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Rocket Owners.... How hot does your #5 cylinder run?


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Hello all you rocket owners... I have a question.

On both my rockets, the number 5 cylinder ( right behind the alternator) runs hotter than the rest.  I never let it get above 380 degrees but I have to climb at a higher airspeed and lower climb rate to keep it that cool.  And it gets more difficult as I get higher.  This does not bug me so much but what does bug me is that I cannot lean very much in cruise without breaking 380 degrees.  If that cylinder ran as cool as the others I could probably save another 1 or 2 GPH in cruise.

Doing gami analysis, the mixture on that cylinder appears to not be the issue.   The rest of the cylinders are down around 350 degrees, #1 at 325.    I have been told this is because the alternator is in the way of the intake on that side of the engine.  I have contemplated some sort of deflector to try to put more air past the #5 cylinder but I dont know if that would help or not.

Are you guys having the same issue? 

 

Thanks

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3 minutes ago, Niko182 said:

Have you done the baffles offered by GeeBee. For the rocket is there a pixie hole modification like there was for the ovations and acclaims?

Yes, I have the Pixie hole.  I'm not sure if the baffles are by GeeBee, but they are in very good condition on both of the aircraft.

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Are they silicon baffles? The change from the stock baffles to the Geebee ones made a massive difference. I remember it being about 20 to 25 degrees change. If i remember correctly, they were 400 bucks and took about 3 to 4 hours to install.

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8 minutes ago, Niko182 said:

Are they silicon baffles? The change from the stock baffles to the Geebee ones made a massive difference. I remember it being about 20 to 25 degrees change. If i remember correctly, they were 400 bucks and took about 3 to 4 hours to install.

Yes, they are silicone.

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1 hour ago, Austintatious said:

Hello all you rocket owners... I have a question.

On both my rockets, the number 5 cylinder ( right behind the alternator) runs hotter than the rest.  I never let it get above 380 degrees but I have to climb at a higher airspeed and lower climb rate to keep it that cool.  And it gets more difficult as I get higher.  This does not bug me so much but what does bug me is that I cannot lean very much in cruise without breaking 380 degrees.  If that cylinder ran as cool as the others I could probably save another 1 or 2 GPH in cruise.

Doing gami analysis, the mixture on that cylinder appears to not be the issue.   The rest of the cylinders are down around 350 degrees, #1 at 325.    I have been told this is because the alternator is in the way of the intake on that side of the engine.  I have contemplated some sort of deflector to try to put more air past the #5 cylinder but I dont know if that would help or not.

Are you guys having the same issue? 

 

Thanks

#5 is not my hottest cylinder. I don't have a consistently hottest cylinder as the four hottest are relatively close and which is the hottest at the moment seems to depend on the stage of flight the configuration and the day.  In 3 flights I just checked #5 was somewhere between 2nd and 4th.

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I'm a 252 Rocket and #5 is my hottest.  Usuallly 15-20 deg hotter than closest next hottest which is #4.  #6 and #1 are coolest.  I fight 380 on #5 most of the time in cruise and generally have to run cowl flap at mid-open and 30", 2300, and about 19 gph to keep it below 380.

I have gamis and #5 has the biggest gami allowed to richen it up. That EGT is also about 110 deg hotter than coolest EGT which is also #1.

I asked GeeBee about a baffle kit for the Rocket in Dec 2019 and he did not have a Rocket kit.  Mine had some work done and that made a little difference.

I also have an oval hole in the plate in front of #5, it's about 2" long and 1" high. there are also a few drilled circular holes in it

I've just learned to live with it. If someone figures out how to make it run cooler I'll pay $$ for that solution!

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42 minutes ago, Cody Stallings said:

Always really cool.

IMO the Rocket has the best cooling of any piston pounding single bug smasher I have flown

 

68996517-E273-473B-95B8-6AF04F02694C.png

I agree. Never a problem in ours.

I kind of wonder why the question about 231/252. I can't imagine once converted the baffles or mount or anything else is different 

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On 11/22/2021 at 11:43 PM, philip_g said:

I agree. Never a problem in ours.

I kind of wonder why the question about 231/252. I can't imagine once converted the baffles or mount or anything else is different 

I asked because as I understand it, The 252 had cooling flow modifications to help cool the engine up to FL280.  I dont know if they stayed there or not with the rocket mod.

Edited by Austintatious
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1 minute ago, Austintatious said:

I asked because as I understand it, The 252 had cooling flow modifications to help cool the engine up to FL280.

 

On 11/22/2021 at 11:00 PM, Cody Stallings said:

Always really cool.

IMO the Rocket has the best cooling of any piston pounding single bug smasher I have flown

 

68996517-E273-473B-95B8-6AF04F02694C.png

That is nice... But I have been running 31" 2200 RPM.  IF I was to pull it back to 28/23 I think I would probably be about 360 on number 5

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24 minutes ago, PJClark said:

Can you run continuous at 32/2300 and 1640 TIT LOP?

Depends how high I am... I think I could do that below 8 or 10 thousand.  In the high teens I am unable because the TIT does not drop off before  rough running.  I typically cruise at FL180 or FL190  running 31/22 at about 200 knots, 17.5GPH and #5 is around 375 degrees... about 1550 TIT

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On 11/22/2021 at 10:04 AM, Austintatious said:

Hello all you rocket owners... I have a question.

On both my rockets, the number 5 cylinder ( right behind the alternator) runs hotter than the rest.  I never let it get above 380 degrees but I have to climb at a higher airspeed and lower climb rate to keep it that cool.  And it gets more difficult as I get higher.  This does not bug me so much but what does bug me is that I cannot lean very much in cruise without breaking 380 degrees.  If that cylinder ran as cool as the others I could probably save another 1 or 2 GPH in cruise.

Doing gami analysis, the mixture on that cylinder appears to not be the issue.   The rest of the cylinders are down around 350 degrees, #1 at 325.    I have been told this is because the alternator is in the way of the intake on that side of the engine.  I have contemplated some sort of deflector to try to put more air past the #5 cylinder but I dont know if that would help or not.

Are you guys having the same issue? 

 

Thanks

It's normal

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