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Intake air temps

Discussion in 'The Garage' started by dyeager535, Jul 30, 2005.

  1. dyeager535

    dyeager535 1 ton status Premium Member

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    I've been waiting to start collecting data on intake air temps with an "open" air cleaner setup of some kind, and a "cold air induction" (stock for later trucks) setup.

    Rule of thumb is that every +10* of inlet air temp is 1% loss of power.

    All of the TPI setups (and TBI car) use a manifold air temp sensor. Pretty easy to gather the data with that.

    So far, with engine coolant temp in the 195-210* range, (varying due to fan on/offs) manifold air temp with "cold air induction" and approx. 85* ambient air temp, manifold air temps were consistently 80* cooler than coolant temp.

    Next test will be to remove the cold air setup, and try to move the air inlet closer to the engine. Kinda tough on mine with the MAF sensor, but I'll try my best.

    Anyone with MAP TPI and a filter on the throttle body and a scanner that wants to try this, will be closer to the engine than what I'm likely to achieve.

    One other thing I just thought of, cooling fan is going to make a difference. Electric fan setups don't measure underhood temps, so engine bay cooling never changes until coolant temp gets high enough to activate the fans, while a clutch, flex or electric fan on a switch will likely decrease underhood temps. Guess I'll have to test that too. :)

    I'm sure this is pretty pointless to most, but I figure I'll share what I find in case it's of interest to anyone else. Everyone knows cooler air makes more power, just a question of how much cooler we are talking about.
     
  2. Mad-Dog

    Mad-Dog 1/2 ton status

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    Oh yeh........i am a big fan of ram-air and/or cold-air induction systems,
    I am going to use either a scoop tray that seals against the bottom of the hood in conjunction with a cowl induction scoop or a twin-snorkel air cleaner housing and run dryer hose's up to the grill.
    My goal is to eliminate the induction system from drawing heated air from the engine compartment.
    Cooler air is denser air and will carry for fuel with it with equates to more power, and we all need more power don't we................. :bow:
     
  3. camiswelding

    camiswelding 1/2 ton status

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    Im interested in this too Dorian....

    On my 89 bb tbi v3500 Ive already removed the silencer as described in the cfm tech website... but the routing is still very restrictive... thru the factory snorkel... down the radiator support to a fairly small hole taking in air below and to the right (pass side) of the radiator...

    I have been looking at doing the older snorkel design ... the ones that come out above and to the right of the radiator.... perhpas they changed this because the 88-91 had dual horizontal headlights(some models) and there wasnt enough room...I havent really looked hard at it yet.... cold aor would really be cool if I could figure out a way not to violate KALIFORNIA smog....

    I am venting my underhood temps, which are excessive, by the use of louvers

    Ill watch this thread...
    thanks
    cam
     
  4. Thunder

    Thunder 3/4 ton status

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    I would like help ya but I dont have a manifold. temp sensor.
    But
    I can tall you this. There is a significant loss of power on my TBI 350 when I tried turning the air cleaner top up side down. And by pasing the factory CAI. This power loss is not as noticeable in the winter. But really shows up in summer when things are hot and the engine is sucking down all that hot engine compartment air. I lost a lot of power towing my boat climbing hills. Flipped the lid back around and it was fine.
    Same thing happend to a guy I know. He spent a bunch of money on a K&N open element air cleaner thingy and filter for his 91 k2500. I told him not to do it wont work with FI.. A few months later he had the stock system back on. Got to say "I told ya so" :D

    I cant really see where the stock system is all that restrictive on my Blazer. I doubt if my modded TBI is sucking more than 530 CFM. Which is about right for a 350 :thumb: The holes on the air box are plenty big enough to feed that much air. But I know that not all TBI intakes are the same. The truck TBI is more restrictive cuz of that big siclencer.
     
    Last edited: Jul 31, 2005
  5. HarryH3

    HarryH3 1 ton status Author

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    My '90 Sub has the side-by-side headlights. It has an air intake tube that goes from the air cleaner to the core support, just to the side of the radiator, near the upper coolant hose.

    I converted it to a dual intake setup by taking parts from a '91 4.3L V6 S-10 from the junkyard. They have the snorkel tube on the drivers side. :laugh: I cut out the part of the housing that includes the intake tube and welded it onto the air cleaner from the Surburban. The 2 aren't quite symmetrical, as the master cylinder is in the way on the drivers side. The intake tube and the air feed tube are turned down on the S-10 for clearance. The S-10 air tube is also somewhat shorter, so you'll need to graft a couple of them together so that the end can reach to the core support. :doah:

    If your '89 is like our '94 Sub, then indeed, the air routing is quite unusual. I removed the large factory air silencer after I found an air tube in the junkyard that would replace it. I had to cut off the end that normally goes to the core support, but then it fit nicely between the air cleaner and the fender. It also sounds awesome when I'm on the throttle! :cool1:
     
  6. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    How DARE you put actual "tech" in The Garage!!! :D
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Yeah there's a 90-91 Suburban in the wrecking yard here, I noticed how the snorkle is setup...draws from above the core support bolt from that support "column" from what I saw.

    I don't think those core supports are setup like the '81-87, since as you mention, the dual headlights would get in the way.

    I ended up knocking the drivers side blockoff plate out, and that's where my TPI draws from now.

    Have to look at the max CFM potential of all the components in the intake tract. The largest restriction is where your loss of flow comes from, so even if you have a great air intake design, if the throttle body (for instance) flows less, you haven't accomplished anything.

    I think I'll go out and see if I can't rig it up to test the hot air issue right now.
     
  8. HarryH3

    HarryH3 1 ton status Author

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    Here's a link to my dual air intake setup:

    http://www.angelfire.com/super/ThunderTruck/tech_articles/dual_air_intake.htm

    A couple of years ago, one of the 4WD mags spent a TON of money on high tech insulating materials in an attempt to keep the incoming air as cool as possible. They wrapped everything in the intake path in the stuff. As I recall, they did pick up a bit of power and mileage by lowering the temp of the air actually entering the engine.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Looks kind of like the one I built for my Olds.

    I've got one for the truck mostly finished in the garage that uses the '81-86 air cleaner and goes to the core support. Need to get rid of that one, no more dual snorkle intakes for me. :)
     
  10. SUBFAN

    SUBFAN 1/2 ton status

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    Will be watching this....I need to set something up for the new 400....
     
  11. opfor2

    opfor2 1/2 ton status

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    I would like to add louvers to my 90 K-5 also. What type did u use and were did you get them. Do you have any pic's?

    Dan..
     
  12. DavidB

    DavidB 1/2 ton status

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    lots of cool air is a good thing. it gets close to 120 here in the summer. my CTD runs way better at night when it cools off to 90 :D
     

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