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

Trying to get more speed with my warbird

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Old 07-03-2011, 10:32 AM
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hyflyer9
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Default Trying to get more speed with my warbird

hello
I am trying to get more speed with my Top flight P39 I am running an ASP .91 red head 2 stroke stock muffler with an APC 13x6 prop and it just doesn't seem to be getting the speed that it should. Can any one recommend a different prop or any thing alse I can try.
thank you .
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Old 07-03-2011, 12:31 PM
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Default RE: Trying to get more speed with my warbird

A Jett 1.20 should do it.http://www.jettengineering.com/engines/bse100.html
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Old 07-03-2011, 12:48 PM
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Default RE: Trying to get more speed with my warbird

While I agree that the ASP is not going to be the first choice for speed it is what you have. If you are looking for a boost ( 10%) you can get a Jett muffler, higher grade bearings and raise the exahust port .030. Once that is all done, run a medium hot ( OS #8, Enya #4 ) plug, 20-25% nitro fuel and an APC 11X9 prop to start with. Obviously that is alot of effort and you may be better off running a different engine. The YS 110, 115, 120 engines are very popular with the warbird racing crowd. Deals can be found on these at E***
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Old 07-03-2011, 06:05 PM
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Default RE: Trying to get more speed with my warbird

First off, that's a big plane. The mfg calls for 60 to 75 two stroke and you put a 91 in it, so it's a bit more power, but not comparably to a YS 91 heli or a YS 115 in a 46 size World models P-51.


On the ASP 91 ,the thing to remember is, low nitro! If it's hot and/or the engine is cowled in, 5% MAX! If it's cool and the cylinder is out in the open MAYBE 10%.
If you try to run 15% there's a good chance it'll run like it's under powered.
It also does not like big lumber, so don't lug it, over 12000 is fine. for a reference baseline the APC 13X6 you are using should be turning about 13200 on 5% if it's running good on the stock muffler.
Try a 12X8 or12X9 with stock muffler.

If you are intent on keeping the engine,(not a bad engine at all) try a Macs tuned pipe (not the black muffler) or a Jett tuned muffler for a big boost.
With the boost in power, make it work harder with a 13X7, 13X8 or 12X10 to keep it in rpm range.
Note: with these steeper props, it will land faster at idle, so keep a dead stick landing as an option.
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Old 07-04-2011, 09:08 AM
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Default RE: Trying to get more speed with my warbird

If looking for another engine then the OS 120AX with jett pipe14x14 APC 9,300, 14.5x14.5 9,200, 15x12 9,000
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Old 07-04-2011, 12:03 PM
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Default RE: Trying to get more speed with my warbird

While I have not run an ASP engine, to the best of my knowledge is it not an OS knockoff? I beleive it is and that would suggest low compression. That being true it would benifit from the higher nitro provided that it be run with the correct heat range plug and not be loaded down with too big a prop. Doing so would just lead to pre-ignition. As I stated before you must shift the power band to a slightly higher RPM. Raising the exahust timing will do this and provide a better RPM match for the Jett Muffler. Lowering the load with a smaller dia. prop with a little more pitch will also help bring the engine into the RPM range that the Jett muffler is tuned to. Remember that ignition timings is determined by 3 things. Compression, nitro content and plug heat range. You will have to do some experimentation along with prop size to get maximum performance. In my case as I race with a Rossi .61 FIRE engine with a pipe. With head shimming, the correct pipe length, correct heat range plug I am able to spin an APC 10X10 in the low 17,000 range with 15% nitro. Makes a 6.5 LB airplane really haul.
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Old 07-04-2011, 12:34 PM
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Default RE: Trying to get more speed with my warbird

Well so far it is all good info and so far I have tried a few different props such as the Master Airscrew 14x8 war bird prop it lowered the rpm but did not give me any added speed in fact it was slower i also tried a Turnigy 13 3/4 x8 beach wood prop and that was just as slow but the rpm was a little higher and I have been running cool power pro pattern 20% for fuel and I have tried a few different plugs as well like an os#8 ' os#3 and a fox miracle plug and all seem about the same and I have even burnt out the #3 the #8 And one of the miracle plugs.
I guess maybe it's time to start saving up for a new engine.
hyflyer9.
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Old 07-04-2011, 12:45 PM
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Default RE: Trying to get more speed with my warbird

So far the props you have used are great for mixing epoxy LOL. You NEED to get some APC props. The fact that you have blown plugs indicates to me that you are per- igniting the engine some. Try a cooler range plug and maybe even a second plug washer. In basic terms, these two things will " retard " your ignition timing some and reduce the combustion temp some. this temp is what is popping your plugs. If this sows improvement, get a second head gasket in the engine.
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Old 07-04-2011, 07:06 PM
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Default RE: Trying to get more speed with my warbird

yes speed is right APC props and also get rid of that cool power fuel............................

If you have never messed with changing the timing on a engine there is alot more involved than just raising the exhaust timing on a engine.

Also you need to get rid of that ASP carb they are the worst ones out there. the spray bar is huge taking up air flow.
Look for a carb with around .380-.390
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Old 07-04-2011, 07:18 PM
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Default RE: Trying to get more speed with my warbird

ORIGINAL: speedracerntrixie

Remember that ignition timings is determined by 3 things. Compression, nitro content and plug heat range.
There is a 4th factor that effects timing....load. A heavy load makes the engine "think" that it's either over compressed or got too much nitro.
Your earlier post shows that you already know this.....

A 5th factor..[some might argue this]...oil content, oil quality. Don't back off on the oil until you see a decrease in performance. I have run 25-30% oil in my Nelsons with great results.
The extra oil allows more aggressive tuning.
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Old 07-04-2011, 07:31 PM
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Default RE: Trying to get more speed with my warbird


ORIGINAL: airraptor

yes speed is right APC props and also get rid of that cool power fuel............................

If you have never messed with changing the timing on a engine there is alot more involved than just raising the exhaust timing on a engine.

Also you need to get rid of that ASP carb they are the worst ones out there. the spray bar is huge taking up air flow.
Look for a carb with around .380-.390
I guess i should have stated that I am using a GMS .76 carb and not the stock ASP also this ASP is one of the older versions with the red hi performance head .
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Old 07-06-2011, 08:48 PM
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Default RE: Trying to get more speed with my warbird

Hello
Thank you all for the good and helpful info. I did a few mods #1 i added two spacers under the head and then went with an APC 12x8 prop and last I changed to omega 15% fuel and I did a test run and the engine seems to be running cooler and now more even power with lower rpm at around eleven thousand one hundred i haven't flow it yet but am planing on it on Thursday and i will re post the info if getting better speeds or not.
Thanks all.
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Old 07-16-2011, 06:49 AM
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Default RE: Trying to get more speed with my warbird

If you plan to rev this motor for speed (high rpms), consider running the OS F (4c) plug. It has thick element and lasts longer than OS 8 or 3.
Regarding props, the best one for speed set up with 91 size motor is apc 11x9.
Regarding fuel, just run standard 10% nitro with all synthetic oil, but add 1 oz of Turbine oil per gallon, and your motor will run cooler and lasts longer from those high revs. Dont' bother with adding castor oil when running at high rpms. You can get a quart of turbine oil from your local private airport for a few bucks.
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Old 07-16-2011, 07:54 PM
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Default RE: Trying to get more speed with my warbird


ORIGINAL: kmtranmd

If you plan to rev this motor for speed (high rpms), consider running the OS F (4c) plug. It has thick element and lasts longer than OS 8 or 3.
Regarding props, the best one for speed set up with 91 size motor is apc 11x9.
Regarding fuel, just run standard 10% nitro with all synthetic oil, but add 1 oz of Turbine oil per gallon, and your motor will run cooler and lasts longer from those high revs. Dont' bother with adding castor oil when running at high rpms. You can get a quart of turbine oil from your local private airport for a few bucks.

He was already having a pre-ignition problem. Going to an even hotter plug will only make it worse! It seems to me the ASP is set up for low nitro just like the Rossi's that I run. This is usually done by running a high compression. What has worked best for me is to add a second head gasket and use an Enya #3 plug. I would agree with the 11X9 prop as a good starting point. My Rossi .61 FIRE with some mods and a pipe spins an APC 10X10 in the low 17,000 range and that is bolted to a 550 sq inch 6 lb Macchi 202

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Old 07-16-2011, 11:07 PM
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Default RE: Trying to get more speed with my warbird

If the glowplug has big wire, it ought to run relatively cool and it ought to be less prone to coming loose and "becoming one with" the engine's piston and liner during a lean / hot run.
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Old 07-17-2011, 03:04 PM
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Default RE: Trying to get more speed with my warbird

Agreed but the F plug is a hot plug. It is designed to retain heat in a 4 cycle engine during the exhaust stroke. Most 2 cycle engines don't like them.
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