cost of running

Discussion in 'InsideTopAlcohol.com Tech Questions' started by hydrotherapy, Dec 30, 2018.

  1. hydrotherapy

    hydrotherapy Member

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    I just wondering what the cost of running a alcohol motor per pass,not a all out motor but a 521 with a screw blower at 76% over and running under 9000 rpm about 36 lbs of boost ,bae 5 fat heads bryant crank,tit valves,11.8 cr
    This in a boat that run 5.30 in a 1000 feet
     
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  2. TOL

    TOL Active Member

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    No hole in block, not too bad. Hole in block, bad. Depends what you consider the "costs" to be.
     
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  3. hydrotherapy

    hydrotherapy Member

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    Without putting a hole in the block, normal parts ,rod ,pistons rings bearings springs ,oil ,valves ,lifters,crankshaft,keepers and retainers,push rods and rockers spark plugs wires msd repair ?
    I was thinking about 300 a pass
     
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  4. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    I have a Top Dragster combination that comes out in that range. BAE 5 521 with PSI screw.

    I have taken a little different road to parts life than most. I like to let the blower do the work. When you are running an index class with one of these hemi's, they can make more than enough power, so there's lots of different roads that will get you to the index.

    Rather than a lower overdrive deal that makes just enough boost to get the job done, I would rather make more boost and less compression. We are running close to 50 lbs of boost in the lights. We run more speed than most of the cars in TD with spark plugs that look like they came out of the box. We also have just over 10:1 compression. We drop the pan every 20 or so runs between races. Change rods/rings at 40-50 runs. Pistons and crank at 120 ish. We take a few tenths of a thousandth off in the hone at the end of the year. Shifts at 8500 and crosses around 9000.

    It's not to say you won't get similar life out of a lower boost/higher compression set up but you are going to have to push that combo harder to run the number. Our high boost combo runs to 2.5-3 seconds with 8-9 degrees of timing out of it.

    My 'theory' behind going with the higher boost was using the intake stroke to build cylinder pressure rather than compression stroke. It definitely drops the peak power potential down being under compression-ed but the parts seem to like it.

    Since we are talking hemi's, I think having reliable valve train is also a big part of being able to run on a budget. I'm a firm believer in the theory that one valve train failure prevented will pay for the cost difference in older used rocker assemblies and the newer ones. The older your rocker assembly is, the higher chance of a failure eventually happening. With our Manton Rockers in the TD, we pull the covers once a weekend to check lash and check spring pressure just because we feel guilty. Having a stable cam is also important.
     
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  5. hydrotherapy

    hydrotherapy Member

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    Thanks Will great info
     
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  6. lucky devil

    lucky devil Member

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    So many runs on the rods Will ?
     
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  7. superpro453

    superpro453 Member

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    Wayne - we run out rods maybe a little longer than Will - usually change them every 2 years and the number of runs will depend on how many rounds we've gone. 452ci TFX, early Brad 5s, PSI D at 60% over, 45 lbs boost in the traps. Shift at 8200, 8900 at the line. Drop the pan only if we find anything in the filter. We've only changed the crank after it cracked (but it was 17 years old then). Our valve train is not as modern as Will's, but it's reliable although we do check it every pass.

    Martyn
     
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  8. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    40-50 or at the end of the year. I think the set we just pulled out has 38 runs.
     
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  9. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    When we first started this combo in TD, I was told by someone I trust we "should" be able to go 75 runs on rods.

    I think the first set of rods we put 28 runs on and sent them back to GRP for inspection. Said they looked perfect, couldn't believe they had that many runs on them. So we rotated them back in at some point. The next set we took to 43 runs and sent them in for a proper 'autopsy.' Brian cut a few caps apart to inspect. One rod had some hairline cracks developing in the thin spot between the journal radius and the bolt hole. He said sometimes you can see a bulge develop on the outside of the cap before imminent failure, and these were a ways from that.

    I have also done 'reverse' stretch checks before disassembly and have found they lose about .0003 to .0005 stretch after 20 or so runs.

    I don't typically check the main bearings on that motor unless I see an issue, so they stay in until freshen up. What I have had happen on both of his motors is find a side bolt snapped off in the shop or in the trailer. One was the old style course thread, one was the newer fine thread. I really haven't pin-pointed what is the cause, but I loosen and retorque the side bolts when I check the rod bearings now. So far haven't had any more issues.
     
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  10. GregM784

    GregM784 Member

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    I too believe your money is WELL SPENT under the valve covers.

    I've seen so much beautiful hardware ruined by poor valve train / valve train issues.

    My blown SBC gets rods @ 100 passes, but we keep it below 8000rpm
     
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  11. Jason Green

    Jason Green Member

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    With a screw combo, what's considered high compression?
     
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  12. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    Depends on your overdrive and to a lesser degree heads
     
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  13. Jason Green

    Jason Green Member

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    I understand that, I guess I was looking for a range, or maybe a "do not exceed under penalty of melted aluminum" lol
     
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  14. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    Well that's kind of a loaded question.

    Here's a point of reference - TAD's with D rotors at 128 over used to be low to mid 10's in compression. TAFC's used to be in the 11's at 92 over. Now with the cylinder heads we have now and the camshafts that go with them, there has been a shift of more compression of .5 to 1 full point in many screw cars. The fuel system/timing window gets much smaller as compression goes up.

    Also remember compression is not a horsepower knob.
     
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  15. TOL

    TOL Active Member

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    Thanks Will. That is interesting information.

    Question if I may.........

    TAFC or TAD, do you know if people are still using "insert plates" with their screws, or has this been pretty much abandoned as a fad? Thinking along the lines of the DMPE or Cantrell inserts.

    My new C-screw is supposed to arrive tomorrow. Looking forward to thrashing it thoroughly. Andy & the people at PSI are great to deal with now!
     
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  16. kosky racing

    kosky racing Comp Eliminator

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    READ YOUR LAST SENTANCE_NOW?
     
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  17. TOL

    TOL Active Member

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    I don't understand?......... Did I miss something here?

    Fantastic relations with PSI. Not like Roger days.

    What did I screw up this time?.

    Thx.
     
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    Last edited: Jan 8, 2019
  18. tad1011

    tad1011 Member

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    Until it needs to be recertified
     
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  19. TOL

    TOL Active Member

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    ?????...........

    What do you mean by this?
     
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    Last edited: Jan 8, 2019
  20. rb0804

    rb0804 Active Member

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    Here’s how the insert deal went down, NHRA polled active teams to see how they felt about running the insert, if it had a performance advantage, etc. Heard nothing about it for awhile then a few months later they come out with a ban on them effective next season (this is how my memory serves but I’m not as young as I used to be). Rumor has it they were outlawed due to the fact that they interfered with the rear nozzle holes in the case. NHRA would pull the rear nozzles and slide a dowel rod in there, if it passes through you are legal and have a D rotor. If the dowel rod hits an obstruction, say like a rotor, you have a C rotor which is illegal for the class. This is what I “heard” and have never had our blower checked this way.

    Short version of the story, no one runs an insert anymore because they are illegal in TAD and TA/FC.
     
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