Well this is weird

Z.hb71

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Manvel, Texas
Sooooo my cylinder for my 70cc has 14:1 compression and I got recommended to use 112 octane fuel by the peeps I bought it from, but I look in the manual and they say 96-100, why? I would think 96-100 is too little for that much compression. Does anyone know/have a logical guess?
 

mark35

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218
Sooooo my cylinder for my 70cc has 14:1 compression and I got recommended to use 112 octane fuel by the peeps I bought it from, but I look in the manual and they say 96-100, why? I would think 96-100 is too little for that much compression. Does anyone know/have a logical guess?
Maybe because you can get 96-100 from the pump
 

Z.hb71

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Manvel, Texas
Maybe because you can get 96-100 from the pump
Yeah, I'm assuming In Italy they don't have 112 ? Or it's really expensive ? My guess is that it's really expensive/not for sale in Italy so it is designed for pump but the science behind it don't make any sense. I guess I might try 100 octane and if it pings put 112. How much compression does ur 48 have? Also I seen a dude who has a rcmax 90gt and he's running 96-100
 

crucialRC

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Maryland, USA
Maybe the ignition is retarded enough so it can use a lower octane. Lessens chances of detonation. That may be why I've seen ignition advance kits on sites like DDM but never a retard kit. That way you can up the ignition and up your octane and get a bigger bang if you want.
 

Z.hb71

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Manvel, Texas
Maybe the ignition is retarded enough so it can use a lower octane. Lessens chances of detonation. That may be why I've seen ignition advance kits on sites like DDM but never a retard kit. That way you can up the ignition and up your octane and get a bigger bang if you want.
How would I retard timing on that set up? I thought u could only change timing on electric style ignition
Also i think im Gunna try 100 octane and if it pings go to 112, also eventually will run E85 OR E98.
 

mark35

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218
Yeah, I'm assuming In Italy they don't have 112 ? Or it's really expensive ? My guess is that it's really expensive/not for sale in Italy so it is designed for pump but the science behind it don't make any sense. I guess I might try 100 octane and if it pings put 112. How much compression does ur 48 have? Also I seen a dude who has a rcmax 90gt and he's running 96-100
I don't know the compression ratio on my 48 tbh, feels high though
 

crucialRC

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Maryland, USA
No, I mean when they built the engine they could have built it with the timing already retarded enough to use pump gas. Timing is controlled by the flywheel pads that are picked up by the coil. It all depends on where the pads are placed on the coil in relative to 360 degree rotation of when to fire the coil. You would have to know what the timing is on that engine and whether or not you can safely advance it to get the full potential of the high compression and big displacement.

It's just like in a real engine I can drive an 11:1 on pump gas all day if the timing is not too aggressive and the heads are aluminum. It's all about timing and heat dissipation. Don't try that on an iron headed engine. Sometimes the higher compression just doesn't warrant the headaches for a few more ponies(at least on full scale:)).
 

Z.hb71

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3,306
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Manvel, Texas
No, I mean when they built the engine they could have built it with the timing already retarded enough to use pump gas. Timing is controlled by the flywheel pads that are picked up by the coil. It all depends on where the pads are placed on the coil in relative to 360 degree rotation of when to fire the coil. You would have to know what the timing is on that engine and whether or not you can safely advance it to get the full potential of the high compression and big displacement.

It's just like in a real engine I can drive an 11:1 on pump gas all day if the timing is not too aggressive and the heads are aluminum. It's all about timing and heat dissipation. Don't try that on an iron headed engine. Sometimes the higher compression just doesn't warrant the headaches for a few more ponies(at least on full scale:)).
Read the manual and it don't say sh!t about ignition. I'll talk to Athena about it. I have absolutely no idea what the timing is on my flywheel, have no idea how to adjust and measure it. I think Ill just run E85 on my motor for it's life b cuz I don't understand/want to be messing about with all the timing and stuff. I'll run 100 and if it pings I'll go E85,
 

1Coopgt

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Rochester,NY
Something to remember if you don't know it already. The higher the octane the slower the fuel burns. The timing of when the plug fires during the compression stroke needs to be considered .
Read the manual and it don't say sh!t about ignition. I'll talk to Athena about it. I have absolutely no idea what the timing is on my flywheel, have no idea how to adjust and measure it. I think Ill just run E85 on my motor for it's life b cuz I don't understand/want to be messing about with all the timing and stuff. I'll run 100 and if it pings I'll go E85,
You won't be able to adjust the timing on your engine . You would have to be able to move the magnet in the flywheel . Or move the pickup coil left to right to change timing .
My GSXR 750 and the Camaro both have the same compression ratio 12:1 . The 750 uses premium fuel. The Camaro I can run on 87 octane. the reason is because the computers in the Camaro are constantly advancing and retarding the timing and monitoring knock sensors to prevent knocking. The 750 isn't as smart so it runs advanced timing and requires the higher octane fuel.
 
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Z.hb71

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Messages
3,306
Location
Manvel, Texas
Something to remember if you don't know it already. The higher the octane the slower the fuel burns. The timing of when the plug fires during the compression stroke needs to be considered .


You won't be able to adjust the timing on your engine . You would have to be able to move the magnet in the flywheel . Or move the pickup coil left to right to change timing .
My GSXR 750 and the Camaro both have the same compression ratio 12:1 . The 750 uses premium fuel. The Camaro I can run on 87 octane. the reason is because the computers in the Camaro are constantly advancing and retarding the timing and monitoring knock sensors to prevent knocking. The 750 isn't as smart so it runs advanced timing and requires the higher octane fuel.
Yeah I can't adjust timing. I could get a power spark electronic system but that's expensive, I guess I'll see how it goes and if it pings on 100 try e85 and if it runs like sh!t buy a powerspark system cuz I'm pretty sure u can mess with the timing there. Just don't like the unsure feeling about this cuz I don't know what's going to happen and have no clue on ignition Timing. Sent a email to Athena about this and I'll see what they say
 

1Coopgt

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719
Location
Rochester,NY
Will you be able to get 112 where you live or are you going to need to add octane booster to get to 112 ? I would have to make my own to get to 112 . Highest in my area is 98 octane .
 

Z.hb71

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3,306
Location
Manvel, Texas
Will you be able to get 112 where you live or are you going to need to add octane booster to get to 112 ? I would have to make my own to get to 112 . Highest in my area is 98 octane .
Could get 112, 40mins tho. I could get 100 just by booster. Actually, I think I'll buy 2-5 gal of 112, 2-5 gal of 100, and 2-5 gal of e85 and see which ones the best
 
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