tooter's manifold adventure...

[tooter]

Had an opportunity to do the water test today.

I taped off the throttle body and hose inlet fittings and filled up the runners while tilting the manifolds around to make certain that there was no captured air. And then I emptied them into a big bucket and poured the water out into a 32 ounce measuring cup.

The results confirmed the obvious... the plenum on the Yaris manifold is much larger than on the Corolla manifold.

Total volume of Yaris manifold 127 ounces
Total volume of Corolla manifold 101 ounces

This makes the total volume of the Corolla manifold about 20% smaller, even though it was designed to flow for an engine with 20% more displacement.

And I have absolutely no idea how this will affect the performance...

...but I'll find out soon.

[packetrace]

cant wait to see :)

[eTiMaGo]

My personal opinion, peak hp and torque changes will be minimal and could be attributed to the margin of error of the dyno itself. But, I think there will be less low and mid-range torque.
so...

+0hp +0tq, weaker midrange

[malibuguy]

Shit id pay 700 for RHs manifold for those kind of gains...and what looks to be on the stock airbox too

[mazilla]

Garm is onto me...hehe

[CrankyOldMan]

Originally Posted by tooter

Had an opportunity to do the water test today.

The results confirmed the obvious... the plenum on the Yaris manifold is much larger than on the Corolla manifold.

Total volume of Yaris manifold 127 ounces
Total volume of Corolla manifold 101 ounces

In my research, I was never able to find conclusive evidence of how the volume of the plenum affects the power curve. It would be better if you could measure just the volume of the runners, but that might be tough since you can't really see where the Yaris runners meet the plenum.

My guess is that the Yaris uses a much larger plenum to reduce the effect of the air entering perpendicular to the runners and provide adequate "reserves" for the runners farther from the TB. I haven't entered a guess yet, but I think the net result will be a shift of peak HP/tq RPMs that is more significant than the change in peak overall.

[tooter]

Originally Posted by CrankyOldMan

In my research, I was never able to find conclusive evidence of how the volume of the plenum affects the power curve. It would be better if you could measure just the volume of the runners, but that might be tough since you can't really see where the Yaris runners meet the plenum.

I can see the first runner in the plenum...



... but there are internal undulations which prevent seeing the others, and I think there's also some kind of chamber in there because the water was captured in the plenum and I had to tip it around all crazy sorts of ways to eventually get it to come out.

My guess is that the Yaris uses a much larger plenum to reduce the effect of the air entering perpendicular to the runners and provide adequate "reserves" for the runners farther from the TB.

Yes. From what I've read, there are issues with the mouths of the runners being perpendicular to the flow of air entering the plenum. Also there are issues when the runner mouths are not raised above the edge of the plenum.

The Corolla manifold gets around that, first ,by having the intake from the throttle body entering into the exact middle of the plenum, which, from what I've read, is a significant design advantage over having the entry at one side putting all of the runners at different distances from it.

And, second, all the runners are only 2 1/2 inches away from the central entrance point and are all equidistant from it, and all "looking" directly at it, so there is no change in the direction of the flow. This design is similar to a backwards flowing exhaust header.

I really like this design as it is a complete departure from the typical perpendicular runner "log" style manifold.

I've been reading about another manifold principle in play called resonance. Sound waves created by the valves slamming closed travel back up the runner and are reflected back to the valves by the plenum. This tuning can pressurize the incoming flow as it enters the valves providing a supercharging effect. These sound waves travel back and forth many times even within one valve cycle. So the plenum is a kind of echo chamber, and the size determines the frequencies of rpms that it favors. This principle is somewhat like the principle of exhaust scavenging which uses resonant pulses of adjoining runners to draw the exhaust down the header.

I haven't entered a guess yet, but I think the net result will be a shift of peak HP/tq RPMs that is more significant than the change in peak overall.

I agree, as my guess is just a very slight positive and negative change in hp and tq. At what rpm frequences this manifold resonates is unknown...

...but they will be clearly revealed in the graphs of the dyno runs.

[CrankyOldMan]

Originally Posted by tooter

I've been reading about another manifold principle in play called resonance. Sound waves created by the valves slamming closed travel back up the runner and are reflected back to the valves by the plenum. This tuning can pressurize the incoming flow as it enters the valves providing a supercharging effect. These sound waves travel back and forth many times even within one valve cycle. So the plenum is a kind of echo chamber, and the size determines the frequencies of rpms that it favors. This principle is somewhat like the principle of exhaust scavenging which uses resonant pulses of adjoining runners to draw the exhaust down the header.

Aah yes, good old Helmholtz Resonators. My first understanding of the Helmholtz resonance was that it applied to the runners and plenum, but that proved to be incorrect since all of the calculators that I found used the volume of the cylinder at bottom stroke. That's where the confusion over the volume of the plenum came in--none of the calculators seemed to care about it--and some calculators even seemed to be based on the runners alone. There was anecdotal evidence that a larger plenum can flatten the torque curve, and that it should be "about 1.5x the displacement of the engine" but no empirical studies or documentation. Perhaps Mr. Holdener had some more definitive results from his 50+ prototypes?

I tried modeling the intake as a series of cylinders in Finite Element Analysis (FEA) software, but wasn't able to get any sensible results. I haven't taken a class in how to do FEA for fluids, a.k.a. Computational Fluid Dynamics (CFD), so it was a rather fruitless effort.

[tooter]

Originally Posted by CrankyOldMan

Aah yes, good old Helmholtz Resonators. My first understanding of the Helmholtz resonance was that it applied to the runners and plenum, but that proved to be incorrect since all of the calculators that I found used the volume of the cylinder at bottom stroke. That's where the confusion over the volume of the plenum came in--none of the calculators seemed to care about it--and some calculators even seemed to be based on the runners alone. There was anecdotal evidence that a larger plenum can flatten the torque curve, and that it should be "about 1.5x the displacement of the engine" but no empirical studies or documentation.

The Corolla plenum is only a little larger than the collector on a header, so I'm really curious what the effect of that will be.

Perhaps Mr. Holdener had some more definitive results from his 50+ prototypes?

I think we'll never know... just like we'll never know why a Yaris intake manifold couldn't be produced for $700 a unit.

I tried modeling the intake as a series of cylinders in Finite Element Analysis (FEA) software, but wasn't able to get any sensible results. I haven't taken a class in how to do FEA for fluids, a.k.a. Computational Fluid Dynamics (CFD), so it was a rather fruitless effort.

I'm using the crapshoot method:

"Run what you brung."

Which also holds great potential for fruitlessness.

[cali yaris]

we'll never know why a Yaris intake manifold couldn't be produced for $700 a unit.

That's an easy one.

1. R&D cost required to prove that a manifold works, produces power, and causes no CEL's.
2. Utter lack of Group Buy interest in terms of real deposits, when #1 is unknown.

Just look at the Weapon R manifold (which is $700 by the way), and the nearly zero sales it generated for the xB market.

But hey... someone's gotta do it.

[cali yaris]

confusion over the volume of the plenum came in--none of the calculators seemed to care about it--and some calculators even seemed to be based on the runners alone.

No confusion there. The calculators don't need a volume number for a reason.

[CrankyOldMan]

Originally Posted by cali yaris

No confusion there. The calculators don't need a volume number for a reason.

Well, my confusion was based on the incorrect assumption that the plenum became a secondary resonator for the back-pulse.

[tooter]

Originally Posted by CrankyOldMan

Well, my confusion was based on the incorrect assumption that the plenum became a secondary resonator for the back-pulse.

If that's true, then it's all for the best because there's almost no plenum on the manifold to resonate anyways.

[tooter]

Originally Posted by cali yaris

That's an easy one.

1. R&D cost required to prove that a manifold works, produces power, and causes no CEL's.

From reading the old thread, Richard had a dynoed working prototype that produced significant gains.

2. Utter lack of Group Buy interest in terms of real deposits, when #1 is unknown.

More than 10 people were on the buy list which he said was the threshold for a production run. After a long gap of no communication, people got discouraged and dropped out when nothing happened.

Just look at the Weapon R manifold (which is $700 by the way), and the nearly zero sales it generated for the xB market.

Wow, I didn't know that they actually came up with a Scion product. Have to take a look at it.

But hey... someone's gotta do it.

Looks like the torch has now been passed on to me.

Today makes exactly two months elapsed time to produce one tooter prototype that's ready to bolt onto the engine...

[Flipper_1938]

Originally Posted by tooter

Looks like the torch has now been passed on to me.

Today makes exactly two months elapsed time to produce one tooter prototype that's ready to bolt onto the engine...

Then go bolt that sucker on!!!!

[3cyltrbo]

if:

-this makes power (fantasizing about 5whp)
-and / or if it changes the intake noise

AND

its not $700 (assuming tooter was to produce them)

I'd be on it like a fat kid on cake

like michael jackson on little boys

like the republicans on helping their rich chronies

like michael phelps on gold medals

(Cliffs notes: if it makes power / and or sounds better = Will wants one)

[Bluevitz-rs]

On a plus side for the cable throttle crowd, we don't need the TB adapter, just the flange for the head.

[malibuguy]

700 for proven significant gains on a already very effecient motor is chump change. I would buy one in a heart-beat and any true motor head that understands this would too