Itb woes (looking for opinions on an air box)
Posted by M0NEYGR1P@reddit | projectcar | View on Reddit | 22 comments
Im struggling with my 2d drawings before i switch over to 3d im hitting a road block with my air box needed to use the factory map. If i enclose the entire system the vacuum lines and fueling are the issue. I can use a v8 throttle body for more area for the linkage being in the air flow. Im thinking im going to have to build a slim air box for the map or modify a stock fuel rail to make it happen. The box needs to stay under the hood
EksCelle@reddit
There is no way to use ITBs with velocity stacks on a MAF equipped engine, as the MAF has to measure the airflow of the entire engine. You would need to enclose all the ITBs in an air box that the MAF would be upstream of.
I'm not understanding your drawings or why you would use a "v8 throttle body". Are you intending to use these ITBs with a stock intake manifold? That would defeat the point of having Individual Throttle Bodies (ITBs). The point of having ITBs is that each throttle body will feed air individually into each cylinder without interference from other cylinders like a traditional intake manifold.
pistonsoffury@reddit
tl;dr - OP needs to run this on a standalone ECU.
M0NEYGR1P@reddit (OP)
Not yet the challenge is to run it on stock equipment i got inspiration from making for motorsports
Data_shade@reddit
It might be doable but it may never ever run right, it may never make power and make the car slower- on a stock factory tune.
BMW uses velocity stacks inside a plenum on the E39 M5, and retains MAF. maybe look into that design and see if you can cherry pick some design elements from something that’s already been figured out, and implement them into your design
pancrudo@reddit
Don't forget the euro e36. S50 also had ITBs and a MAF
Doctah_Whoopass@reddit
You know what, fuckin go for it.
TheAwkwardBanana@reddit
I'm sure it'll run juuuuust fine. đź‘Ť
teastain@reddit
ITBs needs custom ECU.
M0NEYGR1P@reddit (OP)
Yea all the itbs will be inside the box with the stacks in there. Im using the drive by wire throttle as an actuator to move the 6 throttles that will be in the box and i was thinking about packaging constraints and just having the air move through the the throttle body acting as an actuator and having the full itb set up inside of the box for now
legionofdoom4@reddit
In my humble and not very prodessional opinion, It looks like you have all the boxes checked. As long as the maf is in the same diameter piping as stock or you have a new sensor/a workaround that allows for different intake piping, you should be good. I'm curious though about how you managed to hook up the drive-by-wire to the throttle linkage. Please do share the details on that.
mrsockyman@reddit
There's a few videos from a channel called "making for motorsport" where he runs custom itbs on a stock computer, haven't watched it in a while so I'm foggy on the details but I encourage you to watch the few videos in the series
https://youtu.be/zonvcNFbOgw?si=dzB7es-fbZXztpzL
M0NEYGR1P@reddit (OP)
I watched all those videos already thats where i got some inspiration from
BettyBoo42@reddit
This seems like a lot of work to make a cosmetic ITB setup. You may as well tape them on and just link the actuator to make them look functional.
SolidVeggies@reddit
Just need to hook them up mad max style, cut the hole in the bonnet, bolt the itb’s underneath and run a speaker to a switch make fun itb noises
vanwhisky@reddit
I can’t see the benefit of ITBs with a throttle body and MAF. You would be better off porting the heads and run headers/exhaust.
Jay-Moah@reddit
Just enclose the ITBs in a box, and have the inlet to the box metered with the MAF.
Just ensure the inlet diameter of the box is as large or greater than the sum of the areas of each throttle body so you don’t have a restriction.
Keeping ITBs with a box under the hood is very unlikely unless you rotated the ITBs 90 degrees and had an interesting box design.
RacerX400@reddit
So put ITB’s on only to enclose them into a housing that’s supplied by a throttle body and maf? What’s the point of this?
FocusedADD@reddit
Do the velocity stacks come off? Get rid of them, they're not going to help given the constraints. The intake ports on the cylinder head are straight up and down right? Skip the airbox, use an intake tree and silicone couplers. After you get rid of the stock plenum you should have enough room for a central tube of the same diameter as the MAF, with branches coming off going to the individual runners.
You're now up away from the fuel rails, room to run vacuum lines, and you've got access to the throttles to balance them, which you will need to do and even then you might lean the front two cylinders out at high RPM.
echomatt95@reddit
So I come from carb experience so what I have to say is mainly assumptions.
Instead of an air box on top of the TBIs you could put a spacer between each throttle and the intake port with an individual MAF sensor. Plug all six into an arduino or Rpi, do some math to get an average, and then send the average to the ECU. I'd do this so I could have the wow factor when opening my hood. ITBs are great center pieces when done correctly
For your original plan you could put a pipe about the same size of the MAF, it's like a separate piece that goes in between two hoses if I'm not mistaken, and then connect each throttle to the central pipe some how.
You wouldn't need any throttle plate as the MAF would just attach to the opening of whatever airbox you make.
Again these are just educated guesses. I'd personally look up other ITB solutions that use stock ECUs and see how they were done if at all. I imagine most are done on aftermarket ECUs tho.
M0NEYGR1P@reddit (OP)
Youre correct on the computer stuff because i would love to throw out the MAF and just use a map and speed density but we’ll keep it pushing
NexusEvo@reddit
I'm gonna throw my 2 cents in the chat.
If you are able to tune/run the engine off of "speed density", ie. air temp and pressure. You can then delete the need for the MAF. I have done this to my Evo and a few LS vehicles. It works better than a maf if the software is available.
Now, I believe you can use a vacuum block hooked up below the butterflys to get the average air pressure of the itb's and measure the MAP that way (not 100% sure that works but I think I read about this). Then add an intake air temp and boom, speed density.
M0NEYGR1P@reddit (OP)
I meant MAF not MAP sorry