tooter's manifold adventure...

[Golddeenoh]

^ all these pick of them on other cars, I just want to see yours on yours and see a before and after dyno run. :D

[CrankyOldMan]

One other solution to the side-mount TB is to use a tapered plenum:


As far as runner length, all of the material that I have read insists that longer runners = low end power and vice versa. This is all based on the Helmholtz resonator theory. If you look at the first equation (relax, you don't have to solve it) you can see that the mass of air in the neck is in the denominator, meaning that larger masses of air (longer runners) will decrease the resonant frequency (RPMs). Increasing the cross sectional area will increase the frequency, as well as have a slowing effect on air flow velocity in the runners. The variables for the 'cavity' refer to the cylinder, not the plenum.

tl;dr - science says long runner = low rpm boost. Unless this article has empirical evidence to back up their claims, treat it as snake oil.

[tooter]

Originally Posted by CrankyOldMan

One other solution to the side-mount TB is to use a tapered plenum:


As far as runner length, all of the material that I have read insists that longer runners = low end power and vice versa. This is all based on the Helmholtz resonator theory. If you look at the first equation (relax, you don't have to solve it) you can see that the mass of air in the neck is in the denominator, meaning that larger masses of air (longer runners) will decrease the resonant frequency (RPMs). Increasing the cross sectional area will increase the frequency, as well as have a slowing effect on air flow velocity in the runners. The variables for the 'cavity' refer to the cylinder, not the plenum.

tl;dr - science says long runner = low rpm boost. Unless this article has empirical evidence to back up their claims, treat it as snake oil.

Hey Cranky,

I'm certain that was simply an transposing error in the translation. The project was done in Jakarta, Indonesia. And whoever did it had extensive practical automotive experience. I'll bet it did not read that way in the original language.

As to the intake manifold picture... just look at what you need to add to the manifold to try to overcome the inherent runner imbalances from taking fuel/air perpendicular to the axis of flow from the throttle body.

In my opinion it's much easier to simply use a design with no imbalances that need to be overcome in the first place.

Cars today no longer have the luxury of large empty underhood spaces in which to fit those complex wildly expanded designs. My old truck does...


...but those days are long gone.

[tooter]

Originally Posted by Golddeenoh

^ all these pick of them on other cars, I just want to see yours on yours and see a before and after dyno run. :D

As do I.

This is a process that needs to run its course, and I'm taking each step carefully and deliberately so that I don't have to backtrack.

Backtracking triples the cost of any project because of you're adding two more cost layers of undoing and redoing. It's already expensive enough just doing it once!

[tooter]

In 1987, Oldsmobile introduced a DOHC 4 valve "Quad 4" engine. It used an unequal length intake manifold with no plenum...



Later years changed to a log type manifold likely because it worked better.

[cali yaris]

Backtracking triples the cost of any project because of you're adding two more cost layers of undoing and redoing.

More expensive, yes - triple, no. It's never 100% undo and redo, if the original idea was sound at all.

Giving up on an idea is a total loss though, I do know that one! For example, if the intake manifold causes a loss in power, I wouldn't bring it to market.

[tooter]

A nice Corolla engine. Hope mine looks half as nice...

[tooter]

Originally Posted by cali yaris

More expensive, yes - triple, no. It's never 100% undo and redo, if the original idea was sound at all.

Giving up on an idea is a total loss though, I do know that one! For example, if the intake manifold causes a loss in power, I wouldn't bring it to market.

Hey Garm,

You're right. That was a little hyperbolic just for a manifold. I work in construction where the triple rule is more of a reality.

By the way how are your manifolds progressing? I just started and I'm a totally inexperienced amateur, so you had better not let me get a manifold on my car before you get one on yours.

But I bet yours will work better than my junkyard special...

[cali yaris]

I'm pretty sure you'll have yours on first!

We have a prototype now that doesn't hit anything. It's tack-welded though, so it can't be installed on a car. Next revision will be a proto we can put on a car and see what happens. Maybe another week or two?

I wish I could focus on this the way you're focusing on this.

[tooter]

This project is just a hobby to play around with in my spare time. But I've been interested in intake and exhaust designs and how they flow for most of my life, so the opportunity to do this is a dream come true.

[CrankyOldMan]

OK, I've tinkered around with the suggested dimensions you gave me and it doesn't really look right. If you have access to a laser printer with high dimensional fidelity (and 11x17 paper) you could print these off and compare them to the original. I can't find the thermal gasket in the MI store--was it a special order item?

[cali yaris]

^ Haven't put them up yet in stock though!

[edit] uploaded into the store now Yaris > Engine > Mechanicals

[tooter]

Hey Cranky,

Sorry my measurements weren't so good... and I'm presently at a disadvantage as everything is down at the machine shop because they are generating the working drawings.

My own less-than-machinist accuracy is one reason why I simply got both the thermal gasket and a stock manifold. They completely remove all the guesswork, as there is an actual physical representation of everything required to make the adaptor flange fit properly.

Hey wait, I think I see why the measurements aren't working out with your drawing!

None of the Corolla manifold runners are concentric with the Yaris head intake ports. Your part as drawn indicates that they are. First, the Corolla runners are a lot larger, and second they more spread out.

Consider just the two inner Corolla runners first:

The two inner edges of the Corolla runners perfectly line up with the inside edges of the two inner Yaris intake ports. The distance between the two corolla runners and the distance between the two Yaris intake ports are exactly the same. That distance is the only one that matches exactly. All of the other measurements are different. Even the bolt holes bear no symmetrical relationship to the Corolla runners.

Now consider the two outer Corolla runners. Both of their inner edges are 5mm outside of the outer edge of the Yaris runners. This is one reason why I'm specifying the flange be one inch thick, so that there will be sufficient distance to make a smooth flowing transition between the two different arrays of holes.

Just email or call Garm and he'll sell you the thermal gasket. It's made by Golden Eagle. It'll make your task so much easier!

I'm going to use it on my car. And you can make good use of it on yours. The intake manifold flange is really thick aluminium and will pick up conductive heat from the head. The thermal gasket will insulate it and keep it cooler.

[tooter]

Thanks, Garm.

It's an especially useful part because it not only pins down all the measurements exactly, it will get put into use when I install the manifold.

[CrankyOldMan]

Oh, I had intended to cut the runners from the plenum for my design, so I made them concentric. If you look carefully, the runners holes are proportionately wider than the intake holes. I had considered what you were planning, but decided it was too much of a stretch and would make machining it a nightmare.

The 1NZ has 83mm bore spacing and the intake has (iirc) 87.5mm spacing. I had that written down somewhere...

[tooter]

Originally Posted by CrankyOldMan

Oh, I had intended to cut the runners from the plenum for my design, so I made them concentric.

Ok, I get it now.
I didn't know that you were going to cut apart the manifold runners.

If you look carefully, the runners holes are proportionately wider than the intake holes.

Yes... and no wonder you showed them concentric.

I had considered what you were planning, but decided it was too much of a stretch and would make machining it a nightmare.

Are you going to machine it yourself? It would be a tough job trying to correct the offsets which is good you're not going that route. That's why my friend suggested hiring someone with a CNC machine, because it's a simple matter for it to render the difference between the two arrays smoothly.

The 1NZ has 83mm bore spacing and the intake has (iirc) 87.5mm spacing. I had that written down somewhere...

Note how none of the runners surfaces physically touches any of the other runners. When you cut them apart to reposition them, it would be a good idea to make sure that there is no contact between them as under vibration they can chafe. I worked on helicopters as a mechanic in the Army, and preventing aluminium parts from chafing during flight was always an issue... not that our Yaris' could ever fly!

[CrankyOldMan]

Originally Posted by tooter

Are you going to machine it yourself? It would be a tough job trying to correct the offsets which is good you're not going that route. That's why my friend suggested hiring someone with a CNC machine, because it's a simple matter for it to render the difference between the two arrays smoothly.

I have access to CNC mills at school and AutoCAD at home, so that's not a big deal. The issue I was considering was the inset channel for the runners being on the opposite side of the machining face. Any time you relocate a part, you're asking for alignment issues. We're not trained/allowed to use edge finders on the equipment at school, so it has to be a single-sided operation. Now if I could just get AutoCAD to stop crashing, I could get this new plate drawn up...

[tooter]

Originally Posted by CrankyOldMan

I have access to CNC mills at school and AutoCAD at home, so that's not a big deal.

All right, Crank! Man, you're certainly going to win the contest hands down of building the cheapest manifold!

The issue I was considering was the inset channel for the runners being on the opposite side of the machining face. Any time you relocate a part, you're asking for alignment issues. We're not trained/allowed to use edge finders on the equipment at school, so it has to be a single-sided operation.

Oh, this is something I know absolutely nothing about. All I know is that the machinists told me that making the adaptor was a simple straightforward job for them.

Now if I could just get AutoCAD to stop crashing, I could get this new plate drawn up...

Good luck... and do keep me posted on how your project goes. Sometimes two people figuring out how to do the same thing can come up with new and different approaches and techniques.