Pryor

Does anyone make a manifold for itb? I have a forced unduction 1.6 and would like to itb it. But i would need an enclosed intake side of the horns. I have not seen anyone that makes this. It exists obv

DNMakinson

iTrader: (3)

Corky Bell used to make them. I've seen one, recently, but only from the outside.

Here is a review.

EDIT: No, it had internal trumpets, but was not ITB.

Really.... WHY would you want that?

miata2fast

iTrader: (2)

You will have to have one custom made by a fabricator.

Pryor

Gotcha. Ill weld one then. Give me another reason to improve on welding i guess. Thank you for the replies.

Zed.

if you've the budget then Jenvey make manifolds & itb setups for the Mazda 1.6 (& 1.8) engines
https://store.jenvey.co.uk/throttle-...x5-16-tb-mmz03

and for FI they make handed plenum's
https://store.jenvey.co.uk/throttle-...-inlet-apsc-60

also they have pdf drawings on their website that are good for visualising (or copying?) thesize & shape for fitment
https://store.jenvey.co.uk/pub/media...gs/MMZ03_D.pdf
https://store.jenvey.co.uk/pub/media...0_WEB_ISS3.pdf
note that their manifolds position the tb's inline with the port for a straight inlet tract, if you go long then can have bonnet (hood?) clearance issues

I looked into this for my 1.6 build but eventually decided on keeping it na but already had a Jenvey inlet manifold (I made adapters to fit GSXR 1300 gen1 itb's)

https://mighty5s.com/post/45798/thread

Rich.

Pryor

Thank you. This is what i was looking for

technicalninja

ITB's are specifically for separating individual intake pulses in a high compression big cam NA motor.
If you're not running 12 to 1 compression with 300 degree duration cams ITBs will add nothing and on this monster motor the ITBs will only help with idle and part throttle operation.
People think they will add power. This is a false assumption. When you do the induction math on an ITB set up the flow is usually 3-4 times what the engine can flow.
This doesn't mean the engine will now flow 3 times normal, it means the airspeed in the intake will be much lower and mild throttle opening will actually provide less airflow into the chamber reducing low speed torque.
The massive flow that ITBs can provide is ONLY a factor if you original intake becomes restrictive at WOT and 6K plus RPM. Forced induction makes this a moot point.
The only reason ITBs can help part throttle operation on a big cam motor is that they isolate the overlap that occurs at TDC exhaust stroke and keeps the exhaust pressure (that exists because of valve overlap) from effecting other cylinders.

Example: you have a monster motor that will not idle below 1500 rpm with a plenum intake. Pop on a set of ITBs and it will purr like a kitten at 500 rpm. It will eliminate the lumpy idle (that most people want) and make the engine sound stock.
This same engine will exhibit excellent low speed throttle response and will feel stock until you get into the cams "power range" and then it will scream like a Ferrari all the way to redline.
This scream is far more pronounced with NO air filters on it (the air horns increase the scream). You put a filter on it and the scream will be far less noticeable.

They will only create tuning problems in a forced induction motor. They will NOT increase power over a properly sized single throttle body.
Corky Bell is one of my mentors and had nothing but trouble on ITB forced induction applications. Yes, he used to build them for a maximum effort system using Mikuni carbs before the availability of stand alone ECMs
The outer plenum (which enclosed the trumpets) was nearly impossible to seal and when it was achieved it didn't last long.

Go 1.8 engine with a flat top( or Skunk) and end the madness...
I personally like the look and the sound of ITBs. You're going to loose the sound when you boost it so the only thing you will gain is a pretty intake and a super finicky tune.

Pryor

Ill keep the 1.6 the next motor going in is k24 which i have everything for already. Isnt much of a reason to swap yet that or ill put in another miata

HarryB

Amen.

DNMakinson

iTrader: (3)

The Long Version
The Short Version

Pryor

Is the quotes and questions of why directed at me?

M2Ken

I found an F-355 plenum on fleabay that looks like it might work. Price was right, but I haven’t done anything with it. It will need a new backing plate, but that is easy fabrication.

i would look to see what other cars came with ITBs that you may be able to adapt the plenum.

Pryor

The gsxr tb or even the corolla seems like a good start.

technicalninja

That was the super super short version...
I didn't elaborate on the issues that actually occur when boosting an ITB set up.
Airflow and pressure causing throttles to stick in the WOT position. Need bigger throttle springs(or smaller throttles). First time I saw this was on a car with NO electronic cut offs, had to turn off the ignition switch at 8K full boost, scary!
Vastly fluctuating MAP signals below 1500 rpm. Make tuning a pain. Additional plenum can help a bit.
Blow through Mikuni carbs leak everywhere above 15 psi of boost. They leak fuel. Not nice.
The fact of a small amount of throttle movement makes for a large increase in engine speed. The critter is "jumpy" and throttle tip in is rapid. Hard to control. Need progressive throttle linkage.
Sourcing the brake booster connection becomes critical. Change to manual brakes or add an electric vacuum pump for brake booster.
Damn difficult to add a AC kick up for use with air conditioning. It can be done but more complexity.
Normal idle air control valve set ups require an additional "plenum" connected to all intake runners and then doesn't work very well. Adding check valves never works like you want them too.
Hard to connect the PCV system to.
The list goes on...

DNMakinson is a old guy like me, He's been doing this stuff a long time and he gives GOOD advice.
His question is appropriate.
What are you trying to gain with a fancy ITB set up?

It's a bit ironic that the K24 is a FAR FAR better candidate for ITBs.
If you have the K24 and are already planning a swap why are you jacking around with a exotic set up on a airflow limited 1.6 mazda motor?
Properly set up that K24 might hit 300+ HP without adding a hair dryer. It would NEED ITBs at that point, big ones...

And DNMakinson might be making fun of me, he called me out once in a post regarding engine balancing and he was RIGHT!
My answers (and time typing them) are usually too long. His advice is useful and much more concise.

A quicker better way might be to ask WHY?

Don't take offense, have a thick skin, you will get good advice on this forum.
And if DKMakinson is messing with me, that's fine. I have a thick skin and once again he might be right.

Pryor

My k has itb. Hayward itb. I was looking into it for a platform to learn from in a tuning perspective on itb. Since i already have supercharger for 1.6 i wasnt considering removing it for learning. Ill jeep 1.6 supercharged as is and eventually put k itb set up in. Then just move the supercharger set up over to a 1.8 set up for a different vehicle down the road. Unless of course it craps out and damages supercharger set up.

DNMakinson

iTrader: (3)

Naw. I was just pointing out, admittedly a bit awkwardly, that my "why" question was raised and ignored at the beginning of the thread. It just seemed to me to be a total unnecessary complication to a set-up.

I thought you did an excellent job of explaining the Why Not

And... I learned a LOT from your 2 answering posts.

DNM

Pryor

I gotcha. Basically it was something i am willing to do at the time of post. After hearing all the incredibly complex stuff im going to just leave car as is until im ready to k-swap with the itb i already have. Using the kpro that i have. Ill need injectors but whatever that is nothing in the scheme of things.

I think if i had my old buddies still here i would have said whatever and slammed the k in by now. I keep making excuses and doing other parts of the car making it an epic overhaul of utter non-sense. My two other cars i did in stages like a sane human would and they are done basically. Cars are never done right?
800+whp turbo cobra 97
Bmw 335i daily, exhaist, intercoolee upgrade, tuned, suspension, wheels, tires, stereo, tint.

Teejay187

Wrong thread /t

Blkbrd69

Great explanation.