100 replies to this topic

[jsgprod]

don't forget, that alone the position of the injectors farther away from the valve gives a litle power in the high end, and robs in the low end...

Not to mention makes cold starting a B!#$H!

Scott, finding a way to get a decent map signal from ITB is a pain. At idle/low rpm it's damn near impossible due to the pulses from each individual intake runner with it's short length and low volume. Almost every guy I've discussed this kind of thing with has ended up going to what’s called alpha/N tuning. Basically just using the throttle position and rpm points to create an A/F map. But you can’t do that with an OEM ECU.

If you still try this (can’t blame you to much, I’ve gone down a few dead ends myself after being instructed otherwise) You’re going to need a vacuum reservoir. With a vacuum feed from all four intake tracts to it. I would also recommend some kind of inline one-way valve for each line, something like the one that comes in the stock brake booster vacuum line. That way, when the intake valves start to open at the end of the exhaust stroke the positive pressure signal that ‘does’ come up the intake tract won’t (hopefully) put positive pressure into your reservoir tank.

ITB are kind of neat in their own way, not to mention they sound REALLY cool when they’re tuned properly and you’re ‘on the pipe’ so to speak, but I honestly think a properly designed manifold, with bigger runners, plenum, & throttle body can make much better all around power. And not be to far down, if any, in peak HP from ITBs. JMHO.

Jay

[RETROCRX]

BAH!......what do YOU know Jay!?

[firstgencrx]

don't forget, that alone the position of the injectors farther away from the valve gives a litle power in the high end, and robs in the low end...

You bring up an interesting question: What kind of effect does the distance between the intake valve and butterfly of the ITB have?

I've seen the butterfly placed out on the very ends of the intake runner, and right at the cylinder head port.

David

Scott, I hope you don't mind I'm asking questions in your thread. If it's a problem, I'll gladly stop.

[slavteren]

basically, injectors close to the valves give better economy and control at low revs, injecters at og beond the inlet gives better atomization, but poorly control. thereby less economy.

somehow i don't see coldstarts as a problem in this project that lycky bastard lol... anyway, now we are talking cold engine.. the cbr itb's has a highidle system that funktions on the watertemp kindof like our cars, only by a termostat that forces the gas a litle open for higher idle.

[cbstdscott]

Thanks for all the replys and interest in this project.

Justin, I will be around this weekend if you want to come by with my shirt. All the other guys are just jealous of what we have together. Maybe Gunslinger would like to get in on the act.

Back on topic- Stubborn to the point of stupid would best describe me. I will not deny all of the wisdom of those who have gone before me.... but on the surface it seems I can get away with the stock ECU, at least initially.

Let's examine what I plan to do: I am keeping the part of the intake manifold closest to the head. I will use the stock injectors in the stock location with the stock fuel rail. I will weld on four straight runners to the hacked off intake manifold to retain some of that low end oomph we are looking for. The ITBs will go on the end of the runners.

I will fill the ITBs injector ports except for one that will become the port for the MAP sensor. I do not need vacuum for the brake booster, I dropped that a while ago and now have unboosted brakes (and a strong leg).

If I have a working TPS, a working O2 sensor and a working MAP sensor... why won't the stock ECU work? I am counting on the stone simple ECU to only see more air with appropriate signals from sensors.

Yes, I completely understand the advantage of going OBD1 or similar for absolute maximum effeciency. If I was looking for scalpel sharp tuning I would persue that avenue and I may still do so some time in the future. For now I am happy to "just get in to the ball park" for a bit more performance than what I enjoy today.

I have an intake manifold coming in the mail (thanks flashmatrix!) and now I need to source the ITBs. Hello, eBay!

Scott

[cbstdscott]

Update-

eBay has come through! I have a set of CBR 600 ITBs coming in the mail. I will start to source some aluminum tubing for the runners.

Scott

[strudel]

Did you see this?
Megasqirt for sale JS

[strudel]

Scott,

You may want to read this thread to wet your whistle a bit. It is in a Mini of course and using a Suzuki engine but the principle will be similar to what you want to do. He actually built his own manifold by casting it. I started it on page 3 nad you will need to go to Jul 27 to start reading about the ITB's. and it goes tl about page 9 off and on. Later there are a bunch of specs that may be helpful. Realize this is with a Megasquirt system but you can see the process. Good luck. JS

Decisions, decisions!
Standard ECU, Hondate or Megasquirt ?!!

C20XE throttle body conversion

[Buford]

We have a complete bike ITB setup, EW manifold and all. Even has the sensors in the original position.

I've asked my son 'RedSIBarron' if he wants to part with them.

Will let you know. He has pics posted here someware that at least you could use a reference.

Also EPCIVIC has bike ITB's with Megasquirt. He made his own manifold, so you may want to contact him and see if he'll build yo a setup.

[BigOrange]

I dont any reason why you cant slip by with the stock ecu but if it was me doing this I would use a fuel controller at the least to get the most out of the setup and to be sure that your not too lean or rich. I would also def. have a wideband o2 keep a sniff on the a/f's.

[Airjockie]

I was thinking of going with these at one time, a set for the CRX, and a set for the Z.

http://www.extrudabo...ducts/ITBs.html

I'll have an extra intake many for the 1500 head soon...got to figure out which one will work better for my set-up.

[cbstdscott]

I would use a fuel controller... a wideband o2 keep a sniff on the a/f's.

My plan includes employing an adjustable fuel pressure regualtor and an Air/Fuel mixutre guage.

The Extrudabody products are drop dead gorgeous... but they do not fit my budget profile , my goal is to do this on the cheap. Yes I know, this is the wrong hobby for "cheap."

One other consideration I have not mentioned is the Cailfornia Factor: I need this car to slip past emmisions testing every other year. ANYTHING not on the car's engine that was not there the day it left the factory is strictly forbidden unless the new part has been blessed with a CARB (California Air Resource Board) certificate of approval.

This leaves me two choices. I can swap back to the "legal" intake manifold every two years, or I can camouflage the ITBs so that they have the appreance of being "stock." I would rather leave the ITBs in place so that means I will also need to cover the velocity stacks in a suitable looking "air cleaner assembly" for inspections. For this I am thinking about fabbing up another one of my sheet aluminum projects that would tie into the OEM intake hose that I now employ as part of my CAI. But it would look more "stock" if I could make the "air cleaner" out of plastic or fiberglass. I envision an entire seperate project on creating that portion of the system.

But I am way ahead of myself! I need Mr. Postman to deliver intake and bike ITBs so that I can start this project.

Scott

[BigOrange]

I was thinking an actual injector controller like a smc-500 or a safc-II.

[EPcivic]

Here are some pictures of what I did:









I have changed the air horn arrangement since these pictures. The new setup is shorter and fed by a custom fiberglass cold air plenum. Most of the advise given so far has been spot on, but I'll go ahead and put my two cents in.

The bike injector placement does make idle and low rpm fuel control difficult because the fuel 'drops out' of the air stream at low air speeds. It's not a huge problem, but the factory location would be better for a street application.

I could not get my car to run right tuning it off the MAP sensor and rpm. I switched to an Alpha-N setup - using TPS and RPM only. The problem is that the MAP signal on an ITB setup is highly non-linear. With a normal plenum, zero throttle is highest vacuum, full throttle is no vacuum, and points in between there generally fall on a straight line between the to extremes, thus the signal is proportional and linear. With the ITB's, you have several problems to address. First, since each vacuum chamber (runner between valve and throttle) is isolated, they each fluctuate wildly with each valve opening. This makes the MAP signal very noisy. If you connect to only one runner, it will be crazy noisy, and probably won't even run. If you tie all four together it will improve greatly. If you add a vacuum plenum, it will improve more - the larger the vacuum plenum, the better it will get. As you approach the size of the orignal manifold, it may be fine. The other problem is that the MAP signal with ITB's is non-linear. It's still proportional to throttle position, but the points between closed and full open follow an exponential curve. Basically, as soon as you crack the throttle open, you loose all vacuum, so the stock ECU will think you are at full throttle.

I could not get mine to run right at both part and full throttle using MAP and RPM, but I never tried a big vacuum manifold. Some people have used stock ECUs on other Honda motors and been happy with the results, so I think if might be possible - a lot depends on your goals.

Another thing to consider is the air temps when pulling air from the back of the motor. I was datalogging 140deg inlet temps on 90deg days before I added the air box. Now I get about 10deg above ambient.

My car makes good power with this setup, and the throttle response is great. It's also a lot lighter than a typical manifold.

The CBR600 is a good donor. The TPS will work fine with the stock ECU. It even has a coolant based warm up idle feature if you're so inclined. The motion ratio of the throttle cable is not very close to the stock throttle, so if you use the stock pedal and CBR throttle cam, you will only have about an inch of pedal travel. I bought a motorcycle throttle cable (to fit the CBR throttle cam). I then modified the stock pedal to reduce the distance from the pivot to the cable attachment. This got me back to a normal pedal travel. The other option is to modify the attachment at the ITB's but I couldn't think of an safe way to do that.

-Good Luck

-Chris

[cbstdscott]

Chris,

Thanks for sharing your real world experience.

If you have any pictures of the plenum you created it would be appreciated if you could post them. Do you have any tips on how to create your plenum?

It looks like you put a large slit in the side of all of your velocity stacks, is this a good idea?

The issue of sourcing cooler air for the engine leads me to consider doing some sort of cowl induction (getting air from the base of the windshield).

Your points about using a vacuum manifold/plenum/reservoir are well taken, I will have to allow for something like that.

thank you,

Scott