When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I think the concept needs proven on an engine dyno before any in car stuff is done. The 4.2 is only 256 cubic inches of displacement. That's 100 less cubes vs. an LS1. The log manifold is pretty big on these engines and the manifold to pipe port sizing is at least 2.25" but looked larger. That's sewer pipe territory for a small displacement engine. 256" V8 needs what, 1 1/2" to 1 5/8" primary's even though it's pushing 420 crank hp? I think part of what makes these cars sound so good is the 'undersized' pipes for the HP they produce.
From examining it when I did my cats last week I don't think the swap can be done without dropping the drive line from the chassis. The strut tower is huge and blanks off most of the manifold. The bottom also protrudes into the space the header would need to clear if it was bolted to the car.
The good news is there's a lot of room between the tranny and floor where the huge stock cats run. Magnaflow spun cats on both sides. You can see how shrouded the manifold is. If you can't get the manifold off it's going to really suck bolting headers up. Passenger side has the main power to the starter that will need dealt with.
Drivers has the power steering hose in the way along with the trans cooling and what I think it air pump tubing.
Stock H pipe with the spun cats for reference.
Last edited by Ranchero50; 04-04-2017 at 12:00 PM.
Steve_K_xk,
I didn't want to mention that in the message as they may have to do that to fit the area on the 2003-2006....Also, I would have used a better looking set to photograph!
Derek,
You started this Thread in Dec. 2016.....Have you ever started building these 4.2 Headers as you stated? What does one have to do to get a set and also do they fit the 2003-2006 body styles.....How about an update? You've got us all excited, now what do we do?
I'm not sure on fitment for the 03-06 models. I believe the port is the same and bolt pattern. The question is collector location. (I'll be willing to discount a set for someone to test fit once complete)
I had to invest a lot into the carbon production and tooling, thus was waiting on a return to invest into other projects.
I'm considering moving forward, I just put these on hold as I had limited response when I offered up a buy-in to start it up. The fixture cost, scanning, engineering takes time and money. In order to do it right, I was needing to bite the bullet on investing into the project.
I have re-evaluated it and I'm planning everything out again. The main thing in question is how to develop to fit many models. Modifying the existing catalytic location is going to be needed either way I look at it. So the headers will require cut/weld to the catalytic and I will offer a discounted set with header purchase.
I think the concept needs proven on an engine dyno before any in car stuff is done. The 4.2 is only 256 cubic inches of displacement. That's 100 less cubes vs. an LS1. The log manifold is pretty big on these engines and the manifold to pipe port sizing is at least 2.25" but looked larger. That's sewer pipe territory for a small displacement engine. 256" V8 needs what, 1 1/2" to 1 5/8" primary's even though it's pushing 420 crank hp? I think part of what makes these cars sound so good is the 'undersized' pipes for the HP they produce.
From examining it when I did my cats last week I don't think the swap can be done without dropping the drive line from the chassis. The strut tower is huge and blanks off most of the manifold. The bottom also protrudes into the space the header would need to clear if it was bolted to the car.
The good news is there's a lot of room between the tranny and floor where the huge stock cats run. Magnaflow spun cats on both sides. You can see how shrouded the manifold is. If you can't get the manifold off it's going to really suck bolting headers up. Passenger side has the main power to the starter that will need dealt with.
Drivers has the power steering hose in the way along with the trans cooling and what I think it air pump tubing.
Stock H pipe with the spun cats for reference.
If we want to compare apples to apples let's take a look at the Aston 4.3 which cones out of factory with a decent 4-2-1 header system
According to velocityap 40whp can be gained with their upgraded headers, cats and ecu tune
This also leaves me to believe that similar if not more gains could be had from our log system
If we want to compare apples to apples let's take a look at the Aston 4.3 which cones out of factory with a decent 4-2-1 header system
According to velocityap 40whp can be gained with their upgraded headers, cats and ecu tune
This also leaves me to believe that similar if not more gains could be had from our log system
I think Derek is onto a good thing
I don't think it's a bad idea, just not sure if the juice is worth the squeeze of dropping the drive line to install them. At a standard average of $100 per Hp, $2900 for the pipes / cat leaves you with $1100 to get them installed for a 40 hp increase. If it could be done in car, then it's a lot easier venture and more available to the average owner.
The ECU tune also concerns me. Why would it only need a tune for headers? It would be nice to see the data on temps / AFR's between the two. More of a curiosity that the tune does more than the headers, or not.
I don't think it's a bad idea, just not sure if the juice is worth the squeeze of dropping the drive line to install them. At a standard average of $100 per Hp, $2900 for the pipes / cat leaves you with $1100 to get them installed for a 40 hp increase. If it could be done in car, then it's a lot easier venture and more available to the average owner.
The ECU tune also concerns me. Why would it only need a tune for headers? It would be nice to see the data on temps / AFR's between the two. More of a curiosity that the tune does more than the headers, or not.
I see where your coming from
Without the tune I don't see it getting past the 20whp gain and thats being quite generous I could be wrong however to unlock the most out of the new headers (est 40+ whp) and make it worth while it would definitely need that ecu tuned.
So the problems we face are
1) Space restriction
2) The Cat relocation into the mid pipe as the headers will need to be long tube headers
3) Keeping the price below $2000-$2500
4) Will they be an universal fit on all xk150 4.2 models (LHD/RHD) (NA/SC)
5) The owner will most likely need to get a tune , unfortunately no mail order tunes will have this header option built in so it will have to be a custom dyno.
I would be willing to be your test-bed for the 2003-2006 XKR Model.....It looks to me that if you could make a set with pretty tight bends, it would fit both the X-100 and X-150 cars...That would certainly increase your base for sells, as the ports or pretty much the same size and of course they could always be ported-out
Once again, mine is a 2005 XKR and I have XJR Log Manifolds on it. That manifold has a ball connecter on the back exit that 45's down into a 2 1/2" Magnaflow 200 Cell Cat. It continues down and 45's into a Quicksilver system....It works good and is streamlined but I'm sure that Headers would help a great deal more.....
As I told you earlier, Badcat Upgrades in England has a set for sell...They are suppose to be 4 into 1 but I'm not sure about that! He has them on a 4.7 liter Land Rover Engine with bigger valves and hotter cams.....Go look at his web site as it shows that Headers can be made to fit the X-100 and you would think if they would fit the X-100, they should fit the X-150.. Badcat Upgrades
Please let me know what's on your mind....Also, I have access to a set of beautiful Aston-Martin Headers...I don't think they will fit the X-100 as they bend in towards the XKR's Tranny, where A/M's have their Tranny in the rear....I can get you a Photo if you are interested......I problem with those Headers is the Engine in an A/M sets about 6" to 8" lower in the body than the Jaguar Engine......This alone might give them more room..They sure are beautiful!
If you are really interested in any of this. please let me know!
from Badcat's site. Looks like a direct replacement for the log manifold. Or shorty headers for a Fox Mustang. Thought mid or full length would work much better.
One other thought is I wonder how much space is needed through the exhaust tunnels for cooling air? Looks like Jaguar is trying to control the air through the radiator a lot more than other body's do. Just thoughts.
From what I have seen sofar I don't expect any noticeable improvement in performance with enhanced headers. A while back it was tested on a heavily modified 4.0 XJR and at most about 15rwhp could be attributed, but even that was debatable. The badcats headers don't look good with the last exhaust ports grouped together, and so far no dyno results have been shown. Coming back to the AM 4.3, I would rather expect about 25 rwhp increase from a tune and possible 10 rwhp from sport cats, so that would leave 5 rwhp for the headers (at $$$$). Last but bot least, if the stock headers would really offer a significant restriction, wouldn't I with all the HP not see a torque curve that should drop? Another recent post was with the 5.0SC engine, where new headers only gave about 10 or 15rwhp but that was also in combination with sport cats, so not sure which one gave what gains.
Now it would be great if one could improve here something noticeable, and am impressed with the work of Frickenfast, so if there is a chance he might be able to. But again I don't expect much gains for the $ so am more with ranchero50 here.
Best thing is to wait for Derek to look over all this and see what he has on his mind! He may be thinking of something completely different......You never know about those Engineers, they can come up with sorts of stuff and it sounds like he has already started working on this Project......By the quality of his work (see website) I believe he will really make a hit with this!
I will try to get Photos of those Aston/Martin Headers, I've talked about this coming week! They really are beautiful......
Thanks guy.
I am on this, I just have had quite the investment on carbon and other projects. I put in what I can as I dabble all over the place in engineering. These cars are my passion though.
That's why I was looking for validation in interest for some members. If I'm able to produce a nice set that gains, getting a few people on board to buy a set.
Doing a longer tube setup is going to net the best performance, the other critical part is the merge collector. Additionally, what we need to measure is the boost pressure before and after. A more free flowing system will allow the engine to not work as hard to produce the same power. So I expect boost pressure to drop .5lb or so. This will be adjusted via pulley/tune to have a proper comparison. At the same boost level, I expect 30+hp gains. I've had similar projects in past with 2004 Cobra's that have seen even more. The higher the power level, the higher the gain. But more importantly is the power under the curve, mid range.
I'm updating all the suspension at the moment, but I'm dying to get this completed. If anyone is seriously interested, contact me or lets start a list of serious buyers once complete. This helps me justify all the expense and time I would put in.
I have the collectors already tigged, the flanges are CNC'd, and all tubing in just sitting in my garage taunting me everyday.
Very cool that you have some Terminator experience. I never got into them as I couldn't see stop lights due to the ridiculously low windshield bow.
I think your on the right path but it'll need to be a header and mid pipe to be effectively salable. I was up at the Carlisle PA swap meet today and was struck by how similar the stock newer Mustang cat pipe looks to ours. Same 4" of pipe, then the straight input and anlged output with similar o2 locations. Definitely some shared DNA.
Once again, I am interested if they will fit my 2005 XKR Coupe! As I told you, I have the XJR log manifold, which comes out the rear at a 45 degree angle and connects with a Ball & Socket into a 21/2" Magnaflow 200 Cell 12" Cat and then 45's into a 21/4" Quicksilver system. The long tube Headers should fit and then I can make the Cats fit no problem!
Anyway, count me in if you think they will bolt-up!
Attached are the Photos I promised you of the Aston-Martin Headers a Friend bought to install on his A-M V8.....He paid around $4,000. for them....They are pretty and unique but I don't think they would fit a 4.2 Jaguar as they sort of bend toward the center of the car....remember A-M has a Torque-tube, where the Jag has a Transmission...They are really pretty the way they are formed....Note how they merge at the end.....
Maybe this will give you some ideas! I love the way they are formed but I don't know what they call the process..
I see that both Bad Cat and Aston Martin headers are basically a "tri-Y" design, as opposed to a "long tube - 4 into 1.
Suggest researching the differential between tri-y and long tube. My own experience was with a '66 Shelby GT350 which came "delivered" with tri-y headers. The headers soon rusted out and I replaced them with primitive long tube headers (this was 1968), and noticed no material change except a bit of mid-range loss. My understanding is that the tri-y design is better for street usage as it enhances mid-range power. Whereas long tubes are most efficient at high rpm.
Rey I've always been a fan for the tri-y design especially for smaller capacity as you are correct it improves the torque where we exactly need it which is that is in that mid range .
However what I'm seeing is the best gains through the entire rev range are coming from tuned length 4-1 headers (based on factory 4-2-1 removed and tuned 4-1 bolt up)
Having said all of that I would be more than ecstatic to bolt up a set of tri-y onto my xk
Last edited by steve_k_xk; 06-30-2017 at 03:56 PM.
I think a more logical approach would be to throw a factory log on a flow bench to see just how bad it really is. Nobody has done this, and the gains from the badcat headers are a poor indication of what a proper header will do because those badcat headers are just abysmal.
Anyway... Frickenjag, I think you can save yourself and everyone else a lot of time and money by getting a baseline on what we're working with out of the box. I suspect they're not nearly as bad as we think, and it may very well end up being that all the logs need are an extrude hone to get the job done.
If you want to work on something that will be a step in the right direction both in power and longevity, look at ways to improve the thermal management in these cars.
04-04-2017, 11:56 AM
