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Lower air intake butterflies?

Discussion in '1994-2004 V6 Mustang Tech' started by Stewart P, Mar 30, 2017.

  1. Stewart P

    Stewart P New Member

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    I have a 03 3.8 pony pack mustang I am currently reworking the motor on.. I started just by opening up the upper and lower intakes to clean and gasket match and found the lower has a butterfly system in it. Along with the bypass tube from the egr and exhaust. I really had a lot of oil blowby in the intakes and am thinking about blocking the EGR port. My question is do the port holes in the lower come out to open up the air path.
    And my second question is would deleting the lower butterflies cause problems and has anyone ever done this to their 3.8..??
     

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  2. pixapusho

    pixapusho Member

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    Same on mine... however somebody used motor honey in mine and the buildup is so thick it's hard to remove even with solvent. Yours is pretty clean. Others have reported getting oiled up again in as little as a year. I would install an oil catch filter inline. Deleting IMRC's and deleting EGR will require retune.

    You want to know if you can remove the cylindrical EGR ports in each runner? Not sure but I have a spare intake I can try it on for you

    I recently did a V6 swap and had access to both IMRC and non IMRC manifolds. I decided to restore the IMRC system to avoid any check engine light and get that extra 3 HP... and most notably avoid a retune. The SCT system is so much... and they are canned tunes :/ I imagine all of the cost is in the software development for the unit. Everyone says to just go with it, but I've been searching high and low for an alternative.
     
  3. Stewart P

    Stewart P New Member

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    Well my plan wasn't to completely delete the EGR I was just going to put a plate inbetween the input into the lower intake. The EGR value would still be there and all the vacuum lines attached to it would be changes. I was just thinking that by closing off what runs into the intake system I would eliminate the blow by. The back two cylinder inlets are clean but the front four are pretty gummed up. Not to mention the heads are gummed up as well.

    I already have the SCT tuner and between myself and my friends we think if we removed the butterfly plate and left the rest intact that I would run lean and have to up the fuel ratio. Something that I know the tuner will do already.

    I have the CAI from BBK and know this thing sucks in a pretty decent amount of air now. And I wonder why they would have hot exhaust are running back into the intake system. Of course I have found no info about something like this being done online yet so I logged in here to see what the prevailing thought would be.

    More clean air is better in my opinion.
     
  4. Stewart P

    Stewart P New Member

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    I will say if you are going to go with a different rear end ratio then you will absolutely need the SCT. I have a 8.8 swap with a 4.10 in mine and I had to get the SCT tuner just to sort the speedometer..
     
  5. pixapusho

    pixapusho Member

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    EGR flow is compensated for in the computer's final AF ratio... I think you would run rich since you were getting less 'air' than the computer knows about. Or disable it, throw the CEL and it would use a basemap. Now we need someone experienced with the tuner to step in :) I've read about people deleting IMRC's and EGR (with tune). It would be great if we could filter the oil out but I imagine the EGR gasses are still pretty hot and would fry a filter in short order.

    On another note, my IMRC's were stuck wide open for a while and the thing ran fine but threw a CEL

    SCT Tuner is still so much
     
  6. Stewart P

    Stewart P New Member

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    I will be perfectly honest I am no mechanical engineer. And this has been a bit of a learning curve for me. That being said. I know that I'm blocking off the EGR and in doing so cutting that air stream. Yet at the same time I'm opening up another point for more air to get to the cylinder head.. the question to me is by having the cold air intake and gasket matching the intake system wouldn't I be compensating for the air flow lost by blocking off the EGR.

    There has to be someone on here that has done something like this.
     
  7. Stewart P

    Stewart P New Member

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    Oh and I know the tuner was expensive. But I tried to get Ford motor company to look at my car and the set the speedometer sensor for the new rear end gears and was told that it would probably cost some where around 3 to 4 hundred for them to figure it out. So it was spend Four hundred on Ford motor company or spend four hundred on the tuner that can do more than just reset the speed sensor.
    I personally am very happy with the SCT. And I can use it on my f150 as well. Just not at the same time.
     
  8. Phil II

    Phil II Cone Destroyer Staff Member

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    "IMRC delete" and "egr delete"

    Removing the imrc's will sacrifice low end torque and make it harder for the pcm to hold a stable idle.
     
  9. Stewart P

    Stewart P New Member

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    Mmmm, so how does the plates the close on the imrc make it lose flow when they bacillus cut off air to the intake. These are the question I'm looking to answer.
     
  10. Stewart P

    Stewart P New Member

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    Removing the plates.
     
  11. Stewart P

    Stewart P New Member

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  12. Stewart P

    Stewart P New Member

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    The question I guess I'm asking is how does the imrc work. Do they open at low rpm and close at higher rpm. Or is it the opposite. Closed at start and open at higher rpm..
     
  13. 6 Shooter

    6 Shooter Well-Known Member

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    IMRCs operate on vacuum from the upper intake. Same with EGRs. During decel, the vacuum will get to a pull of almost 20 inches of mercury. At WOT, vacuum will go to zero inches of mercury. In boost, the upper intake will become pressurized and the psi will go above zero into positive territory.
     
  14. Stewart P

    Stewart P New Member

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  15. Stewart P

    Stewart P New Member

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    So from this if the flow out of the motor is increased with say better header flow. And compensating for intake air flow with more fuel then it shouldn't create to much back pressure in the intake system..?
     
  16. Phil II

    Phil II Cone Destroyer Staff Member

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    WOT = wide open throttle

    IMRC = something like Intake Manifold Runner Control

    Removing the imrc will only raise peak power if your head and bottom end can use the additional flow. Otherwise there is a negative impact on port velocity and the flow into the chamber will tend to be less turbulent.

    In other words, if your car is primarily for street duty, keep the imrc.
     
    pixapusho and Stewart P like this.
  17. Stewart P

    Stewart P New Member

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    OK makes sense. No it is now my project car. The heads are going to get worked on and with the ability to do what I need to with the SCT tuner I am planing on making it for a track day car.
     
  18. Stewart P

    Stewart P New Member

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    Update had the heads worked on this week and the caked up oil from the EGR port not only caked up the lower intake but also caked up the exhaust valves to the point that they weren't sealing. Losing compression for sure. EGR delete is a definite must. Any people know the nest route to do this. Looking for different ideas.
     
  19. 6 Shooter

    6 Shooter Well-Known Member

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    Pull the intakes and clean them up with a rotating wire wire brush. Remove the IMRC butterflies, pull the IMRC rods out, have the holes welded shut. An alternative would be to find a used 99-00 Mustang V-6 lower intake which did NOT have IMRCs.
     
  20. Stewart P

    Stewart P New Member

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    I'm definitely going with the 99-00 lower intake. Have determined that the oil in the intake issue came from the exhaust line running the EGR valve. The port from the EGR into the front of the lower intake is what I want to cut out of the equation. Suggestions.