Magnum .91FS!  
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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Tachometer Readings >> Magnum .91FS!
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Magnum .91FS! - 3/26/2005 5:44:40 PM   
Cogburn



Posts: 213
Joined: 3/12/2004
From: Brookings, SD, USA
Status: offline 		Just got done running in my new magnum .91fs. 150$ on sale at tower! Adjusted the valves and tried a few props. Here's what i'm getting!

39'f , 30.15"pressure
15% omega with 2% castor added

11x9 apc 11600rpm 1.47hp
12x8k ma 10650rpm 1.43hp
14x6k ma 10250rpm 1.77hp
Peaked
HP from thrusthp
These things must fall off fast after 10000rpm.
       Post #: 1

RE: Magnum .91FS! - 3/31/2005 4:51:04 PM   
bako


 

Posts: 105
Joined: 5/8/2004
From: tbilisi, GEORGIA
Status: offline 		don't trust thrusthp calculator.
I have same engine, running on 5%nitro and 18% castor
here are some results

MA 13X8k 8.3lb
MA 13X8 3blade same, but more speed
top flight 15X6 9.7 lb

(in reply to Cogburn)
       Post #: 2

RE: Magnum .91FS! - 4/14/2005 11:13:41 PM   
Dart373


 

Posts: 1098
Joined: 10/20/2002
From: Chapel Hill, TN, USA
Status: offline 		I dont touch the valves. I ran 2 tanks through my $149 tower motor too! I put a Master Airscrew 14x6 and pulled consistently 10,500 static. I put a 15x6 APC on it and pulled 8900. This is with Cool Power 30% Heli. This motor is a hog man, I love it.

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       Post #: 3

RE: Magnum .91FS! - 4/28/2005 5:35:26 AM   
w8ye



Posts: 17279
Joined: 12/11/2001
From: Taylortown, OH, USA
Status: offline 		I ran mine a couple years ago and was 9500 with a 14-8 APC 1,100' @40F.

It was stronger than my OS 91 Surpass I which was 9400 with a 14-6.

Saito 80 was 9200 with a 14-6.

All same day with Omega 10%

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Attended the CutFinger Institute of DirtNap University for years but never did graduate....

Club Saito Member #7
Original AMA #31261

(in reply to Dart373)
       Post #: 4

RE: Magnum .91FS! - 5/9/2005 3:49:55 AM   
Dart373


 

Posts: 1098
Joined: 10/20/2002
From: Chapel Hill, TN, USA
Status: offline 		Now 3 gallons through my Magnum .91 for $149 on 30% Heli..... I spin an APC 15x6 at 10,000 even. This motor is incredible. Stronger than my newer .91 OS Max!!

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Where there is confusion, there is profit.
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       Post #: 5

RE: Magnum .91FS! - 5/12/2005 6:25:33 AM   
bako


 

Posts: 105
Joined: 5/8/2004
From: tbilisi, GEORGIA
Status: offline 		thats joke yea? how can 91 magnum spit 15X6 on 10k? I can't believe. check thrust or recheck tchometer. if it'sso, lets god be with u. just wonderfull

(in reply to Dart373)
       Post #: 6

RE: Magnum .91FS! - 5/12/2005 11:36:48 PM   
Dart373


 

Posts: 1098
Joined: 10/20/2002
From: Chapel Hill, TN, USA
Status: offline 		It the 2nd one I have that turns a 15x4 or 6 at static 10,000. I have a Magnum tac and a Glow Bee tach. Both the same. The motor is screaming, I believe it. I will get some vid clips up soon. Take in mind, I run 30% nitro too... I run them rich, always run afterrun oil, and let the good times roll. Its 3D, So I dont need to wind them up, but they will!

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       Post #: 7

RE: Magnum .91FS! - 5/19/2005 3:39:58 AM   
RCAddiction



Posts: 883
Joined: 3/29/2002
From: Waxhaw, NC, USA
Status: offline 		14x6 APC 9900 rpm on Wildcat 15% full synthetic

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Lee

(in reply to Dart373)
       Post #: 8

RE: Magnum .91FS! - 11/21/2005 11:59:36 AM   
Gringo Flyer



Posts: 2153
Joined: 1/16/2004
From: Formosa, ARGENTINA
Status: offline 		HOw long after break in does it take to get to these rpm´s

I was breaking mine in yesterday and with a 14X6 MA prop and 10% fuel I was getting around 7500. It was super rich but I cant see another 2500 RPM´s coming out of this engine.


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       Post #: 9

RE: Magnum .91FS! - 11/21/2005 12:07:57 PM   
Gringo Flyer



Posts: 2153
Joined: 1/16/2004
From: Formosa, ARGENTINA
Status: offline 		I just looked through some tach readings on other four strokes and you guys are getting close to the same readings that guys are reporting on Saito 100.

I just dont see how that is possible. Am I the only one not getting huge numbers on a Magnum 91?


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       Post #: 10

RE: Magnum .91FS! - 11/22/2005 6:25:06 PM   
seanychen



Posts: 2914
Joined: 7/20/2002
From: Canton, MI, USA
Status: offline 		High nitro helps a lot in 4-stroke engines nowadays. Usually you can get 500+ rpm gain going from 15% nitro to 30% nitro.

Having said that, the Saito 100 and Magnum 91 4-stroke differ in power by about 500 rpm on the same prop and same nitro. So I can believe that Magnum 91 on 30% nitro will catch up with Saito 100 on 15% nitro, if both use the same prop that's within comfortable range of the 91. However, running expensive 30% nitro fuel on a Magnum sort of defeats the benefit of Magnum's economy. I've found that 20/20 fuel is a good compromise between fuel cost and performance.

Saito 100 will out-pull a 4-stroke 91 significantly when you go to larger prop, like APC 16x4W.

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       Post #: 11

RE: Magnum .91FS! - 11/23/2005 12:56:12 PM   
Sport_Pilot



Posts: 7600
Joined: 1/21/2002
From: Acworth, GA, USA
Status: offline 		I think you will lose a couple of hundered Revs when it is over 80 degrees out. Anybody rememember what they were getting last summer?

(in reply to seanychen)
       Post #: 12

RE: Magnum .91FS! - 11/23/2005 10:22:21 PM   
Gringo Flyer



Posts: 2153
Joined: 1/16/2004
From: Formosa, ARGENTINA
Status: offline 		Over 80 degrees. We hardly fly when its under 95!


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       Post #: 13

RE: Magnum .91FS! - 12/13/2005 12:16:54 AM   
akschu



Posts: 411
Joined: 3/23/2005
From: , AK, USA
Status: offline 		Magnum calls for no more than 15% nitro, so what happens when you run 30%? Are any of you running into detonation issues?

(in reply to Gringo Flyer)
       Post #: 14

RE: Magnum .91FS! - 12/13/2005 9:47:00 PM   
Harry Lagman


 

Posts: 1140
Joined: 11/19/2003
From: Auckland, NEW ZEALAND
Status: offline
quote:

ORIGINAL: Gringo Volador

I just looked through some tach readings on other four strokes and you guys are getting close to the same readings that guys are reporting on Saito 100.

I just dont see how that is possible. Am I the only one not getting huge numbers on a Magnum 91?


Gringo, I'm with you. Some of these numbers are just incredible. I bet some of these guys have got the special "one that got past QA" car that does 1000 mpg too.

I mean...., one guys gets 10,000 with an "APC 15x4 or a 15x6". Well which one - or were they the same load?

Also, 9500 with an APC 14x8 on 10% nitro. This is not only at least 600 rpm stronger than any OS, Saito or TT .91 I've ever tested (and I've tached a few now) but is more than 200 rpm stronger than my Saito FA100 can get on 20% nitro.

I wish some guys would take more care when reporting rpms.

(in reply to Gringo Flyer)