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Log manifolds, Perrently not so crap

Lord Tentacle

Anime Lord
Joined
Aug 6, 2005
Location
Sydney, AUS/Appleton, WI
As found on the McLaren MP4-12C
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8500rpm, 616+hp....
 
Well ****. Let's all dump our tube headers and start using log manifolds now.

I know Right ! I presume the post from Lord Tentical was meant to be amusing. But wouldn't it be right to assume that the cast log manifold is used to fit the constraints within the engine compartment along with bring down production costs? Granted even if it is on a super car the company producing it needs to make a profit on their production.
 
I know Right ! I presume the post from Lord Tentical was meant to be amusing. But wouldn't it be right to assume that the cast log manifold is used to fit the constraints within the engine compartment along with bring down production costs? Granted even if it is on a super car the company producing it needs to make a profit on their production.

The point is that although nice
99.9% of this board will never make more then log turd will support

Also... they had more then enough room to fit even a slightly less log like manifold into place and didn't bother
 
How psi will log support?

I replaced the log on my 16V with a nice tubular manifold and things got a lot zoomier, but I really couldn't tell you if it was the turbo upgrade that went with it vs. the log manifold.
 
The point is that although nice
99.9% of this board will never make more then log turd will support

Also... they had more then enough room to fit even a slightly less log like manifold into place and didn't bother

OK I can understand the statement above. But at the same time as we all know the red block is not the most efficient engine to build up, most of us do it for the challenge and or for fun. But if you can afford to build out a tuned header why not do it ? There are considerations while building out the header, such as its purpose and which turbine you are using. After all its all about how well we can support the modifications to the engine with maximum efficiency. Yes for some one whom is trying to +T and cannot get their hands on a 90+ manifold it would be better to just make a log header for cheap fix (if they have the tools to do it). As for the rest of us whom are working toward other goals then everything counts. The best way to look at this is, that engine was designed for a specific purpose. All of the components where selected and designed to meet the needs of that purpose. The same considerations should be well thought out while we are modifying and building our Turds :-P
 
Under boost pulse supercharging doesn't exist since the chamber pressure and pistons are forcing out the gas, there isn't any scavenge effect. A tubular exhaust manifold won't last as long as a cast inconel or additive manufacturing (3D printed) exhaust manifold as is now common with the race teams. They can 3D print a titanium exhaust manifold that will flow better and be more durable than a tubular stainless header.

I've seen tubular headers seriously warp and collectors balloon just from 1/4 mile passes. A McLaren is going to undergo a lot more heat stress getting up to top speed than the 7-10 seconds it takes to make a 1/4 mile pass!
 
Under boost pulse supercharging doesn't exist since the chamber pressure and pistons are forcing out the gas, there isn't any scavenge effect. A tubular exhaust manifold won't last as long as a cast inconel or additive manufacturing (3D printed) exhaust manifold as is now common with the race teams. They can 3D print a titanium exhaust manifold that will flow better and be more durable than a tubular stainless header.

I've seen tubular headers seriously warp and collectors balloon just from 1/4 mile passes. A McLaren is going to undergo a lot more heat stress getting up to top speed than the 7-10 seconds it takes to make a 1/4 mile pass!

Agreed

We have moved to exclusively cast manifolds for longevity, reliability, and sealing at interfaces. It also allows us to fit in tighter places. For anything street, I am a strong proponent of good, cast manifolds.

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It's magic, inside that log is 9" of tuned length manifold. Just shows when designing a complete system, not every single element of it has to be optimized. I'm sure many hours of R&D are in that log too
 
It's magic, inside that log is 9" of tuned length manifold. Just shows when designing a complete system, not every single element of it has to be optimized. I'm sure many hours of R&D are in that log too

Another consideration for them is Cat lightoff. Headers don't perform as well on this.
 
I know Right ! I presume the post from Lord Tentical was meant to be amusing. But wouldn't it be right to assume that the cast log manifold is used to fit the constraints within the engine compartment along with bring down production costs? Granted even if it is on a super car the company producing it needs to make a profit on their production.

yeah production costs on a mp4-12c
 
yeah production costs on a mp4-12c

Every production car has a BOM cost and the lower you can make it the more $$$$$ you get into your bank account.

Cast manifold = $50 each X 3000 units = $150000
Tube manifold = $150 each X 3000 units = $450000

Thats a saving of $300K a year going into your bank.

These numbers are just guesses but you get the idea.
 
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