Quest For 450 Horsepower
Senior Member
Joined: Aug 2015
Posts: 206
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From: El Paso
No it doesn't!!!
Caldoofy has an X358...
The engine in his car has variable valve timing. His ECU is also the later version Pan-Pag Denso ECU which is the same one used on the XF SV8 and the X150 XKR.
The engine and engine management system in his car is already capable of much more power than the early AJ33S in our 2003-2005 XJR's and STR's.
The VVT is actually a major contributor to MORE POWER especially in the top end >5000rpm.
The early non-VVT cars had quite a compromise in the cam specs to reach emissons targets and driveability requirements i.e. a really fat mid-range with heaps of torque.
We have been looking into the cams as part of the bigger picture and it seems for the 2003-2005 cars they are the bottleneck, at least one of the major contributors.
Some testing on a later car by manipulating the VVT operation did prove this, by fixing the intake cam to the same timing spec as the non-VVT engine there was a considerable loss of power in the top end.
The plan at the moment is to make a test of retarding the intake cam on a non-VVT engine to a similar position of the VVT engine at higher rpm, and see if this is resulting in more power in the top end (what we expect).
However it's also expected that there would be a loss of torque in the low-mid range (not a great tragedy, there is plenty of low-end power, we can afford to lose a little) BUT it could also mean that the engine is harder to start with the intake cam in that position.
Hopefully there are some results to talk about in the coming weeks.
Have not forgotten about the tune either, but it seems that the tune itself is not enough to get around these mechanical restrictions of the engine, so it's probably a case of cams adjustment + tune to get some decent results.
The other option is to fit the VVT cams and VVT system but it's a big job and not really cost effective. Ditto for new cams (ala Aston Martin grind) so hopefully just this minor adjustment to the timing will do it.
Caldoofy has an X358...
The engine in his car has variable valve timing. His ECU is also the later version Pan-Pag Denso ECU which is the same one used on the XF SV8 and the X150 XKR.
The engine and engine management system in his car is already capable of much more power than the early AJ33S in our 2003-2005 XJR's and STR's.
The VVT is actually a major contributor to MORE POWER especially in the top end >5000rpm.
The early non-VVT cars had quite a compromise in the cam specs to reach emissons targets and driveability requirements i.e. a really fat mid-range with heaps of torque.
We have been looking into the cams as part of the bigger picture and it seems for the 2003-2005 cars they are the bottleneck, at least one of the major contributors.
Some testing on a later car by manipulating the VVT operation did prove this, by fixing the intake cam to the same timing spec as the non-VVT engine there was a considerable loss of power in the top end.
The plan at the moment is to make a test of retarding the intake cam on a non-VVT engine to a similar position of the VVT engine at higher rpm, and see if this is resulting in more power in the top end (what we expect).
However it's also expected that there would be a loss of torque in the low-mid range (not a great tragedy, there is plenty of low-end power, we can afford to lose a little) BUT it could also mean that the engine is harder to start with the intake cam in that position.
Hopefully there are some results to talk about in the coming weeks.
Have not forgotten about the tune either, but it seems that the tune itself is not enough to get around these mechanical restrictions of the engine, so it's probably a case of cams adjustment + tune to get some decent results.
The other option is to fit the VVT cams and VVT system but it's a big job and not really cost effective. Ditto for new cams (ala Aston Martin grind) so hopefully just this minor adjustment to the timing will do it.
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Joined: Feb 2015
Posts: 2,408
Likes: 599
From: Nelson New Zealand
No it doesn't!!!
Caldoofy has an X358...
The engine in his car has variable valve timing. His ECU is also the later version Pan-Pag Denso ECU which is the same one used on the XF SV8 and the X150 XKR.
The engine and engine management system in his car is already capable of much more power than the early AJ33S in our 2003-2005 XJR's and STR's.
The VVT is actually a major contributor to MORE POWER especially in the top end >5000rpm.
The early non-VVT cars had quite a compromise in the cam specs to reach emissons targets and driveability requirements i.e. a really fat mid-range with heaps of torque.
We have been looking into the cams as part of the bigger picture and it seems for the 2003-2005 cars they are the bottleneck, at least one of the major contributors.
Some testing on a later car by manipulating the VVT operation did prove this, by fixing the intake cam to the same timing spec as the non-VVT engine there was a considerable loss of power in the top end.
The plan at the moment is to make a test of retarding the intake cam on a non-VVT engine to a similar position of the VVT engine at higher rpm, and see if this is resulting in more power in the top end (what we expect).
However it's also expected that there would be a loss of torque in the low-mid range (not a great tragedy, there is plenty of low-end power, we can afford to lose a little) BUT it could also mean that the engine is harder to start with the intake cam in that position.
Hopefully there are some results to talk about in the coming weeks.
Have not forgotten about the tune either, but it seems that the tune itself is not enough to get around these mechanical restrictions of the engine, so it's probably a case of cams adjustment + tune to get some decent results.
The other option is to fit the VVT cams and VVT system but it's a big job and not really cost effective. Ditto for new cams (ala Aston Martin grind) so hopefully just this minor adjustment to the timing will do it.
Caldoofy has an X358...
The engine in his car has variable valve timing. His ECU is also the later version Pan-Pag Denso ECU which is the same one used on the XF SV8 and the X150 XKR.
The engine and engine management system in his car is already capable of much more power than the early AJ33S in our 2003-2005 XJR's and STR's.
The VVT is actually a major contributor to MORE POWER especially in the top end >5000rpm.
The early non-VVT cars had quite a compromise in the cam specs to reach emissons targets and driveability requirements i.e. a really fat mid-range with heaps of torque.
We have been looking into the cams as part of the bigger picture and it seems for the 2003-2005 cars they are the bottleneck, at least one of the major contributors.
Some testing on a later car by manipulating the VVT operation did prove this, by fixing the intake cam to the same timing spec as the non-VVT engine there was a considerable loss of power in the top end.
The plan at the moment is to make a test of retarding the intake cam on a non-VVT engine to a similar position of the VVT engine at higher rpm, and see if this is resulting in more power in the top end (what we expect).
However it's also expected that there would be a loss of torque in the low-mid range (not a great tragedy, there is plenty of low-end power, we can afford to lose a little) BUT it could also mean that the engine is harder to start with the intake cam in that position.
Hopefully there are some results to talk about in the coming weeks.
Have not forgotten about the tune either, but it seems that the tune itself is not enough to get around these mechanical restrictions of the engine, so it's probably a case of cams adjustment + tune to get some decent results.
The other option is to fit the VVT cams and VVT system but it's a big job and not really cost effective. Ditto for new cams (ala Aston Martin grind) so hopefully just this minor adjustment to the timing will do it.
are you test muleing your car with these cam mods . if so that sure is brave.
are you making new offset cam gears . or locking some vvt gears in a specified position ? i knew the vvt was an improvement in power , but the specs only show a 20hp increase .
Senior Member
Joined: Jan 2014
Posts: 433
Likes: 138
From: England
Why did Jaguar initially fit VVT to the N/A 4.2, but not the S/C, but only add it in 2006?
How much do you think the VVT added to the top end?
This explains when I drove Shukan's VVT STR at SP it felt better at the top end, but it still could not keep up with my X350...
How much do you think the VVT added to the top end?
This explains when I drove Shukan's VVT STR at SP it felt better at the top end, but it still could not keep up with my X350...
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Joined: Aug 2014
Posts: 6,264
Likes: 1,764
I see the 200 cel cats mentioned quite a bit.
Would I see any noticeable performance increase if I had them fitted to my 2005 XJR ?
Are they street legal in all States?
I already have a stage I type air intake with flap mod. I will also be re-installing my
modified SC with the smaller pulley. I probably will not bore out my TB.
Would I see any noticeable performance increase if I had them fitted to my 2005 XJR ?
Are they street legal in all States?
I already have a stage I type air intake with flap mod. I will also be re-installing my
modified SC with the smaller pulley. I probably will not bore out my TB.
Veteran Member
Joined: Aug 2014
Posts: 6,264
Likes: 1,764
Why did Jaguar initially fit VVT to the N/A 4.2, but not the S/C, but only add it in 2006?
How much do you think the VVT added to the top end?
This explains when I drove Shukan's VVT STR at SP it felt better at the top end, but it still could not keep up with my X350...
How much do you think the VVT added to the top end?
This explains when I drove Shukan's VVT STR at SP it felt better at the top end, but it still could not keep up with my X350...
Also what do you mean when you say Shukan's car could not keep up with your X350?
What Octane gas do you use?
Senior Member
Joined: Jan 2014
Posts: 433
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From: England
Since that run I have gone for 200 cell cats and full custom 2.5 cat back exhuast. Definitely more power now...
Both cars running 99 RON (UK)
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Joined: Aug 2014
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We both ran against each other at Santa Pod 1/4 mile, at the time both stock performance wise, except both having the Caldoofy tube and I had the pulley. My best time on the day 13.4 vs his best 13.6.
Since that run I have gone for 200 cell cats and full custom 2.5 cat back exhuast. Definitely more power now...
Both cars running 99 RON (UK)
Since that run I have gone for 200 cell cats and full custom 2.5 cat back exhuast. Definitely more power now...
Both cars running 99 RON (UK)
Also is the exhaust sound on your car appreciably louder particularly when simply cruising?
Last edited by jackra_1; Sep 24, 2016 at 09:43 AM.
Senior Member
Joined: Jan 2014
Posts: 433
Likes: 138
From: England
Yes the system is louder, as I wanted a V8 muscle car sound, rather than the silent stock sound. The system does not drone at 70mph, but you can hear it in the background (not tiring), actually much louder at slower speeds.
Senior Member
Joined: Jul 2013
Posts: 422
Likes: 106
From: Wales, United Kingdom
Here's a little video:
https://youtu.be/5nqh4QJy8Hg
https://youtu.be/5nqh4QJy8Hg
Senior Member
Joined: Jan 2014
Posts: 433
Likes: 138
From: England
Cheers! All done by VR Dyno tuning Kendal, my local Longlife agent. Cost £500 for both cats, £1400 for the whole lot.
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Joined: Aug 2014
Posts: 6,264
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Here's a little video:
https://youtu.be/5nqh4QJy8Hg
https://youtu.be/5nqh4QJy8Hg
I need to find out whether they are street legal here in the USA.
Thread Starter
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Senior Member
Joined: Nov 2015
Posts: 793
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From: CT
What about the front cats? Wont they stifle the motor and restrict performance? I am designing a ram air system for the entrance of the airbox where the flap is...It should look factory when I'm done...To me removing the flap will just allow hot air from the engine bay to flow in thus maybe even lose power with it off...
Senior Member
Joined: Jan 2014
Posts: 433
Likes: 138
From: England
What about the front cats? Wont they stifle the motor and restrict performance? I am designing a ram air system for the entrance of the airbox where the flap is...It should look factory when I'm done...To me removing the flap will just allow hot air from the engine bay to flow in thus maybe even lose power with it off...
Senior Member
Joined: Aug 2015
Posts: 206
Likes: 22
From: El Paso
Here's a little video:
https://youtu.be/5nqh4QJy8Hg
https://youtu.be/5nqh4QJy8Hg
By the way, which mufflers are those? I like the look.
Last edited by BlacXJRcat; Sep 25, 2016 at 12:59 PM.
Senior Member
Joined: Jan 2014
Posts: 433
Likes: 138
From: England
You mean the exhuast tips? They are 4" slash cut, but now thinking of changing them to the style of the early Portfolio models...
once again cambo , you have me on the edge of my seat waiting for results .
are you test muleing your car with these cam mods . if so that sure is brave.
are you making new offset cam gears . or locking some vvt gears in a specified position ? i knew the vvt was an improvement in power , but the specs only show a 20hp increase .
are you test muleing your car with these cam mods . if so that sure is brave.
are you making new offset cam gears . or locking some vvt gears in a specified position ? i knew the vvt was an improvement in power , but the specs only show a 20hp increase .
When it comes to the earlier 4.2 S/C cars it will be a case of adjusting the cam position on the sprocket using a degree wheel. Which will be the plan for my engine.
As for the tune this is not finished yet, it's plainly obvious now why the mainstream tuners don't want to touch these cars with the early Denso 32-bit anymore. KessV2 does not work for tuning these ECU's, the ECU has to come out and it's bench-flashed using a K-Tag. The iniital plan was to then take that tune from the K-Tag and work it into a tune file which could be loaded with IDS/SDD so there was no need to crack open the ECU (as this has been done with custom tunes for later cars).
BUT there is a complication here as the Denso 32-bit has a 2nd layer of data in the processor, kind of like checksums, but not exactly, and this data is generated from IDS, not calculated like a regular checksum. This is key to getting a flash with IDS to work on this ECU, and it's proving hard to crack... we'll have another go on my XJR this week (5th time lucky haha)
I guess 20hp on a stock engine, but if the engine is tuned then there is a lot more to be had, whereas the non-VVT engine is really out of breath in the top end.
There was a non-VVT STR here on the forum that was tuned and it only picked up 10hp. But there are VVT XKR's and others that have picked up 30-40hp, if not even more. It's all in the top end, because of the cams.
The times and trap speeds at Santa Pod (and other 1/4 mile drags) are interesting and are probably a better indication of power than dyno sheets.
When I was in the UK my XJR made 340rwhp on a local dyno, and trapped 105.45mph at Santa Pod
Yet in Australia same car made 320rwhp on one local dyno (and even just 300rwhp on another one) but has trapped 105, 106, 107 mph at WSID, which is pretty consistent, and goes to show you can't really compare dyno numbers...
As for cats, well I have 100 cell on mine, it got VERY loud after fitting them and the engine felt much more responsive, but, no change to the top end hp numbers, because the cams are holding it back...
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Joined: Feb 2015
Posts: 2,408
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From: Nelson New Zealand
thanks for your efforts cambo . good luck with your tune . sure hope you crack it .
BTW my trap speeds are very similar to yours . 164-169 . its all about the launch really .
it so wants to light that tire !!
cheers
BTW my trap speeds are very similar to yours . 164-169 . its all about the launch really .
it so wants to light that tire !!
cheers