87na_rx7

so i guess you do use math after school

bambooseven

If only I could find a practical use for that calculus 2 I took a couple years back.

EGYSOL

i can't find the turbo i need we only have stock volvo turbos here no one told me what i use and i think it'll take a long time to put the turbo on so untill then i'll stick bor the ITB if i can really understand

where to cut in my intake "use my injectors?"
+where does the map sensor hoock or do i cut after the map sensor i can get almost any motorcycle throtel so which on would b best ?

bambooseven

there is a pretty good write up on the main page

https://www.homemadeturbo.com/tech_p...itb/index.html

SkunT

this is the best homemade ITB thread on the net that I have found.

http://www.honda-tech.com/zerothread?id=775280

TunerToys

Dang Bambi,

That was some great math and education you laid down there. I really hadn't thought about the 12K RPM consideration either. That is almost twice the RPM of the, 1.6L Engine.

So now I have another question...or two.

Is there a way to calculate the maximum possible airflow through the stock 62mm TB versus 251mm of the ITB? I can't remember if it is a hard number for a given pressure and opening.....

Wracking my cells...Craig

bambooseven

yes, there is a way. it has more to do with velocity then it does pressure. if you take pressure as a constant we'll say one atm. (14.7 psi, not boost but normal atmospheric pressure) and density also as a constant ( which would vary upon altitude among other things) you can determine how much air will be going through a throttle body in cfm.
however, any amount of air can go through any amount of space when forced to do so. a given engine will only flow a certain amount of cfm naturally the only thing that we can do is open up the flow. say for example a given motor at wide open throttle with a completely free flowing intake tract flows 120 cfm, that motor with 1 62mm throttle body will only flow, let say, 111 cfm because of restriction put on the air flow by the throttle body and the intake manifold. or the same motor with 4 40 mm throttle bodies and no intake manifold, might flow, let's say, 117 cfm. The motor is the limiting factor, not the throttlebody. If you had a motor that at wide open throttle with a completely free flowing intake tract flows 150 cfm might flow 125 w/ a 62mm throttle body, but with 4 40mm throttle bodies it has the room to breathe that it needs and might flow more near it's free flow capabilities. the size of the throttlebody will make the most difference on the motor that is bottlenecking to get the air through.

did that all come out anywhere near comprehensible?

I hope it made sense. I didn't take AP chem for nothing.

87na_rx7

damn smart bastard

TunerToys

Excellent Bamboo!

That makes total sense to me. Once you add boost to the equation, it makes it a lot easier to get larger amounts of air through the same diameter opening. Simple enough, now that you have edified me.

So when you switch from the big single TB feeding four cylinders, to individuals, you get rid of the need for the big air chamber behind the TB, right? The air chamber is there so that the individual cylinders are not sucking air from each other, correct?

So it would be possible to turbo an ITB setup, you'd just need to pipe the charge air into four locations, instead of just one.

Thanks Bamboo. (it's Drew, right?)

Craig

bambooseven

lets just say I have a top secret project in the works right now that will tackle that subject. You'll all be pleased when it is unveiled

BTW yes, that is why you don't need the plenum on the 4 TB's. 4 throttle bodies is kind of the same reason why we have tuned equal length turbo manifolds. the plenum acts in the same way that a log manifold does, where as ITB's act like a tubular, merge collected one (only reversed).