ITB's for KA

[nismopu]

I have sent an E-mail out to a few that I know of who have managed to build a set of these for the KA24. I am currently developing a set for the DE but if all pans out I will make a set for the E also. The thing I am currently concerned about is my adapter design and how I am going to meter the air. Either MAP style or MAF i am not really sure what is easiest. From some people I have e-mailed they say a plenum style with MAF is the best way to meter the AIR for ITB's. the thing i find a problem with in that design is a flow restriction and ability too make alot of power N/A, but i might not know what I am talking about either since this is new to me. The size ITB's I am gonna be using are 53mm and since people have done the math for me I know this size is adequate.

If anybody has any helpful hints as to a change of design in my adapter or whatever please lemme know. peace.

Also I know the adapter is not complete and looks rough but its only one piece of the full four piece adapter. plus the stepdown for the toolpaths is high so there are ridges. in the final product there are zero

my adapter pics are on page six of my car domain link below

http://www.cardomain.com/ride/1796507/6
Modified by nismopu at 11:45 AM 10/8/2005

[pregmantis]

why not eliminate the njector pionted part and just make it a complete oval? nice work though. amyone know where to get a kade dual sidedfaft/twm/webber manifold? devious? can anyone here make?

[nismopu]

I was looking for a smooth transition for the air to follow. Its only 1 inch in depth because the runner lengths are not supposed to be very long. The head has that injector point and so does the stock manifold for the injector bung. I see though i could probly eliminate it. hmmm.

[DjPantsSpecR]

yeah because if at all possible you want to introduce the fuel at the beginning of the air stream. The KA intake manifold kinda needs to have the fuel introduced at the back of the intake valve because the air has to make a 180 degree turn from the plenum and that makes it alot easier for the fuel to drop out.

ITBs are straight so you'll never face that problem and its much better for atomization to put the injectors farther back

Plus thats gonn make your machining life way easier

however, this is where making it into an oval is the most retarded idea that ive ever heard. the ports on the head aren't ovals, why wouldn't you want to match those ports as best you can? i know i hate smooth airflow....

definately don't eliminate it, but i dont think you should put an injector bung there, if thats not what you were thinking of doing, i apologize

[PandaS14]

yeah, introducing the fuel the earliest possible is definately a good idea. that's actually why I'm thinking of making a new setup and selling my current one. I really want to make a setup that utilizes the stock gsxr location or even better yet, hanging over the velocity stacks. I'd love to hang them over the stacks, but I'm worried it'll mess with induction. I need to do some more research. Keep up the work on the TB's, It'll pay off. It sure has for me! I fell in love with my car again, that's for sure.

[DjPantsSpecR]

i gotta agree, and just to further drive that point home, and just incase we needed to oogle these pictures again...

i would once again like to thank TODA for existing, and for this Miata 1.9, 3SGE and SR20DE







Now try to put it back in your pants and note the location of the injectors on these ridiculous N/A motors

[projectka-t]

NOW those are SEXY!!!! mmmmmmm

[sunnys14]

i wonder what that SR with itbs would sound like.... ROAR!

[deviousKA]

Hey Nismopu, I think you shot me an email I remember seeing it in my box. I have been a bit strapped for time lately so I havent been able to respond.

There are many ways to accomplish ITB system you just need to weigh your options. The factory nissan efi system with MAF has plenty of tunability to do just about anything that you would need. Some would argue you are limited by a MAF size, but building a system like this in the first place (plenum) allows you to route much cooler air into your engine. Depending on the year of your truck your current ecu has the capability, check out eccs.hybridka.com for more info.

If you wanted to go MAP and take advantage of all the possiblities in intake manifold design (ie. open stack), the hands down best option is megasquirt. To be honest, I would take MS over more expensive "name-brand" MAP ecus (AEM) any day of the week. It flat out has more potential,capability, and support (not to mention is 1/5th the price). Check out msefi.com for more info.

[pregmantis]

the intake ports arent oval because of the injector, but since the injector will be moved wouldnt it be retarded to not reshape the port into an oval? I would think so.

[dickie]

how much for just the ka, please...

[DjPantsSpecR]

pregmantis if you say that one more time i WILL slap you. If you ever saw the intake side of the head on a KA24DE, which i assume you haven't based on the other ridiculous posts you have, you would see that that shape matches the head perfectly

now since you aren't smart by any means i'm gonna lay it out like i would to a kindergarden class:

Unless you wanted to mess with the KA's port shape which is retarded, in case you were wondering, you want the airflow from the runners into the head to be as smooth as possible (air flow wise, not polished or anything).

So if you made an oval its obviously not going to match the port and air will be extra turbulent around the inlet of the head.

this = crap

sunnys14, if you really need to wonder, just picture your all motor KA with 7000 rpm limit, but less displacement and 270 horse....

[DjPantsSpecR]

also, something i just noticed from the TODA motors:

if you look real close you see that they are all venturis (i wonder how you really make that word plural). It would be really nice if we could see something like that for the KA ITBs.

that venturi design has to help increase high end because its definately helping increase air velocity. That SR has a rev limit of 7000 and makes 270 horse. There can't be too much secret work here other than the cams, cam timing, exhaust manifold, tuning, and the ITBs

of course that dry sump and the sexy *** pulleys are helping just a bit... and come on now, a titanium alternator bracket?

270 horse, how far away are we?

[nismopu]

well one last question for you guys. what do you think about fuel puddling with the super smooth runners and distance between the injector location and the port?

What set of GSXR ITB's are you using? I am curious to see some pics of your guys's setups. Not anyhting you guys want to keep to your selves of course but maybe just some basic layouts? Yeah those TODA motors are insane and kinda my inspiration to the whole project.

One last thing I plan to sell these kits for the advanced engine builder! Due to the fact I am not gonna sit on ebay and motorcycle wreckers all day people are gonna have to provide there own set of ITB's. I am just merely machining the adapters, venturis, plenum, or MAP style pieces. I hope to have this kit out soon and with your guys's help so far I am sure it will be sooner than i thought. peace.

[headstrong]

Is the third pic a SR motor?

[DjPantsSpecR]

yeah the third pic is an SR N1 motor, but easy there boy, its not possible to own one

as for fuel puddling, i'm not the absolute authority on this, but yeah the super smooth runners are gonna help contribute to fuel dropping out, but at the same time because the runners are a straight shot now, you have to worry a lot less about fuel puddling

you might be asking the wrong people then again too...

[PandaS14]

No, having the fuel injecting farther away from the head does not increase fuel puddling. Quite the opposite, it aids in mixing the fuel with the air, and makes for better atomization. Having an injector close to the head is good for low rpm usage. General rule is that the higher the rpms the engine is going to be operated at, the farther the injectors should be placed from the head. For example, F1 cars have 2 and sometimes 3 different injectors per cylinder. they change the rates that each of them flows as the car moves through the rpms. 1 of those injectors (mainly for higher rpm use) is hanging over the inlet of the velocity stacks, shooting down at the trottle plates. Injecting the fuel befor the throttle plates makes for excellent mixing and atomization. Hence why my new ITB setup will have one set of injectors just after the throttle plates (for now) and a set hanging over the inlet of the velocity stacks (in the not too distant future).

[pregmantis]

Im just talking about covering up the pionted part for the injector. that is there for the injector, but if theres a custom intake and the injector is moved then you would have that cavity there(like the one in your head) which may hurt performance. just kiddin bout the cavit stuff. why you gettin mad?

[DjPantsSpecR]

Definately, i couldnt agree with that more, also having the injector farther away sprays the fuel at the air just as it enters. well duh, but keep with me here.

the air, with the fuel flows forward into the head just until the intake valve closes. The valve closes and the air stacks up on itself. It is forced back up the intake runner where it reaches the plenum, or in this case the air horn at the tip of the velocity stack. At this point it inverts from a high pressure wave to a low pressure wave and "bounces" back down the intake runner towards the valve. When it hits the valve it doesnt invert because the valve is closed, but it reflects back up the intake runner still as a low pressure wave. Once again it reaches the open air side of the velocity stack and it inverts and reflects towards the intake valve. now if your runner length is just right, at a certain rpm the intake valve will open just as this high pressure wave hits and it will force some more air in

i've read some motors that cram in as much as 7psi

now why are you still reading this? Well, that cycle is figured out using an equation with a reflective value of 1, and thats too low, actually those cycles happen either 2 or 3 times, so its not uncommon for the air to bounce back and forth 8 or more times before it is actually used.

Now if the injector has to spray all the fuel at the end of the intake runner, i'm not sure how well you can control how much fuel is in the air fuel mixture bouncing back and forth in the runner. whos to say some wont be just sprayed on the back of the intake valve? But if you have an injector at the beginning of the velocity stack not only does the air fuel mixture atomize much much better, the left over air fuel mixture already has fuel in it, so the next time intake valve opens and more air is rushed in the mixture wont be lean, thus better control of fueling.

i've never seen any equations for creating runners that are velocity stacks, or venturis, but i can imagine the helmholtz effect is only amplified, thus more free high pressure air

[nismopu]

I can see if i can come up with that formula! I know some guys who are pretty smart about figuring out these kinds of things. Lemme see what i can dig up. Thanks for all the insight so far and you guys have deffinately done your homework more than i have. I actually feel kinda dumb hoping to make these into a kit, lol

[DjPantsSpecR]

well thats why fools like me waste all this time in IT, because we want those ITBs and we wanna see em made right

i know i wanna help you as much as i can because i want a set...

i think the best you can do is find an ideal diameter set of ITBs that are readily available. So it might be larger or smaller than the size youre trying to tune for, but the point here is the ITBs need to be easy to find and cheap. Then you wanna make a nice transition from that diameter to the outlets you already machined.

you cant really get too crazy with that tuning aspect, you wanna sell as many of these as you can, and the easier you can make this set ot assemble, the more youre gonna sell...

the only thing you gotta worry about is losing low end with too large a diameter, but making the velocity stack should help increase cylinder filling.

so to recap i think what you need to worry about more than that is making the set of ITBs we need to get easy to find and cheap...

[pregmantis]

A couple of months ago I read an article bout what your talkin about re ram, pressure pulses reversion whatevers. forgot the site but it was about mopar and their crossram manifold, and they had some equations on how to calculate for runner length and rpm etc. hope you guys can find it.

[PandaS14]

^^^^^^

Yeah, that's helmholtz.

As of now there are no equations for open ended intake paths such as ITB's.

[DjPantsSpecR]

i don't want too much misinformation going on here, but the pressure wave reversion, while similar to helmholtz theory isn't exactly the same thing. ITB's in the open air will still have this pressure wave reversion, as well as at least another pressure wave reversion. all this is branched off both exhaust scavenging when both valves are open and about a second later when the piston is traveling down the bore.

either way once the air reflects off the intake valve and reaches the open air its not just gonna piss out, it will invert and reflect just because the pressure it has is higher the atmospheric pressure, and similarily when it is lower than atmospheric

additonally i just wanted to point out to nismopu that i found there should be about 1.7 to 2.5% increase in runner area per inch of runner, this represents about 1.5 degrees of taper. anything past 2.5% is pretty much past the limit of helping airflow. So you do the math, cuz for now i gotta go study fr my mutlivariable calc exam at 6 tonight

[nismopu]

I dont know if you guys can see this whole article because you have to be a member for most of the articles.http://autospeed.drive.com.au/....html

this is just an interview from my favorite performance website with a gentlemen who builds HI-PO race engines.

heres some info provided by autospeed and some tests they did using IPT ITB's with some varying intake runner lengths. these are numbers from a ford 2.3 pinto engine, using a very high lift cam and larger valves. 44mm int 38 mm ext, .500 lift cam, racing header, and the IPT ITB's. "The Injection Perfection throttle bodies take bolt-on intake trumpets, and Mike had a whole variety of lengths and designs to play with. We won't show all of the tests - just three. The blue line shows the power with a 14.5 inch intake runner length (from the end of the Weber trumpet through to the intake valve). As you can see, power peaked at 88kW. Pulling these off and swapping to 12 inch intakes took that up to 98kW, while 13.5 inches was the optimal length giving an even 100kW. These changes were made one straight after the other, so it can be said with certainty that swapping intake trumpets gave a change of 12kW!" "Yup, fine - getting good results from 13.5 inch trumpets. But were they going to remain bare and open - or were filters going over the top? Mike believes that sock-type filters wrecks the flow into the belllmouths, so he intended using an airbox over them. But what would this do to the intake tuning? He made a cardboard airbox and placed it over the intakes." "The red line shows the starting point - using long runners and with a bit of a wobbly power curve, peaking at 98kW. The blue line shows what the airbox did - lifting power at one point but causing a 5kW dip in the curve at higher revs. So yup, an airbox sure does change the tuning characteristics! So what about putting a feed tube to the airbox? A short 3-inch intake duct was fitted, with the power then made shown by the green line. The power curve was smoothed out, still peaking at 98kW but being a few kilowatts down at lower rpm."

And my favorite quote from the whole article! "Some of these tuning changes made a radical difference to power, while others didn't do much at all. Unless you do lotsa dyno runs - or carefully time the acceleration on the road - you could be working totally in the dark. One thing's for sure, there's a lot more to setting up an engine than just building it!"

[nismopu]

OK from all the recent info I have collected and based on my current design I have to go back and rethink the whole system! I have figured out even with the advice people had given me before that my ITB's could be too big. Based on the knowledge from TWM induction, IPT, and the articles I have dug up. There's a broad range of sizes I could use from 45mm on up to 54, that is a huge range! If I wanted a snarling top end beast that shot fire out the ITB's on low end acceleration but just flat out hauled in the upper rev range then i could go with the 54's. If i wanted a streetable setup like we ahve been talking about then something like the 45mm's are a good start! From there I could play with different runner lengths, tapers, and injector locations. For an engine operating in the upper 9k rev range it sounds like a 7/16" radiused bellmouth attached to a desired runner length(depends where you wanna make power), injector before or after, and even both(depends on how your going to drive the vehicle), the angle in which the ITB's direct air to the intake valve. Last but not least is injector angle! Yes! Injector angle plays probably the biggest factor in drivability in these setups(as little as 5 degrees). I had no idea that it would play a factor and along with that factor comes injector style. I think based on what improvements have been made in motorcycle EFI is that the newest style pin injectors will work well in our applications. If the spray from the injectors is to light it can actually be pushed backwards and cause engine fires(bad idea). Injectors that spray a strong steady fog directly are more of what I am after.