V8 Swap Header Design

[jalopi]

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

[unnatrl]

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.

[ponchiz318]

What about headers like Fendbass did on his coyote swap?
https://www.bimmerforums.com/forum/s...p-Build-Thread

[jalopi]

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

[htrdbmr]

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.

[Schitzo]

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

[ponchiz318]

My drivers side is a tri-y. Clears the steering shaft and doesn't hit the abs once I moved it over a bit. Getting out though is a problem because I have to tilt the engine.

[Joh]

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.


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