Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Secondaries Finally Removed

There is a difference between pinning and removing the butterflies regardless of the IMRC. There is more air going through the secondaries with the butterflies removed because of the rod has a slot in the middle for the butterfly. multiply the amount of air that can pass through the slot the butterfly goes in by 6 and that is the amount of overall additional air going into the secondary valve opening. It is additional metered air. You don't need dyno proof to understand this. Tis is also why people cut the Bar that holds the tb butterfly and report gains. The best way to do this mod is to remove the bar completely and do the IMRC spring mod. It tricks the IMRC int thinking it is still functioning.

1. They mean cut the ends off the bar to fill the holes and use to work IMRC cable. The rods are NOT in the ports. That's the part that is cut off.

2. Incorrect. If you do that you are waiting for the PCM to open the secondaries (or think it's opening it) before you get your timing & fuel increase.
You are better off running with a CEL and no spring.

The best way is to rig a rpm switch to make the IMRC open early (say 2000-2500rpm) so the PCM ramps up the timing early. Used in conjunction with a return spring and you get the early timing & fuel and do not have the CEL.

chezzter - Look at it from the frontal view. Straight up and down it has the same cross section with or without plates.

Mike - The secondary plates are not setup like the TB plate. No slot between the rods. It attaches to a counter sunk slot on the top side of the rod.

~With the rods left in = the same are normal test pinning. Plus the tiny area gained for the loss of the screws.

I wouldn't be to quick to question Demon, we've talked a number of times over the phone and he know's his stuff. Do you folks know anyone else with a N/A 2.5 Tour that can lose complete traction in 2nd and get wheelspin in 3rd, I don't think so!!!

I don't think you need a dyno to tell you that your car is putting some serious power to the wheels in his case, although it would be nice. D-man will dyno and I'm sure it will be some good numbers, Altima even from 1000cc less.

There is no one out there that is going to convince me that the surface area with the butterflies is the same without. It doesn;t take a genius to figure that out even with the secondaries opening with butterflies; yes I do believe that you could gain even more with the rods removed but at this point in time I didn;t want to go that far as of yet. I will be removing the rods at some point in the future. I do have a CEL but it's due to the Ford POS O2 sensors and EGR before I did this mod which I will repairing soon.

Silva,

I dont doubt that Demon knows his stuff... I just want to have a discussion about this with him, nothing wrong with that.

Demon,

I know that by looking at the plates head on the surface area is the same. I never took any classes in fluid dynamics or airflow stuff, but I would just think that the large flat area that the air travels over cant be that great, or at least not as good as a severall mm thick bar.

I wonder how we could prove which allows more air to flow? Would you just have to monitor with an OBD-II scan tool on the MAF? I guess you could hook the entire assemble (UIM, LIM and HEADS to a flow bench and see which setup flows more air.... food for thought...

Anyways, like i said, as soon as I can get my hands on a second LIM, I wil more than likely do this mod and see how it affects HP on a dyno and track times. No one else seems to be in a hurry to find a dyno to prove to the rest of us this mod really helps....

Nikolas

I too, believe that Demon knows his S h i t. But I think that he is being far too focused on the full removal and not looking at the advantage to having the plates out with the rods in. There IS a reduced (no matter how small) surface area with the plates out. This is from the lack of the plate and screw profile. The pull also starts as soon as the secondaries are cracked, not when the are finally, fully opened. The advantage to that is obvious as well. I am just trying to state the reasons for doing the mod without removing the rod. Some of us (me included) are still under warranty (remember that silly thing?) and want to be able to reverse this easily, if needed. The fact that w/o the plates is better than w/ the plates, to me is obvious. The surface area argument makes no sence to me. The FACT is that there IS less without the plates. Not much less, but less. I will have dyno numbers soon. I do realize the benefit of removing the entire rod, but you have to crawl before you can run!

Oh, and by the way... I have 550 miles on my Butterfly-less intake and no CEL.

I fully agree with PO-PO

Eric

So you hooked the IMRC linkage back up to operate normally, just with no plates on the throttles?

If so, that means you are not getting the early timing & fuel ramp up.

You have more low end power just waiting for you...

As for the surface area difference.

Surface Area of the Plates
The plates are .9mm wide x 34mm wide = 30.6 x 6 ports = 183.6mm total frontal area

The area of each 32mm Primary port is 804.3mm x 6 ports = 4825.8mm

The area of each 34mm Secondary port is 907.9mm x 6 ports = 5447.5mm

12 port total area: 10273.3mm

That's a 1.8% (maximum) increase in total area.
Zero increase in primary ports.
That's a 3.3% increase in the Secondary ports.

Surface Area of the Rods
Primary port - The rod diameter is 5mm x 32mm = 160mm x 6 ports = 960mm

Secondary Port - The rod diameter is 3.4mm x 34mm = 115.6mm x 6 ports = 693.6mm

That's a 16.1% (maximum) increase in total area. (minus plates = 18% overall)
That's a 19.8% increase in the Primary ports.
That's a 12.8% increase in the Secondary ports.
~Minus the plates = 16.1% increase overall.

So the numbers say the rods are over 9 tenths of the obstruction itself.

BTW - I measured the smallest part of the rod so the actual improvement would be slightly larger. Like ~1-3% Nothing noticeable.

The rods are round, right? If so, then you can't just use L x W due to a round & cylindrical object. Surface Area = 2(pi r 2) + (2 pi r)* h

God, I really HATE MATH