.91 Four Stroke Readings
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.91 Four Stroke Readings
Post your .91 four stroke tach engine readings, any brand...
ASP .91
%10 Wildcat %18 oil
MA 14x6 8900
Zinger 14x5 10500
ASP .91
%10 Wildcat %18 oil
MA 14x6 8900
Zinger 14x5 10500
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RE: .91 Four Stroke Readings
HOMEBREWER reports a THUNDER TIGER .91 FS was reported to turn an APC 14x6 at 10500 on 10%... don't know the other details. The only reason I remembered the numbers was because I wanted to buy one and researched it here first. BTW, I did buy the TT FS 91, but haven't run it yet. I am going to put it in a CMPRO/GSP Spitfire.
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RE: .91 Four Stroke Readings
Some more readings...
Engine: ASP .91
Fuel: 10% Wildcat
Prop/Tach #s:
APC 14x10 7,600 While it has a low static rpm, it gives pretty good performance in the air
Zinger 14x8 7,900
Zinger 13x10 7,900
My engine is still pretty new(about 1/2 gal.) but I'm not really impressed with my numbers yet. The only prop that will get sufficient RPM is a Zinger 14x5 @ 10,500. Anything with much pitch really loads the engine down.
Engine: ASP .91
Fuel: 10% Wildcat
Prop/Tach #s:
APC 14x10 7,600 While it has a low static rpm, it gives pretty good performance in the air
Zinger 14x8 7,900
Zinger 13x10 7,900
My engine is still pretty new(about 1/2 gal.) but I'm not really impressed with my numbers yet. The only prop that will get sufficient RPM is a Zinger 14x5 @ 10,500. Anything with much pitch really loads the engine down.
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RE: .91 Four Stroke Readings
All of mine to date...
Engine : ASP .91
Fuel : Wildcat %10
Glow Plug: OS #F
APC 14x10 = 7,600
APC 12x12 = 9250*
APC 12x10 = 9500*
APC 11x12 = 9600*
Zinger 14x8 = 7,900
Zinger 14x5 = 10500
Zinger 13x10 = 7,900
MA 14x6 = 8900
Again, my engine is still breaking in, so I'm hoping my numbers will improve
* = New for this post
Engine : ASP .91
Fuel : Wildcat %10
Glow Plug: OS #F
APC 14x10 = 7,600
APC 12x12 = 9250*
APC 12x10 = 9500*
APC 11x12 = 9600*
Zinger 14x8 = 7,900
Zinger 14x5 = 10500
Zinger 13x10 = 7,900
MA 14x6 = 8900
Again, my engine is still breaking in, so I'm hoping my numbers will improve
* = New for this post
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RE: .91 Four Stroke Readings
ORIGINAL: Sport_Pilot
Thuunder Tiger .91 FS
...
APC 14-6 10,300
Thuunder Tiger .91 FS
...
APC 14-6 10,300
#10
RE: .91 Four Stroke Readings
How do you know the HP? From a propeller HP thrust caluclator? Seems .2 HP off is a pretty good estimate to me. Also an honest manufacture would have ratings of the AVERAGE engine, not the best or most pampered engine. But IMO TT made some changes without updating the specs. Their marketing seems off, or maybe their marketing people are just as lazy as their service people.
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RE: .91 Four Stroke Readings
ORIGINAL: Sport_Pilot
Also an honest manufacture would have ratings of the AVERAGE engine, not the best or most pampered engine.
Also an honest manufacture would have ratings of the AVERAGE engine, not the best or most pampered engine.
I did use the Thrust HP program to find the HP. Again, I wasn't trying to make anyone mad, I was just curious. It doesn't seem far off at all now, because I tried an APC 14x6 Sport on my .91 and I got 9700. After my engine breaks in fully I'm hoping to get about 300rpm which would put it close to your number. No offense!
TT Does need to up their marketing. If their service/marketing was as good as their engines they'd be in good shape
More #s...
Engine: ASP .91
Fuel: Wildcat %10 Nitro
OS #F Plug
APC 14x6 - 9700
APC 13x8 - 9650
Zinger Pro 14x6 - 8900
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RE: .91 Four Stroke Readings
Yes, I was routinely getting 10,500 -10,600 k on my TT .91s but if I said it was with 10% fuel, I was mistaken. I use only 15% or 20/20 in my engines.
The point is that the TT .91 will smoke most engines in its class other than YS. Yes, its a little heavier but most airplanes I built needed the extra weight in the nose anyway.
The point is that the TT .91 will smoke most engines in its class other than YS. Yes, its a little heavier but most airplanes I built needed the extra weight in the nose anyway.
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RE: .91 Four Stroke Readings
My OS FS-91 II with pump turns MA 14x6 at 9650 rpms.
Fuel is Model Technics Dynaglo 10% nitro with 14% (enriched) oil (12% synthetic + 2% castor).
Stelios
Fuel is Model Technics Dynaglo 10% nitro with 14% (enriched) oil (12% synthetic + 2% castor).
Stelios
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RE: .91 Four Stroke Readings
TT F91S running 10% Wildcat 18% syn/castor blend
Zinger 15x6 = 8200 rpm
Zinger Pro 14x5 = 9700 rpm
OS .91 Surpass II running 10% Wildcat 18% syn/castor blend
Zinger 15x6 = 8400 rpm
Zinger Pro 14x5 = 9500 rpm
Both engines are still breaking in and running rich. Each has about a half gallon through them.
The OS seems to like the 15" prop better than the TT.
The TT turns the 14" prop better than the OS.
I will get an APC 14x6 or maybe a 15x4W and see what I get.
Zinger 15x6 = 8200 rpm
Zinger Pro 14x5 = 9700 rpm
OS .91 Surpass II running 10% Wildcat 18% syn/castor blend
Zinger 15x6 = 8400 rpm
Zinger Pro 14x5 = 9500 rpm
Both engines are still breaking in and running rich. Each has about a half gallon through them.
The OS seems to like the 15" prop better than the TT.
The TT turns the 14" prop better than the OS.
I will get an APC 14x6 or maybe a 15x4W and see what I get.
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RE: .91 Four Stroke Readings
Give the TT another gallon or so, its potential is not as apparent till then. If you are not getting over 10,000 with the 14-5, then something is wrong.
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RE: .91 Four Stroke Readings
I got an APC 14x6 and ran it yesterday. It was hot and humid and started raining while I was running them. I need a cool dry day to see what they will really peak at. Both are really still getting broken in so I am not too worried about the performance.
TT F91S running 10% Wildcat 18% syn/castor blend
APC 14x6 = 9400
idle was 1800
OS .91 Surpass II running 10% Wildcat 18% syn/castor blend
APC 14x6 = 9700
idle was 1700
TT F91S running 10% Wildcat 18% syn/castor blend
APC 14x6 = 9400
idle was 1800
OS .91 Surpass II running 10% Wildcat 18% syn/castor blend
APC 14x6 = 9700
idle was 1700
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RE: .91 Four Stroke Readings
AnthonyH - nice comparo work - keep it coming!
For the record, my OS .91 S2 Pump spins a 13x10 APC at 9200 rpm with a stock exhaust and 9400 rpm with an OS EX-502 header.
For the record, my OS .91 S2 Pump spins a 13x10 APC at 9200 rpm with a stock exhaust and 9400 rpm with an OS EX-502 header.
#21
RE: .91 Four Stroke Readings
Anthony H,
Wat altitude were you at? Have you checked the valve gap since breaking them in? The TT seems to be getting weaker instead of stronger.
Wat altitude were you at? Have you checked the valve gap since breaking them in? The TT seems to be getting weaker instead of stronger.
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RE: .91 Four Stroke Readings
Sport_Pilot,
I checked the valves on both the day I ran them. I was giving them both a final go-over before mounting on their planes. My first post was a cooler and dry day. My second post was a hot rainy day. I am at 605 ft. ASL. I think both are still not broken in good and will get better once I get them in the air for about a gallon. I have ran them enough to get stable needle setting and a reliable, low idle.
I think that .91 four-strokes should be swinging a bigger prop at lower rpm anyway. A four-stroke turning above 10k seems a bit much. A 15x6 gets it in the 8k range which should be more in the power-band on a four-stroke since they make their power more with torque than high rpm. With both engines I cannot tell a difference in the throttle response between the 15x6 and 14x6 so I would say the 15x6 is not too much prop for a .91. What do you guys think? Am I crazy or missing something that is the reason most people use 14x6 on .91 FS?
I checked the valves on both the day I ran them. I was giving them both a final go-over before mounting on their planes. My first post was a cooler and dry day. My second post was a hot rainy day. I am at 605 ft. ASL. I think both are still not broken in good and will get better once I get them in the air for about a gallon. I have ran them enough to get stable needle setting and a reliable, low idle.
I think that .91 four-strokes should be swinging a bigger prop at lower rpm anyway. A four-stroke turning above 10k seems a bit much. A 15x6 gets it in the 8k range which should be more in the power-band on a four-stroke since they make their power more with torque than high rpm. With both engines I cannot tell a difference in the throttle response between the 15x6 and 14x6 so I would say the 15x6 is not too much prop for a .91. What do you guys think? Am I crazy or missing something that is the reason most people use 14x6 on .91 FS?
#23
RE: .91 Four Stroke Readings
I think that .91 four-strokes should be swinging a bigger prop at lower rpm anyway. A four-stroke turning above 10k seems a bit much. A 15x6 gets it in the 8k range which should be more in the power-band on a four-stroke since they make their power more with torque than high rpm.
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RE: .91 Four Stroke Readings
Engine : OS .91 Surpass
(loooow time, 8-10 tanks)
Fuel : 15% Omega
Glow Plug: OS #F
Prop: 14x6 Zinger
RPM: 10,200
Prop: 14x6 Master Airscrew
RPM: 10,000
Prop: 14x7 Graupner Nylon
RPM: 8,900
Prop: 13x6x10 Zinger
RPM: 9,900
Why all the props? Because the darn thing wasn't running right out of the box - only turning in the mid sixes. Re-plumbed fuel tank and lines AND loosened a way-too-tight intake valve. Tried all the props and am running the master airscrew for now. The 14x6 Zinger was best, but it's a loaner. A 14x6 APC is probably the best.
The engine has easy duty just dragging our big [link=http://aeroplano.home.comcast.net/hangar/telemaster.jpg]senior telemaster[/link] around the patch.
(loooow time, 8-10 tanks)
Fuel : 15% Omega
Glow Plug: OS #F
Prop: 14x6 Zinger
RPM: 10,200
Prop: 14x6 Master Airscrew
RPM: 10,000
Prop: 14x7 Graupner Nylon
RPM: 8,900
Prop: 13x6x10 Zinger
RPM: 9,900
Why all the props? Because the darn thing wasn't running right out of the box - only turning in the mid sixes. Re-plumbed fuel tank and lines AND loosened a way-too-tight intake valve. Tried all the props and am running the master airscrew for now. The 14x6 Zinger was best, but it's a loaner. A 14x6 APC is probably the best.
The engine has easy duty just dragging our big [link=http://aeroplano.home.comcast.net/hangar/telemaster.jpg]senior telemaster[/link] around the patch.