Flow Dynamics 101:...engineers Welcome

[CarMichael Angelo]

I'm trying to determine how big of a box that I'll have to make to cover the throttle bodies, and how big of an round opening will be required to adequately provide air to them.

I don't even know where to start...thinking maybe a 5-6" wide base that runs the length of the 6 throttle bodies. A short side of probably 2" and a long side of 3.5" will run the length of the thing. A flat top that'll end up being 3x24". The reason I want to do a long side/short side is because the throttle bodies are angled at 45 degrees, and I want the top on the same plane that the valve cover will be.

So,...you have this metal box encapsulating the throttle bodies. The volume of that box probably equivalent to a 24" piece of 3.5" exhaust tubing. At the front of the metal box, there'll be a 3" diameter tube that'll do a dog leg drop, and turn out 90* with a K&N style Conical filter capping off the end of the thing.

Will a 3" tube be adequate to provide air to this thing?

Does anybody have any thoughts here?

 

[Mustang5L5]

Picture of TB setup? Are you making a plenum over the TBs

estimated CFM you think engine would move at WOT?

 

[CarMichael Angelo]

Picture of TB setup? Are you making a plenum over the TBs

estimated CFM you think engine would move at WOT?

The box in question will be the "plenum" I guess. Each TB will have a bellmouth'd entrance.

As far as CFM,...I'm clueless. Each of the TB's have 2" blades.

 

[90sickfox]

Well.... there's more to exhaust than there is to intake. The fuel that's sprayed isn't accounted for in the intake volume.

What size is your exhaust ?

I would think the 3in intake pipe would be big enough. The box would need to be atleast 2in off the top of the throttle bodies. Any closer and i think the air turbulence will affect your airflow.

I'm no engineer but ....

 

[General karthief]

What size tube did the tbs breathe through in their original configuration?

 

[CarMichael Angelo]

What size tube did the tbs breathe through in their original configuration?

3",...but it was force'd in.

 

[Mustang5L5]

This isn't my area of expertise, but the key is keeping the air velocity up through the intake track and into the throttle bodies. Too large of a plenum and you slow the air down before it enters. It would require a lot of testing to determine the effects of this. However, if I had to come up with a rough first draft...I'd do something like the setup to the left in this photo

3" diameter can support a lot of airflow provided not a lot of bends and distance. I'm assuming you are just doing a short filter to plenum opening for your intake duct.

 

[RaggedGT]

 

[Mustang5L5]

^^ KISS theory

 

[RangerJoe]

Anderson sells their cheaper power pipe at 3". I would think that since it can feed a 400hp 5.0L motor, it could feed your 300hp 6 cylinder.

Joe

 

[srtthis]

you should be fine with a 3" pipe for how much air youll need to move, those 2" throttle bodies will flow way more than each cylinder will actually take or at least should. IIRC a 90mm throttle body flows something like 1500CFM. and you have the cross section of a 305mm throttle body LOL

 

[hoopty5.0]

Some 3" PVC, 1/4" Acrylic sheets, and an oven. Use the PVC as your jig, form the acrylic into a half moon, make sides and then attach it to a sheet metal base.

https://www.wikihow.com/Easily-Mold-Acrylic-Plastic-Sheets


Similar to this:

 

[CarMichael Angelo]

So, what does everybody think about this idea? 6 of these breathing the air under the hood. Period. The fact that I have a flow through system that lets air in at the front, and lets air right back out at the rear, and considering that my exhaust is on the other side of the engine...heat would be somewhat less than what a V8 compartment would experience.

 

[95BlueStallion]

I think I would start simple with air filters on each TB. Get it running, and then since you know it runs well, play with the box idea and see how it is affected.

 

[HotFox]

Just make sure you have provisions for the air cleaners to catch the fuel and oil residue from the blow back.

 

[srtthis]

dont think fuel injection will have the issues pulling fuel out like a carb does hence why the fuel injected nitrous race cars no longer use scoops

 

[HotFox]

I meant the reversion that will take place due to sizing, single unshared runners. Fuel will want to come back and bouce off the back of the butter fly. Let me just say this will be a miserable for drivability down at low Rpms. Having all those butterflies cracked at low RPM to try and maintain any kind of velocity. Mike should understand why this setup looks cool in a Museum NOT running and NOT on a cruiser. It will make peak power way higher then what the cam is ground for let alone what the crank and rods could handle at that rpm.

 

[CarMichael Angelo]

I meant the reversion that will take place due to sizing, single unshared runners. Fuel will want to come back and bouce off the back of the butter fly. Let me just say this will be a miserable for drivability down at low Rpms. Having all those butterflies cracked at low RPM to try and maintain any kind of velocity. Mike should understand why this setup looks cool in a Museum NOT running and NOT on a cruiser. It will make peak power way higher then what the cam is ground for let alone what the crank and rods could handle at that rpm.

These came off of a car that had them...all six of them, on a daily driven street car. That was fully 1 liter smaller than the Monster. The low speed drivability of a 2006 BMW M3 has never been an issue...I do not see why it would be here.

 

[a91what]

 

[droopie85gt]

I'm of the test the itb theory in action first, and if you are satisfied with the driveability then work on a box. So just some simple filters to start with.