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Trying to keep my engine cool

Discussion in 'Nitro Engines' started by Scottbot302, Sep 12, 2017.

  1. Scottbot302

    Scottbot302 Active Member

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    Hey all. Savage has been running good ever since i did the tank mod, threw in a Fresh Cold O.S plug. Finally been able to get a decent tune, running a little rich right now actually. But I've run into some problems involving heat of the engine. She likes to get hot really quick, id say around 7-10 minutes depending on temps. I've checked the engine multiple times for air leaks, sealing issues, compression tests, etc. It all checks out, but the thing still gets hot. I've cut out the entire windshield on the original body. I'm getting a new body soon and I'm going to cut holes appropriately. How do you guys keep your engine cool / what are your runtimes? any tips? I'd like to add some runtime that didn't mean stopping every 7 or so minutes.

    P.s - I do a lot of speed runs up and down the street. Full throttle for a run or two, then cool down lap, repeat that and thats usually what I do.
     
  2. coreyh29645

    coreyh29645 Active Member

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    what temps do you get to?
     
  3. Scottbot302

    Scottbot302 Active Member

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    Stopped at 260 F
     
  4. olds97_lss

    olds97_lss Well-Known Member

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    260F isn't too bad on a 80F+ day.

    Too high of gearing will cause it to strain and run hot. Too low of gearing and running at WOT for a long time will also cause it to run hot.

    My engines run between 230-255 all day long when it's 80F out. I don't do anything special other than be aware of my gearing in regards to how the engine is doing with it.
     
  5. Scottbot302

    Scottbot302 Active Member

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    I'm running a 17T clutch bell and stock spur which I think is 60T. However, It appears my clutch bell seems to rub against the spur a little bit when it should spin freely. need to look in to that... seems fine when running though.
     
  6. Jam Racing 1

    Jam Racing 1 NPTB Monitor, Master of the known universe.... HPISF Staff

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    The spur should be like a 46, 47, 48 or possibly a 52 if is an XL, and any undue rubbing by the spur/ bell will cause heat buildup to be a factor in engine temps...

    Is your gear mesh too tight perhaps? you need just a tick of play between the bell and spur when holding the bell still and rocking the spur slightly...

    Maybe a clear pic or 2 will help someone see something amiss so please post if you can....
     
  7. Scottbot302

    Scottbot302 Active Member

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    Gear mesh is fine, but i think its a 47T actually. Its the steel spur the truck came with. When I was rebuilding the entire clutch, I got a new collet, cranked that thing down as hard as i could and the flywheel seemed like it was farther away from the block then it was before. Starting to think thats whats giving me this heat problem, but I don't know how Id solve it... suggestions???
     
  8. Jam Racing 1

    Jam Racing 1 NPTB Monitor, Master of the known universe.... HPISF Staff

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    Pics are going to help alot if you want suggestions
     
  9. olds97_lss

    olds97_lss Well-Known Member

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    What fuel are you running, what pipe and engine?
     
  10. Scottbot302

    Scottbot302 Active Member

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    20% O'Donnells, Hpi polished Aluminum Performance Pipe, Gen 2 F4.6. I've noticed that my clutch bell is looking pretty worn down. I'm thinking I may just upgrade the clutch and clutch bell while I'm waiting for winter to role around... Any suggestions of what to get?
     
  11. Jam Racing 1

    Jam Racing 1 NPTB Monitor, Master of the known universe.... HPISF Staff

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    I am using the Robinson Racing spur (48 tooth steel wide) and the hard clutch bells and HPI Savage XL Alloy shoes and 1.0 springs and LOVE the performance and toughness of these parts....
     
  12. olds97_lss

    olds97_lss Well-Known Member

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    I use the same as Jam Racing 1, but I use an HPI 47T steel spur.

    Forgot to ask, what wheels/tires are you running?

    You may want to try a medium plug instead of cold. Usually you don't use a cold plug unless your running 25%+ nitro.

    I run byrons race 25% with odonnel purple plugs and all my engines like a medium temp plug the best. With 20%, you would want a medium or hot plug I would think.

    Plug temp changes the combustion timing. It doesn't have any real relationship to the "temperature" of the engine or the ambient temps. The more nitro you have, the easier the fuel combusts, so you use a cooler plug to avoid having it fire too soon in the rotation. When you go above 25%, it's also suggested you add a head shim to reduce compression as the higher percentage fuel is easier to ignite with higher compression as well.

    Running too cool of a plug would cause your combustion to happen after the piston as reached TDC, so your losing some of your power out of your exhaust, which tends to cause you to run lean to try and get some power back. You want combustion to happen just as the the piston approaches TDC. If it happens too early, then the engine is fighting itself to even run, which also causes bad performance and piston damage.
     
    Last edited: Oct 12, 2017
  13. Scottbot302

    Scottbot302 Active Member

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    I was running a medium plug. I have a cold plug in there now and it seemed to like it much more. Started easier and seemed to run better. I am also running the stock wheels and tires
     
  14. olds97_lss

    olds97_lss Well-Known Member

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    That's odd. I never ran a cold plug in anything before. Perhaps I should try one. :)
     
  15. Scottbot302

    Scottbot302 Active Member

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    I'm going to experiment with different plug setups soon. Go from Cold to Medium to Hot to V Hot to see how it goes. I also need a new clutch bell because the old one seems rather worn. If only I can find some time to do all this now...
     
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