Hello friends at BFC
After sitting for a little bit over one year, I've finally started working on my 351W E36 swap again. The current issue I'm running into is headers. I'm incredibly short on both space and motivation. I just can't see how I'll be able to fit a collector for the headers in this engine bay and still make it to the 2-1 merger, even if I shorten the primary stubs on the flanges. Here are a few shots of the space (or lack thereof) I'm working with
So I had an epiphany while I was in the garage today. Why not make a set of "log" manifolds instead of traditional style headers? The models below are what I've got in mind
My thought process is that turbo guys have been using log manifolds for decades without major issues. I'm not delusional though, I realize that those guys usually see gains when they switch to tubular style manifolds (the ballpark gains I've seen on the internet seem to range between a 10%-20% improvement) but the "log" style manifolds that I usually see appear to be restrictive in both pipe size and flow. My proposed design shouldn't have sizing issues, though I can easily see how flow could be an issue
More than anything, I just want to see what other people have to say about this. I really wanna get to driving this car again
Popular engine swap weights & stock engine weights
M42 + trans - 427lbs
302 + t5 trans - 475lbs
m20b27 + g260 - 497lbs
m52b25 vanos + g250 - 544lbs
351w + t5 trans - 572.5lbs
LS, aluminum block + t56 - 609lbs
LS, iron block + t56 - 719lbs, EST.
http://www.bimmerforums.com/forum/sh...60-m42-1jz-2jz
You will probably see a loss of power with log manifolds, but it may be the only way to make it work. If that's the case, go with it. Turbos work fine with the log manifolds because of the pressure on the opposite side. You could do a set of log manifolds and top them off with a turbo or two. Problem solved.
Last edited by unnatrl; 04-27-2017 at 10:23 PM.
What about headers like Fendbass did on his coyote swap?
https://www.bimmerforums.com/forum/s...p-Build-Thread
Tri-Y headers? Nah, seems like too much effort. Besides, Laminar found an interesting article and posted it in my drifting thread
http://www.hotrod.com/articles/hppp-...-vs-manifolds/
Basically, tubular vs stock-log manifolds are about 5% more efficient on an engine with a similar displacement. Granted, I'm sure that the difference would become greater at speeds exceeding 5400RPM (what the guys in that article did for testing) but my max speed will be 6000RPM
According to the internet, most guys with my setup are making about 320hp wheel with about 350ft/lbs of torque. A 5% reduction is more than acceptable to me
Popular engine swap weights & stock engine weights
M42 + trans - 427lbs
302 + t5 trans - 475lbs
m20b27 + g260 - 497lbs
m52b25 vanos + g250 - 544lbs
351w + t5 trans - 572.5lbs
LS, aluminum block + t56 - 609lbs
LS, iron block + t56 - 719lbs, EST.
http://www.bimmerforums.com/forum/sh...60-m42-1jz-2jz
Building headers is a bit**. If you build your own, and the car goes down the road, declare victory and have a beer. Very few people do it, and those that have, will salute you.
Plenty of factory cars out there with log style exhaust manifolds on N/A engine. Below is an example which is not too far from what you have. Only change I would make to your design is remove that short extension on the opposite side of the outlet.
http://s254.photobucket.com/user/jfg..._1960.jpg.html
Last edited by Schitzo; 04-28-2017 at 12:09 PM.
2003 M5 LSx l 6 Spd Manual l 4.10 LSD
Build Thread
The chassis must always be regarded as a means to an end and never as an end itself
I have a set of Patriot headers (https://www.summitracing.com/parts/p...view/make/ford). I just HAD to have headers and 2.5" exhaust all the way back. I haven't run the car with them in yet.
IMG_4232.JPG
IMG_4233.JPG
IMG_4234.JPG
Bookmarks