust manifold that
you’ll want to remove. You can also remove the 1st set of mufflers which
lets you hear the car but is certainly not loud. The consensus I’ve seen
is that the muffler removal is good for about 15 HP increase with the
cat & mesh removal more than that.
Brian Welker
Dallas, TX
89 XJS convertible
93 VDP
Chris111 wrote:
In reply to a message from tonysxjs sent Thu 17 Nov 2005:
The car is 17 years old. I will have to do one more emissions test
next year because it failed this year.
// please trim quoted text to context only
These are some mightily impressive figures I’m seeing.
I have a slew of XJS road tests and I’ll post some of the info. I don’t
necessarily put 100% credence in magazine road tests because you never know
just how hard they are (or aren’t) flogging the car, or if they are taking
editorial license, or if they’ve gotten there hands on a specially prepped
“press car”. But, anyways…to add some perspective, perhaps.
An asterisk indicates a USA-spec car
1993 XJRS 6.0/318hp 0-60 7.1 seconds 1/4 mile 15.3
seconds
*1992 XJS 5.3/280hp (?) 0-60 7.8 seconds
1993 XJS 6.0/308hp 0-60 6.8 seconds
1993 XJS 6.0/313hp 0-60 6.6 seconds 1/4 mile 15.0
seconds
1990 XJS 5.3/262 hp 0-60 9.9 seconds 1/4 mile 17.5
seconds
*1988 Lister 6.0/475hp 0-60 4.8 seconds 1/4 mile 13.1
seconds
1985 XJS Cab 5.3/299hp 0-60 7.7 seconds 1/4 mile 15.9 seconds
1982 XJS 5.3/299hp 0-60 6.5 seconds 1/4 mile 14.9
seconds
*1982 XJS 5.3/262hp 0-60 8.1 seconds 1/4 mile 16.3
seconds
*1977 XJS 5.3/244hp 0-60 8.6 seconds 1/4 mile 16.5
seconds
1977 XJS 5.3/285hp 0-60 7.5 seconds 1/4 mile 15.8
seconds
My hat’s off to you guys who, with minor mods, are nearly at the level of
the $151000, 475hp “Brandenberg Lister XJS”. You are welcome to do the
fine tuning on my car any day 
My own XJS has low restriction mufflers, opened air inlets, and a
Superenhanced ECU. I am guessing 0-60 in about 7.5 seconds and mid-15s in
the 1/4 mile. I know my Mustang GT would easily run away and hide from the
Jag–14.6 quarter mile.
Hope some of you found this info interesting
Cheers
Doug Dwyer
Longview, Washington USA
1987 Ser III XJ6
1988 XJS V12
// please trim quoted text to context only
Ooops. I meant to post this with the “0-60” thread…
Doug Dwyer
Longview, Washington USA
1987 Ser III XJ6
1988 XJS V12
I have a slew of XJS road tests and I’ll post some of the info.
// please trim quoted text to context onlyFrom: “Doug Dwyer” <@Doug_Dwyer3>
Ok, here are some UK and Euro 0 to 60 times from the
major magazines there.
1983 Coupe V12 Auto 7.5
Coupe 3.6 manual 7.6
Cabriolet manual 7.6
1985 Coupe V12 Auto 7.5
Cabriolet V12 auto 7.7
Coupe 3.6 manual 7.4
Cabriolet manual 7.2
1986 Coupe V12 Auto 7.5
Cabriolet V12 auto 7.7
Coupe 3.6 manual 7.4
Cabriolet manual 7.2
Emission devices were added about here… Cats +
1991 Coupe V12 Auto 8.1
Convertible V12 auto 8.4
Coupe 3.6 manual 7.4
Coupe 4.0 auto 8.4
1993 XJR-S Coupe auto 6.5
Coupe V12 Auto 7.8
Convertible V12 auto 8.1
Coupe 4.0 manual 7.5
Coupe 4.0 auto 8.4
Convertible 4.0 auto 8.6
1984 Lister 6.4 litre V12 manual 5 speed 440 hp 5.4
Geoff Green
95 XJS 4.0 conv 61 E-type OTS
International Cabriolet Register Jag92hot@aol.com
3.6 XJS Register paulzimmer@btopenworld.com
// please trim quoted text to context only
Doug Dwyer wrote:
My hat’s off to you guys who, with minor mods, are nearly at the
level of the $151000, 475hp “Brandenberg Lister XJS”. You are
welcome to do the fine tuning on my car any day
Actually, things seem pretty consistent here to me. Pretty much all
the 6.0 cars go 0-60 in about 7 seconds. The 5.3’s are slower, 8-9
seconds. The euro-spec cars are a bit quicker. Several reports
we’ve gotten seem to indicate that putting in a manual transmission
brings the 0-60 down to around 6 seconds – for either the 5.3 or the
6.0.
I find all of that totally believable, as I’m one of the guys who has
installed a manual tranny. The difference was astounding. I never
actually timed mine, but guesstimated high fives or low sixes at the
time. It might have done better if I had bothered to address the
wheel hop issue.
My conclusion is that the A/T really holds this car back, the 3-speed
A/T holds it back more than the later 4-speed A/T, and the A/T holds
back the revvy 5.3 more than the stroked 6.0. An A/T with a kickdown
system that isn’t working will REALLY hold it back – and I’ll bet
they don’t work more often on the 5.3 than on the 6.0.
I also had a 4.11 rear end. I actually don’t put that much stock in
the final drive ratio for 0-60 times; it might be good for a couple
of tenths, but as long as 1st is low enough to break the tires loose
and the ratios in the transmission are unchanged, you just continue
to shift at the same rpm and acceleration is unaffected. With a
taller final drive gear, you simply reach 60 in 2nd rather than
having to grab 3rd before you get there.
Now, much hubbub has arisen as a result of ONE report of a screamin’
hot 5.1 time in a car with “minor mods”. I’m waiting patiently to
hear all about those minor mods, because they must be juicy indeed.
Is nitrous considered a minor mod?
I know my Mustang GT would easily run away and hide
from the Jag–14.6 quarter mile.
I think it’s interesting to compare the XJ-S to cars like the
Corvette and Mustang over the couple of decades the Jag was in
production. When the XJ-S was introduced in the mid-70’s, I suspect
it would slay all. The Corvettes of that era were dog slow, so
bogged down with emissions equipment that they would barely break 120
mph. The Jaguar was subject to those same emissions requirements,
yet managed to put together 250+ hp and a 140+ mph car.
I think one and all would agree that the changes that the Corvette
has undergone in the meantime are nothing short of astounding. The
Jaguar was scarcely altered during the same time span. It just goes
to show what you can do when you can afford to do development.
– Kirbert
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Actually, things seem pretty consistent here to me. Pretty much all
the 6.0 cars go 0-60 in about 7 seconds. The 5.3’s are slower, 8-9
seconds. The euro-spec cars are a bit quicker.
Well, yes, so long as remember the the difference between, let’s say, 7.5
seconds and 8.5 seconds, is quite dramatic.
Even a .5 second difference can be readily discerned. A reduction of 1.0 or
1.5 seconds in 0-60 time is a darn good accomplishment. A reduction of 3
seconds is…well…as someone just mentioned…you’d likely need to
find about 140 more horsepower
Several reports
we’ve gotten seem to indicate that putting in a manual transmission
brings the 0-60 down to around 6 seconds – for either the 5.3 or the
6.0.
Quite possible. A pre-HE V12 with the 4-speed managed 6.5 seconds according
to one UK road test
My conclusion is that the A/T really holds this car back,
Oh, yes, agreed…further crippled by the 2.88 diff. The V12 is not a
torque monster, and the 400 trans is notoriously parasitic and the ratios
just don’t seem to work.
An A/T with a kickdown
system that isn’t working will REALLY hold it back – and I’ll bet
they don’t work more often on the 5.3 than on the 6.0.
I agree again. I’ll wager the one test showing a 1990 HE going to 60 in 9.9
seconds was lazily shifting a 4000 rpm @ WOT , something that has come up a
few times here on the list.
I think it’s interesting to compare the XJ-S to cars like the
Corvette and Mustang over the couple of decades the Jag was in
production. When the XJ-S was introduced in the mid-70’s, I suspect
it would slay all. The Corvettes of that era were dog slow, so
bogged down with emissions equipment that they would barely break 120
mph. The Jaguar was subject to those same emissions requirements,
yet managed to put together 250+ hp and a 140+ mph car.
From the mid-70s to mid-80s the XJS was certainly competetive, perhaps even
approaching king of the hill in the late 70’s. In '85 or so the Corvette
began growing some genitals again.
I only mentioned my (old and now sold) Mustang GT as basis of comparison in
that its true acceleration times are known to me, and I know my XJS couldn’t
even come close to matching it, as-is.
I think one and all would agree that the changes that the Corvette
has undergone in the meantime are nothing short of astounding. The
Jaguar was scarcely altered during the same time span. It just goes
to show what you can do when you can afford to do development.
True indeed. Working at a Chevy dealer all these years I’ve driven nearly
every iteration, the oldest being a '59, the newest an '06. They really are
quite a nice car now. For one thing, they are tolerable to sit in and drive
for more than 15 minutes at a time 
Cheers
Doug Dwyer
// please trim quoted text to context onlyFrom: “Kirbert” palmk@nettally.com
In reply to a message from Doug Dwyer sent Fri 18 Nov 2005:
Dear Kirbert
My old 1977 Pre He 5.3 with the Type S 10.5 pistons a 3.07
rear axle a BW Type 12 auto box 225/60X15 on 8j Dulop SP and wide
throttle bodies cleaned up manifolds not AJ6 high tourque though
and Aj6 silencer substitute pipes. Will still see 60 in a little
over six seconds if you can throw the weight back on the rears fast
enough to keep it fairly stuck down. I have driven a few HE’s and I
have an idea that over 5000 revs the HE 400 box is making lots of
heat. Also it fells like the box and axle is much higher geared in
first. Cant get the rear tyres to spin much on an HE. No bother
with mine loads of smoke. If you bang it hard without letting the
weight go back. If the road is at all greasy you will hit the red
line in first without moving an inch. I think that’s why they upped
the ratio.
You can end up facing the wrong way just pulling out of a junction
a little quickly in even dry but misty conditions.
Regards Mark
PS Maybe its cos its so rusty most of the weight fell off.–
Bassmec, XJS V12 1977 Coupe
Ipswich, Suffolk., United Kingdom
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Bassmec wrote:
My old 1977 Pre He 5.3 with the Type S 10.5 pistons a 3.07
rear axle a BW Type 12 auto box 225/60X15 on 8j Dulop SP and wide
throttle bodies
That’s three reports of fast XJ-S’s with throttle body mods. Can any
of you guys give us some idea how much difference that one mod made?
– Kirbert
// please trim quoted text to context only
Mine are bored out from 63mm to 71mm (just a tad over 2 3/4 inches) with
2 3/4 diameter intakes and K&N cone filters on the end. My feeling is
that while the larger throttle bodies definitely allow more air, about
22% if my math is right, the additional air flow is only helpful at high
revs. For average driving, opening up the standard air boxes from the
aprox. 1 1/2 inch diameter snouts to 2 1/2 or more and adding a high
flow filter will result in a noticeable improvement and is probably
enough for most folks. That said, I’m glad that have the larger throttle
bodies for when I get fired up and push the car hard.
Brian Welker
Dallas, TX
89 XJS convertible
93 VDP
Kirbert wrote:
Bassmec wrote:
My old 1977 Pre He 5.3 with the Type S 10.5 pistons a 3.07
rear axle a BW Type 12 auto box 225/60X15 on 8j Dulop SP and wide
throttle bodiesThat’s three reports of fast XJ-S’s with throttle body mods. Can any
of you guys give us some idea how much difference that one mod made?– Kirbert
// please trim quoted text to context only
At 22:09 2005-11-17 -0800, Doug Dwyer wrote:
My conclusion is that the A/T really holds this car back,
Oh, yes, agreed…further crippled by the 2.88 diff. The V12 is not a
torque monster, and the 400 trans is notoriously parasitic and the ratios
just don’t seem to work.
There’s an article in Feb/Mar 1997 Musclecar_Review titled Turbo 400 Hop
Up. I spotted the magazine while waiting in a waiting room one afternoon
a few years back (accompanying a relative for a CAT-Scan), and jotted down
the magazine specifics and ordered up a copy from their backissue department.
I’ve not yet performed the modification on any of my TH400s (three cars
with them), but removing a few valve balls and replacing the transfer plate
whill give you harder shifts. It also shows a plug you can install to set
the transmission to hold first as long as it’s in first (not that the TH400
setup in the XJ-S needs to hold first past 6260 RPM, or that you’d want to
race the engine much higher). There’s comment about a TRUCK pan for the
TH400, which gives you 2.5 quarts more fluid capacity, which affords you
cooler running (which = longer transmission life). I dunno if the deep pan
would be suitable on the XJ-S though: exhaust lines and the low ride both
might pose issues. There are various other pointers in the article as well.
As maligned as the TH400 is by some, it remains a very popular tranny
amongst hot rodders (those running A/Ts at least), because it’s pretty much
indestructable. Yea, a TH350 squanders fewer HPs, but a TH400 can handle more.
I only mentioned my (old and now sold) Mustang GT as basis of comparison in
that its true acceleration times are known to me, and I know my XJS couldn’t
even come close to matching it, as-is.
My wife owns a 5.0L Mustang GT Convertible (1993, last year of the “fox”
body), and it is quite a bit peppier off the line than the XJ-S. Same goes
for my Buick GS (which, despite being relegated to storage in the wide
parking area alongside my garage right now, will still smoke most cars off
the line). However, the front of the Buick starts to “float” somewhere
above 100mph (which is amazing considering how much weight there is up
front - it is an iron block, not aluminium), and the Mustang isn’t the best
handler at speed either. I’ll take the XJ-S for a high speed run any day
over the competition.
I think one and all would agree that the changes that the Corvette
has undergone in the meantime are nothing short of astounding.
The new ones are butt-ugly though. Was browsing them while waiting for
some service on my Suburban (which has a 454 engine ) recently. I’m not
really sure what it is they’re trying to do. There’s painted bodywork
INSIDE the cabin between the seats, which makes it look more like a toy
than anything else, and the ass end is, cripe, I don’t know how to describe it.
My (foster) father was really into Corvettes. He had nearly completely
restored a 1969 from the remnants of THREE separate cars (frame, plus
front and rear ends from two separate totals, and of course obligatory
replacement pieces here and there) before he passed from a stroke about 3
years ago. IMO, prior to the 70’s, the Corvette was a much nicer looking
car than it is now. Since then, it’s just gone downhill, even if they’ve
beefed it up in the engine department.
— '88 Jaguar XJ-SC 5.3L V12 (LHD) ‘Black Cat’
Sean Straw '85 Jaguar XJ-S 5.3L V12 (LHD) ‘Bad Kitty’
Sonoma County, California '91 Jaguar XJ40 4.0L (LHD) ‘Trevor’
http://jaguar.professional.org/ '69 Buick GranSport 455 V8
// please trim quoted text to context only
In reply to a message from Kirbert sent Fri 18 Nov 2005:
Dear Kirbert
My Aj6 throttles and ecu were fitted by the owner before the
bloke I bought it from. But having driven the stock pre he I would
say that the car gives a slightly false impression of much higher
performance because you have more power for less foot travel.
At high revs I think it seems to rev out more than stock. With an
Italien tune up holding it in second before sliping it into drive
just at the right time before the red line. Even though the gearbox
chainge time seemed similar you do notice the wide throttle body
car hits the red worryingly quickly you know waiting for the box to
change at full bore. I understand for those with more money you can
get a good deal more midrange punch by going to the Plus Torque
manifold then there is the real flash stainless four pipe half way
down the car TT extractor exhaust. This will give the most top end
and then if you nip over to Linconshire we have the Wizzards of Nos
who do a special proportional rate system they have shown on BBC
Top Gear a rusty old Xjs HE straight out of a scrap yard take on
the might of the worlds supercars in a straight line drag on an
airfield. It beat the lot including the new porche Turbo and the
ferrari 360 The Xjs went through the 1/4 mile at 13 seconds dead on
200Hp Jets.Send you a video if you like.
Regards Mark
PS Roger Bywater will give you a graph of what you will gain.–
Bassmec, XJS V12 1977 Coupe
Ipswich, Suffolk., United Kingdom
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As maligned as the TH400 is by some, it remains a very popular tranny
amongst hot rodders (those running A/Ts at least), because it’s pretty
much
indestructable. Yea, a TH350 squanders fewer HPs, but a TH400 can handle
more.
'Tis the 400 that squanders the power, Sean. That’s one of the reasons GM
eventually dropped it when fuel economy became an issue…together with it
being over-built and too expensive. By 1980 GM was beginning a “cheaping
down” of many components and assemblies … a trend that was in full swing
by '82 or so and for which they paid dearly.
The TH350, sturdy in its own right, can be massaged to hold up very well in
many HP applications and consumes less power than the 400 doing so. I ran
one behind a big-block Olds for years. I reckon one would do quite well
behind a Jag V12 although, like the 400, some mods would be required to
tolerate 6500 rpm use. Of course, nowdays most prefer the 700 trans.
My wife owns a 5.0L Mustang GT Convertible (1993, last year of the “fox”
body), and it is quite a bit peppier off the line than the XJ-S. Same
goes
for my Buick GS (which, despite being relegated to storage in the wide
parking area alongside my garage right now, will still smoke most cars off
the line). However, the front of the Buick starts to “float” somewhere
above 100mph (which is amazing considering how much weight there is up
front - it is an iron block, not aluminium), and the Mustang isn’t the
best
handler at speed either. I’ll take the XJ-S for a high speed run any day
over the competition.
Having owned both a Mustang GT and a GS400, I can only agree with all you’ve
said although I never had the Mustang over 100 mph or so, so I can’t
comment much on high speed stability…seemed Ok at that point. But, yes,
not the rock solid feel of the Jag.
Considering its humble origins and low price, the Mustang, I felt, was
surprisingly capable in many areas.
I think one and all would agree that the changes that the Corvette
has undergone in the meantime are nothing short of astounding.The new ones are butt-ugly though. Was browsing them while waiting for
some service on my Suburban (which has a 454 engine ) recently. I’m
not
really sure what it is they’re trying to do. There’s painted bodywork
INSIDE the cabin between the seats, which makes it look more like a toy
than anything else, and the ass end is, cripe, I don’t know how to
describe it.
I have to agree again. They are marvelous to drive, though. But, yes, not
attractive and waaaay too “Johnny Space Boy” for me.
IMO, prior to the 70’s, the Corvette was a much nicer looking
car than it is now. Since then, it’s just gone downhill, even if they’ve
beefed it up in the engine department.
The last good looking one was the '67 Stingray, IMHO. But, in fairness, its
much more than just the engine that has been improved upon.
Cheers
Doug Dwyer
// please trim quoted text to context only
At 19:37 2005-11-18 -0800, Doug Dwyer wrote:
As maligned as the TH400 is by some, it remains a very popular tranny
amongst hot rodders (those running A/Ts at least), because it’s pretty
much
indestructable. Yea, a TH350 squanders fewer HPs, but a TH400 can handle
more.'Tis the 400 that squanders the power, Sean. That’s one of the reasons GM
eventually dropped it when fuel economy became an issue.
Please re-read my post: the TH350 squanders FEWER HPs…
— '88 Jaguar XJ-SC 5.3L V12 (LHD) ‘Black Cat’
Sean Straw '85 Jaguar XJ-S 5.3L V12 (LHD) ‘Bad Kitty’
Sonoma County, California '91 Jaguar XJ40 4.0L (LHD) ‘Trevor’
http://jaguar.professional.org/ '69 Buick GranSport 455 V8
// please trim quoted text to context only
In reply to a message from sean.straw%2BJaguar@mail.professional.org sent Sat 19 Nov 2005:
in reply to thread. I have 3 of the cars mentioned a '93 xjr-s,
a '83 mustang conv 5.0 5 speed and a '69 corvette conv 350/300 4
speed. all three are entierly different cars. the jag is probably
the car I like to drive most. with the twr modifed suspension and
modifed th400 car handles exceptionally shifts at red line @ wot
what more could you ask. also the seats are more confortiable than
the other 2. the corvette is old school stiff suspension a blast to
drive but wouldnt want to drive it on an extended trip. the mustang
is in between. suspension not as stiff as the corvette but still
handles well and is a blast to drive @150k miles. it dosen’t get
light in the front untill max speed. don’t know what that is since
it only has a 85 mph speedometer. in the end 0-60 speed is whoever
is driving the car and reaction time.–
The original message included these comments:
As maligned as the TH400 is by some, it remains a very popular tranny
amongst hot rodders (those running A/Ts at least), because it’s pretty
much
indestructable. Yea, a TH350 squanders fewer HPs, but a TH400 can handle
–
awa
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// please trim quoted text to context only