I am running a kings stage 1 kit with the log manifold and for some reason i keep getting the itch to switch to a tubular manifold because a saw a few people gained big power. I know i will not spool as fast but it would be nice to get some personal responses from people that made the switch. How much power can i expect to pick up? Currently i am at 461whp on 16psi running on e85. If i can gain around 40whp on the same power ill be happy.

 

https://www.s2ki.com/s2000/topic/100...#entry22271490

Those were my results. With the same turbo and nothing being changed except going from a log manifold to a tubular sidewinder i gain 60whp and lost 800rpm of spool on straight 91 octane.

 

Yea i saw your thread and was surprised. Thats actually what got me thinking. Lol

 

I also made the switch back in 2005 or so. I kept the same turbo, intercooler, and exhaust, and only the manifold changed. I saw huge gains in my fuel map, the VTEC crossover plummeted, and VTEC was fun again. It was clear that the car was making a lot more power, but I never found out how much because I had never been happy enough with the log manifold to put it on the dyno.

Tim

 

Sidewinders are terrible spoolwise because the runner length and cause lost velocity, thermal losses etc.

Topmount or bottom mount is what you want if you want to retain spool.

Why do you think Subarus struggle to spool a 35r at reasonable RPMs even with 2.5L of displacement? The answer is runner length.

 

Yeah that's true. The ptuning manifold would be an ideal manifold. It is tubular and still has a 4 into 1 merge collector. So it will make a lot of power just like any side winder but it's also very short so it will spool much faster than all other tubular and espically sidewinder manifolds. The draw way with that ptuning manifold is you have to run their crap motor mouth which will cause stupid vibrations and you have to run a oil scavenging pump to pump the oil out of the turbo since it mounts the turbo so low.

 

The other option is pfab but they use crap 304 and don't warranty if you coat your manifold because they know it will Crack.

My solution was to just make my own and integrate a quick spool valve with an efr 9174. Goal is to have 18psi by 3700 rpm

 

This is the first time I've heard something negative about Pfab's quality. I'm planning on upgrading to their top mount twin scroll manifold at some point.

 

You can find plenty of instances of Pfab manifolds cracking after use. It comes down to the material that 304L is. If you are looking for a material that doesn't have to support a lot of weight, and don't have a lot of material for it to have minimal expansion and contraction, 304L is fine. For long sidewinder style, or topmount with a heavy turbo, 304 is simply not the correct material choice, especially if you want to to last.

Most race teams use 321 since it's not as pricy as inconel 625 but has a good amount of the strength and holds up to repeated abuse at high temperatures. If you're running antilag constantly and above 1500f, you have to use inconel or your manifold will fall apart.

The other great thing about 321 is that you can get away with schedule 10 pipe instead of schedule 40, which saves about 25% weight.

Again, to restate: I'm pretty sure Pfab doesn't warranty it after its coated just because they know the coating will retain more heat in the manifold, and that their welds won't stand up to it, by virtue of how much more the 304 will expand and contract.


Anyway, shots of my 321 schedule 10 stainless manifold. Turbo is an EFR 9174 and I'm using a Sound performance quick spool valve.

Attachment 174627
Attachment 174628

Attachment 175025


You don't have to take my word for it, you can google the material spec of 304 and 321. Killer B motorsports for Subarus exclusively uses 321 on their manifolds because the manifold design acts like a huge lever on the material. They don't crack.


Final thought: The reason why companies don't use 321 is because 304 is cheaper. The BOM is around twice as much as using plain 304L, but material cost is only a portion of the cost of a manifold

 

There is no comparison power wise. The logs do not make great power compared to the tubular manifolds.

You may have a bit slower spool, but you will have way more midrange and top end once the boost does hit.