Ok, so I'm now all in with this RC stuff

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Z.hb71 said:
How much do one of them big ass drums go for? Too feking lazy to google it ??
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$86
JT3 said:
The gas salespeople have really done an amazing job with their marketing by convincing the majority of the population that higher octane is somehow better for your vehicles. It's just marketing. Certain engines are designed to run on certain fuels. That's pretty much it. A lot of higher-end cars call for "premium" because they are designed to be run on that fuel. Now, you can take the same engine and tune it so that it NEEDS to be run on higher octane, but if you're taking the same engine and not changing anything but the fuel, it really shouldn't change anything else. Ever notice there's no "premium" for diesel? lol.
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It's all about compression. Higher the compression ratio the more the higher octane needed. The c12 is good to 15:1. Not sure what my 65 and 50 compression is at to be honest.
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crucialRC said:
$86

It's all about compression. Higher the compression ratio the more the higher octane needed. The c12 is good to 15:1. Not sure what my 65 and 50 compression is at to be honest.
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Better than I thought thought it was gunna be 100+ tbh. Not bad. Btw, the 70cc cylinder that alx used is rated at 14:1 so your 65 is around there probably. No clue on the 50
 
I wasnt posting to stop you from using it mate. And you'd hear the knock. It would sound like your slamming two rocks together, in a 2 stroke. The tune will change a little if your running pump gas with ethonal in it. That's a fact. But running in general shouldn't be much different.

Higher octane doesn't make engines run better or worse, if it's not called for. And normally any thing much over 12to1 will need a higher octane then what you can get at the pump. You could push 13to1 with the right timing set up, but 93 would be a push, 97 would be preferred.
Now if we want to talk static pressure (compression pressure) my 50cc race saw pumps 220psi on a stone cold engine. I have the timing conservatively set at 25*btdc. This engine lives around 16k rpm in a cut. And it lives happily on 97 octane pump gas.
So I will be interesting to see what your results are. I would like to know what your engines are rated for compression and compression ratio. (If available or easily attainable) and it would also be interesting to see if you could bump the 65 up a little, either by removing a shim from the head (if used) on swapping out a higher comp dome (if used) I think that's where the higher octane fuel would really give you a net performance gain. ( just because you should easily be able to do this on the 65 of you desired to)
So I'll sum up my guess.
First you'll need to tweak the tune a bit.
Second you wont notice any major gains.(this should at minimum be set up as a timed lap or such, so you have viable data for comparison)
Third, you will no longer have storage issues, related to phase separation, or water ingress as it's an ethonal free fuel.
Keep us posted mate.
 
Seandonato73 said:
I wasnt posting to stop you from using it mate. And you'd hear the knock. It would sound like your slamming two rocks together, in a 2 stroke. The tune will change a little if your running pump gas with ethonal in it. That's a fact. But running in general shouldn't be much different.

Higher octane doesn't make engines run better or worse, if it's not called for. And normally any thing much over 12to1 will need a higher octane then what you can get at the pump. You could push 13to1 with the right timing set up, but 93 would be a push, 97 would be preferred.
Now if we want to talk static pressure (compression pressure) my 50cc race saw pumps 220psi on a stone cold engine. I have the timing conservatively set at 25*btdc. This engine lives around 16k rpm in a cut. And it lives happily on 97 octane pump gas.
So I will be interesting to see what your results are. I would like to know what your engines are rated for compression and compression ratio. (If available or easily attainable) and it would also be interesting to see if you could bump the 65 up a little, either by removing a shim from the head (if used) on swapping out a higher comp dome (if used) I think that's where the higher octane fuel would really give you a net performance gain. ( just because you should easily be able to do this on the 65 of you desired to)
So I'll sum up my guess.
First you'll need to tweak the tune a bit.
Second you wont notice any major gains.(this should at minimum be set up as a timed lap or such, so you have viable data for comparison)
Third, you will no longer have storage issues, related to phase separation, or water ingress as it's an ethonal free fuel.
Keep us posted mate.
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You got it @Seandonato73 . I gotta finish my last bit of pump gas anyway so I'll get some rpm and lap times to see if theres a difference. Where do you get your 97 octane from? Do you use octane booster?
 
Lol no booster, sunoco stations have it as high test at the pump, but it has ethonal. Steve Heins store sells vp fuels. He has 97 ethonal free at the front pump island. That's just a idk 15 min drive or so, which is about the same as it it to get to any other station from me.
Also theres a little air port that sells low lead avgas. Think its 100 octane.
 
Just did some quick googling. 91-93 (depending on elevation) is all that's required for 13:1. So if you're less than that you should be fine.
Seandonato73 said:
Lol no booster, sunoco stations have it as high test at the pump, but it has ethonal. Steve Heins store sells vp fuels. He has 97 ethonal free at the front pump island. That's just a idk 15 min drive or so, which is about the same as it it to get to any other station from me.
Also theres a little air port that sells low lead avgas. Think its 100 octane.
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I think some "RaceTrac" gas stations have 100 octane. Don't know if yall have those up north.
 
Z.hb71 said:
Y'all are saying all this , but people are running pump gas in the 90gt and that thing has rediculous compression. It's their timing setup that compensates for the compression, there motors are meant for pump gas . I wouldn't over think it
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I just run whatever the manufacturer recommends and don't give it a second thought.


Just found this on RCMax site in the manual for the smaller BB engines. 40/46/50.

"This must be mixed at a fuel/oil ratio of 25:1. Only good quality 95+ Octane must be used to prevent the possibility of detonation or seizure. We recommend using an additive called Tetraboost with your fuel for the ultimate in reliability. (or run a two-stroke friendly leaded race fuel such as VP C12.)"

Just went through, all the way up to 90GT says 95+ octane. So I'm guessing the ratio is somewhere between 14-15.
 
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JT3 said:
I just run whatever the manufacturer recommends and don't give it a second thought.


Just found this on RCMax site in the manual for the smaller BB engines. 40/46/50.

"This must be mixed at a fuel/oil ratio of 25:1. Only good quality 95+ Octane must be used to prevent the possibility of detonation or seizure. We recommend using an additive called Tetraboost with your fuel for the ultimate in reliability. (or run a two-stroke friendly leaded race fuel such as VP C12.)"

Just went through, all the way up to 90GT says 95+ octane. So I'm guessing the ratio is somewhere between 14-15.
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From rcmax website under the 65 installation and operation manual.
20200627_162758.jpg
 
JT3 said:
Does anybody happen to know the horsepower specs on the motors? I'm trying to decide if I should do an E-word build. The new MGM 800 ESC and Lehner 30100 motor are capable of 53hp. Insane.
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None of these bigbores are even close to 53hp. The alx 85 makes 28hp+ so I assume the 90gt and supreme 80 are around there too. For the 71cc motors I'd guess somewhere in the 18+ hp range. The 50-60 are probably 14-16. They don't state their hp ratings (except the alx 85) so that's all a guess. They haul ass tho, the Mgm would just be uncontrollable, and they don't make any brap brap sounds
 
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