MAC Straight Shot & Accufab Throttle Body??

Discussion in 'SVT Tech Forum' started by 1268, Aug 19, 2004.


  1. gemex

    gemex New Member

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    Uncle Meat, I had the new Predator with the increased flexibility in timing and so forth. I did not get a custom tune sent to me because of the situation I was in at the time. As it was with the ported blower 95mm M.A. along with our 91 California gas we just couldn’t get it down with the out of the box tune + user adjustments. After two hours we gave up and went back to the previous tune I had and just messed with the A.F. The timing could be moved forward some more but we were out of time. Apex is the closest dyno shop to me and it’s a two-hour drive one-way.

    I will say that I feel if I didn’t have the 95M.A. and the blower ported the Predator would have worked great for me. :nice:
    #41
  2. Jpjr

    Jpjr New Member

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    Hey Gemex did you have any more luck tuning with the 95MAF? I'm only cat-back and Straight Shot for now but would be inerested to know if someone sorted out the tunes with the bigger MAF or if its just not worth it.

    Thanks
    #42
  3. gemex

    gemex New Member

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    The 95mm works by giving a slower air speed reading thus “tricking” your computer into thinking it’s getting less air and leaning out the A.F. giving you more power. The problem down the road is if you decide to due the smaller pulley, and or porting mods most programs out there are set up using the factory M.A.S. readings, so if you have the 95mm m.a. then the programs need to be reworked to get it down right. This extra time and effort costs money, for me it was $100.00 an hour and it took four hours to play with, and the tune could still be better. So I spent all the time and money over the 95mm m.a. and the end result was no noticeable gain compared to other Cobras with the same mods.

    So, if you DON'T plan on getting the smaller pulley, and or porting the blower I say go for it! You will see good power gains and you wont need to mess with the computer thus voiding your warranty! :nice:
    #43
  4. Jpjr

    Jpjr New Member

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    -Well, the larger MAF is a recent phoenomenon for the '03 Cobra. I think that if it got more popular someone would take care of the R&D needed to get a good custom tune out of a predator. Hopefully by then is right around the time I add pulleys :)
    #44
  5. Rogue Cobra

    Rogue Cobra New Member

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    ok, I want to understand this, but I guess I am not getting this. The idea of using a cai is to bring in more air. A smaller mas tube will restrict the air more, thus defeating the purpose of having a cai. You get a bigger filter with more open element, you flow more air. At any point on the way to the engine, that air can be restricted by smaller diameter tubing or inlets. The 95 mm mas tube will allow more air to follow into the super charger and then into the engine. How is that slowing down the air? As I see it, it would speed it up, if anything.

    Patrick
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  6. Uncle Meat

    Uncle Meat Banned

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    The CAI does not bring in more air. It allows the same amount of air into the engine as the stock airbox & filter. What a CAI does is makes it easier for the engine to breath this air in. Less restriction is where the gains are being made. In the case of the K&N FIPK, they added a velocity bell to the front side of the MAF to create a low pressure point, which in turn makes it even easier for the engine to get the air in. (see attached pic).

    The 95MM MAF's do make it easier for air to flow into the motor, up to 70CFM more air to be exact. The problem here is that you use the original stock MAF sampling tube/electronics inside the new 95MM MAF. The electronics and sampling tube are calibrated to read how much air is being sucked through a 90MM opening, not 95MM. The engine is actually getting MORE air than the MAF is reporting. This causes the A/F ratio to be a little lean, which in turn makes more power. On top of this, when the tuners get their hands on these cars they tweek the ECM's fuel tables to adjust the A/F ratio based on the readings from the MAF. If those readings are not factual (because of the 95MM MAF) then it makes their job much more difficult. If C&L or MAC would provide new sampling tubes/electronics calibrated for 95MM with these MAF's the data being reported to the ECM would be correct, but then you wouldn't see the additional HP/TQ gained from the lean condition now would ya???

    U.M.
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  7. Jpjr

    Jpjr New Member

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    The new MAC has the velocity bell as well, no?

    I think the take-away here is that if you start tuning your going to lose the trickery, but I don't think its enough reason to ditch the bigger MAF if they came out with a good custom tune or updated electronics. Reason being its a great looking system and appears very high quality. It's too new to make a thorough judgement, but I've installed CAI's on my last 3 cars and the new MAC was definitely the best fit and the best looking.
    #47
  8. Rogue Cobra

    Rogue Cobra New Member

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    Thanks UM!

    I think what you are saying in the two paragraphs contradict themselves. NO?

    This I get:
    "The 95MM MAF's do make it easier for air to flow into the motor, up to 70CFM more air to be exact. The problem here is that you use the original stock MAF sampling tube/electronics inside the new 95MM MAF. The electronics and sampling tube are calibrated to read how much air is being sucked through a 90MM opening, not 95MM. The engine is actually getting MORE air than the MAF is reporting. This causes the A/F ratio to be a little lean, which in turn makes more power. On top of this, when the tuners get their hands on these cars they tweek the ECM's fuel tables to adjust the A/F ratio based on the readings from the MAF. If those readings are not factual (because of the 95MM MAF) then it makes their job much more difficult. If C&L or MAC would provide new sampling tubes/electronics calibrated for 95MM with these MAF's the data being reported to the ECM would be correct, but then you wouldn't see the additional HP/TQ gained from the lean condition now would ya??? "

    This makes sense to me. It does flow more air and the stock MAF is not calibrated to the increased airflow. I think you should say "leaner" not "lean" condition. That implies that the A/F is too lean for the engine, I don't believe that is true in all cases. Yes, as the mods are added on the condition does have a chance to be more of a problem, but a good tune/tuner should be able to overcome this problem. I would agree the manufacturer should have an option for a calibrated MAF. Is it worth it?????? I don't know. :bang:
    #48
  9. gemex

    gemex New Member

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    Thanks for getting technical U.M., I new I could rely on you. :nice:

    Like we said above, you can get the tune down with the 95mm mass air, but it takes a lot longer to due it, and in the end like U.M. said you lose the trickery! Remember that your airflow is limited by the most restrictive part between two points, and the mass air is not one of them. If you due the math the throttle body opening followed by the part of the inlet tube that meets the blower are the most constrictive points.

    There are Cobras out there with 700hp that still have the stock M.A. on them.
    #49
  10. stvdman

    stvdman Founding Member

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    More air doesent mean its moving "faster". When the opening is made larger (95mm), the velocity of the air flow DECREASES. You put on the 90mm unit and the same volume of air still passes through in the same time which equals INCREASED velocity.

    Thats why the air "slows down" with the 95mm unit.

    As far as CAI's being BS mods, I would have to agree...mine was such BS :bs: ..it only gave me 22 more horsepower to the wheels. ;) :rlaugh:
    #50
  11. gemex

    gemex New Member

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    P.S. I have had the C&L C.A. with the 95m.a. for a year next month and I still don’t have the perfect tune. :shrug:
    #51
  12. Jpjr

    Jpjr New Member

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    -Good point. But I'm willing to be that once MAC starts hearing people getting turned off for this reason, they will invest in a custom tune for their product. They probably won't 'sell' it, but they will make sure someone out there has it. Just my opinion..
    #52
  13. DaMessenger

    DaMessenger New Member

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    Do you Have C&l's? Mac's does increase the velocity do to the entry angle in the mass air & thier velocity stack.Check out Rpm Outlet's web site they have dyno's on both.
    AEW did flow test on both c&l - mac.
    Even with the 95mm mass air mac's increased velocity & flow. Also my opinion is Pro M & Mac thier depth of the sensor has a lot to do with mixture.Just a guess!
    #53

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