ITB Intake Manifold interest
#183
Nordschleife Master
The intake looks good. If you want some feedback, I'd make sure you have sufficient room above the bellmouth for runner #4. You need to have a volume above the entry that will fit a sphere with a radius 1.5 times the radius of the runner. The "picture" is a scoop of ice cream in a cone (where part is down in the runner). You may, it is hard to tell from the picture. If you can make the plenum surfaces less flat, that would help with noise and durability (fatigue), as well.
#184
Race Car
Imagine an ice cream cone. If it is 1 unit in diameter, then imagine teh scoop of ice cream sitting on the top of it being 1.5 units in diameter. That is what you need. You can trig out where exactly it needs to be, as far as how far into the cone the scoop sits. More room won't hurt, but less will.
#185
Nordschleife Master
Imagine an ice cream cone. If it is 1 unit in diameter, then imagine teh scoop of ice cream sitting on the top of it being 1.5 units in diameter. That is what you need. You can trig out where exactly it needs to be, as far as how far into the cone the scoop sits. More room won't hurt, but less will.
These I think are from Blair's RET article originally. My instinct says that as long as the walls are at the zero Mach area in the below graphs, then one should be ok. But that's just instinct.
Simple straight pipe end sucks like you describe from the ice cream scoop:
Bellmouth looks a lot flatter:
If you measure from the bellmouth center, then it's maybe 1 D up and 1.5 D to the sides. Of course, if you measure from the floor, then it's about 2.5 D from up and 1.5 D to sides.
I don't know how the graph would change if we would sink the bellmouth to the floor or actually put walls around the whose thing.
#187
I milled a couple plates to add Hayabusa ITBs to a nissan 4 banger once (NA). Looked pretty cool and woke the engine up. The guy had to weld in tubes between the plates and had trumpets on hand.
#191
Rainman
Rennlist Member
Rennlist Member
wonder how much of the "gains" from ITBs are from matching all the runners in length so they all tune to a certain (high) rpm, rather than having mixed lengths to broaden the tuning effect...
would you rather make equal length or unequal length runners?
ITB is something i've thought about playing with, i of course have an idea to build a setup for pretty cheap with a near-limitless supply of OEM throttles in either 39 or 50mm sizes, with larger ones available from the aftermarket...into a plenum to run a MAF. but the easiest way to do it that i can come up with would likely result in a slight mismatch of one pair of cylinders in runner length.
would you rather make equal length or unequal length runners?
ITB is something i've thought about playing with, i of course have an idea to build a setup for pretty cheap with a near-limitless supply of OEM throttles in either 39 or 50mm sizes, with larger ones available from the aftermarket...into a plenum to run a MAF. but the easiest way to do it that i can come up with would likely result in a slight mismatch of one pair of cylinders in runner length.
#192
Three Wheelin'
Why run MAF when you have installed ITB's? I would understand if you run forced induction and then use existing MAF system, but I personally wouldn't even bother installing MAF when using ITB's. It is just another restriction and just another thing to fail... Plus MAF sensors do not like pulsing air that is present with ITB's and/or wilder cams...
#193
What would you use instead of MAF? Asking cause I don't know
Why run MAF when you have installed ITB's? I would understand if you run forced induction and then use existing MAF system, but I personally wouldn't even bother installing MAF when using ITB's. It is just another restriction and just another thing to fail... Plus MAF sensors do not like pulsing air that is present with ITB's and/or wilder cams...
#194
Rainman
Rennlist Member
Rennlist Member
Why run MAF when you have installed ITB's? I would understand if you run forced induction and then use existing MAF system, but I personally wouldn't even bother installing MAF when using ITB's. It is just another restriction and just another thing to fail... Plus MAF sensors do not like pulsing air that is present with ITB's and/or wilder cams...
plus, i already have the MAF
the sensor is so narrow that any restriction it may pose would be pretty minimal.
#195
Three Wheelin'
When going through hassle of installing ITB's, going some standalone would be pretty much the only reasonable way. This is purely because there is almost no OEM ECU that has proper control strategy for ITB's. Only ECU's that comes to mind is Nissan RB26DETT, BMW S engines and some others too.
MAF will not make ITB's easier to tune and with standalone using Alpha-N+load compensation (MAP hose connected before throttles) gives the best result.
But, to each their own.
MAF will not make ITB's easier to tune and with standalone using Alpha-N+load compensation (MAP hose connected before throttles) gives the best result.
But, to each their own.