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Why 1.94s instead of 2.02s?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by weisel, May 4, 2001.

  1. weisel

    weisel 1/2 ton status

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    Why do 1.94 heads produce more torque than heads with 2.02 valves? The same reason for a RV cam procuces more low end power than a high lift cam? Wouldn't more flow produce more power over all?

    Insurred by Smith & Wesson
     
  2. Blazer79

    Blazer79 1/2 ton status

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    I'm no expert, but I'll try to explain it as I understand it:

    The engine needs a certain amount of airflow, depending on RPM. When RPMs are high, you need big valves to allow lots of air into the combustion chamber quickly.

    If you have low RPMs and big valves, air would move too slowly into the combustion chamber. Slow enough to allow the air and fuel molecules to separate, giving you an un-equal mixture. This is not as efficient as having smaller valves moving air quickly into the combustion chamber.

    I picture it as if there's an ideal range of speed to allow the air/fuel mixture into the combustion chamber. You'll need the appropriate valve size for your RPM application.

    <font color=blue>//////
    <A target="_blank" HREF=http://blazer79.coloradok5.com>http://blazer79.coloradok5.com</A>
    </font color=blue>[​IMG]
     
  3. Twiz

    Twiz 1/2 ton status

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    This is one of those "ask 10 people, get 10 different answers"
    -most of those would be corrtect- it's all about perspective I think.

    Heres my perspective;

    It's all about VELOCITY. Intended r.p.m. range, and keeping the atomized fuel in the air stream. Also depends on the cyl. head style. (port flow/vavle shrouding/tumble and swirl etc.)

    It's all a system, and it all works togather.

    Twiztid
     
  4. WOODYJ

    WOODYJ 1/2 ton status

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    I will give you personal experience example. I put 202-160 heads on a 383 I built up for my Blazer for torque. Well it just didn't have crap for guts! I got to talking to the "People In The Know" and they said that the 202's don't come into play unless you are 5000RPM's or above. I ended up rebuilding a set of 305 heads due to the small combustion chamber and small weird sized valves, and now the ole Blazer screams-guess I better say it groans but it has 10 times the torque and get up and go on low end as when I had the 202's on it.

    k5woody

    k5woody I Don't Understand The Jeep Thing Either!!!
     
  5. Pure Insanity

    Pure Insanity 1/2 ton status

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    watch out for 305 heads they have tiny combustion chambers and will raise the comp. ratio,and as you said strange valve sizes.IOM go w/ vortec heads,you cant beat the price,i seen them in jegs in the new catalog for like 4??.??a pair(they price them each)as an added bonus ive been told they will out flow the old 202 heads and you dont lose torque.i run them on mine and they perform well.the only drawback is they take a different int. man.they say you can get them drilled to accept early man. but the runners are higher than the early man.so i went w/ a vortec spec. man.look into them they are killer heads.just about every magazine did vortec head builds and they all got great results!![​IMG]

    PURE INSANITY
    86 blazer see it at:<A target="_blank" HREF=http://www.zing.com/album/pictures.html?id=4292792569>http://www.zing.com/album/pictures.html?id=4292792569</A>
     
  6. ftn96

    ftn96 1/2 ton status

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    You are all correct. Its all about Velocity and Volume. Again all this depends on what RPM range you want the motor to wake up. And 2.02 heads are too high range for torque.
    Those vortecs are about 499.99. The is a vortec conversion kit. Little pricy but it is 1099.99 from Pace parts. Comes with the heads, intake, gaskets, everything you need. Should give about 40 more ponies straight out of the box.

    Will work for beer, parts and tools.
    90-350TBI-TCI700-241-33"-10/12 bolt w/4.10's,
    <A target="_blank" HREF=http://www.nashvillek5.freeservers.com>http://www.nashvillek5.freeservers.com</A>
     
  7. timebomb1602

    timebomb1602 1/2 ton status

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    Heres a link to a site with VORTEC heads <A target="_blank" HREF=http://www.sdpc2000.com/default.htm>http://www.sdpc2000.com/default.htm</A> Hope this helps!

    <font color=red>1991 GMC Jimmy 350tbi 3.42</font color=red>[​IMG]
     

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