Contour Enthusiasts Group Archives Forums Modifications Duratec Performance UIM CFM flow

Whats the max CFM flow of a Max EH UIM?

Thanks didn't think to look there.

So the best they got was ~285cfm, and Demon had a further honed one that he didn't list specs on.

The formula I used off his site equates to ~392cfm draw at for 7500RPM. I'd like to get alot more of that air into this motor. I don't know if he got big numbers but I had a couple ?'s about a custom manifold setup.

But first things first, can you get the SVT UIM to flow that much? If so great and thats all I need.

Setup 1: Custom machined split port LIM that maintains oval port head shape (slightly enlarged) w/ a split port opening to utilize an offset injector position. The LIM would taper down for a venturi effect for optimum performance.

I would want to do this so you don't have to cut a huge "hole" in the head to use the split port LIM where there is still a large gap (more than you I think you would need for the expansion of the primary intake into the secondary for swirl effect) that you lose velocity from.

The UIM I had a couple ideas about. One would be a variable runner length like the SVT ( or just a max EH SVT UIM) and the other would have two identical length tuned runners (like the corvtte ZR-1). One having a smaller crossection for low end TQ and the other having a larger for high end. Balance and optimization would be key here to keep similar curves to the SVT while being able to supply more air for the high revs (~7500).

Option 2: This would keep the oval shape. Custom machined LIM. UIM w/ 6 tapered runners fed form two opposite plenums like the SVT.

I thought about having the UIM's being fed from a common plenum but from the looks of things, even if you could package all this it looks like the you couldn't make all the trumpets fit in there. So it looks like it will be of a dual plane design.

Forgive me but I'm still VERY ignorant on the subject of intake tuning and have a lot to learn about it. Discuss please.

I think there needs to be a balance of raw CFM flow vs intake air velocity. If you make your UIM too big the intake air's velocity drops too much and you actually loose power. I could be wrong, I'm sure one of the brains will chime in here.

392cfm draw at 7500rpm??? Not on any NA engine that fits in our car.

The stock 2.5L engine pulls about 260cfm at 6750rpm.
An SVT 2.5L engine pulls about 285cfm at 7000rpm.
A full bolt on SVT 2.5L engine pulls about 305-315cfm at 7500rpm.

A typical 3L build pulls about 330cfm above 7000rpm.
A 3L build (SVT cams) pulls about 340-350cfm at 7500rpm.
A balls out 3L pulls about 370-375cfm at 7500rpm.

A modified 302 V8 at 6500rpm pulls 455-475cfm.

Ok that makes sense. How do you factor in the VE then or do you have to actually datalog it?

You have to estimate it based upon real world data at this point.

If you assume 90% VE at the point on the dyno where the torque curve is highest, e.g.

150 ft-lbs at highest peaks is 90% then (VEmax*0.9=150)
VEmax=167ft-lbs
then say you start at 2000 rpm with 125ft-lbs, you would have 125/167= ~0.75 or 75%
Then you can hand plot your estimate of VE based upon your torque curve. Of course diff. mods react diff. But if you get a car that was essentially the same with only a cam change we'll say, you can see how and where VE was effected by the cams.
Or an intake, headers, etc.