spurdy Posted September 2, 2009 Report Share Posted September 2, 2009 Did you read what I wrote? I said as a base to be safe 20cc was a good starting point. I cant run 20cc domes here at sea level but someone higher up can. At 2500' yes you can run a smaller dome. This is why I said, YOU HAVE TO DO YOUR RESEARCH!!!!! Also you cant just go by compression. A drag ported motor is going to have lower compression then a stock motor with the same size domes. Also he didnt ask if it would hurt, he asked if it would help. To answer that question like I did, No it will not help unless you motor NEEDS the octane. Higher octane fuel slows down the burn to reduce detonation. So really if your motor doesnt need the higher octane its almost like running too rich. The motor doesnt burn all the fuel so its not running efficiently. So when a motor isnt running efficiently its not producing as much power as it can. Exactly, the burn rate of the fuel ties directly to the timing. Higher octane burns slower so the timing can be advanced more. The height of the exhaust roof plays a part in your compression as much as the dome size. This is why a drag motor produces a lower static compression then stock or other port type motors. All things have to be considered. Dome size, porting, timing, elevation, etc. There is no blanket statement regarding compression if you want to run on the fine line. Higher octane fuel can diminish performance if not needed. Higher octane fuel is needed to prevent detonation caused by the way the engine is set up. It is not used to increase performance. People that use race fuel will have higher performance engines but this isn't because of the fuel, it is because of the set up which makes the fuel necessary. SP Quote Link to comment Share on other sites More sharing options...
sandman81 Posted September 2, 2009 Report Share Posted September 2, 2009 It depends on what size domes you put in. You should be safe with a high quality 93 octane up to a 20cc dome. But depending on alot of factors that will be different. Best thing to do is do some research on it. Someone at 3500' above sea level can run a different size dome with pump gas then someone at sea level. Did you read what I wrote? I said as a base to be safe 20cc was a good starting point. I cant run 20cc domes here at sea level but someone higher up can. At 2500' yes you can run a smaller dome. This is why I said, YOU HAVE TO DO YOUR RESEARCH!!!!! Also you cant just go by compression. A drag ported motor is going to have lower compression then a stock motor with the same size domes. Also he didnt ask if it would hurt, he asked if it would help. To answer that question like I did, No it will not help unless you motor NEEDS the octane. Higher octane fuel slows down the burn to reduce detonation. So really if your motor doesnt need the higher octane its almost like running too rich. The motor doesnt burn all the fuel so its not running efficiently. So when a motor isnt running efficiently its not producing as much power as it can. I did read it. You said "You should be safe with a high quality 93 octane up to a 20cc dome." Meaning anything lower then 20cc and he'll have to use higher octane. No mention of a base or starting point. And I'm helping him by giving him some input on setups. e.g. my friends setup and another members setup. Even though it is word of mouth. Don't get what you ment by "you can't just go by compression," then you put "A drag ported motor is going to have lower compression then a stock motor with the same size domes". I told him it would be pointless, meaning no help. 3YLSYKR, my friend's banshee stock, except for timing, 18cc domes, vforce reeds, pods and toomey t6. Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted September 2, 2009 Report Share Posted September 2, 2009 Ok like I said SAFE. 20cc domes are safe. You should not have a problem with them running pump gas. If you live higher up then you can running smaller domes. As far as what I said about drag porting being lower compression its true. Because the exhaust port and intake ports will over lap each other with extreme porting your compression will drop. But the drag motor and stock motor with the same size domes will need the same fuel even though the compression numbers will be different. Dude, do yourself a favor and start reading man. Maybe you'll actually learn something. Quote Link to comment Share on other sites More sharing options...
sandman81 Posted September 2, 2009 Report Share Posted September 2, 2009 Ok like I said SAFE. 20cc domes are safe. You should not have a problem with them running pump gas. If you live higher up then you can running smaller domes. As far as what I said about drag porting being lower compression its true. Because the exhaust port and intake ports will over lap each other with extreme porting your compression will drop. But the drag motor and stock motor with the same size domes will need the same fuel even though the compression numbers will be different. Dude, do yourself a favor and start reading man. Maybe you'll actually learn something. Ok, DUDE. Do yourself a favor and learn to write so we can understand you. I don't know if your talking about cranking compression, dynamic compression, or static compression. Static compression ratio, is measured in volumes in relation to BDC to TDC. Like 12:1 or 6:1. It doesn't change that is why it's called static, meaning, standing fixed in one place. Dynamic compression ratio, is measured where the position of the piston is in relation to the exhaust port height and TDC. Cranking compression, is the pressure that is produced in the cylinder. So your statement about "Also you cant just go by compression. A drag ported motor is going to have lower compression then a stock motor with the same size domes." Makes no sense you tell me you can't just go of compression but then you give a example of a drag ported motor that is going to have a lower compression. And if compression doesn't make a difference when choosing a octane grade fuel, then why use compression as in example. I do know how to read, you just don't know how to explain yourself. So don't give me shit. 1 Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted September 2, 2009 Report Share Posted September 2, 2009 Dude its right there. Its very simple to understand. the point I was making is that you cant go by cranking compression. You can have two motor with the same static compression but different cranking compressions. You go by static compression over cranking. As far as not understanding, most people understand that when saying COMPRESSION its cranking compression we are talking about. When your talking static compression that COMPRESSION RATIO or 14:1. Sorry for not being totally specific with what I said. Most people know what Im saying. Quote Link to comment Share on other sites More sharing options...
steenasbanshee Posted September 2, 2009 Report Share Posted September 2, 2009 i run 110 in my banshee. i bought it that way, im not sure what size domes i have either. sometimes i wish i was on regular pump cause its a PITA to find, cost money and you have to worry if the shit is fresh or not. BUT once i fire it up, i can inhale that ALLLLLLLL day, i love it! Quote Link to comment Share on other sites More sharing options...
sandman81 Posted September 2, 2009 Report Share Posted September 2, 2009 Dude its right there. Its very simple to understand. the point I was making is that you cant go by cranking compression. You can have two motor with the same static compression but different cranking compressions. You go by static compression over cranking. As far as not understanding, most people understand that when saying COMPRESSION its cranking compression we are talking about. When your talking static compression that COMPRESSION RATIO or 14:1. Sorry for not being totally specific with what I said. Most people know what Im saying. I'm not most people, LOL. Cool I get what your saying, it's just that your comment about not just going of compression when picking a octane fuel and then using a example of engine's compression and didn't explain why, is what didn't make sense. People that I have dealt with think that cranking compression is what to go by and don't know that other compression exist. I think it would be safe to say that 3YLSYKR doesn't understand this, by the race fuel question. Not start shit, but I don't see how elevation should matter when it comes to picking a octane grade if cranking compression is not important, only time I have used elevation with relation to cranking compression is to see if the engine is nicely sealed. I've seen engines at higher elevation that have high cranking compression run great at sea level, they just need to do minor adjustments. Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted September 3, 2009 Report Share Posted September 3, 2009 Yeah sorry man. I think we are both saying the same thing just different ways. As far as the higher elevations its just like the difference between hot and cold days. Since the air is thinner you need less gas to satisfy the motor. Im guessing since the compression is lower at higher levels that the it doesnt build as much heat from the motor compressing the air. That means that you need less octane. You get what Im saying? Quote Link to comment Share on other sites More sharing options...
sandman81 Posted September 3, 2009 Report Share Posted September 3, 2009 Here we go again making no fucking sense, LOL, just fucking with you. Yeah I get what your saying. Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted September 3, 2009 Report Share Posted September 3, 2009 Actually I think I confussed my self on that one. Quote Link to comment Share on other sites More sharing options...
spurdy Posted September 3, 2009 Report Share Posted September 3, 2009 (edited) I was confused on the static compression also. I mis spoke when using the term and meant cranking compression. My bad. Edited September 3, 2009 by spurdy 1 Quote Link to comment Share on other sites More sharing options...
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