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Upper / lower pulley combo

Discussion in 'Engine/Tuning' started by Frankycheechoo, Nov 28, 2019.

  1. Frankycheechoo

    Frankycheechoo Member Established Member

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    I’m thinking of installing a lower pulley to help boost up the torque is what I hear .
    What’s the best combo ? I’m not going to ever port the blower but eventually add a bigger one .
    Right now I have a 2.76 upper
    Cai, x pipe Borla ATAK and tune 480/470
    If I go with a 4lb lower does it mean I have increase the size of my upper unless it’s ported ??
    Pls post some results to ..



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  2. e85svt

    e85svt Member Established Member

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    Most that go with a 4lb lower pulley are ported. Unless you run a fuel system and are on e85 I wouldn't add a lower pulley to your current upper. Though you could opt for a 2lb lower and pulley up. Full bolt ons with the 2.76 upper is right around the max (450-475) with an unported eaton. Any more boost and you start spinning it a little to fast thus creating heat. The 2.93 upper and 4lb lower is a very popular combo for ported blowers and can make anywhere from 500-525 rwhp.

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  3. Frankycheechoo

    Frankycheechoo Member Established Member

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    So if I go 2.8 upper and 4 or 6 lower and stay stock it’s not good ?



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  4. olympic

    olympic Well-Known Member Established Member

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    Spinning the blower too fast just makes more heat than power.
     
  5. e85svt

    e85svt Member Established Member

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    Not on the stock blower as it's not efficient enough. A 2.8 or 2.93 upper and 2lb lower would be ok for an unported blower on pump gas. But if going with a 4lb or 6lb porting the blower would be highly recommended.
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  6. Frankycheechoo

    Frankycheechoo Member Established Member

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    Ok that sounds about right for a combo would like to see what kinda numbers or difference it would be if it’s a big difference I would go with that otherwise just stay stock until bigger blower .


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  7. stangfreak

    stangfreak Well-Known Member Established Member

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    so you would recommend people who are running a 2.80 upper to run a 6lb lower? Thats 20lbs of boost being shoved through a little eaton m112. so what if its ported. You are still spinning the blower at x amount of rpm regardless. The heat will be insane. Not only the heat, but you are lowering the efficiency of the eaton big time. yea the eaton in certain situation run hard being a little overspun. For example, when we run a 2.80 upper or a 2.76 upper we make more tq than hp. That means the blower is being overspun. But it runs well.

    Most of us street our cobras. If you are cruising around having fun looking for a race or come across a race, one pull and your car is toast. Maybe if you are at the track and ice down the blower and wait between runs I can MAYBE see a aggressive pulley combo. I just feel the power will taper off up top and not be productive.

    shit even twinscrews run of out efficiency. I ran my 2.9 at 25lbs of boost on stock motor and it made zero power than my 22lb setup. It made nothing. You also have to consider the motor. stock motors can only do so much. whats the point of running the eaton with a 2.80 upper 6lb lower ON A STOCK MOTOR? lol

    I had a 2.80 upper 4lb lower and removed it. My car started to run better with a 2.80 upper 2lb lower. I had 20 different pulley combos.

    my friend john venomous03cobra who is still on the eatons fastest list which is posted in the sticky section, had a 2.76 2lb lower that ran the fastest time. it ran faster than his more aggriessive pulley combo. Is it a coincidence that his car ran faster when he dropped the boost on his eaton?
     
    Last edited: Dec 1, 2019
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  8. stangfreak

    stangfreak Well-Known Member Established Member

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    franky, back in 2004, my tuner told me, if you listen to everything on the internet you will end up "having" a 1,000rwhp cobra with a ported eaton. People make a million hp on there dyno with a upper only and 2 degrees of timing. Thats why my tuner never got involved with posting on the forums. I have owned my cobra for 16 years. I have seen and driven every combo you can think of.

    Also, the lower pulley doesn't magically increase tq. You are increasing tq bc the blower is being spun harder. The lower pulley was made to increase belt wrap. For example, according to pulley size and boost, if one cobra is making lets say 16lbs of boost with a upper only and another cobra has a upper lower pulley combo making 16lbs of boost, both cars wll make equal tq. Both cars will be spinning at the same rpm. That was just an example.

    This is just advice from what I have learned. Hanging out with jimmy vaccaro ( the god father of mustangs ) venomous john, aj, and conversing with the pioneers of the cobra world who no longer post on the internet, this is what I learned. just advice bro. end of the day its your car and you hve to be happy with it.

    2.80 upper 2lb lower. That is all you need. If you are not happy with that, then a ported eaton is not for you. skip it and go with a twinscrew or a tvs.

    Im a cool guy and sorry if my posts come off badly. Its just after owning this car for close to 17 years I just get tired of seeing the same stuff. can I buy a 4.0 whipple and run 18 lbs of boost on 91 octane? or man my car is crazy. I have a 2.60 upper a 10lb lower. Its just good for one pull but damn I lost the race bc of heat soak. Nothing is be re invented. This stuff has been done back in 2003. Ye the advice people give is like its being created again for the first time. stick to what works
     
    Last edited: Dec 1, 2019
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  9. stangfreak

    stangfreak Well-Known Member Established Member

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    my boy venomous way back in the day when brian from apten was doing the first ever ported eatons. No crazy lower combo.

     
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  10. Frankycheechoo

    Frankycheechoo Member Established Member

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    Well that video is extremely impressive dam !
    So basically 2.80 or 2.90 is good with a 2lb lower but won’t be a huge difference from just staying with a 2.76 upper ??? Is that what it comes down too ??
    Or is it worth it to just go 2.8 and 2 lbs lower ?? Yes or no ?
    What would I gain from what I have 10-20 hp/tq ??
    Thanks for the reply


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  11. e85svt

    e85svt Member Established Member

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    Yes some have ran the 2.93 upper with the 6lb lower on an max effort e85 set up. It's the most I would go on an ported eaton period. 2.8 and 6 lb is overkill.
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  12. e85svt

    e85svt Member Established Member

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    A 2.8 upper and 2lb lower is ok on an unported eaton. However spinning that fast or any faster will create more heat.
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  13. CobraBob

    CobraBob Authorized Vendor Premium Member Established Member

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    My Eaton ('03 Cobra) was one of the first 3 Apten ports done. Just an FYI. Apten didn't actually port the Eatons. Bob Steigmeier did the porting.

    I remember (Uncle) Jimmy Vaccaro and the other guys from back in the day. That NYC group was infamous. Jimmy (and Dom) were awesome. They had their own Terminator forum site for awhile.
     
  14. apex svt

    apex svt MEAN STREAK Established Member

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    I’d personally run just a 2.8 on a non ported Eaton.
    Heat kills, I run a 3.1 8#lower (same as a 2.76 4# lower) ported and it gets stupid hot. We picked up over 30hp on the dyno from icing the car down, no changes to the tune. So in all reality when I street drive my “500hp” car it’s really 450-470 because it’s going to lay over.
     
  15. 01yellercobra

    01yellercobra AKA slo984now Established Member

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    I ran a 2.8 upper on my stock eaton for a few years and thought it was a good set up. At least with the Accufab throttle body and plenum. I could usually get a few runs in with my friends before the IAT's would creep into the 130's.

    I'm kinda missing that set right now to be honest.
     
    Last edited: Dec 6, 2019

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