GM LFX V6

Discussion in 'General Auto Conversion Discussion' started by pfarber, Apr 26, 2019.

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  1. May 14, 2019 #81

    pfarber

    pfarber

    pfarber

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    Are you serious? LOL like I would be stupid enough to post anything about myself. For example, I say I have 900 hours and some nutter says something stupid like 'well I have 901 hours so I know more than you'.

    If you want to discuss putting a car motor in the front of an E-AB I'm all ears. If you want my tinder/grinder/GothicMatch.com profile I'll politely have to refuse.
     
  2. May 14, 2019 #82

    Toobuilder

    Toobuilder

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    Yes, I'm serious. I don't give a **** about your SSN or gender identity, but it would be useful to know if you have any time managing an aircraft engine because it appears that you have some "unusual" thoughts on the subject.

    This is an airplane forum. Do you have any time flying or not?
     
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  3. May 14, 2019 #83

    pfarber

    pfarber

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  4. May 14, 2019 #84

    pfarber

    pfarber

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    Hmmmm....

    1. Participate - Be yourself, have fun, invent, innovate, chat, plan, day-dream, and enjoy any other activity associated with this wonderful sport.

    2. Respect Others - Personal attacks are strictly prohibited. Its fine to debate and challenge one another’s ideas, but when the discussion turns personal it’s no longer acceptable. What crosses the line will be left to best judgment of our exceptionally good looking and hard working moderators.

    Wow you got two birds with one stone. Sad that some people cannot simply talk about ideas. And reported, just in case you were wondering.

    I will not post any personal information. I don't care how many forum posts you have or who you are. My ideas stand, or fall, by their merits.

    Please don't post if you don't have anything engine related to say.
     
    Last edited: May 14, 2019
  5. May 14, 2019 #85

    poormansairforce

    poormansairforce

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    Wrong! They specifically tested 1 electric pump and 2 mechanical pumps. And the alternator was not hooked up while testing the pumps. Read your own info! They only added it at the end while using a mechanical pump.

    Quote from the article:
    We swapped the Trans-Dapt parts for the March Performance underdrive pulleys and regained almost all of the lost performance from the mechanical pump. The dyno kicked back 530.8 hp and 474.1 lb-ft on average, almost making the mechanical water pump and underdrive pulleys the Meziere’s equal in power.

    And when you add in the power needed from the alternator you'll lose more power with the electric! Always remember that they are selling something to the gullible.
     
  6. May 14, 2019 #86

    Toobuilder

    Toobuilder

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    You think that was a personal attack? Far from it. Simply trying to get a sense of your frame of reference.

    Anyway now I'm done. That's what, 5 bridges burned in 2 days? That must be a forum record!
     
  7. May 14, 2019 #87

    Voidhawk9

    Voidhawk9

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    Don't feed the trolls. The intent of the OP is abundantly clear at this point.
    Also useful, click the offending user's name, then look on the right side of the screen that comes up for the 'ignore' option.
    Have a happy day. :)
     
  8. May 14, 2019 #88

    pfarber

    pfarber

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    Please stop buggering up the thread with non-motor related posts. You don't like me? Cool. Have a nice day.
     
  9. May 14, 2019 #89

    BJC

    BJC

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  10. May 14, 2019 #90

    pfarber

    pfarber

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    https://www.hotrod.com/articles/hrdp-1201-baseline-testing-do-water-pumps-suck-power/ Is the article.

    Meziere electric pump and no other accessories, the small-block put out 531.2 hp at 6,600 rpm and 475.9 lb-ft of torque at 5,300 rpm

    We bolted on the Weiand Action Plus water pump and Trans-Dapt 1.0:1 billet aluminum pulleys and found 527.5 hp and 474.5 lb-ft of torque at the same rpm points, resulting in a loss of 3.7 hp and 1.4 lb-ft

    March Performance underdrive pulleys and regained almost all of the lost performance from the mechanical pump. The dyno kicked back 530.8 hp and 474.1 lb-ft on average, almost making the mechanical water pump and underdrive pulleys the Meziere’s equal in power.

    When we swapped to the GMB water pump, using the March underdrive pulleys, we recorded an average of 523.1 hp and 470.9 lb-ft of torque, 8.1 hp less than the Meziere electric pump

    Conclusions
    The lightest and most powerful combination of parts was the simplest–the Meziere electric water pump

    Now this is the hard part to comprehend. The electric water pump will flow max GPM no matter the engine RPM. Are you really going to consider an UNDER DIVE pulley to cool you motor while taxiing?? REALLY? So I ignored the one case that would have had serious consequences... low cooling flow at low RPM.

    I know now everyone is going to see this (well, considering how few read the article)

    "The alternator ate up 8.1 hp and almost 4 lb-ft of torque."

    But this is a red herring, and I'm not sure how or what this was supposed to prove. There is no way it costs 8hp to make 12V 8 amps. The Dyno tests initially did not have an alternator installed. Yes. So the tests were not perfect. But who here is going to remove their alternator??? Anyone?? They also did not run the water pumps WITH an
    alternator.... and the conclusion is still valid.

    From Weilands web site:

    https://www.meziere.com/Products/Co.../Electric-Pump-Center-Section-100-Series.aspx

    Amperage draw: Under normal use the pump will draw 6-7 amps
     
  11. May 14, 2019 #91

    wsimpso1

    wsimpso1

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    Well, here is one. https://sites.google.com/site/tailwindn999br/olds-v8-engine

    Steve's plans direct us to make an extension housing out of a manual trans/bell housing to take thrust loads and much of prop moments. It looks like the device to make a direct drive work is a big fraction of the mass of popular PSRU. Then there is the whole issue of putting the prop so low on the engine, so you end up either with the engine way high on the airframe or figuring out how to run it inverted.

    Billski
     
  12. May 14, 2019 #92

    poormansairforce

    poormansairforce

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    Ah, the fine print always weeds things out:

    16 volt systems: The 12 volt pump will work for limited use applications. The pump should not be powered while charging your 16 volt system

    No wonder they never ran it with an alternator.
    And:

    Standard motor provides 35 gallons per minute free flow rating

    No free flow situation in a motor, always back pressure. Good luck.
     
    Last edited: May 14, 2019
  13. May 14, 2019 #93

    mm4440

    mm4440

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    I believe automotive alternators are not great in efficiency (50% ?) and motors can be 90%. Belt drive is about 90+ %. Given equal water pumps, there is no way the electric drive can out perform the belt drive. The electric drive is just not moving as much water and I suspect it is running off a battery and not the alternator. Reliability, cost and weight are higher. I can see advantages to an electric pump in series with an underdriven belt driven pump. When there are suitable OEM electric pumps available, consider them.
     
  14. May 14, 2019 #94

    poormansairforce

    poormansairforce

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    BTW, your going to need at least 125 gpm to cool a 250 hp engine at full throttle assuming a 20° delta across the radiator! Your not even close which pounds home the point of drag applications where the system can cool off between floggings. And now you know why pumps absorb the hp that they do.

    Edit: changed 175 to 125
     
    Last edited: May 15, 2019
  15. May 15, 2019 #95

    pictsidhe

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    I make it 63gpm, assuming cooling load is the same as the power output. That is also a rather small delta.
    35gpm free flow for a 500hp motor is definitely inadequate, though.
    Math time!
    Get back in your seats, boys and girl!
    I don't like elvish, so I'm going to be using the black speech. Stop cringing at the back!
    35gpm is 2.2 l/s. We don't know thew flow characteristics, so lets be generous and assume no flow drop in actual use.
    Plucking 20kPa out of my backside (3psi for you heathens) as the pressure drop, the power to pump the water is an amazing 44 Watts. the 8A 12V pump would therefore be 46% efficient. Pulling 80% out of my backside as the motor efficiency, that's an impeller efficency of 57%. That's about right for a reasonably well designed centrifugal pump.
    But, what about the mechanical pump?
    Pay attention Smithers, strange as it may seem, maths may actually be useful to you one day!
    It supposedly ate 8hp, or 6000 Watts. To do 44 Watts of work? 0.7% efficient? That's truly appalling. Something is seriously wrong there.
    I have no idea how to even start to design a centrifugal pump with less than 1% efficiency, maybe one of the water pump gurus out there could clue me in? The least efficient water pump that I have designed and built managed 22% efficiency. That one had no moving parts and a construction error, I was hoping for high 20's...
     
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  16. May 15, 2019 #96

    poormansairforce

    poormansairforce

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    Your probably technically correct but if your taking off on a hot day with a smallish radiator optimized for cooling and drag at cruise speeds all tucked inside a sleek cowling to reduce drag then where does that leave us? I think in that situation a 20° delta is probably generous? After all, we need to design for worst case conditions....

    IIRC, autos have similar deltas and they have large frontal radiators and they are not cruising at 75% power...

    Either way, the idea of saving 8 or 20 hp in an airplane environment just isn't viable.
     
  17. May 15, 2019 #97

    poormansairforce

    poormansairforce

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    Edit: ok, I see my mistake. I wrote 175 instead of 125 gpm. I had doubled my number to be safe since I think the delta could be much lower but wrote it wrong. Sorry about that.
     
  18. May 15, 2019 #98

    pfarber

    pfarber

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    Well I'm pretty much decided that for $170-ish I'll defiantly try the electric water pump while the motor goes through install and testing.

    No one has given me anything close to a reasonable reason why not to.

    I'll post my thoughts and see if anyone has a coherent response:

    PROS:
    Full cooling flow at taxi/climb - most auto conversions struggle with cooling.
    Lighter weight - every pound counts.
    Reduce belt routing - having an alt and water pump would require an idler.


    CONS:
    Will not last as long - easily fixed, assign a 1000 or 2000 hour replacement interval. Its only $170
    Electric motor will stick out farther - might have a fitment issue, motor is taller than stock pulley.
    Not done before in AC - extensive ground testing should give an indication of suitability. Swapping back is 30 minutes of work.

    If I am missing something please let me know.. but I can't see a real downside.
     
  19. May 15, 2019 #99

    BJC

    BJC

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    Is the engine for a BD-4 or something else?

    If a BD, did you build the wing with the bonded skin?


    BJC
     
  20. May 15, 2019 #100

    rv6ejguy

    rv6ejguy

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    You don't need 125GPM to cool a 250hp engine. Plenty of OEMs like BMW have been using electric WPs for years now. Cool their 300+ turbo engines cruising on the Autobahn at 180+ KPH on on a race track flat out just fine. Subaru 6 cylinder 230-250 hp WPs flow around 80 GPM. They are flogged on the dyno at WOT for hours on end. You typically don't see 20F delta on liquid cooled engines in aircraft.
     
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