cfm per square area?

[fe66comet]

I am trying to determine what size EGR plate I would need to flow 1200 cfm. My 90 mm throttle body I ordered flows about 1170. The largest EGR plate I could get is 75mm. Is their a formula to determine how much flow by unrestricted square area I would need to enlarge if any my plate considering the absence or a throttle rod and plate? Thanks Jon

[My427stang]

Although you could calculate the area of the throttle rod and thickness of the throttle plate and subtract it from the area of 90mm of throttle body, I think it would be math for the sake of math and get you poor results.

My reasoning is that you would end up slightly smaller than 90mm and then have a turbulent area where the TB met the EGR plate.

If it were me, I would blend the plate to whatever is in front and behind it, and it that's a 90 mm TB, that's what I would machine it to.

Now you could get fancy and try to dimple the short side after machining if you are trying to slow air around a corner, etc, but hard to do that stuff without a flow bench and I have to tell you, even HARDER to find a 1000+ cfm flow bench.  I tried to when I did my MAF work and never got there, so ultimately had to go TLAR.  (That looks about right)

[fe66comet]

I was also thinking of boring the plate and pressing in an iron cylinder sleeve. My only concern for that is the possibility of a coolant leak from one side to the other. I would think a 85mm bore would be enough to flow what I need.

[My427stang]

If the bore OD is smaller than the TB OD, you will end up with turbulence that reduces airflow overall at the juncture.

There is a reason we "port match" and not "port calculate"

I understand if you have a water issue, but you could just plug the water and bore as big as you want. 

[cjshaker]

I tried to when I did my MAF work and never got there, so ultimately had to go TLAR.  (That looks about right)

Another process I often use but never knew the actual term for...LOL

[fe66comet]

I was going to use a 1" spacer plate to give myself room to transition. As I looked at the EGR plate it suddenly occurred to me that the EGR draws off a port in the intake for exhaust gas. Being that the Trick Flow Box R intake does not have that provision I am going to have to externally plumb the EGR valve. That in turn will give me more room to install a 3.5 bore sleeve in the plate, 90mm works out to 3.543 so that gets me real close.

[Cyclone03]

5.0 type intake?
Bore the EGR to whatever you want,plug the water holes,bolt the EGR valve on,hook up the wires and vacuum so it looks functioal then retune for the lack of exhaust gas .

You NEEDING a 90mm TB pretty much says emissions are not top of your list.

[fe66comet]

I want to keep it functional so I can pass. I can work with the EGR but my CFM requirements fall between a 90 and 80mm throttle body. Really 85mm is about right but only available for a LS.

[My427stang]

Again Jon, there is no maximum like a carb, matter of fact, a carb only has a maximum due to the limit of velocity pulling fuel through a booster.  If it had a way to move fuel that didn't rely on low pressure areas, you could go as big as want to.

As big as you can on that side of the plenum.....it'll take whatever it wants on that side of the plenum

Mine was rated for 1200 and then we ported it, ended up with 400 cfm per barrel, fully assembled.  I wanted to flow it with the MAF but couldn't find a bench to support all 4 at once

[fe66comet]

When I did the math, my port is 1.5/2.1 on the intake. That works out to 3.15 square inches, that times eight gives me 25.15 square area total. The upper supports a 90mm throttle body with no modifications. That comes to a 3.543 bore which comes to 11.125 area, so actually I am less than half total port capacity of mg intake. The next size up throttle body is a 105mm or something like that but I would think that would just make more work for no gain?

[My427stang]

I think you have plenty of TB with a single 90 mm, I just wanted to make sure you realized that there was no benefit for LESS airflow.  Let the plenum get a nice clean flow of air, as smooth of a transition from the TB to the EGR plate to the upper manifold is what you want. 

The plenum will act as a surge reservoir for lack of a better term for resonance coming back from valve operation, all the pulses will bang around in there, you just want the TB to give that plenum as much as it wants

[fe66comet]

The plenum is a pretty large box style, my thought on that was that it would buffer some reversion and also feed the extra 95 cubes that I have. The intake is a 351 Cleaveland design for 2500- 6500 rpm. For now I am putting it all together with just a port match with a complete port and polish possible one the heads,intake adapter and lower later. For now like you said my goal is to take out the bumpy stuff.

[Joe-JDC]

You really do not need an EGR spacer with that intake on a FE.  Even if you just use a spacer to gain volumn, it does not need to be plumbed for water circulation on a performance build.  The hot water was used to warm up the engine quicker for emissions control and cold weather driveability issues.  We always plugged the water line to the HO mustangs to keep the plenum cooler.  I have seen the ported plenums frost over on humid days at the race track.   I would not use one, but that is just me.  Joe-JDC

[fe66comet]

If I do not make it comply with 1996 model year standards and I move it becomes a trailor ornament. In the county we live now there has been talk for years about starting testing also, I just want to be prepared.