300hp can it be achieved...?

Discussion in 'St. Louis Area SHO Club' started by illSHOyou, Nov 11, 2007.

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  1. illSHOyou

    illSHOyou Active Member

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    I've spent a long time today looking at old threads and came across the infamous 300hp n/a. Thats another one of those touchy topics like electric supercharging, but anyway back on subject.

    There seems to be an opinion that the SHO intake can only support up to 7,000 rpm before drastically falling off. Lets assume that at 6,500 rpm power is starting to fall off indicating that the engine is struggling to breath the necessary air flow required to continue building horse power. Chances are that vacuum inside the intake around 5,500-7,000 rpm is increasing rapidly. My question is simple...Why not open another valve?

    The patent on the SHO intake is easily accessible. Every time the engineers started to see vacuum in the manifold they simply opened another valve to another set of runners. A second patent yamaha made did exactly that, open another valve. The problem here is that manufacturing wins out in the end and the cheaper yet still affective intake wins out over the more complicated one.

    For shits and grins lets say another valve was hypothetical installed on the SHO intake that opened at 6,000 rpm. I would be willing to bet that hp may continue to build close to 7,000 rpm. There are limitations though. Unfortunately at 6,500 rpm we are starting to see limitations in the head flow and valve lift. With that said though would could still potentially move the curve a little higher.

    I personally have a problem with a lack of header for the SHO,and influences like HUGE BBB that might not really show any more potential, and look at the time spent to create them. Not to say that HUGE BBB are not neat, but what about an additional set of runners controlled by a valve? As far as headers there is no way one could even think of achieving 300hp with the stock exhaust manifolds. Why not focus a good portion of money into a well desgined anti reversion stepped header?

    Just some thoughts I am throwing out there...
     
  2. 1993MTXSHO

    1993MTXSHO Its a Taurus...

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    EH and BBB'ed intake is fine for 7k rpm and even more, and as far as making 300hp n/a yeah you can its not to to hard, but thats flywheel, if you mean wheel, get everything possible like I am and you will still probably fall short at 275 wheel or something like that. This is also assuming you arnt making a stroker, a 3.6L I think can make 300 wheel.
     
  3. St Louis SHO

    St Louis SHO Rollin' coal Staff Member Club Mod

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    300 n/a is possible at the crank, not at the wheels though. 7000 rpm is the limit on stock valve springs, they have been known with good springs to turn more like 8-8500. Of course cams would be a must. The stock exhaust manifolds on these cars are engineered very well. I have yet to see a blower SHO running headers, and they can make upwards of 500+ HP. Headers will hurt low end TQ and I'll prove it with my SS Long tubes I have.

    James
     
  4. illSHOyou

    illSHOyou Active Member

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    How do we know 7,000 rpm is the limits of the valve springs? We would expect to see bad activity like bounce. With a 7,300 redline I wouldn't expect to see valve problems till maybe the 8,000 rpm area. If someone were to spend some time with header design those new stepped headers are the way to go. The stepped design doesn't hurt you in the midrange tq and your top end screams. Its one of the very few automotive best of both worlds designes.

    After looking over the patent again, yamaha added another tube that dumped into each endtank about midways with a smaller total cross-section area than what feeds them now and the car made better maximum bhp. I would guess between 6,500-7,500 rpm falling at 8,000rpm.
     
  5. egroce11

    egroce11 New Member

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    Bull, 300 hp is possible at the wheels n/a. The headers that Shobros puts out is fairly good, you just need an exhaust system thats going to help them evacuate the exhaust.

    I'm not saying one way or the other that our intake is a restriction, but I know that there are 200 mph cars running that only have an intake that is under 3 inches in diameter.

    And it is possible to get an N/A sho to spin like a small blower car.
     
  6. Phoenix

    Phoenix SHOHOLIC

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    Im expecting the 300 crank HP with the mods in my sig , I will dyno it this spring , headers and accel super coil will be added to the list.
     
  7. SuperchargedSHOguy

    SuperchargedSHOguy Got 1000 hp?!? Staff Member Club Mod

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    There are a couple of them actually...
     
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  8. SinisterSHO

    SinisterSHO Rust free

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    3.2 with stage 2 cams, head work and the rest of the bolt ons will get you 250 whp which is in the area of 300 crank.

    However, I think with an increase in compression, some headers with a well designed exhaust, and some tuning 300 whp is possible. However, yes, your car is going to lack low end torque. But I dont think an engine like that is being built strictly for street use.
     
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  9. SASHO91

    SASHO91 Zoom Zoom

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    I disagree.
    My buddy, whom which happens to build race motors(which he went to school for... AND turned down a job @ Nascar), has run the math on the stock springs, said that you wouldn't get valve float till around 9000-9500 (I forget the actuall number) with stock valves.
     
  10. St Louis SHO

    St Louis SHO Rollin' coal Staff Member Club Mod

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    Math don't mean shit here. You're telling me a set of 100,000 miles valve springs are gonna handle 9k?



     
    Last edited: Nov 11, 2007
  11. SASHO91

    SASHO91 Zoom Zoom

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    My 180k valve springs handled 8050RPM's just fine, MANY times.
     
  12. SuperchargedSHOguy

    SuperchargedSHOguy Got 1000 hp?!? Staff Member Club Mod

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    Yeah, I have to agree that you will not see 9000rpms without float on these springs. 8K was what I have seen and heard about.
     
  13. SuperchargedSHOguy

    SuperchargedSHOguy Got 1000 hp?!? Staff Member Club Mod

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    Just cause they "handled" it does not mean there was not any float involved. I would not run 8000 on any of my SHOs with the stock springs...
     
    Last edited: Nov 11, 2007
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  14. SASHO91

    SASHO91 Zoom Zoom

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    Don't shoot the messenger.... :oogle: He used to be on the forum, JoshM was his screen name.
     
  15. St Louis SHO

    St Louis SHO Rollin' coal Staff Member Club Mod

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    Is that why its borked?

     
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  16. SASHO91

    SASHO91 Zoom Zoom

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    I didn't hear any... however, that does not, in any way, mean that there was not.
     
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  17. SASHO91

    SASHO91 Zoom Zoom

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    That has nothing to do with that problem. I smashed a bearing, farting around with the nitrous system while the car was off.... but that's not the topic here.
     
  18. SinisterSHO

    SinisterSHO Rust free

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    :rofl: really puttin that 'race motor school' to good use, eh?
     
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  19. SuperchargedSHOguy

    SuperchargedSHOguy Got 1000 hp?!? Staff Member Club Mod

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    In theory and in real life are 2 different things. There are a few guys on here that know when valve floats from experience. New springs designed for the higher rpms are the added security to run past 8000rpms.
     
  20. SASHO91

    SASHO91 Zoom Zoom

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    Wow, your'e cool... making fun of a third party that isn't even here, let alone doesn't even know we're talking about him... :rolleyes:

    And I wouldn't be running your mouth about someone "putting that race motor school to good use".... you know what I mean. :wave:

    EDIT: Sorry for the hijack.
     
    Last edited: Nov 12, 2007
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