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.91 Four Stroke Readings

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Old 09-17-2004, 10:35 AM
  #26
AnthonyH
 
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Default RE: .91 Four Stroke Readings

New reading on the TT 91
I purchased some different fuel and wow what a difference! I changed from the Wildcat Supreme 10% nitro and 18% oil with a 80/20 blend to the Wildcat ProMix 20% nitro and 18% oil with 95/5 blend.

The TT F91S is now turning what I had expected it to.

APC 14x6 - 10500 rpm
Engine temp - 178°F
Idle - 1700 rpm

I did not have a chance to run the OS 91 due to darkness. I will run it with same fuel and post results. I will also run a 15x6, 14x5 and 15x6/10 on both.

Has anyone tried the APC 15x4W prop on the TT or OS 91? If so what did you think of it? I have the TT in a Hog Bipe and the OS in a GP SpaceWalker. I am thinking the 15x4W would be a good prop for the Hog Bipe.
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Old 09-21-2004, 06:31 PM
  #27
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Default RE: .91 Four Stroke Readings

Following up on my prior post. I ran the OS 91 Surpass II on the Wildcat ProMix and got good readings from it as well. It looks like the OS will swing a bigger prop than the TT, but the TT will swing the 14x6 better than the OS. See results.

OS .91 Surpass II on Wildcat ProMix 20% fuel.
15x6 Zinger = 8700
14x6 APC = 9800

TT F91S on Wildcat ProMix 20% fuel.
15x6 Zinger = 8200
14x6 APC = 10500

I thought it was interesting that the ProMix 20% nitro did not do as much for the OS, but made a huge difference with the TT, spinning the 14x6. The TT just does not like to swing the big lumber (as evidenced by the 8200 rpm with 10% and 20% nitro), but it really likes the APC 14x6. I am going to try the APC 15x4W and see what it will do on the TT. I am happy with the 15x6 Zinger on the Spacewalker. It has a scale look and great performance with the OS 91.
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Old 09-21-2004, 09:49 PM
  #28
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Default RE: .91 Four Stroke Readings

Quote:
ORIGINAL: DTB

I can't believe nobody has posted this yet.

Engine:
YS .91FZ
APC 15x6 @ 9600
15% nitro
2.0 HP rating
That's less than I thought YS would make. This is about the same as my Saito 100 on 15% nitro. I guess YS really needs 20%+ nitro or to shine above Saito of the similar "class".

My YS 110 is swinging a Zinger 16x5@ 9200 rpm on 20/20 fuel. It's still breaking in though.

Back to topic...

Magnum 91 4-stroke:
APC 15x4W @ 9800 RPM on 15% Omega fuel
Zinger 16x5 @ 7800 RPM on 15% Omega fuel

Saito 91:
APC 15x4W @ 9700 RPM on 15% Cool Power 4-stroke fuel
Dynathrust 14x6 [sm=thumbdown.gif]@ 9800 RPM on 15% Cool Power 4-stroke fuel
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Old 10-14-2004, 09:14 PM
  #29
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Default RE: .91 Four Stroke Readings

My flying buddy and I were checking our OS 91's this past week, with the the same tachs.
Mine is an older OS 91 Surpass and his is a newer SurpassII. Neither is pumped, and we are both running a MA 14-6 with Morgan Cool Power 15%.

The older OS 91 turned 10,400
The Newer Surpass II turned 9800 - 10K
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Old 05-09-2005, 02:35 AM
  #30
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Default RE: .91 Four Stroke Readings

magnum 91 fs. 5% nitro 18% castor.

MA 13X8 K 10000
top flight 15X6 8200

as i see this is good results
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Old 05-09-2005, 02:38 AM
  #31
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Default RE: .91 Four Stroke Readings

and forgot to say, this is not peak rpm, this is alredy set up. if u believe me. it comes, that magnum is as powerfull, as os and sayto
wanted to check 15X4, but stripped thread in glow plug hole
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Old 06-30-2005, 12:03 PM
  #32
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Default RE: .91 Four Stroke Readings

For all those guys with Saito 91's, How do they run i heard they are really rough and eat a lot of fuel because I need a 91 Engine and I am not shir what to get but it looks like I will be gettin a Saito 91.
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Old 07-02-2006, 01:40 AM
  #33
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Default RE: .91 Four Stroke Readings

Pump os 91 without exhaust.

cool power 15%

MA 14x6 10,000

cool power 25%
Same prop @10,600
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Old 07-29-2006, 04:10 PM
  #34
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Default RE: .91 Four Stroke Readings

Magnum 91, APC 14x6, 10200 sustained
OS 91, APC 14x6, 9600 sustained
Both on Magnum 15% blended fuel
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Old 07-29-2006, 04:41 PM
  #35
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Default RE: .91 Four Stroke Readings

Quote:
ORIGINAL: ptarp
I'm just trying to figure out if my enigne is under performing, or if people are inflating their numbers a bit.
Judging by what I've read here in the Tach Readings forum, some folks have engines that are good for 1000 rpm more rpm than every type engine I've owned and tested. I must have monumental bad luck in buying engines.
If someone has the tendency to bash a particular brand, where better place to dump on it than this forum. The same thing applies when someone is trying to hype up a certain brand. The amazing thing about the internet ( almost magic), they don't have to have ever owned or ran the engine in question.
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Old 07-29-2006, 07:29 PM
  #36
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Default RE: .91 Four Stroke Readings

Quote:
ORIGINAL: TimC

Quote:
ORIGINAL: ptarp
I'm just trying to figure out if my enigne is under performing, or if people are inflating their numbers a bit.
Judging by what I've read here in the Tach Readings forum, some folks have engines that are good for 1000 rpm more rpm than every type engine I've owned and tested.
Aint that the truth!

I was taching my YS 1.10 the other day with an APC 14x10 prop. It was showing readings in the mid nines and the light was starting to fade and suddenly it showed 14,000 rpm.

AS a result, I'm very proud to report that my YS 1.10 does 14,000 rpm with an APC 14x10 on 20/20 fuel! I can even show you a photo of the tach showing this - this makes it more credible apparently.

YS rulez!!! All other engines suck!!!
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Old 07-29-2006, 07:36 PM
  #37
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Default RE: .91 Four Stroke Readings

I just tached my Saito .91 with a 14x7, 20% nitro/15% oil at 9480 RPM with about 56oz. of fuel through it.
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Old 08-03-2006, 08:09 PM
  #38
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Default RE: .91 Four Stroke Readings

Magnum .91
15 percent PowerMaster
14X6 APC prop
10200 Static 9800 to fly...
Runs like a Swiss watch
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Old 08-07-2006, 08:37 AM
  #39
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Default RE: .91 Four Stroke Readings

Does anyone fly Magnum .91 on 0%nitro / 20% rizinus oil?

Matt
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Old 08-07-2006, 02:44 PM
  #40
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Default RE: .91 Four Stroke Readings

One of the guys at the field got a used (carefully and lovingly, judging by its apearance) OS .91 Surpass pumper off "that auction site", which we ran up the other day.

OS .91 S2 Pump
15% Nitro, 18% Oil
13x10 APC prop
9200 peak, reliable 1700 rpm idle

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Old 08-07-2006, 03:25 PM
  #41
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Default RE: .91 Four Stroke Readings


Quote:
ORIGINAL: Harry Lagman

AS a result, I'm very proud to report that my YS 1.10 does 14,000 rpm with an APC 14x10 on 20/20 fuel! I can even show you a photo of the tach showing this - this makes it more credible apparently.

YS rulez!!! All other engines suck!!!
Dude!!!!! I just heaved all my motors in the trash.

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Old 08-11-2006, 06:23 PM
  #42
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Default RE: .91 Four Stroke Readings

Quote:
Dude!!!!! I just heaved all my motors in the trash.

Have you put the trash can out front yet?
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Old 08-21-2006, 07:20 AM
  #43
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Default RE: .91 Four Stroke Readings

If he sold all his engines, he just might be able to buy one years worth of batteries.
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Old 08-22-2006, 03:07 PM
  #44
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Default RE: .91 Four Stroke Readings

Skalov. I just came home from the field. Today I tried a cheap fuel 0% nitro 20% oil, about half of that oil is castor. When taching my sc 91 fs(same as magnum) on 15% nitro I get a peak of 10200 on the mas 14-6 k-series and when I tached the same prop on this 0% fuel I leaned it out to 10000, so there`s no big difference there. I flew one flight and really couldn`t tell much difference at all. I had to lean the needle about 1/4 revolution so I guess my engine will run quite a bit longer on that 0% fuel
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Old 08-27-2006, 02:11 PM
  #45
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Default RE: .91 Four Stroke Readings

Thats because nitro burns at a 2.5/1 ratio with air while alcohal burns at 6/1, thats why you lean your engine with less nitro. I have run my Saito 65 on 5% to 20% and you don't see alot of difference in rpm, but Saito's are easier to deal with with more nitro. Easier to start, not as fussy to tune etc. With low nitro you get better gas milage and the fuels cheaper to boot. A Magnum will run just fine on low nitro.
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Old 08-28-2006, 03:59 PM
  #46
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Default RE: .91 Four Stroke Readings

asmund thanks for information! I don't understand why nitro fuel is more than twice more expensive in Europe than in US...
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Old 08-30-2006, 08:07 AM
  #47
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Default RE: .91 Four Stroke Readings

OS FS91 Surpass unpumped, Zinger 15x6-10, 10%nitro, onboard glow driver.

Peak 7,100
Rough Idle 2,100
Smooth Idle 2,350

I know the peak is low and the idle is high. If anyone has the same setup, please post your rpm readings? I figure there are few who run this same prop and I know it is maxed out. Is it correct that a larger diameter and higher pitch prop will help reduce reliable idle rpm?

Thanks,
Bobby
Dunn, NC
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Old 08-30-2006, 09:29 AM
  #48
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Default RE: .91 Four Stroke Readings


Quote:
ORIGINAL: Skalov_

asmund thanks for information! I don't understand why nitro fuel is more than twice more expensive in Europe than in US...
Import tax?
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Old 08-30-2006, 06:21 PM
  #49
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Default RE: .91 Four Stroke Readings

Quote:
ORIGINAL: Sport_Pilot


Quote:
ORIGINAL: Skalov_

asmund thanks for information! I don't understand why nitro fuel is more than twice more expensive in Europe than in US...

Import tax?

Perhaps, but joust for example... 1 gallon coll power 10% in us cost 14$, in Europe costs 21€ that is 27$ and this is (one of) the lowest price... this is one good reason why is good to be American
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Old 08-31-2006, 01:35 PM
  #50
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Default RE: .91 Four Stroke Readings

Tax, tax and tax, and then profit[:'(] let me give you an example of the 30% nitro 24% oil heli coolpower. In Norway it costs about equal to 72$ for one gallon. So I have never tried that fuel in my ys 110, it is to damn expensive around here
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