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Old 08-28-2007, 07:30 PM   #1
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Default RB R3 Engine Running Really Hot!

I picked up a brand new modified RB R3 a few weeks ago. Since breaking it in I can't get the thing to perform without running it at nearly 300 degrees. A couple times it's come in over 320! Yikes!

I'm temping the head with a brand new Exergen DX501 so I'm fairly confident it's not that. I'm running 30% Werks fuel but the head has been shimmed for it. What else could it be? I've been over the clutch and 2 speed.

After reading a few other threads the consensus seems to be to tune to performance and don't worry too much about the temp but the temps I'm getting seem to be something to worry about.

I feel like I've got a decent grasp on how to tune an engine. My needle setting are reasonably close to how others are running the engine. I feel like throwing my hands in the air on this one.
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Old 08-28-2007, 09:15 PM   #2
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Quote:
Originally Posted by SlamMan View Post
I picked up a brand new modified RB R3 a few weeks ago. Since breaking it in I can't get the thing to perform without running it at nearly 300 degrees. A couple times it's come in over 320! Yikes!

I'm temping the head with a brand new Exergen DX501 so I'm fairly confident it's not that. I'm running 30% Werks fuel but the head has been shimmed for it. What else could it be? I've been over the clutch and 2 speed.

After reading a few other threads the consensus seems to be to tune to performance and don't worry too much about the temp but the temps I'm getting seem to be something to worry about.

I feel like I've got a decent grasp on how to tune an engine. My needle setting are reasonably close to how others are running the engine. I feel like throwing my hands in the air on this one.
I would pull that carb off and replace it with another one if you have one... Any current Nova carb will fit the Sirio with no problem as well. Then check and see if the same tuning problems appear. If all is fine, then it was something with the Sirio carb.. ie.. leak or bad tune... Now, if the same problems happens with the Nova carb, then you have a air leak some place else...

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Old 08-28-2007, 10:04 PM   #3
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RB R3 is a Nova base engine.
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Old 08-28-2007, 10:12 PM   #4
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Questions...
  • Can you be more specific about what you mean by "... can't get it to perform..."?
  • What is the exact head clearance?
  • What plug are you using?
  • What pipe?
  • How did you break-in the engine?
  • What are your clutch settings?
  • Are you using the white or yellow clutch shoe?
  • Are you seeing smoke?

It's possible that because of the head design, the temp is reading higher than it actually is. You might want to try another temp gun just for comparison.

I know what you're saying about not taking the temp, but you can usually tell when an engine is running too lean by how it sounds - especially when it temps over 300F.

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Old 08-28-2007, 10:14 PM   #5
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RB R3 is a Nova base engine.
My Bad... I was thinking of the RB Matrix...

Well if you have another Nova based carb laying around, swap it out with the one you're having problems tuning with and see if that solves the problem... If the problem is still there, then there's a air leak some place else, a bad tune or your clutch is not set correctly ...

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Old 08-28-2007, 11:18 PM   #6
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  • Can you be more specific about what you mean by "... can't get it to perform..."?
    Basically it just runs like it's too rich.
  • What is the exact head clearance?
    An extra .3mm for a total of .6mm
  • What plug are you using?
    I tried the RB 6 that came with it and an OS 7 plug over the weekend
  • What pipe?
    RD Logics Turbo III pipe. I've been looking at the Nova 2630 pipe though
  • How did you break-in the engine?
    Cryul method. Although, like last time, I had trouble getting the temps up.
  • What are your clutch settings?
    .6mm clutch gap. Spring preload is fairly tight.
  • Are you using the white or yellow clutch shoe?
    White clutch shoe
  • Are you seeing smoke?
    A good amount of smoke is coming out.

It's possible that because of the head design, the temp is reading higher than it actually is. You might want to try another temp gun just for comparison.
I suppose this is possible. I'll certainly try a couple other guns on my engine and others this weekend to try to get a better feel for things

I know what you're saying about not taking the temp, but you can usually tell when an engine is running too lean by how it sounds - especially when it temps over 300F.
When I think of a motor that sounds like it's too lean it's tinny or pinging. I can't say I really picked that up when tuning the engine.
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Old 08-29-2007, 06:49 AM   #7
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Slamman,
YGPM
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Old 08-29-2007, 07:36 AM   #8
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Quote:
Originally Posted by SlamMan View Post
I picked up a brand new modified RB R3 a few weeks ago. Since breaking it in I can't get the thing to perform without running it at nearly 300 degrees. A couple times it's come in over 320! Yikes!

I'm temping the head with a brand new Exergen DX501 so I'm fairly confident it's not that. I'm running 30% Werks fuel but the head has been shimmed for it. What else could it be? I've been over the clutch and 2 speed.

After reading a few other threads the consensus seems to be to tune to performance and don't worry too much about the temp but the temps I'm getting seem to be something to worry about.

I feel like I've got a decent grasp on how to tune an engine. My needle setting are reasonably close to how others are running the engine. I feel like throwing my hands in the air on this one.
The R3 runs hot just like the Novarossi +12 engines. The engine does not make good power under 300 F. We have found that the temperatures do not matter on the newer Novarossi engines. They will make optimum power above 300F until the piston/sleeve fit loosens up, even then they will run hot. The most important thing is to keep checking the head to make sure there is not pre detonation going on. The Novarossi 2630 with short header seems to be a good pipe to use with the engine. I would also go to a # 6, or 7 glowplug after break in. I have put hours of hard racing on my +12 engines at temps of 325+ F, with no detonation, and they keep getting faster.
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Old 08-29-2007, 07:40 AM   #9
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In the last weeks I do hear a lot about no headshims or wrong amount of headshims in Novarossi (based) engines, there is also a topic about that on the R&B forums.

Last Weekend I was busy with a Plus-2 kit with a training-engine becomming very hot and no right adjustment possible but also his 353 had the same problem. Adding an 0.2mm shim did the trick for his 353 and maybe his training-engine will need the same.

Beside that, your engine is modified so the modifier must did his job....
Otherwise the engine is normally set to 16% nitro, going to 30% it will need 0.1 or 0.2 mm extra shims.
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Old 08-29-2007, 08:50 AM   #10
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Quote:
Originally Posted by Grinder View Post
The R3 runs hot just like the Novarossi +12 engines. The engine does not make good power under 300 F. We have found that the temperatures do not matter on the newer Novarossi engines. They will make optimum power above 300F until the piston/sleeve fit loosens up, even then they will run hot. The most important thing is to keep checking the head to make sure there is not pre detonation going on. The Novarossi 2630 with short header seems to be a good pipe to use with the engine. I would also go to a # 6, or 7 glowplug after break in. I have put hours of hard racing on my +12 engines at temps of 325+ F, with no detonation, and they keep getting faster.
Thanks Uriah. That makes me feel a lot better about the temps. After coming from an unmodified OS engine it completely threw off what little I knew about tuning engines. The engine is nothing short of ridiculous fast at the higher temps.

How do I go about checking the head for detonation? What am I looking for?
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Old 08-29-2007, 12:24 PM   #11
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Originally Posted by SlamMan View Post
Thanks Uriah. That makes me feel a lot better about the temps. After coming from an unmodified OS engine it completely threw off what little I knew about tuning engines. The engine is nothing short of ridiculous fast at the higher temps.

How do I go about checking the head for detonation? What am I looking for?
Look at the glowplug after each run. Make sure that it does not look dry. The bottom of the plug should look shiny, or glossy. If it looks flat, or dry that is too lean, and could cause detonation if you continue to run at that setting, or go any leaner. If the plug looks wet, then you have more room to lean the engine. This is the best way to tell if you are running optimally, not the temp gun.
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Old 08-29-2007, 12:45 PM   #12
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I could be wrong but, I seem to recall others saying that the OS plug has a slightly different bevel to it & may not seal up properly. Perhaps someone could shed more light on this.
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Old 08-29-2007, 02:23 PM   #13
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Quote:
Originally Posted by Grinder View Post
Look at the glowplug after each run. Make sure that it does not look dry. The bottom of the plug should look shiny, or glossy. If it looks flat, or dry that is too lean, and could cause detonation if you continue to run at that setting, or go any leaner. If the plug looks wet, then you have more room to lean the engine. This is the best way to tell if you are running optimally, not the temp gun.
Thanks again. I'll definitely start looking at the plug more and at the temp gun less. When I'm not worried about the temps the tuning is a lot more straight forward.

I'll compare the OS and RB plugs I've got to see if they're different. I've been thinking about going to the RB or Nova plugs only in the R3 because of this.
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Old 08-29-2007, 02:47 PM   #14
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As you're finding out, all the engine brands run differently. That is what makes nitro challenging, rewarding and frustrating all at the same time. Just wait until you get your 3rd and 4th engine performing to your satisfaction. Then you'll really start to know what you're doing.

I'm glad Grinder responded to your post. Nothing quite like getting the info from an expert.
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Old 08-30-2007, 06:37 AM   #15
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Slamman forgot to mention that we are running at a mile high. Add in hot weather and we're looking at 9000+ feet of adjusted altitude.....
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