Performance Optimum Exhaust headers
#1
03-24-2021, 08:17 AM
Performance Optimum Exhaust headers
Hi,
I am planning on designing and producing cost efficient optimum exhaust headers for my own car.....4.2 xkr. Many people have upgraded their exhaust but it is still restricted primarly at manifolds and especially if there are existing other upgraded mods on the car also.
The cost to custom produce them as one-offs are crazy expensive so i was wondering if any one else is interested as could easily reduce the cost significantly to achieve this as design work & Shop Drawing for production only has only to be done once, 3-D jig created once, which is majority of the time involved and then produced as per demand requirements. This could bring costs down to affordable level. I have been quoted approx $2100 so far so this could be reduced by at least half if there were interested parties. Let me know anyway, thanks.
I am planning on designing and producing cost efficient optimum exhaust headers for my own car.....4.2 xkr. Many people have upgraded their exhaust but it is still restricted primarly at manifolds and especially if there are existing other upgraded mods on the car also.
The cost to custom produce them as one-offs are crazy expensive so i was wondering if any one else is interested as could easily reduce the cost significantly to achieve this as design work & Shop Drawing for production only has only to be done once, 3-D jig created once, which is majority of the time involved and then produced as per demand requirements. This could bring costs down to affordable level. I have been quoted approx $2100 so far so this could be reduced by at least half if there were interested parties. Let me know anyway, thanks.
#2
03-24-2021, 03:49 PM
Veteran Member
Not sure if you have seen it but there is a thread (several really) in the engine section about headers.
https://www.jaguarforums.com/forum/jaguar-engines-transmissions-47/sanderson-headers-151246/
In particular I noticed this post where the Count discusses some options that were considered before settling on the boring old log style used on the AJ33.
https://www.jaguarforums.com/forum/j...6/#post1588886
You might be able to get something if you long tubes but I can't imagine you will find the space to fit what would really be needed.
https://www.jaguarforums.com/forum/jaguar-engines-transmissions-47/sanderson-headers-151246/
In particular I noticed this post where the Count discusses some options that were considered before settling on the boring old log style used on the AJ33.
https://www.jaguarforums.com/forum/j...6/#post1588886
You might be able to get something if you long tubes but I can't imagine you will find the space to fit what would really be needed.
#3
03-24-2021, 05:44 PM
Hi,
I have read conflicting information on several threads which adds to the problem. But i also read on this forum of 40bhp gain on a rolling road from custom headers on an XJR with similar engine. So that gave me confidence on the topic. Also have been in contact with someone, who has custom headers on his X100 xkr running 632bhp and 600 lbs torque which is more evidence of their contribution. He installed a 4 into 2 into 1 short version headers which suits well with lack of space to install. Common sense would assume a less restrictive path for exhaust gases reduces workload to expell the exhaust and soaks less power to do so. Whether there is a 4 in 1 or 4 in 2 in 1 arrangement.......the same scenario of 4 exhaust flows from each reapective port converging into one larger pipe on each bank still remains unchanged. So without any actual testing on fluid mechanics flow rate/flue set up. As an engineer myself but not an expert in this field, I would estimate the difference would be at most negible. The restrictions in the type and severity of the bends in the pipes may be more significant when comparing. And i am not sure what the effect is on the torque or why more back pressure would increase it either? But the car i mentioned has the 4/2/1 system with massive torque at low range and it appears it has not had a negative affect on it at all! I have also see the rolling road graph for this so it is real.
The only issue everybody seems to agree on is there is limited space. And as the cats pipes are running vertical on the xkr, there is no room for the long version header pipes anyway,.especially if there is new manifold back system installed which is the case for my set up with 200 cell cats running on 3inch straight thru system. Most mass produced headers for other similar Ford V8's are $300-500 so it is definitely viable.
Anyway thanks for your response and if anyone else has any contribution or would like to express an interest please let me know.
I have read conflicting information on several threads which adds to the problem. But i also read on this forum of 40bhp gain on a rolling road from custom headers on an XJR with similar engine. So that gave me confidence on the topic. Also have been in contact with someone, who has custom headers on his X100 xkr running 632bhp and 600 lbs torque which is more evidence of their contribution. He installed a 4 into 2 into 1 short version headers which suits well with lack of space to install. Common sense would assume a less restrictive path for exhaust gases reduces workload to expell the exhaust and soaks less power to do so. Whether there is a 4 in 1 or 4 in 2 in 1 arrangement.......the same scenario of 4 exhaust flows from each reapective port converging into one larger pipe on each bank still remains unchanged. So without any actual testing on fluid mechanics flow rate/flue set up. As an engineer myself but not an expert in this field, I would estimate the difference would be at most negible. The restrictions in the type and severity of the bends in the pipes may be more significant when comparing. And i am not sure what the effect is on the torque or why more back pressure would increase it either? But the car i mentioned has the 4/2/1 system with massive torque at low range and it appears it has not had a negative affect on it at all! I have also see the rolling road graph for this so it is real.
The only issue everybody seems to agree on is there is limited space. And as the cats pipes are running vertical on the xkr, there is no room for the long version header pipes anyway,.especially if there is new manifold back system installed which is the case for my set up with 200 cell cats running on 3inch straight thru system. Most mass produced headers for other similar Ford V8's are $300-500 so it is definitely viable.
Anyway thanks for your response and if anyone else has any contribution or would like to express an interest please let me know.
#4
03-24-2021, 07:24 PM
Veteran Member
I might be interested. My XKR is heavily modified, twin screw and all, so stands to benefit from a good system.
But I'd be curious if you have some expected gains from all this. Or a particular design approach in mind, with consideration for diameters, lengths and gas velocities.
Just not sure I would be up for spending $2k in a pure experiment with no data based expectation of seeing an increase and a real possibility of a decrease.
But I'd be curious if you have some expected gains from all this. Or a particular design approach in mind, with consideration for diameters, lengths and gas velocities.
Just not sure I would be up for spending $2k in a pure experiment with no data based expectation of seeing an increase and a real possibility of a decrease.
The following users liked this post:
CA Jag (05-04-2022)
#6
03-25-2021, 12:34 AM
Veteran Member
The 421 system you refer to is not a true 4-2-1 system, on the lh bank he has 7 and 8 combined, and he never shown any dyno proof of its performance.
I take it you have seen my numbers, and am using stock headers, my torque line (its not a curve) is probably even better, but that doesn't tell anything about my headers alone.
Don't want to discourage you here of course, but be careful going of some info you read, and I would guess optimizing the exhaust for heavily modified cars would probably help, but for how much and at what price?
I take it you have seen my numbers, and am using stock headers, my torque line (its not a curve) is probably even better, but that doesn't tell anything about my headers alone.
Don't want to discourage you here of course, but be careful going of some info you read, and I would guess optimizing the exhaust for heavily modified cars would probably help, but for how much and at what price?
#7
03-25-2021, 08:55 AM
Hi All,
Obviously it is difficult to isolate which modifcation is responsible for an increment increase in power/torque without an isolated before or after test scenario. I will request data from the manufacturer who has the most experience in this field from race set ups to mod cars. As agreed with Avos some info is conflicting on this and its definitely the case of 'the devil's in the detail' here.
Some costs back from manufacturer, £150 x 2 set up cost for 3D Jigs and £4500 per production of 5 Sets. Cost per pair headers is approx $1315. If we get more than 5 takers....price will go down further. As you can see this is significant reduction in cost so far.
There is no point wasting everyones time going back and forth debating this until i get definitive tech info from manufacturer which we can discuss.
But one point to note, everyone here and in car sport world has a modified exhaust? As it reduces the restrictions for gases to exit by removing boxes, cats, increasing pipe bore etc. Changing the headers is along the same principle, so if you are debating whether effective or not.....its already a bit late for that......otherwise all would have standard exhaust systems unchanged......🤣
I think i read correctly before Avos (please correct me if i'm mistaken!) is only person in that boat.......but the boat he is in has a massive Kenne bell twin screw on it! So the exhaust in that case neglible factor in power change.
Actual design can be discussed at later stage if we have the interest, but based on waht i have seen so far a symmetric 4 2 1 system would fit best in limited space permitted and would allow bigger bore to be used also.
Obviously it is difficult to isolate which modifcation is responsible for an increment increase in power/torque without an isolated before or after test scenario. I will request data from the manufacturer who has the most experience in this field from race set ups to mod cars. As agreed with Avos some info is conflicting on this and its definitely the case of 'the devil's in the detail' here.
Some costs back from manufacturer, £150 x 2 set up cost for 3D Jigs and £4500 per production of 5 Sets. Cost per pair headers is approx $1315. If we get more than 5 takers....price will go down further. As you can see this is significant reduction in cost so far.
There is no point wasting everyones time going back and forth debating this until i get definitive tech info from manufacturer which we can discuss.
But one point to note, everyone here and in car sport world has a modified exhaust? As it reduces the restrictions for gases to exit by removing boxes, cats, increasing pipe bore etc. Changing the headers is along the same principle, so if you are debating whether effective or not.....its already a bit late for that......otherwise all would have standard exhaust systems unchanged......🤣
I think i read correctly before Avos (please correct me if i'm mistaken!) is only person in that boat.......but the boat he is in has a massive Kenne bell twin screw on it! So the exhaust in that case neglible factor in power change.
Actual design can be discussed at later stage if we have the interest, but based on waht i have seen so far a symmetric 4 2 1 system would fit best in limited space permitted and would allow bigger bore to be used also.
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#8
05-20-2021, 10:18 AM
Update
Hi Guys,
just to update on this and what information i have obtained so far on the proposed set up. I had been in discussion with two exhaust manufacturers and here is their take. Car is going in for custom headers build this Monday. So to summarize main key points and to note this is optimum for V8 forced induction set up only, for V8 S/C set up only
1. Type will be shorties version for following reasons, car is street car so torque/power at lower end more beneficial than high end more suited to open track.
2. Will go with unequal primaries as limited space for fitment, equal primaries advantage is negligible as we are not naturally aspirated as forced induction.
3.This will also allow larger bore primaries which will improve exhaust flow and less restrictions so less of engines power used to expel exhaust gases. Pressure will be twice pressure of air inlet as forced induction with boost on S/C up to approx 24psi.
4. System configuration to be 4in2in1 to allow fitting of max primaries and secondaries in limited space. Primaries to be 13/4 " or 45mm
5. This configuaration allows 2inch or 50mm secondaries at branch flue connection.
6. This allows secondaries to merge into 21/2 " or 63mm bore which will tjen connect direct flush connection to existing 63mm downpipes already installed.
7. Order of firing from port has been advised ports 1&3 and 2&4 respectively combined at primary, and oppositely 5&7 and 6&8 on other bank. This set up is optimum for when scavenging is a lesser factor. Due to the fact that firing times are lot slower than a 4 cylinder engine where scavenging plays a more significant role. And also because unequal length primary will result in different time taken for eaxh port gases to exit and flow through to secondaries due to different distances travelled.
8. Also taken into consideration of 3 inch scavenging x box further downstream at downpipes end connection anyway.
9. EGR valve to be made redundant so no circulation of exhaust gases.
10. The cost factor of ceramic coating versus any power gains in my opinion is negligible as i already have low temp thermostat which engine runs cooler anyway, have interchiller installed which keeps S/C coolant circuit at near zero degrees with charge header tank also. And will have water/meth injection which also reduces combustion heat. May just add simple heat shields afterwards.
Finally economics, i will get these made for my car anyway, if i invested in 3D Jigs for further production will result in vastly reduced reproduction and labour time for others. Obviously i would have recover the cost and time on it also. This i will discuss with fabricator once he has finished the first set based on what time has taken and if all was achievable.
Also a dyno run will come eventually, the power gains will depend on set up in each car, that is on what power mods are installed already. The bigger S/C or forced induction the more dramatic affect of headers though.
I would like to invite anyone to add any other feedback or observations to consider?
Many thanks,
Paddy.
just to update on this and what information i have obtained so far on the proposed set up. I had been in discussion with two exhaust manufacturers and here is their take. Car is going in for custom headers build this Monday. So to summarize main key points and to note this is optimum for V8 forced induction set up only, for V8 S/C set up only
1. Type will be shorties version for following reasons, car is street car so torque/power at lower end more beneficial than high end more suited to open track.
2. Will go with unequal primaries as limited space for fitment, equal primaries advantage is negligible as we are not naturally aspirated as forced induction.
3.This will also allow larger bore primaries which will improve exhaust flow and less restrictions so less of engines power used to expel exhaust gases. Pressure will be twice pressure of air inlet as forced induction with boost on S/C up to approx 24psi.
4. System configuration to be 4in2in1 to allow fitting of max primaries and secondaries in limited space. Primaries to be 13/4 " or 45mm
5. This configuaration allows 2inch or 50mm secondaries at branch flue connection.
6. This allows secondaries to merge into 21/2 " or 63mm bore which will tjen connect direct flush connection to existing 63mm downpipes already installed.
7. Order of firing from port has been advised ports 1&3 and 2&4 respectively combined at primary, and oppositely 5&7 and 6&8 on other bank. This set up is optimum for when scavenging is a lesser factor. Due to the fact that firing times are lot slower than a 4 cylinder engine where scavenging plays a more significant role. And also because unequal length primary will result in different time taken for eaxh port gases to exit and flow through to secondaries due to different distances travelled.
8. Also taken into consideration of 3 inch scavenging x box further downstream at downpipes end connection anyway.
9. EGR valve to be made redundant so no circulation of exhaust gases.
10. The cost factor of ceramic coating versus any power gains in my opinion is negligible as i already have low temp thermostat which engine runs cooler anyway, have interchiller installed which keeps S/C coolant circuit at near zero degrees with charge header tank also. And will have water/meth injection which also reduces combustion heat. May just add simple heat shields afterwards.
Finally economics, i will get these made for my car anyway, if i invested in 3D Jigs for further production will result in vastly reduced reproduction and labour time for others. Obviously i would have recover the cost and time on it also. This i will discuss with fabricator once he has finished the first set based on what time has taken and if all was achievable.
Also a dyno run will come eventually, the power gains will depend on set up in each car, that is on what power mods are installed already. The bigger S/C or forced induction the more dramatic affect of headers though.
I would like to invite anyone to add any other feedback or observations to consider?
Many thanks,
Paddy.
The following users liked this post:
giandanielxk8 (05-20-2021)
#10
11-22-2021, 04:37 AM
#11
11-22-2021, 04:47 AM
I also went for ceramic coating in the end which will make big difference on heat dissipation.........have not driven the car much since as S/C is being rebuilt.....upgraded rotor pack, bearings, seals, and completley ported and matched inlets etc.......due to the fact upper pulley came loose months ago and getting a tighter smaller pulley cold forged/pushed on and also cross pinned so no loss of traction. While the S/C is off the engine i decided to go with spray matched 1000CC 95lb bosch fuel injectors and upgraded Wallbro 450 race pump, high flow fuel filter and adjustable fuel pressure regulator. Car already has a lot of mod work done to it so will be interesting to see how it goes on the dyno remap........the headers were to open the remaining restriction on the engine. EGR Valve was also deleted. Looking forward to December.......Santa may come early this year! 😂
#14
05-04-2022, 11:14 AM
one reason may be the stock blower on the 5.0 is limited on max airflow/power so doesnt really get the benefit from the increased flow of the headers,, there comes a point where its just heating up the air,the intercooling system is not the best either,, Id say a real 600hp to the rear wheels would be about max you would want to have with the stock blower, it all comes down to Jag stuffing everything under that low slung hood,, a whipple with a chiller would probably get us 800hp at much lower intake temps but would require a higher hood line or bump in the bonnet
Last edited by htrdlncn; 05-04-2022 at 11:16 AM.
#16
10-30-2022, 04:08 PM
Hi,
Yep they sure were but have not really got to test them yet, as so many other modifications ongoing with this car......its been a long road. Its finally at the tuners now the last several weeks after many issues getting it back running correctly. It was running too rich and high idle.......as the throttle body was changed over for larger one, custom cold air induction, ported/matched elbow inlets along with rotor pack and ported s/c etc. Before that the pulleys had slipped so got reduced further and had it pinned along with lower crank pulley also. It was thought the 1000cc injectors were the problem but turned out after many hours remapping and smoke test that the one air inlet gasket was crimped and was sucking air in unaccountable to the ECU. Installed water meth system, upgraded fuel delivery etc So finally!! Its running now normal and ready for dyno. The car has had so many modifications it will be hard to say what the isolated power contribution the headers will add to it. But i know it will be an improvement nonetheless.......i also deleted the EGR valve and got the headers ceramic coated. They look great and sound is phenomenal as have a dual 3inch custom exhaust system with scavenger, all box deletes including cats and just single straight thru' box on the rear. So hopefully will have some figures in next week........🙏
Yep they sure were but have not really got to test them yet, as so many other modifications ongoing with this car......its been a long road. Its finally at the tuners now the last several weeks after many issues getting it back running correctly. It was running too rich and high idle.......as the throttle body was changed over for larger one, custom cold air induction, ported/matched elbow inlets along with rotor pack and ported s/c etc. Before that the pulleys had slipped so got reduced further and had it pinned along with lower crank pulley also. It was thought the 1000cc injectors were the problem but turned out after many hours remapping and smoke test that the one air inlet gasket was crimped and was sucking air in unaccountable to the ECU. Installed water meth system, upgraded fuel delivery etc So finally!! Its running now normal and ready for dyno. The car has had so many modifications it will be hard to say what the isolated power contribution the headers will add to it. But i know it will be an improvement nonetheless.......i also deleted the EGR valve and got the headers ceramic coated. They look great and sound is phenomenal as have a dual 3inch custom exhaust system with scavenger, all box deletes including cats and just single straight thru' box on the rear. So hopefully will have some figures in next week........🙏
The following 2 users liked this post by Paddy Dunne:
giandanielxk8 (10-30-2022),
White Out (11-03-2022)
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