How much WHP you think a stock Ej257 sti engine block can Handle?

Discussion in 'General Subaru Discussion' started by engstb, Dec 9, 2011.

  1. engstb
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    engstb Well-Known Member

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    Just seeing what people think how much WHP a stock sti block can handle?
     
  2. bikerboy
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    bikerboy Subie GOD Staff Member

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    For how long?
     
  3. engstb
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    engstb Well-Known Member

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    One dyno run
     
  4. engstb
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    engstb Well-Known Member

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    or three ;)
     
  5. readymix
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    readymix ...Lest ye be trod upon... Staff Member

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    And do you care if it runs at all after the dyno run? If it only has to make it through 3 dyno runs, I'd say you could probably get about 800hp out of it. But afterwards, it'll be toast.
     
  6. engstb
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    engstb Well-Known Member

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    Basically looking at doing 3 pulls maxing out at 550
     
  7. readymix
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    readymix ...Lest ye be trod upon... Staff Member

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    Then what? Who puts a motor together just to get dyno numbers? What are you doing after the dyno with it?
     
  8. phi11
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    phi11 Well-Known Member

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    Because racecar?
     
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  9. Subie Lovers
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    Subie Lovers Well-Known Member

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    $10,000 dyno run... every one should do it
     
  10. 4drcivicmaster
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    4drcivicmaster Well-Known Member

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    move to off topic?
     
  11. blackozone
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    blackozone Well-Known Member

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    I'm sorry, but I don't understand this question. What else is there to do with cars besides put them on the dyno?
     
  12. readymix
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    readymix ...Lest ye be trod upon... Staff Member

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    It'll end up there if it doesn't start going somewhere worth a damn.
     
  13. Medic_538
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    Medic_538 Well-Known Member

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    While I am sure he wants to still drive it post dyno runs, I would say it will be limited more to the heads/transmission your running rather than the block. I have no idea what your sti head will take, especially since your information is so limited.
     
  14. readymix
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    readymix ...Lest ye be trod upon... Staff Member

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    The Pistons and Rods are the weak points. The 6 speed can handle some decent power. From a pure power standpoint, yes, the heads will likely need some sort of work in terms of internals. But that is why this thread is stupid, there's no parameters to work within.
     
  15. blackozone
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    blackozone Well-Known Member

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    I think a stock STI block could only handle about 200WHP. I can't imagine driving over the block would be very good for it.
     
  16. fobiawrx
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    fobiawrx Fabiola

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    we make 526 with just pistons at 30psi. been on that all year and no problems so far. beat the **** out of it as much as we can and it takes it. i ran 450-488whp for 2 years on a bone stock motor and had no problems. i spun a bearing at the end of the year on my car do to me not paying attention to the oil temp and pressure but nothing to do with power. i think if you luck out and don't have a ring land fail (i don't think is power related) our motors can take a lot more then people give them credit for.
     
  17. Nuke
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    Nuke Well-Known Member

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    The stock 'block' case can handle quite a bit
    The stock pistons are crappy
    Stock rods are ok
    Stock crank is fine
    Stock bearings are decent

    Problem is, its all assembled by monkeys
     
  18. sneefy
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    sneefy Well-Known Member

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    The OP is getting a nice response from his trolling.

    I vote this thread for most pointless of the day.
     
  19. AWDimprezaL
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    AWDimprezaL has more posts than you

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    Depends on what year shortblock. 2008 +? half a run at 300 whp :)
     
  20. Back Road Runner
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    Back Road Runner Well-Known Member

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    Air flow. The stock engine is only good for flowing a certain amount of air. If you want a simple example of this, you look at the boost curve and then look at the torque curve on any given dyno chart. Flow restriction is when you have constant boost, but you see that torque curve die off. Then you see that hp curve flatten off and sort of stops at this certain maximum. In a very rough sense, 1.45cfm = 1hp. To make 500hp, you need an engine that can flow 725cfm. This means you need an intake that supports 725cfm, a turbo that supports 725cfm, heads, cams, exhaust, etc. all need to support 725cfm. Now the car in its stock design was geared to flow 435cfm (300hp). Now you're asking these same tubes and opennings to flow 50% more, 100% more, or whatever. How does this work? It doesn't. You pretty much need to re-engineer the engine to flow what you want it to just to make the power you seek. You don't just throw a big turbo on and pray to the car gods that hp will magically appear. The big hp cars are the ones with actual re-engineering done. The intake's not stock. heads are not stock. The cams are not stock. The exhaust is not stock. You're modifying the engine to flow what you need.

    So let's say you can flow 10,000cfm easy. What's next?

    Well, for a given fuel type and static compression, you can only shove so much into the combustion chamber before it blows up by itself. Let's say you're stuck at 21psi with a stock STI. 21psi means X torque. We'll just pick 400 ft-lbs at the crank. That's what 21psi produce. Now hp = torque x rmp / 5252. Then it becomes a matter of rpm. Then you run into a revving limitation. Pretty soon you're floating valves or something and not going any higher. Again, let's say that's 7500rpm as that max point. Now we have hp = 400 ft-lbs x 7500 rpm / 5252 = 571 hp at the crank. You can't make more than this without changing something. You simply can't shove more stuff into the combustion chamber without knock, and you can't rev any higher before you float valves.

    So 571 hp is it. Sure, if you can flow enough and rev enough. How do I make more?

    Well...you can change fuel type, say E85 and allow higher compression and more stuff into the combustion chamber. More stuff means more torque. More torque means more hp. If you can make 500 ft-lbs, then you can make 714hp at the same 7500rpm redline. You can also make it rev higher. Make it rev to 9k rpm and the same 400 ft-lbs will produce 685 hp.

    I know all of this is very crude, basic stuff, but there are basic laws that you are bound to. Why do you have 2000 modded STIs all making 350-400hp? This is why. Why do you see certain ones making more power? It's because they actually did some work.
     
  21. anthony mendenhall
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    anthony mendenhall Member

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    He is trying to destroy the motor and move on to bigger and better things. New pistons, rods, and the such. He was just taking your thoughts.
     
  22. Tash
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    Tash Well-Known Member

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    Disappointed op