Official ITB Performance Discussion

[Ponyboy]

There are a few ITB options in the market now and I thought it'd be nice to have a specific thread discussing them. As I search through old ITB posts, I'll merge them into this thread to add to the content. FWIU, these are the various ITB options: - ScienceofSpeed - Revolution - TODA - Advance Flatout This is just the thread start. Feel free to add other vendors (I'll revise the list as necessary), descriptions, and photos. If we can get enough content, we can make this a sticky...

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[Top Ramen]

The SoS ITBs are really Hayword, which gives them a huge advantage in my opinion. Lance does a good job designing and building manifolds and linkages and he uses Jenvey throttle bodies, which are the best available. Thesy use 48mm (at the plate) Jenveys and are tapered overall. It is by far the cheapest system ($4.5K) and is probably the most complete - including a vaccuum accumulator and cold start mechanism. I think it also has the longest overall runner length, which is nice on a motor not known for torque.

I have heard Revolution has a new design, which is good news, because their old set-up was crap. I think they scavenged parts off of a Porsche system instead of starting from scratch and it showed. Hopefully the new system is better, but it is hard to get technical information from them. They are 787,500 Yen plus whatever it costs to get them here.

The Todas are okay, but those guys are way too in love with their parts. There is absolutely no way they are worth the asking price. They come in 45mm or 47mm.


Modified by Top Ramen at 9:50 AM 5/21/2007

[Top Ramen]

Science of Speed
note the overall length and the nice injector placement



Toda



New Revolution
Looks like it would be tough to build a box for these without interfering with the linkage.



Old Revolution

[Ponyboy]

I've heard the same about the SOS/Haywood ITBs - about the Jenvey throttle bodies and the cold start mechanism. The cold start and idle issues seem to be where the systems get hung up.

Here's closer up pic of the TODA itbs:



Man, I'm in love with that CF airbox/plenum.

And another pic of the Revo itbs w/ a decidely unstock transmission and mounts:



And some "to be determined:"





Old Revo's?

[Top Ramen]

Originally Posted by Ponyboy

Man, I'm in love with that CF airbox/plenum.

I don't think one like that would be hard to build at all using either CF or aluminum. The tricky part is making it work on a car without the hatch scoop.

I would run big tubes down to the side scoops (both of them) and use cone filters to feed cold air from both sides into the ITBs. You sould need to loose the fan on the passenger side, but it is pretty pointless anyway. You could easily build a small box that enclosed the cone filters and sealed up against the side scoops.

Like this:



Now that is just sweetness. . . .

[prospeed]

hmm pretty nice carbon manifold. Do you know the company that produces that?

[EK4 hatchback]

Originally Posted by Ponyboy

That is the photo i took few month ago here in HK.........It is a custom make unit with some kind of stand alone ECU.

[JDM knowledge]

anyone have numbers of what each ITB setups can produce?

[Top Ramen]

Originally Posted by JDM knowledge

anyone have numbers of what each ITB setups can produce?

Earn your screen name and let us know. . .

[JDM knowledge]

Originally Posted by Top Ramen

Earn your screen name and let us know. . .

haha thanks i will try. Search initiated.

[Ponyboy]

Nice pics of that CF airbox/plenum, Davey. I wonder what the formula is for determining the ideal plenum volume though?

Although hatch induction would be much easier, I'm not a big fan of the JGTC scoop either. Maybe the Advance slotted hatch would work though.



Looks like Advance has their own ITB system as well:

[JDM knowledge]

that slotted glass is nice but i think the scoop would yield more air inside.

[Ponyboy]

Very likely but, man, are those an eyesore. I think if one is thinking about going in that direction, they may as well go for the whole "shark fin" and get even more pressurized air in the plenum.

I wonder if a NACA(s) duct would work...

[Top Ramen]

I don't think there is an "ideal" plenum size on set-ups like this. You just need to get it big enough to provide even (and plentiful) air to each throttle assembly. The overall ITB/runner/stack length is what gets tuned for resonance.

[Ponyboy]

I'm thinking that by adding a "tuned" plenum, one could tune another 2 (total of 6) resonance frequencies.

From what I've read, a short wide intake runner favors higher RPM torque peak b/c they have a higher resonant frequency and the larger diameter is less air flow restrictive. A longer narrow intake runner favors lower RPM torque peak b/c of a lower resonant frequency and narrower diameter increases velocity. And examples of the varying philosophies are above in the pics as well. Good stuff.

Now I know why F1 engines use a variable intake.

[jdmbotnik.]

itb for the win.

[Top Ramen]

Originally Posted by jdmbotnik.

itb for the win.

Way to contribute. . . .thanks, really.

Originally Posted by Ponyboy

I'm thinking that by adding a "tuned" plenum, one could tune another 2 (total of 6) resonance frequencies.

If you take a hard look at the Helmholtz models, you will notice that once you get past the first several resonance fequencies, they become trivial. Each has a smaller amplitude than the previous.

[Westrock2000]

You could always go open mesh over your engine bay. Seriously its not that bad, you learn how to use the side mirrors real quick. Plus the engine cools down like you wouldn't believe.

I too am thinking about ITB's on my Exige. The hard part is that we use e-throttle, which might be OK depending on how an e-throttle motor works. But even harder is that we use MAF, so finding a way to measure the air is alot harder. You guys are at least lucky enough to have MAP systems.

[Ponyboy]

Originally Posted by Top Ramen

If you take a hard look at the Helmholtz models, you will notice that once you get past the first several resonance fequencies, they become trivial. Each has a smaller amplitude than the previous.

Law of diminishing returns, eh. So where's the greatest variance - past 4 or 6 resonance frequencies? I'm reading a white paper on the "Effect of Intake Pipe..." - fairly long but really interesting. Thought you'd get a kick out of it as well.

And I've been looking on the SAE website for books on intake theory and design but...nothing.

Originally Posted by Westrock2000

You could always go open mesh over your engine bay.

Not sure I'm getting you. Open mesh similiar to the filter element from F1 cars of yore?

Found a new close-up pic of the Revolution ITBs ganked from the Top End website:

[Ponyboy]

Originally Posted by EK4 hatchback

That is the photo i took few month ago here in HK.........It is a custom make unit with some kind of stand alone ECU.

Get some more info on it! Please!

[Top Ramen]

Originally Posted by Ponyboy

Law of diminishing returns, eh. So where's the greatest variance - past 4 or 6 resonance frequencies?

My understanding is that most designers don't even try to incorporate anything past the first four Helmholtz harmonic resonances. If I remember correctly (college was a LONG time ago) the first order harmonic is worth around 10% more air if tuned perfectly and each one drops down after that. Something like (scratching head) 10% - 7% - 4% - 2%. I believe the deminishing orders are due to changes in amplitude.

[Ponyboy]

Found a good pic of the plenum internals:



Think that's 5.4 liters?

[Top Ramen]

Originally Posted by Ponyboy

Think that's 5.4 liters?

Looks at least that big with the top part. Guesstimate the dimensions and run the math. . .

[Westrock2000]

Originally Posted by Ponyboy

Not sure I'm getting you. Open mesh similiar to the filter element from F1 cars of yore?

Instead of the glass "window" above the engine, just an open style metal mesh much like my Exige. Keeps the engine very cool. But would probably be hard to execute and still look good for ya'll.

You could also look into discrete intake manifolds for the banks. 3 cylinders get a single manifold with its own throttle body (like a 60mm or so). Link the 2 throttle body actuators together and read the TPS off one of them. Connect the MAP sensor to both of them. The IACV may be a little interesting though. Kind of like how the bigger V engines are with dual throttle bodies.

[Ponyboy]

That's certainly possible. Though, for me, I think I'd like to keep whatever I go with as stock looking as possible - at least on the outside.

Found a good filter idea:





And the site: http://www.verycoolparts.com/Stack.htm

This may be the easiest way to go along with the Advance hatch.