log vs merge style turbo manifold

[bhearts]

https://www.youtube.com/watch?v=0F5XiATZ7Ro

thats a pretty significant hp increase.

[Hot_Wheels]

Cool video!

[bhearts]

I don't trust in house testing though. So it's hard to tell about these results.

Sent from my SM-G900V using Tapatalk

[sketchman]

There seem to be 2 schools of thought.

1. Pressure is what makes boost, so a log is fine.

2. A better flowing system is better. Period.

Grossly oversimplified, I'm sure, but that's what I've seen.

[ZephTheChef]

I am mostly in the first school of thought. I believe the turbo is always the choke point...if there was no significant pressure differential across it then it would not function. I believe there may be some exhaust gas velocity improvements from reduced turbulence and such with a proper collector, but I firmly believe it is super insignificant in the big picture. It's easier and more effective to maximize the pressure differential across the turbo by improving the piping post-turbo than it is to design a complicated, bulky, expensive manifold like that. I mean I have seen 2-3,000HP setups on twin turbo V8s out of log manifolds, and I've seen a hell of a lot of 150hp setups out of fancy-pants manifolds. And vice versa, of course the point is it doesn't much matter. There are advantages and disadvantages to both but for 99% of people, the log will work just as well.

The only scenarios I could see mods like that worth doing would be in an all-out competition scenario where you have limitations/rules on what you can do and need to extract absolutely the most power/efficiency from a given setup. If you aren't running your stuff all out already, then it would make a lot more sense to turn up the boost than build a ridiculous overkill manifold that isn't going to give you any significant power gains if you're limiting your turbo anyway. The other scenario is if you want it for cosmetic purposes. Show car/to impress your buddies. If that's important to you and worth the extra money then by all means go for it.

As I pointed out to Bryan, they utilized a completely different wastegate setup on the ram horn and the power gains could have easily been from differences in the way the gates control the boost, or that the huge TIAL wastegate on the second one may flow a lot more exhaust, freeing up more power when it opens. It wasn't really an exact apples to apples comparison like they are billing it to be. Also if you look at the dyno, the second pull starts fully a thousand RPMs sooner, so naturally the turbo would be up to boost at a slightly lower rpm as well, they may have just carried that extra power up the chart and then made more up top due to the wastegate difference. I can't see the manifold being worth that significant a % hp increase...ever.

Maybe I'm wrong...and if I had the time and money and skills to make something that pretty and efficient I probably would too. So I wouldn't say I'm really hating on tubular manifolds. I just think they are in general given more credit than they are due.

[ZephTheChef]

http://turbo-moteurs.cnam.fr/publications/pdf/ASME99.PDF

[14carrot]

I want one.

Sent from my ALCATEL A845L using Tapatalk