100 replies to this topic

[cbstdscott]

I want to start a thread about making the conversion to Individual Throttle Bodies... but I do not know where to place it.

It is a Technical issue, but it is not model specific to 1st or 3rd Gen. And it certainly is not a Carb issue, nor a Swap issue.

I am thinking of going the route that this guy took with his B series. He makes it look fairly easy to do.

Scott

[firstgencrx]

I want to start a thread about making the conversion to Individual Throttle Bodies... but I do not know where to place it.

It is a Technical issue, but it is not model specific to 1st or 3rd Gen. And it certainly is not a Carb issue, nor a Swap issue.

I am thinking of going the route that this guy took with his B series. He makes it look fairly easy to do.

Scott

Just make it a build thread under projects.

I will be watching...........

[RETROCRX]

What displacement Gixxer are those off of?

My neighbour works for Suzuki, he might be able to get me a set to try?

Rob

[VaporParanoia]

is it too much to ask for you to dyno before and after to see what the gains are out of ITB's? i've always wanted to know if it was worth doing and how it affected performance.

anyways i'll be watching closely

[slavteren]

hey, a place where i can help... we did this just for fun on my friends civic... a can only say one thing: honda cbr units...

everything fits directly over, the tps has same values, only a conversion harness for that is nessesary. even the oem fuelpressure unit is a direkt bolt on, only thing needed is to raise tha rail a litle with spacers...

litle vid:

cbr 600 itbs on civic 3g

as i remember, mine 959 tbs (42mm in stead og 39mm) had a better fit, but couldnt hold the origininal injectors. holds d16ai injectors though.

we didnt dyno or even took the time to tune it properly, it was only a: "because we could" projekt. drove it a few times, and after very roughly tuning, it pulled way harder then with the oem induction.

no way near as hard as with the t25 thoug

[RETROCRX]

So the CBR 600 fits the standard Honda injectors with a smaller spacing between runners.

But CBR 959 fits the runner spacing better but you have to use different injectors or MAKE the originals fit.

Is that correct?

Rob

[slavteren]

yes, only, as i remember it, the oem injecters have no chance in hell to fit on the 959's.

i am only 90% sure of that info, it is a long time ago we did this... anyway, my zc1 injectors, wich should be the same as yours d16a1 fits perfectly... i'll try to text my friend and find out, he remembers a lot better then me.. must be the age

[slavteren]

ok, as suspected, i rememberred it wrong...

we used zc1 injectors, he had 400cc injectors, but they did not fit any of the itb's

[Christ]

ok, as suspected, i rememberred it wrong...

we used zc1 injectors, he had 400cc injectors, but they did not fit any of the itb's

DSM 400/440/450 injectors fit the ZC1's manifold if you dremel out the lower (green) seals... you use the OEM Honda/Rover seals, and put them in the manifold, use a dremel with a drum sander bit, and round them out until the injectors fit in TIGHTLY. They already fit the OEM fuel rail.

Dunno if that's what you were using, but that's how that works, if you need larger ones.

[ibcnya]

hey, a place where i can help... we did this just for fun on my friends civic... a can only say one thing: honda cbr units...

everything fits directly over, the tps has same values, only a conversion harness for that is nessesary. even the oem fuelpressure unit is a direkt bolt on, only thing needed is to raise tha rail a litle with spacers...

litle vid:

cbr 600 itbs on civic 3g

as i remember, mine 959 tbs (42mm in stead og 39mm) had a better fit, but couldnt hold the origininal injectors. holds d16ai injectors though.

we didnt dyno or even took the time to tune it properly, it was only a: "because we could" projekt. drove it a few times, and after very roughly tuning, it pulled way harder then with the oem induction.

no way near as hard as with the t25 thoug

I knew this was possible...glad someone did it. Can we get some more info on the install, possiblly a write up?

Edited by ibcnya, 03 December 2008 - 07:06 PM.

[cbstdscott]

I can not leave well enough alone.

The D15A3 in my '87 CRX Si runs perfectly. With over 160,000 miles on the stock bottom end, it has been measured on a reliable dyno as having 99hp at the wheels. The guys at the dyno swear that they find that the same engines will test 20% higher on their engine dyno, so this gives my engine a flywheel number of 123.75 hp. Not bad considering that the factory rated this engine at 91hp at the flywheel... but that was before I started to improve the engine.

Just a small digression-I am not too hung up on dyno numbers. Your dyno will read different numbers from my dyno. I only use the dyno as a tool to measure how tuning settings affect the engine.

Back to my topic- The greatest difference in my engine from stock is the induction and the head: I was lucky enough to pick up the pieces of a failed racer's project and I got his "goodies." This included a professionally ported and polished head, a port matched intake manifold and a 66mm RC Engineering Throttlebody along with a new cam and some ignition tuning. The point is, my engine is running stronger than the day it left the factory and there is no denying that.

So I should be happy. My engine runs great and passes California smog inspection without any "friends" at the smog station. But there is a hollowness within me. I know that there is about 15-20 more horsepower available to my engine if I had a bit more free breathing on the intake side of the head.

The real racers among us are making impressive hp numbers with their engines by employing a pair of side draft carbs or Individual Throttle Bodys (ITBs). Essentially we have discovered that the stock induction system on the EW4/D15A3 is the "cork in the bottle." Once you open up the breathing on the intake side of the head, that old engine really shines. And to this end I want to take the next step and build my own ITB set-up for my engine.

Why not a turbo or side draft carbs? I am not a huge fan of turbos. And I will NEVER dick with carbs ever again. If you like carbs and turbos keep your damn opinion to yourself because I prefer NA and fuel injection.

This guy did a step-by step review of how he used a set of 2001 Suzuki GSX-R Throttle bodies on his B series. He makes it look pretty easy and fairly cheap. Cheap and easy? That is my kind of project.

RPR member Slavteren and his buddies in Denmark have already put ITBs on a old school Honda and they posted a video here. Sadly, my Danish comprehension skills are not very strong so I can not read the commentary posted on that site. But we do know that they used ITBS from a Honda CBR 600 and that the TPS matched the car's operating system.

My plan is to use the motorcycle ITBs and the car's stock injectors. Why not go Hog Wild with monster injectors? Because I have found that the stock injectors flow plenty fine and only require a small increase in fuel pressure to meet the engines's new requirements. If I find that I need more injector flow, I can easily upgrade. But I think that the stock ECU and injectors will be suffcient for my purposes.

Stock ECU? Yeah. Until I get the nerve to build a crank-fired, distributor-less Megasquirt system the stock ignition should be adequate.

Please chime in with your comments and observations. Specially welcomed is anyone who has done this modification to any type of engine.

So now I need to source an intake manifold (I am not goiong to hack up my existing manifold) and a set of ITBs....

Scott

[Christ]

I think someone had a pre-cut up manifold in the FS ads. Should be pretty OK to use for IC's or ITB's.

[ef91]

scott, it's cool to see your still fooling around with your crx and getting the most out of the stock engine... i thought of this idea for my 3g but i heard it is kinda hard to tune itb's without a stand alone ecu... i also don't know too much about itb's still learning so i don't have any info for you... i'll be following this thread to see how it goes and maybe borrowing some idea's form you later on down the road.... good luck..

[Christ]

scott, it's cool to see your still fooling around with your crx and getting the most out of the stock engine... i thought of this idea for my 3g but i heard it is kinda hard to tune itb's without a stand alone ecu... i also don't know too much about itb's still learning so i don't have any info for you... i'll be following this thread to see how it goes and maybe borrowing some idea's form you later on down the road.... good luck..

The biggest problem I've ever seen about tuning ITB's is with the TPS settings and sensors that use the intake manifold.

benefits of ITB/IC setups are slightly increased power, but 4 TIMES the throttle response. Think about it, there is next to no flow obstruction in a nicely built ITB setup, and the flow does not have to change direction 90* to the initial flow (after the throttle plate).

[JU5TIN]

I had the same idea and have drawings for what i want to do.
although my crx is on the back burner waiting for funds to allow a repair.
i'm looking at about the 10th of january the car having a new front end (non crumpled) and then i will be working on my ideas.
we can help each other since we live so close.

Justin

P.S. can i bring your shirt by on saturday afternoon