ITB questions...

[89crxz6]

im just curious...where do u get itbs? wheres a website that tells u how to install them? and what kind of gains do u get with them? what about itbs vs. turbo?

[t0p_sh0tta]

They won't make as much power as a turbo. They're usually found in pretty extensive NA builds.

Most of the DIY setups come from motorcycles.

BTW, there's lots of tunning and know-how involved in ITB setups.

[89crxz6]

i wasnt planning on doing it i was just curious

[K2e2vin]

Some people have lost HP with ITBs(a couple of the B-series NA builds on H-T) , while others have had substantial gains(like Dru Barrios, he got up to 140whp IIRC on a D16Z6 or Y8).

[Slimm-rw-]

what is IIRC?

[s_18]

what is IIRC?

"If I Remember Correctly" is one of it's meanings.

[modsHXcivi]

Doesn't DOG have a sticky on ITB???

[s_18]

Doesn't DOG have a sticky on ITB???

Yes, he has. Too bad most of the pictures are gone.
Read through it about a month ago, and it made less sence without the pictures.
But check out the sticky :TU:

[Jcazz]

UNLESS you have HIGH COMP pistons ITB's on a D are a waste of money....They will be hard to tune. Make sure you have all the bolt on mods and high comp....to see full benifets from them...better yet! go TurBLoW...SHwOHsh! :mikej:

[rushi]

UNLESS you have HIGH COMP pistons ITB's on a D are a waste of money....They will be hard to tune. Make sure you have all the bolt on mods and high comp....to see full benifets from them...better yet! go TurBLoW...SHwOHsh!

That's complete BS and nonsense. I got significant gains in my D15, with just a bit retarded A6 cam and around 10:1 compression.. Stock exhaust/header.
Why wouldn't they work/give good gains, if properly tuned(measures)?

And what comes to "hard tune", they really are not. If they are, either the tuner is an idiot who doesn't understand what he's doing, or he's messing with wrong/bad engine management.
I've found ITBs very easy, fast and straightforward to tune with VEMS and MegaSquirt (Alpha-N = TPS-based control).

[Jcazz]

That's complete BS and nonsense. I got significant gains in my D15, with just a bit retarded A6 cam and around 10:1 compression.. Stock exhaust/header.
Why wouldn't they work/give good gains, if properly tuned(measures)?

And what comes to "hard tune", they really are not. If they are, either the tuner is an idiot who doesn't understand what he's doing, or he's messing with wrong/bad engine management.
I've found ITBs very easy, fast and straightforward to tune with VEMS and MegaSquirt (Alpha-N = TPS-based control).


No its not complete Bs, and or nonesense......i never said they "wouldnt" make any power.....i merly said that they wont even make close to the power you have without having a high comp setup....your better off on a "close to stock block" going with a Skunk 2 manifold or an Edelbrock manifold, with a B16 TB and call it a day.....Now if you had a built block and bolt ons, Sure ITBS will make VERY good response and more power, Still an impractical route in the end unless you are full on racing....and no FI is allowed ect......on the street, if you are looking to exceed and squezze every amount out of an N/a Setup, then youve Exceeded a "cheap" budget, and a Turbo build would simply walk all over the ITB setup... :fruit:

Unless, B-H-F-K series......ITBs; on a D-series = blah in my "opinion" nice but blah....

[K2e2vin]

ITB's make less peak power than a manifold; it's biased towards road race guys because of response. The only "trouble" with tuning ITBs is when using a MAP and trying to tune via vacuum instead of TPS.

Turbo D=blah compared to Turbo B, H, F, K :p

[Jcazz]

lol......i give up haha....

[goforbroke]

Some people have lost HP with ITBs(a couple of the B-series NA builds on H-T) , while others have had substantial gains(like Dru Barrios, he got up to 140whp IIRC on a D16Z6 or Y8).

They probably weren't tuned correctly.

[Eyal 951]

ITB's make less peak power than a manifold; it's biased towards road race guys because of response. The only "trouble" with tuning ITBs is when using a MAP and trying to tune via vacuum instead of TPS.

Turbo D=blah compared to Turbo B, H, F, K :p
Though it is true that ITB's give great midrange, a great torque curve, and gains almost all across the curve. (A very flat tq curve) WHat you just said is not. Well, that is unless somebody went ahead and made a set without giving though to harmonics. You have to tune the length to hit 2nd or 3rd harmonic close to the end of the rpm range you plan to use. The builder needs to know what he is doing, as does the tuner. Otherwise, some guy building itb's and slapping em em, and self tuning, yea you probably will experience a loss. If they are done right, there is a lot to be gained. I'll show you, in a few months.

[K2e2vin]

Of course ITB's will gain power, but compared to a manifold, a manifold can make more peak power. This is good for the drag guys because they spend most of their time in a small portion of the rpm band. Road course is all over the rpm band.
Not only does a manifold benefit from runner volume tuning like ITBs, but they can take advantage of resonance, which ITB's can't unless you stick a manifold on there.

[sl@sh]

hmmm, if one was to ask "what gains can be had" then i think it is best to stir away from the idea's of ITB,s

but a few would know, what ITB's can do, and could help if u know what u want, and that if u know the motor has what it has to take advantage of it,

with that said, its just like any other modification to an engine set-up,
gains can be had (if done correctly) and powerloss can accur (if not done correctly)

[sl@sh]

Of course ITB's will gain power, but compared to a manifold, a manifold can make more peak power. This is good for the drag guys because they spend most of their time in a small portion of the rpm band. Road course is all over the rpm band.
Not only does a manifold benefit from runner volume tuning like ITBs, but they can take advantage of resonance, which ITB's can't unless you stick a manifold on there.


uhm u can tune an ITB, WeberDCOE mikuni sidedrafts length to take advantage of resonant tuning...

http://www.bgsoflex.com/intakeln.html

that link i believe was i think shared by Transzex
and in turn was suggested by Bisi ,
it is to calculate intake runner length for individual runners

uhm Bisi runs weber sidedrafts (4throttle) on his drag insight

[K2e2vin]

that program you posted is for manifolds. on ITB's, there's no wall for pulses to bounce back(unless the firewall is close or you have a manifold over the ITB inlets). That's where manifolds have advantage over open-air ITBs.

Best of both worlds; ITB's on a manifold setup. :)

[sl@sh]

uhm, when pulses reach the opening of the bellmouth of an ITB (atmosphere) the postivie wave is reflected back as negative wave

IIRC

[K2e2vin]

what reflects the wave?

[djsgtrip]

The link of the formula posted by sl@sh is actually for a carburetor/itb setup. Not for a single tb manifold. This is the same formula i used and it's very accurate at determining the length of the ITB's from horn to valve. I calculated that a D16 with a rpm range up to 8000 rpms (peak) will require a 16-16.5" length from horn to valve to achieve a "ideal" powerband between 5500-8000 rpms. As far as the peak power theory, my ITB's made the same peak power, but with more midrange and no "dip" commmonly associated with intake manifold setups. You can make your powerband anyway you want it depending on length, diameter, and overall taper. ITB will also carry the HP higher in the RPM range (8000+) than a manifold, assuming it's correctly built and tuned. For a mild setup, I would recommend just going with a Skunk2/Edelbrock setup. They both make excellent power and are easier to tune and maintain.

[K2e2vin]

Given a ITB setup vs. Manifold, both design for the same app, which do you think will make power peak and which one broader power?

[djsgtrip]

A properly designed intake manifold will make just as much as an ITB setup, but it's gonna have to be completely custom built for each specific application. Just like ITB's, a manifold for a certain compression, bore, cam, rpm will need to be specifically made to that application. But a well made ITB setup will make more power across the board than mass-produced aftermarket intake manifolds.

[sl@sh]

yup i agree with djsgtrip,

there is in no way a properly built and tuned ITB set-up gona have less peak power than a stock z6/y8 manifold,

now if u put into account a Skunk2 or Edelbrock intake manifold, then yea we will see good peak gains in this, but since it is an aftermarket unit, we must compare it to a well built ITB , or an Aftermarket ITB, like Jenvey or TWM , then gains are gona be good too,

its just ITB's have to be built or designed properly to ur aplication,
as previously stated
midrange, peak and torque can be had, given that the proper taper, length and throttle size is calculated correctly for the ITB,

[Fooshitinkinjssomethingorother]

ITBs resonate plenty. You don't need a solid wall opposite the throttle plate in order for stuff to bounce around. Otherwise you'd see ITB setups all with plenums instead of simply running open.

Having them make power is like slash said, it depends on where you want it. Runner length, inner diameter, and overall taper can make or break a setup in terms of efficiency, so just throwing a homebrew CBR build on there will prolly do more worse than good unless you do it right the first time and properly tune your setup mechanically before you start worrying about tuning it via engine manangement.

There's a lot of mystique and misunderstanding about ITBs. I think most of that is ignorance and people making false assumptions/claims about their benefits/drawbacks. I count myself lucky to have a car that has had a lot of research go into developing a kit that works great with the stock management and also gives some decent gains as well. I'm hoping to have some solid numbers before the end of the year when I upgrade the exhaust. :)

[sl@sh]

nice!! thats sumthing i wana see.. show us some numbers once the time comes... hehe

also to add..
i think the main reason why autoX and track peepz resort to ITB's often is cuz of the excellent throttle response it gives..

[K2e2vin]

I still believe manifolds will make more peak power on our Honda. When I said manifolds make more peak power than ITB's, I was talking about a custom manifold, since the ITB's are custom too. Almost all of the ITB race cars making more peak power than a manifold setup are either carbs(like Bisi, taking advantage of better atomization and cooler air from emulsion)or ram-air setups(like K20s which have the intake in the front, motorcycles, F1 cars, etc.) And yes, a lot of high-end race cars do use a plenum over the ITBs, but it's mainly for ram-air.

That still doesn't explain how it would resonate, since any pulse that would "shove" more air in will dissipate in the engine bay. I do believe there is a pulse, but you take advantage of it via taper. Here's a good read: http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=466

Best comparison is to build ITB's set up for a certain rpm band, and have a manifold that is set up for the same range. You can't compare mass-produced manifolds because there aren't mass-produced ITB's.

Manifolds use tuned runner length too you know.

[Plankton]

im planning on putting ITBs on my z6

[Eyal 951]

im planning on putting ITBs on my z6
do you know what your doing?

[Fooshitinkinjssomethingorother]

You can't compare mass-produced manifolds because there aren't mass-produced ITB's.

Hmm?

http://www.jenvey.co.uk/
http://twminduction.com/
http://www.rsaizawa.co.jp/product/engine/eg002.html
http://todaracingusa.com/category?section=product&cid=11&id=2
http://www.maruhamotors.co.jp/injection/injection.htm

They're out there, just need to know where to look ;)

[K2e2vin]

I was talking about D-series, but if you want to bring that up; ; none of those are mass produced except for maybe the TWM runners. Those are custom units, put together by hand and are manufactured in small numbers(hence the high price tag). The plenum manifolds leave the manufacturing plant ready to be installed; ITB kits have to be assembled. Also those links, the only one making their own throttle bodies is TWM I believe. The others are using Jenvey throttles, while the Toda uses AE101s.
The closes thing I've seen to a "mass produced" ITB setup for a Honda is the prototype Omnipower one.

[Fooshitinkinjssomethingorother]

I was merely pointing out that ITB manis are just as easy to get a hold of as an aftermarket plenum mani. Granted anyhting for a D-series is going to be rare, if non-existant. I guess it's the price we pay for dealing with economy engines :lol: