tooter's manifold adventure...

[xnamerxx]

Originally Posted by Shinare

^^^ RE: "long tube header" - Please forgive this noob question, it really is a question and not a troll, but why does it matter the length of a pipe? Don't you want the exhaust to just get out via the back of your car rather than in the engine bay?

Its about exhaust scavenging. At a certain length and diameter, the exhaust pulse will create a sonic negative pressure wave at the valve creating a vacuum. That vacuum helps pull up on piston, clear out the cylinder, and suck fresh air into the cylinder. The exhaust itself still exits in the original location in most situations. On most otto cycle engines exhaust contributes to about 5-15% of the engines theoretical performance potential, on 2 stroke engines it can be as much as 40%.
In my case I picked up 7hp and 6 tq over a DC header with the long tube header I designed.

[CrankyOldMan]

Originally Posted by xnamerxx

In my case I picked up 7hp and 6 tq over a DC header with the long tube header I designed.

Is that design, by chance, available for the rest of us? I'm sure there's a thread, but I'm really lazy in the morning.

[xnamerxx]

Originally Posted by CrankyOldMan

Is that design, by chance, available for the rest of us? I'm sure there's a thread, but I'm really lazy in the morning.

Nope, spent a bit too much time with it to show off.

[tooter]

Who could forget the freaking awesome sound of your dyno runs, namer?

http://www.youtube.com/watch?v=fpkgkDjwHVg

I thought of your project every time I saw these.




But like you said, they only adjust for attitude, but not for length.

Had you come up with any other ideas to resolve the issue of engine arc travel? You seemed to be so close to a functional product.

[cali yaris]

Don't you want the exhaust to just get out via the back of your car rather than in the engine bay?

Remove your header and see how much power you lose with no exhaust at all. A LOT.

[Yoda]

Originally Posted by cali yaris

Remove your header and see how much power you lose with no exhaust at all. A LOT.

I can attest to that

[Shinare]

Originally Posted by cali yaris

Remove your header and see how much power you lose with no exhaust at all. A LOT.

Well that's strange, I never would have guessed that would even affect the performance of a car. So exhaust pipes on the header make the engine work better rather than having nothing there to restrict... to me that's just really weird, hehe

[CrankyOldMan]

Originally Posted by Shinare

Well that's strange, I never would have guessed that would even affect the performance of a car. So exhaust pipes on the header make the engine work better rather than having nothing there to restrict... to me that's just really weird, hehe

It's all based on the Helmholtz principle, the Bernoulli effect and fluid velocity. Lots of crazy physics and maths to explain it, but not really relevant unless you're into that sort of thing. Here's my understanding of it: escaping exhaust pulses down each tube (Helmholtz), drawing a slight vacuum on the adjacent tubes (Bernoulli). Velocity and pressure of a fluid in a tube is decreased by increasing the diameter. Decreasing the pressure means easier flow, but lower velocity and less scavenging effect...I think.

[TOLMACH]

^ That is his yaris

[TOUGEghost]

Originally Posted by tooter

Nice wheels!

[tooter]

Originally Posted by TOUGEghost

Nice wheels!

Thanks,

They were the closest truck wheel match to the ones on our Yaris.

[cali yaris]

^ he puts them on everything.

[malibuguy]

That header is georgeous. Do you have any pictures of inside the collector?

[tooter]

Sorry, no. But the runners are as clean and neat on the inside as it they are on the outside. And I agree, it's an excellent example of the exquisite beauty of flow design, and I bought it solely because of its visual appeal.



Note the similarity?

[CrankyOldMan]

So many Freudian themes in this project! I was wondering where the actual seam would be on the bellmouth--for some reason I was thinking you would put it all the way up to the squared shoulders.

[tooter]

Originally Posted by CrankyOldMan

So many Freudian themes in this project! I was wondering where the actual seam would be on the bellmouth--for some reason I was thinking you would put it all the way up to the squared shoulders.

That's right, Cranky. I had originally planned for it to drop all the way down to the square corners, but that makes the round part of the bellmouth drop below the contact surface of the hemisphere creating a gap. While the welder could easily fill that gap, I want to try to keep burn through to a minimum by retaining complete contact between the two surfaces so that the inside surface is not compromised.

It took a couple of hours of handwork to get the fit as precise as possible, and I'm totally satisfied with the results.





When I bead blast the whole assembly to normalize all of the surfaces, you'll hardly be able to see the seam even with no welding.

The raised square corners will end up working out nicely as the whole circle of the contact seam is easily accessible to be welded from the outside of the hemisphere. Exploring how to make the best of each detail in the design process is what makes this project no end of fun.

[cali yaris]

It looks from the picture, that because of the angle, the throttle body points more directly at two runners, which are slightly further away. See your second picture above. It would be interesting to see a flow test for to see how much each runner is getting.

[tooter]

Originally Posted by cali yaris

It looks from the picture, that because of the angle, the throttle body points more directly at two runners, which are slightly further away. See your second picture above. It would be interesting to see a flow test for to see how much each runner is getting.

I know. The offset angled orientation of the throttle body axis in the original plenum was even more offset than the one I'm building. So I softened it slightly. If it wasn't an issue for Toyota, it isn't for me. I think it was done just to get the throttle body pointing slightly upwards to line up with the stock air filter box, so I did the same thing so as to line up with mine.





This is the original manifold throttle body axis orientation.



And this is the tooter et throttle body orientation.



This is why I don't believe that it was ever an issue. First because the flow is so direct, and second the runners are pulling from the plenum That's what I like most about this particular design. It completely eliminates the 90 degree "kink" runner to throttle body axis orientation found in all of the other typical plenum designs.