DIY Modification to Improve Performance and Fuel Economy of AJ16 and AJ6 Engines
#521
05-16-2018, 07:24 AM
Veteran Member
OR...they're less than honest, and it is one of Andy's but not new...OR they've reverse-engineered Andy's bracket; meaning the listing may be accurate/honest...but the seller is of dubious character.
The following 3 users liked this post by aholbro1:
#522
05-20-2018, 01:21 PM
I sent a message to the seller of this item on ebay. I have now been contacted by the company which is offering this item for sale. The company apparently found one of my brackets on a car that they were breaking for spares. They thought it was a good design, and so made some of their own to sell. We are now in negotiations regarding me supplying them with their future requirements of my revised design of crank sensor bracket.
The following 5 users liked this post by XJRengineer:
aholbro1 (05-20-2018),
Don B (05-27-2018),
Lady Penelope (05-24-2018),
Richardhw (05-20-2018),
Scotlad (05-20-2018)
#523
05-24-2018, 02:31 PM
Senior Member
#524
05-25-2018, 01:13 PM
I can understand people's potential scepticism just reading the title of this thread. Could there really be a cheap and simple modification that improves both performance and fuel economy? If it was that simple why didn't Jaguar do it?
Well the reasons are quite complex, but I will try to explain them.
When I worked at Jaguar between 1988 and 1995 it was std policy to map the ignition timing 3 degrees retarded from borderline knock on a mid-limit compression ratio engine, at all speeds and load where the engine was knock limited. The ignition timing to achieve borderline knock was determined by running the engine steady state on a dynamometer at each speed and load until the combustion chamber temperatures were fully stabilised. This is not a condition that tends to happen in normal driving in the UK where it is difficult to operate the engine at wide open throttle for more than a few seconds at a time, during which time the temperatures due not reach their high stabilised values.
Consequently the lower temperatures that occur during normal driving mean that the mapped ignition timing is significantly retarded from the level at which knock would occur.
A couple of years ago I designed a revised crank sensor bracket to take advantage of this situation. It was initially designed for the AJ16 engine and moved the position of the crank sensor with respect to the engine. As a result the signal to the engine ECU which should indicate when each piston is at TDC is generated 5degrees early.
Consequently each ignition event generated by the ECU occurs 5degrees earlier than the mapped value. It's a bit like advancing a distributor in the days when they contained contact breaker (unlike the one on an AJ6 engine). The extra ignition advance increases the performance at all speeds and load where the engine was deemed to be knock limited when tested on the dynamometer. I initially implemented my bracket on the AJ16 engine as the engine management system on this engine also has a knock sensing system, which I helped to develop.
This meant that in extreme circumstances should the extra 5 degrees cause any knock, then the system would simply retard the ignition timing out of knock. This bracket proved very successful and I have now sold over 120 of them.
About a year ago I was asked to produce a couple of brackets for some AJ6 engines which were fitted to race cars running on super unleaded fuel. At the customer's request, the bracket was designed with an extra 7 degrees of ignition advance. The two engines fitted with these brackets went on to complete a season's racing and the cars they powered were quite successful in their class in terms of performance. This was quite a severe test of an AJ6 engine to run at this level of ignition advance.
I was recently asked by another Jaguar owner to design a bracket for AJ6 engines. Having produced a batch of these brackets which provides an extra 5 degrees of advance I thought I would offer these to other owners as well.
It takes under an hour to replace the std bracket with one of my brackets using nothing more than std tools. In fact, if like me you have had a lot of pratice, you can do it in 15mins on an AJ16SC engine which is the most complicated installation due to the neeed to remove the SC drive belt tensioner.
If you would like any more information about these revised crank sensor brackets for either AJ16 or AJ6 engines then feel free to email me directly andystodart@metronet.co.uk
Well the reasons are quite complex, but I will try to explain them.
When I worked at Jaguar between 1988 and 1995 it was std policy to map the ignition timing 3 degrees retarded from borderline knock on a mid-limit compression ratio engine, at all speeds and load where the engine was knock limited. The ignition timing to achieve borderline knock was determined by running the engine steady state on a dynamometer at each speed and load until the combustion chamber temperatures were fully stabilised. This is not a condition that tends to happen in normal driving in the UK where it is difficult to operate the engine at wide open throttle for more than a few seconds at a time, during which time the temperatures due not reach their high stabilised values.
Consequently the lower temperatures that occur during normal driving mean that the mapped ignition timing is significantly retarded from the level at which knock would occur.
A couple of years ago I designed a revised crank sensor bracket to take advantage of this situation. It was initially designed for the AJ16 engine and moved the position of the crank sensor with respect to the engine. As a result the signal to the engine ECU which should indicate when each piston is at TDC is generated 5degrees early.
Consequently each ignition event generated by the ECU occurs 5degrees earlier than the mapped value. It's a bit like advancing a distributor in the days when they contained contact breaker (unlike the one on an AJ6 engine). The extra ignition advance increases the performance at all speeds and load where the engine was deemed to be knock limited when tested on the dynamometer. I initially implemented my bracket on the AJ16 engine as the engine management system on this engine also has a knock sensing system, which I helped to develop.
This meant that in extreme circumstances should the extra 5 degrees cause any knock, then the system would simply retard the ignition timing out of knock. This bracket proved very successful and I have now sold over 120 of them.
About a year ago I was asked to produce a couple of brackets for some AJ6 engines which were fitted to race cars running on super unleaded fuel. At the customer's request, the bracket was designed with an extra 7 degrees of ignition advance. The two engines fitted with these brackets went on to complete a season's racing and the cars they powered were quite successful in their class in terms of performance. This was quite a severe test of an AJ6 engine to run at this level of ignition advance.
I was recently asked by another Jaguar owner to design a bracket for AJ6 engines. Having produced a batch of these brackets which provides an extra 5 degrees of advance I thought I would offer these to other owners as well.
It takes under an hour to replace the std bracket with one of my brackets using nothing more than std tools. In fact, if like me you have had a lot of pratice, you can do it in 15mins on an AJ16SC engine which is the most complicated installation due to the neeed to remove the SC drive belt tensioner.
If you would like any more information about these revised crank sensor brackets for either AJ16 or AJ6 engines then feel free to email me directly andystodart@metronet.co.uk
Just ran across your posting. I have a 97 XJ6 L with 73K
and it definitely does not measure up to my late, great 5 speed X type ( victim of Hurricane Sandy - Jaguars make terrible amphibious vehicles ). I'd like to know more about this, for US versions and perhaps any other workarounds to squeeze a bit more performance out her royal highness.
Martiin
#525
06-04-2018, 12:20 PM
I've just installed the bracket yesterday and I gotta say it's exactly the last pinch of liveliness that the car needed! Totally worth the money. Slight change in sound, especially higher in the rev range the car just growls now, loving it. After next roadtrip I'm going to report back with mpg numbers.
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XJRengineer (06-06-2018)
#526
06-06-2018, 06:39 AM
Yatchboy,
Thank you for your interest. If you want to know any more about ordering one of my brackets, then please email helenstodart@gmail.com
We are currently out of stock, but the next batch should be available at the end of this month.
Thank you for your interest. If you want to know any more about ordering one of my brackets, then please email helenstodart@gmail.com
We are currently out of stock, but the next batch should be available at the end of this month.
#527
09-27-2018, 02:39 PM
Member
#528
09-27-2018, 04:11 PM
Join Date: Feb 2014
Location: Crossroads of America
Posts: 19,391
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Welcome to the Jaguar Forums and congratulations on your X300. It's great to have you with us.
If you will send an inquiry to the email address in the post just prior to yours (post #526 from 06-06-2018), you will receive an authoritative reply from Andy or his wife.
Cheers,
Don
Last edited by Don B; 09-30-2018 at 10:29 PM.
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XJRengineer (09-30-2018)
#529
09-30-2018, 12:39 PM
Dear All,
I have a new machinist making these revised crank sensor brackets again now. The first batch from the new machinist went on fulfilling the back-orders that had built up since my original machinist retired. I collected the second batch of brackets on Friday, and so finally have some parts in stock to meet future demand. Thank you to everyone for your patience while I've been establishing a new source for these brackets.
I have a new machinist making these revised crank sensor brackets again now. The first batch from the new machinist went on fulfilling the back-orders that had built up since my original machinist retired. I collected the second batch of brackets on Friday, and so finally have some parts in stock to meet future demand. Thank you to everyone for your patience while I've been establishing a new source for these brackets.
The following 3 users liked this post by XJRengineer:
#532
11-17-2018, 08:28 AM
The following users liked this post:
XJRengineer (11-23-2018)
#534
11-28-2018, 04:04 PM
#535
12-20-2018, 04:39 AM
Senior Member
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XJRengineer (12-26-2018)
#536
01-03-2019, 08:08 AM
I can understand people's potential scepticism just reading the title of this thread. Could there really be a cheap and simple modification that improves both performance and fuel economy? If it was that simple why didn't Jaguar do it?
Well the reasons are quite complex, but I will try to explain them.
When I worked at Jaguar between 1988 and 1995 it was std policy to map the ignition timing 3 degrees retarded from borderline knock on a mid-limit compression ratio engine, at all speeds and load where the engine was knock limited. The ignition timing to achieve borderline knock was determined by running the engine steady state on a dynamometer at each speed and load until the combustion chamber temperatures were fully stabilised. This is not a condition that tends to happen in normal driving in the UK where it is difficult to operate the engine at wide open throttle for more than a few seconds at a time, during which time the temperatures due not reach their high stabilised values.
Consequently the lower temperatures that occur during normal driving mean that the mapped ignition timing is significantly retarded from the level at which knock would occur.
A couple of years ago I designed a revised crank sensor bracket to take advantage of this situation. It was initially designed for the AJ16 engine and moved the position of the crank sensor with respect to the engine. As a result the signal to the engine ECU which should indicate when each piston is at TDC is generated 5degrees early.
Consequently each ignition event generated by the ECU occurs 5degrees earlier than the mapped value. It's a bit like advancing a distributor in the days when they contained contact breaker (unlike the one on an AJ6 engine). The extra ignition advance increases the performance at all speeds and load where the engine was deemed to be knock limited when tested on the dynamometer. I initially implemented my bracket on the AJ16 engine as the engine management system on this engine also has a knock sensing system, which I helped to develop.
This meant that in extreme circumstances should the extra 5 degrees cause any knock, then the system would simply retard the ignition timing out of knock. This bracket proved very successful and I have now sold over 120 of them.
About a year ago I was asked to produce a couple of brackets for some AJ6 engines which were fitted to race cars running on super unleaded fuel. At the customer's request, the bracket was designed with an extra 7 degrees of ignition advance. The two engines fitted with these brackets went on to complete a season's racing and the cars they powered were quite successful in their class in terms of performance. This was quite a severe test of an AJ6 engine to run at this level of ignition advance.
I was recently asked by another Jaguar owner to design a bracket for AJ6 engines. Having produced a batch of these brackets which provides an extra 5 degrees of advance I thought I would offer these to other owners as well.
It takes under an hour to replace the std bracket with one of my brackets using nothing more than std tools. In fact, if like me you have had a lot of pratice, you can do it in 15mins on an AJ16SC engine which is the most complicated installation due to the neeed to remove the SC drive belt tensioner.
If you would like any more information about these revised crank sensor brackets for either AJ16 or AJ6 engines then feel free to email me directly andystodart@metronet.co.uk
Well the reasons are quite complex, but I will try to explain them.
When I worked at Jaguar between 1988 and 1995 it was std policy to map the ignition timing 3 degrees retarded from borderline knock on a mid-limit compression ratio engine, at all speeds and load where the engine was knock limited. The ignition timing to achieve borderline knock was determined by running the engine steady state on a dynamometer at each speed and load until the combustion chamber temperatures were fully stabilised. This is not a condition that tends to happen in normal driving in the UK where it is difficult to operate the engine at wide open throttle for more than a few seconds at a time, during which time the temperatures due not reach their high stabilised values.
Consequently the lower temperatures that occur during normal driving mean that the mapped ignition timing is significantly retarded from the level at which knock would occur.
A couple of years ago I designed a revised crank sensor bracket to take advantage of this situation. It was initially designed for the AJ16 engine and moved the position of the crank sensor with respect to the engine. As a result the signal to the engine ECU which should indicate when each piston is at TDC is generated 5degrees early.
Consequently each ignition event generated by the ECU occurs 5degrees earlier than the mapped value. It's a bit like advancing a distributor in the days when they contained contact breaker (unlike the one on an AJ6 engine). The extra ignition advance increases the performance at all speeds and load where the engine was deemed to be knock limited when tested on the dynamometer. I initially implemented my bracket on the AJ16 engine as the engine management system on this engine also has a knock sensing system, which I helped to develop.
This meant that in extreme circumstances should the extra 5 degrees cause any knock, then the system would simply retard the ignition timing out of knock. This bracket proved very successful and I have now sold over 120 of them.
About a year ago I was asked to produce a couple of brackets for some AJ6 engines which were fitted to race cars running on super unleaded fuel. At the customer's request, the bracket was designed with an extra 7 degrees of ignition advance. The two engines fitted with these brackets went on to complete a season's racing and the cars they powered were quite successful in their class in terms of performance. This was quite a severe test of an AJ6 engine to run at this level of ignition advance.
I was recently asked by another Jaguar owner to design a bracket for AJ6 engines. Having produced a batch of these brackets which provides an extra 5 degrees of advance I thought I would offer these to other owners as well.
It takes under an hour to replace the std bracket with one of my brackets using nothing more than std tools. In fact, if like me you have had a lot of pratice, you can do it in 15mins on an AJ16SC engine which is the most complicated installation due to the neeed to remove the SC drive belt tensioner.
If you would like any more information about these revised crank sensor brackets for either AJ16 or AJ6 engines then feel free to email me directly andystodart@metronet.co.uk
Thought I would post my results in an mostly non technical way.
So I install the bracket the Saturday before Christmas. I also used the opportunity to replace some belts that needed replacing. So upon first start with the bracket the engine seemed to be like hey what did you just do? No check engine lights or anything, just seemed to stumble a few times during the first minute of running with the new bracket. Then in smoothed out really quickly after that. I let the car warm up to normal then took it for a drive in normal mode. Actually didn't even try sports mode for a few days. The car definitely accelerated quicker, seemed to have more torque, and generally have a lot more pep. Then I tried sports mode for the first time on the way to work one day last week. Other than Holy Crap! I am actually just speechless. So this is the way the car should of possible run from the factory. Wow!
Now for a little bit of technical specs for those who care. So the preferred fuel normally in the tank is Sunoco 94. Seems to be the best fuel I can get around here and the station is close to me. Second preference is Shell.
My daily commute is 26 miles in each direction. That is a mixture of 6 miles of country roads with a few traffic lights and 20 miles of highway driving at normal speeds. So before the bracket I averaged 14.2 MPG. after the bracket I average 14.5 MPG, that is keeping it out of sports mode and driving it as normal as possible with its new found pep. Using sports mode in short bursts for a few minutes at a time seemed to reduce the average down to 14.4 to 14.3 MPG.
My final thoughts- The engine seems happier with this bracket. It seems to breath better generally, specially in sports mode. Also the engine warms up a lot sooner, I get heat from the vents about 3 minutes sooner than i did before the bracket. I know that effect is from the bracket because when I got the car in September it had a failed open thermostat that I replaced. When I have the opportunity, I intent to try some of the over 100 octane race fuel that is sold at a gas station that is over an hour away from me in a direction i don't normally go in a lot. Really only to see if fuel without 10% ethanol in it will effect the average MPG at all in our X300's
The car this bracket was installed in is a 1996 Jaguar XJR6 with 141,000 plus miles and is my daily driver even here in New England.
For anybody trying to decide if they should get this bracket i hope this helps convince them they should.
The following 3 users liked this post by jagy4321:
#537
01-03-2019, 04:05 PM
Hi Paul,
I'm really glad that you are pleased with the bracket.
As you are in the US, I assume that when you write that the fuel you are using is 94 this is "pump octane" which is = (RON+MON)/2.. The standard ignition timing is mapped for use on 95RON fuel. The MON rating of a fuel is typically about 10 units lower than RON, so a fuel that is 95RON could be expected to have a pump octane value of 90. I don't think this is a standard fuel grade in the US, and that the next standard higher grade is 91 pump octane. Therefore 91 pump octane fuel should be considered normal for an X300. Having advance the ignition timing by 5 degrees with my bracket, there may some benefit using higher octane fuel than 91 pump octane, but it is not necessary to run a higher octane fuel. If you can feel a benefit, then you can decide if its worth the extra cost.
I don't know your driving style or traffic conditions, but 14mpg (even if these are the smaller US gallons) seem quite low for a 26 mile journey that includes 6miles of country roads and 20miles of highway. I'm assuming that these figures are from the trip computer and were after the thermostat was replaced, as if this was stuck open it certainly would make the fuel economy worse. I wonder if you have something wrong with the car. It is very difficult to make comparisons of fuel economy between different vehicles, because the conditions can be so different. If you got the engine fully warm, then reset the trip and then cruised at a steady 60-70mph with an unloaded car, with no AC, I would expect you to get low to mid 20s mpg (imperial) average over many miles of flat roads. This is the most comparable test condition. Under such conditions, my manual XJR6 will achieve about 26mpg (imperial)
I'm really glad that you are pleased with the bracket.
As you are in the US, I assume that when you write that the fuel you are using is 94 this is "pump octane" which is = (RON+MON)/2.. The standard ignition timing is mapped for use on 95RON fuel. The MON rating of a fuel is typically about 10 units lower than RON, so a fuel that is 95RON could be expected to have a pump octane value of 90. I don't think this is a standard fuel grade in the US, and that the next standard higher grade is 91 pump octane. Therefore 91 pump octane fuel should be considered normal for an X300. Having advance the ignition timing by 5 degrees with my bracket, there may some benefit using higher octane fuel than 91 pump octane, but it is not necessary to run a higher octane fuel. If you can feel a benefit, then you can decide if its worth the extra cost.
I don't know your driving style or traffic conditions, but 14mpg (even if these are the smaller US gallons) seem quite low for a 26 mile journey that includes 6miles of country roads and 20miles of highway. I'm assuming that these figures are from the trip computer and were after the thermostat was replaced, as if this was stuck open it certainly would make the fuel economy worse. I wonder if you have something wrong with the car. It is very difficult to make comparisons of fuel economy between different vehicles, because the conditions can be so different. If you got the engine fully warm, then reset the trip and then cruised at a steady 60-70mph with an unloaded car, with no AC, I would expect you to get low to mid 20s mpg (imperial) average over many miles of flat roads. This is the most comparable test condition. Under such conditions, my manual XJR6 will achieve about 26mpg (imperial)
#538
01-03-2019, 06:52 PM
Veteran Member
Yes, we have plenty of brackets in stock. Please email helestodart@gmail.com for more details
Last edited by Jagboi64; 01-04-2019 at 11:16 AM.
#539
01-03-2019, 06:56 PM
Veteran Member
#540
01-04-2019, 05:03 AM
