Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Jett 50 and Shrike 40 Questions

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Old 11-25-2002, 02:58 PM
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dave long
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Default Jett 50 and Shrike 40 Questions

I am running a Jett 50 with the stock Jett Stream pipe on a Shrike 40 and 8.75x9.0W APC prop. I get 17,500 rpm on the ground. This seems to be as high as I can go and allow enough room to lean out in a turn and not burn up plugs. I have a Stalker Radar Gun and clock 145 mph coming out of a dive (at peak) and 130 mph on the flat. Any advice to get more from this engine? I am also fighting "foaming". Any advice here other than a smaller tank and more padding? The muffler sits very close to the wing. On my last run, heat from the exhaust gases (2" behind the muffler exit) burnt the Monokote covering which then pealed off back to the elevator. Any thoughts on fixing this (without adding much weight)?
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Old 11-25-2002, 03:06 PM
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Default foaming

add five drops of armor all per gallon fuel. it will not foam even with no padding.
Need a pipe on that engine and it will scream.
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Old 11-25-2002, 03:15 PM
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dave long
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Default Jett 50 and Shrike 40 Questions

I have seen the comments about Armourall. Man that sounds wierd. Any word from the manufacturer of negative impact on the engine? Sounds like the Jett Stream pipe is inadequate. Any suggestions on who's pipe? Any information on tuning it?
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Old 11-25-2002, 04:17 PM
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Default Jett 50

First, 17,500 rpms and 145 mph is no slouch. But if you want more, Call Dub or Dennis at Jett. They will get you set up with a Q500 or Q40 pipe for your Jett 50. No tuning required.

I have the Q40 pipe on my Jett 50. I tached an 8.75x9W at 19,000. I now fly it on a Predator with a 8.75x8.5W. It gets on the pipe better, with a little less prop. I haven't yet tached it, but I can tell it screams. Amazing engine.

Paul
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Old 11-25-2002, 05:17 PM
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dave long
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Default Jett 50 and Shrike 40 Questions

PDX Paul,

Thanks for the information.

Does your tach of 19K give you enough room to lean out (in a turn/dive) without burnig up plugs?
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Old 11-25-2002, 06:29 PM
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Default Jett 50 and Shrike 40 Questions

Dave,

First, I wouldn't recommend running the 8.75x9W because that prop is inefficient. That prop is the older design and it was great back then, but now we use the more efficient design from 8.8x8.5, 8.8x8.75, 8.8x8.9, 8.8x9, 8.8x9.25, 8.8x9.5 to 8.8x9.75. Also, for the Jett .50, I would recommend you run it with at least 8.8x9.25 or higher. The Jett .50 should turn that prop without any fuss and should give you more speed.

Here are some tips... especially for more power from your engine. First take all the head shim and leave only a .002 shim in the head so you can increase the compression for more power. Second, use the McCoy #9 Plug, which is a cold plug that can withstand the higher compression of the engine without blowing plug. And third, but only if you know what you're doing, is calll Dub and get a Cylinder Shim of .006, which would raise the Exhaust Timing to about 2 more degree for more RPM on smaller prop (9" vs. 10" that the engine was tuned with). With these changes, you would get more rpm's and more speed out of your current airplane in the air when the engine unload, but may not see any changes on the ground.

As for the air bubble or foaming... that usually happen with standard fuel tank. To eliminate that, you can use a bladder tank either made by Jett or the Tettra tank. These tanks works the same, but the Jett tank comes ready to use. Hope this help.

Sam
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Old 11-25-2002, 11:14 PM
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Default Jett 50 and Shrike 40 Questions

Sam,

Thank you for the advice. I will start with the prop and tank changes then move to shims. I will keep you posted.
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Old 11-25-2002, 11:31 PM
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Default Jett 50

Dave,

I also use McCoy #9's now, without any trouble.

I thought the 8.75x9W was a just little too much prop. The 8.5 gives me a little room to work the needle. I don't hear it unloading in dive, but I also don't think it is running lien. I could touch the head right after a flight, and the exhause on the bottom of the plane had a good color.

As for speed, one person said my Predator/Jett combo would compete with a Nelson quickie. I don't know about that, but it does go like stink.

Paul
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Old 11-25-2002, 11:52 PM
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Default Jett 50 and Shrike 40 Questions

Thanks Paul. I am going to set up a tripod with my Stalker Radar gun, activate the remote timing switch and clock 5 passes looking for peak speed. I will do this with different size props and report the results. No other variables..........for now.
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Old 11-26-2002, 02:52 AM
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Default Jett 50 and Shrike 40 Questions

Dave,
Buy a bigger engine!!

Mike H.
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Old 11-26-2002, 03:19 AM
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dave long
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Default Jett 50 and Shrike 40 Questions

I have done that with other aircraft only to discover that the perfect combination/ balance of engine, prop, fuel, aircraft and exhaust system is more effective then radically changing any one of the components. Synergy is what it's all about. But thanks for the advice anyway!
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Old 12-01-2002, 06:04 PM
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Default Re: foaming

Originally posted by jlong34016
add five drops of armor all per gallon fuel. it will not foam even with no padding.
Need a pipe on that engine and it will scream.
DONT DO THAT
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Old 12-01-2002, 07:08 PM
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Default engine problems

hey dave, sounds like you have a real problem with speed. have you thought about checking into a rehab? you can solve the tank problem with a bladder tank. see ya at the field
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