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Thread: Poor Performance When Hot

  1. #21
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    A big part of keeping the coolant temperature low is to be able to run more ignition timing and make more power. Or at least consistent power from run to run.

    Years ago, I ran a dragster that didn't have a radiator or water pump at all, as most did and still do. The normal procedure in any weather was to dump the coolant between runs. Sometimes twice. And no way could you "hot lap" that kind of car especially in the summer.

    Also, spraying the radiator with water between runs is useless unless you are circulating coolant. That's why most doorslammer race only cars have an electric water pump that can be run when the engine isn't running and generating heat. Unless you go to a lot of trouble these pumps don't push the kind of flow that a stock style belt drive pump will. And often, it's shut off during a run, as it won't make any difference in the few seconds that it takes to make a pass.

  2. #22
    Registered Member chevynut's Avatar
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    Quote Originally Posted by 55 Tony View Post
    You evidently do not understand what I wrote about air/fuel ratio. Also, a turbo does not use exhaust heat to force more air, it uses the flow of the exhaust top power itself. Don't some have intercoolers? That's because heat is bad. If the turbo runs cooler it works better.
    You evidently don't understand thermodynamics. A turbocharger utilizes waste energy in the exhaust and turns it into work, to pump air into the intake and increase efficiency and power. If it wasn't there, the exhaust would go out the tailpipe anyhow.

    And you're confusing engine temperature with inlet air temperature. An engine "sees" the coolant temperature and ambient temperature has little effect on it. Colder air is more dense, therefore you get more oxygen into the engine and you can add more fuel, or the fuel that's there will produce more power due to more complete combustion. Every gasoline molecule that combines with an oxygen molecule increases the combustion energy and therefore the power. The point is, the engine ambient temperature has little effect on performance with a constant inlet air temperature.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


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  3. #23
    Registered Member chevynut's Avatar
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    Quote Originally Posted by Rick_L View Post
    A big part of keeping the coolant temperature low is to be able to run more ignition timing and make more power. Or at least consistent power from run to run.
    Yes, that makes sense if more timing advance is needed or beneficial. But how much more timing can you add at 160 versus 180?

    I don't believe Tony's problem, if he even has a problem, is due to engine temperature or under-hood temperature.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
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    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  4. #24
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    Quote Originally Posted by chevynut View Post
    Personally I think it looks fine, but I would have used regular tubing instead of that corrugated stuff for the actual hose. Are you sure that's titanium? Why would it need to be?
    It's a titanium alloy. I don't know how much titanium is in it. I'm guessing it's mostly stainless steel, and the good kind since a magnet is not attracted to it. It is made for small chimney flue's, so the alloy needs to be able to take a lot of heat. I couldn't find any other tubing that looked better. Most of it is plastic garbage with 90° angles or the really ugly plastic flex stuff they make for the purpose. K&N makes some ugly stuff. Although under that lid I do have a K&N filter. I do have a piece of big diesel truck exhaust flex pipe that is the same diameter, but it's galvanized and really ugly. I don't know what kind of "regular tubing" you mean?
    Tony

    1955 Bel Air Sport Coupe

  5. #25
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    But how much more timing can you add at 160 versus 180?
    Probably only a degree or two. Maybe a better way to put it is how much do you have to pull out if the engine is hot?

    I agree that something else is amiss other than the weather, coolant temperature, or underhood temperature. We really don't have enough info to help him since there's nothing to diagnose except that he says it feels like it has the power level of a low compression engine. And it's not audibly missing or stumbling.

  6. #26
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    Regarding power with a stoichiometric mixture or a richer mixture..... Maximum energy will be created with a stoichiometric mixture. That means that every molecule of oxygen combines with every molecule of gasoline. If you add one more molecule of gasoline, it won't burn because it has nothing to combine with. So additional gasoline creates no more heat, and therefore no more power. Engines are tuned to be slightly rich at full power to ensure you have enough fuel to consume all of the oxygen. Unburned fuel is wasted out the exhaust. A too-lean mixture can run too hot and cause detonation and engine damage. A slightly rich mixture cools the combustion chamber so detonation isn't as likely. The cooling effect can also facilitate adding more timing advance as Rick pointed out, which may allow it to make more power.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  7. #27
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    I don't recall the fuel Tony runs, but to run good in heat you must run a good quality race fuel with a 10-1 BBC.

  8. #28
    Registered Member chevynut's Avatar
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    Quote Originally Posted by 55 Tony View Post
    I don't know what kind of "regular tubing" you mean?
    I mean mandrel bends, either aluminum or stainless.....

    https://www.ebay.com/sch/i.html?_fro...bends&_sacat=0
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  9. #29
    Registered Member chevynut's Avatar
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    Quote Originally Posted by markm View Post
    I don't recall the fuel Tony runs, but to run good in heat you must run a good quality race fuel with a 10-1 BBC.
    If the engine isn't detonating, higher octane won't make any difference. You can actually run too high of octane and reduce performance since higher octane slows the burn rate so it doesn't detonate and produces more even burning. Race gas has the same energy content as any other gasoline (as long as there's no ethanol in it) and some very high octane gasolines actually have slightly less energy content than pump gas. It's resistance to detonation is big difference.
    Last edited by chevynut; 06-14-2018 at 09:15 AM.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  10. #30
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    Quote Originally Posted by chevynut View Post
    Regarding power with a stoichiometric mixture or a richer mixture..... Maximum energy will be created with a stoichiometric mixture. That means that every molecule of oxygen combines with every molecule of gasoline. If you add one more molecule of gasoline, it won't burn because it has nothing to combine with. So additional gasoline creates no more heat, and therefore no more power. Engines are tuned to be slightly rich at full power to ensure you have enough fuel to consume all of the oxygen. Unburned fuel is wasted out the exhaust. A too-lean mixture can run too hot and cause detonation and engine damage. A slightly rich mixture cools the combustion chamber so detonation isn't as likely. The cooling effect can also facilitate adding more timing advance as Rick pointed out, which may allow it to make more power.
    That is not correct. Also I was way off with my 10:1 to 11:1. Looks more like 12.8:1 for max power.
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    Last edited by 55 Tony; 06-14-2018 at 09:31 AM.
    Tony

    1955 Bel Air Sport Coupe

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