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ASP 1.08 questions - 12/31/2005 12:25:46 AM   
!joeman


 

Posts: 6
Joined: 7/22/2003
From: phx az
Status: offline 		i have an ASP 1.08 that i just broke in and taken a couple flights on. It seems to run ok, but never really opens up like i think it should - seems bogged down. I'm running 10%, OS # 8 plug, stock muffler, and a 14x8 prop and its maxing out around 8600 rpm. Is this normal for this size engine? I'm used to hearing the high pitched whine of the smaller engines. is a 14x8 too much prop? Thanks for the help.
       Post #: 1

RE: ASP 1.08 questions - 12/31/2005 12:51:53 AM   
Kweasel


 

Posts: 1087
Joined: 1/7/2004
From: fort worth, TX, USA
Status: offline 		A 108 will turn 14-8 around 10,000 rpm depending on the brand of prop. This will sound slower than the average .40 at 14,000.

(in reply to !joeman)
       Post #: 2

RE: ASP 1.08 questions - 12/31/2005 12:56:52 AM   
w8ye



Posts: 17492
Joined: 12/11/2001
From: Taylortown, OH, USA
Status: offline 		You might try a 14-6 but it's never going to sound like a 46.

I was at the field today and there was a Bearcat with one on it. It ran perfect. I didn't ask about his prop.

Enjoy,

Jim

_____________________________

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

Club Saito Member #7
Original AMA #31261

(in reply to Kweasel)
       Post #: 3

RE: ASP 1.08 questions - 12/31/2005 1:22:45 AM   
SteveW



Posts: 160
Joined: 12/27/2001
From: Rockledge, FL, USA
Status: offline 		Are you sure it's really broken in? ASP take more than just a few tanks to really work themselves in. Are you sure it's not detonating? If it's an older red head engine they were really designed for zero nitro. You may need to shim the head to lower the compression ratio if you want to keep using the 10%.

(in reply to w8ye)
       Post #: 4

RE: ASP 1.08 questions - 12/31/2005 1:32:27 AM   
bdtsr


 

Posts: 1466
Joined: 9/3/2002
From: Egg Harbor Twp., NJ, USA
Status: offline 		Shim the head as already posted or drop the nitro to 5% or less. My ASP 1.20 hates anything above 5% nitro. My ASP .61s loved 15% though.

(in reply to SteveW)
       Post #: 5

RE: ASP 1.08 questions - 12/31/2005 1:45:44 AM   
Ed_Moorman



Posts: 3684
Joined: 1/5/2002
From: Shalimar, FL, USA
Status: offline 		If the ASP 1.08 is the same engine as the Magnum 1.08, you need more prop. A buddy and I have a pair of them and they are happier being lugged down. We like a 15-8 or a 16-6 prop. With the smaller props, it seems to get to a certain rpm and not go any further. Turns about the same with a big prop.

If you are used to a .46, any 1.08 will sound slow, more like a 4-stroke. On the ground, it seemed like a 14-8 was the best prop, but on my old Joss Stick, a 16-6 was the prop for it. On a scale plane like our Northrop A-17 a 15-8 gives a little more speed so we like it better.

You probably should forget comparing rpm on the ground and see how the plane performs in the air. I've had a tach for years and rarely ever use it. They can get you into trouble unless you know what you're looking for. And trying to compare your engine to another one in some other part of the country is also hard. The degree of break-in, temperature, humidity, density altitude, fuel, prop, glow plug, all have an affect of how your engine runs. In addition, big engines generally require several tanks of fuel to get completely run in. I would not be concerned unless the engine isn't pulling your plane and you know someone else with the same set-up and his runs a good bit better.

< Message edited by Ed_Moorman -- 12/31/2005 2:14:41 AM >

_____________________________

Ed Moorman, AMA 553, KD4QBM, Revver Bro #156
R/C Report Magazine, Fun Aerobatics Column

(in reply to bdtsr)
       Post #: 6

RE: ASP 1.08 questions - 12/31/2005 2:21:13 AM   
!joeman


 

Posts: 6
Joined: 7/22/2003
From: phx az
Status: offline 		thanks for the info. It's not the red head version, but i'll try lower nitro. the prop is a wood zinger 14x8. As far as breaking in, I've put almost a whole gallon of fuel through it - i'd almost like to hear that it'd take longer if that'd lead to more power later on. I have read elsewhere that shimming the head is beneficial - would these be the part to use?

http://www.horizonhobby.com/Shop/ByCategory/Product/Default.aspx?ProdID=ASP10813

one shim? two? what do you suggest?

at least i know i should expect more from this engine and i'll tinker with it til its there.

(in reply to !joeman)
       Post #: 7

RE: ASP 1.08 questions - 12/31/2005 4:13:52 AM   
soarrich



Posts: 2375
Joined: 2/1/2002
From: Middletown, NJ, USA
Status: offline 		Just a thought on something basic that is sometimes overlooked, make sure you're using large fuel line, the engine may be starved for fuel if you use .40 sized fuel line.

_____________________________

Rich Border

(in reply to !joeman)
       Post #: 8

RE: ASP 1.08 questions - 12/31/2005 5:54:48 AM   
Ed Cregger



Posts: 7745
Joined: 1/31/2002
From: Ringgold, GA, USA
Status: offline
quote:

ORIGINAL: !joeman

i have an ASP 1.08 that i just broke in and taken a couple flights on. It seems to run ok, but never really opens up like i think it should - seems bogged down. I'm running 10%, OS # 8 plug, stock muffler, and a 14x8 prop and its maxing out around 8600 rpm. Is this normal for this size engine? I'm used to hearing the high pitched whine of the smaller engines. is a 14x8 too much prop? Thanks for the help.



-----------------


The older red head ASP 1.08's instructions said that the engine was not to be run above 9k rpm or so. It was stated that it was a torquer and not a revver, in so many words, and that the operator would not be happy with the engine above 10k rpm. Remember, I'm trying to recall information from over a decade ago. I don't know which version you have, but once I knew that it was not a revver, I became impressed with its ability to turn large props for its size.

The red head was also set up to burn 0-5% nitro. More than that and the user would experience overheating and deadsticks. Of course, a headshim would have alleviated the problem with higher nitro fuels.

I would be surprised if this changed significantly for newer models of this engine.


_____________________________

Artisan

"Flying models since the Fifties - I'll get the hang of this yet!!!"

(in reply to !joeman)
       Post #: 9

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