Hey guys/gals.
M62 owners, both 4.4 and 4.6 (possibly 4.8is's too) versions, I have a treat for you.
Just so happens that a friend of mine is building custom headers. He built a set for his s62 and compared his dyno numbers against his dyno with Dinan headers and he gained about 25hp with 23 ft lbs increase, OVER THE DINAN's. That's like 65hp over stock!
This is great I thought but when I asked him about the "lesser" V8's he shocked me and said that since the ports and bolt patterns were the same that his headers would not only fit on the 4.4 and 4.6, he tuned his secondaries to mount on his e53.
So I asked if he'd be making a few more and his answer was "yes"
I give you the "Unicorn" header.
FROM THE DESIGNER/BUILDER
*"I started development on these headers April of 2014, right after I had finished the M5 wagon build. What I thought was going to be just a few months of work, turned into almost a year long challenge, but absolutely rewarding in every aspect. By every definition I had underestimated the cost, effort, time, blood, sweat and tears required for such an endeavor. Going through this exercise though, gave me tremendous insight into what really goes into developing such a product.*
So right about now, you’re asking yourself why? Why go through all this trouble and expense? The E39 is an aging model, everyone else has moved on. Well, I don’t really care about everyone else. If you’re reading this, and you’re like me, we are not ready to move on and let go. In fact, we find every excuse to dump more money into the beast. I plan to keep my E39 M5 for as long as I can. We will all be probably driving electric vehicles in 10 years, but the legacy of the gasoline engined e39s will forever be a permanent part of my life.***
About a year into the M5 wagon build thread, when I was refreshing the S62 that was to go into the wagon, I had a chance to study the Dinan headers that was also going into the wagon, since they were off the car collecting dust on my garage floor. As I observed the Dinan headers, I marveled at its complexity and quality. But as days and weeks passed, (during those staring sessions in the garage after dinner and before bed times - you know exactly what I’m talking about!) staring at them closely, I started seeing things, and asking questions.*
Why did they do it this way? Why didn’t they do it that way? Why is this thing like this? Why is this not like that? This was especially the case when I installed them for the very first time on my Anthracite M5, in my garage floor, on my back! Right about the same time, I had a set of Supersprint headers lying around from a parts car I purchased – same car where the S62 I used for the wagon came from. I also studied the Supersprint design and started asking a bunch of questions. Why 4 into 1? Why spring clamps? Why modular construction instead of solid 1 piece design like the Dinans? Why this? Why that? Why does the SS merge collector hang so low down on the car? Etc, etc.*
Also, at about the same time, I went with a group on a Saturday morning run up GMR where I had a chance to hold in my hands a set of Evolve headers that a fellow enthusiast just purchased. Staring at the Evolve headers, first question popped on my mind was why aren’t these equal length? Where’s the stepping? Are these really made in the UK? Lots of questions indeed.**
I don't consider myself an expert on the subject, far from it, but I’m not completely foreign with headers and header design. Prior to this project, I had been playing with 4 different sets of headers on my E60 M5 (RD Sport, Agency Power, RPI and experimenting with my own variations). Previous to this, was playing with euro headers for my old E28 M5. Add in all the wrenching I’ve done in the garage for 20 years on BMWs; theory though, was learned as I went, consulting with experts in the field and master fabricators. The rest, I just mix in the passion and love for the hobby.**
After observing closely those 3 brands of headers mentioned above, I said to myself, “man, I wish there was a set of headers that had all the features I liked.” Also asked the question, “can there be any more improvements made over what is out there?” “Can it be done better?” I do believe in the equal length and tri-Y design of the Dinans, but I love the modularity of the Supersprints, I hate the 2-bolt flange type on the Dinans, I certainly didn’t like the quality of the Supersprints and the Evolves. I didn’t like that the Dinans were ceramic coated. I didn't like that the exit pipe was only 2.5" diameter. I didn’t like that certain primary runners were angled so aggressively at the entry flange that the only way to screw in the nut was to move the entire header 1mm at a time closer to the head, tighten the nuts 1mm, rinse and repeat. I really loathed the fact that the front subframe had to come down to install any type of headers. But the one big question that kept coming back to me was, could there still be unfound horsepower to be gained by improving the design?*
What if I were to combine all those features that I liked in the different headers and took out the features I didn’t like? I needed a stronger and more worthwhile reason to justify this whole exercise. Like…more power throughout the rev range? Is that a good enough of a reason? But how much more power can be had? And at what cost? Wouldn’t it be just ridiculously amazing if we get to that point? Such deep probing questions indeed.
Finally got the dyno results on my own header design. For those that are looking for more power, this can be a good option. My headers had a gain of 25hp & 23 ft/lb over the Dinan headers. So over stock, perhaps 65 hp, can be more with some tweaks and a tune. Test car used was my 2000 540iT that underwent a full M5 conversion build a few years ago."
Without disclosing too much, I’ll share with you what we did. I’m sure you’ll understand if I leave out some details for obvious reasons.*
Working with a master fabricator, we gathered every spec I could find on the S62. Taking into consideration for the design, *the following:***
Engine configuration
Maximum RPM range*
Useable RPM Peak HP/Peak Torque Discplacement/Bore/Stroke Compression ratio*
Throttle body diameter Intake/Exhaust port dimensions*
Intake/Exhaust lift at valve Intake/Exhaust duration at .050 lift*
Intake/Exhaust opening at BBDC Intake/Exhaust rocker arm ratio Intake/Exhaust lobe centerline Intake/Exhaust closure at ABDC***
The specs above in addition to a few other considerations helped us determine all aspects that were built into the design. With my own wish list of features, we made the every effort possible to not leave anything out. In other words, if I was going to set out to build my own headers for the S62, here is my chance to incorporate everything I can and leave out things I don’t want.*
The springs hold the merge collectors against the runner that feeds it. A double slip joint is used at each merge collector, all other joints are butt joints and TIG welded. The whole system, once in place is pretty rigid and won't run the risk of "coming apart" from vibration.*
The double slips allow the header system to expand as it heats up and at the same time alleviate any stress or pressure at the joints, hence cracking or stress fractures are completely avoided. The springs allow the system to expand and still keep things in place. At maximum expansion, the spring tension is nowhere near its tensile limit, since the spring hooks are positioned exactly to minimize spring tension.
Another point I should mention was the issue of dropping the subframe to install headers. I wanted to see if I it was possible to install headers with the subframe in place, along with the steering box, steering column and hoses in place. The packaging constraints of the headers were many. If you are familiar with the lower part of the engine bay, there isn’t much room down there.*
Until the nuts are finally torqued down, the whole system has some flex to it to help in the assembly. The install is very straightforward.*
For someone who doesn't have access to a lift, it can still be installed on your own.
Also, knowing that the exhaust ports on the S62 heads share the same pattern and size on the M60/M62 engines, I thought it would be great if these headers worked for the 540i/740i brothers looking for headers for those powerplants.**
So, fast forward to today. My headers were designed and built for every reason you can think of and for no reason at all haha. Are these what unicorn dreams are made of? Who the hell knows. But I know that I’ve been dreaming of these headers for quite a while, and to see them finally a reality is absolutely astonishing."
So, here's what you get;
4 -2 -1 (Tri-Y) modular design*
True equal length runners*
Full T304 Stainless Steel construction 100% Mandrel bent tubing*
TIG welding, fully back purged w/ Argon Solar Flux type B in cases where back purging is not applicable*
Laser cut exhaust port flanges*
Oversized exhaust ports to accommodate ported cylinder heads*
3” V-band flange exit pipe*
Profiled merge collectors*
Double-slip joints w/ stainless steel spring clamps*
Tuned stepping*
Removal of front subframe not required for installation*
100% of raw materials & supplies sourced from USA manufacturers.*
Mandrel bending, welding and fabrication services provided by USA vendors.
Any questions?