91 Octane is what i need for my mini-me, right?
08-16-2006, 10:05 PM
#1
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91 Octane is what i need for my mini-me, right?
I was using 85 before i did the mini me swap (Y7 block Y8 head) and someone told me i needed to put 91 in because it has a higher compression, is this correct? Also if possible what would my compession ratio be at? the compression test showed 180 across the board.
08-16-2006, 10:36 PM
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That's completely false and incorrect. You can continue putting 85 octane in there.
Has nothing to do with your compression. Has to do with your compression ratio. The higher the octane numbers, the harder it has to be compressed to spontaniously combust (like how diesel engines work, they use high combustion to squeeze it until it detonates rather than use spark plugs). When the fuel detonates, it can "preignite" if your octane isn't high enough to match your compression ratio. So if you put high compression pistons and valves in there to up your compression, then maybe you'd have to go with 89, 87, or 91 octane due to the compression ratio being raised to the point where it'll preignite before the piston hits TDC (top dead center) (where the gas is the most compressed and the spark plug fires).
The Y8 head does have more compression than the Y7 I do believe, but it's not much, not enough where you're going to preignite anyways. All the stuff you hear about putting higher octane in your car to make it run better is all bullshit. It's all how high your compression ratio is, like diesel trucks have compression ratios of like 18:1, so obviously diesel fuel (if in the form of gasoline) would have a really high octane rating..but your civic's got like a 9.5 compression ratio...and raises to like a 9.5001 with the new head. The difference is too null. I don't know the compression ratios exactly, but you get the idea. I think Honda recommends 87 in their engines, in a Y7 or a Y8 though, it won't matter, continue putting your 85 octane gas in there and you'll be fine. And 10 years from now if you still have the car it'll last just as long as the guy that said he had to treat his car right and continued putting 97 octane in there, only difference is his wallet would be a lot lighter than yours :-P.
EDIT:
What you measured was the compression, that just tells you the compacity of the combustion chamber at BDC (bottom? dead center...where the piston is the lowest). Obviously you want it to be the same accross but doesn't have anything to do with octane - that's your compression ratio. The compression ratio or "CR" basically means (using the example 9.5:1 CR) that when the piston is all the way down you have 9.5 volume in there (not an actual measurement of anything, just a ratio). Then when the piston's all the way up it makes the volume 1, so it's basically a fraction, 9.5:1 means you had 9.5x more volume when the piston is all the way down, then if you bump the CR, to say, 11:1 CR, you'll have to use higher octane gas b/c now you have 11x more volume when the piston is all the way down...and it usually starts to preignite around that area on a civic and you'll neeed higher octane. You don't really need to understand CR's completely, just know that you can continue using 85 in your car and you'll be absolutely fine and your car won't run less or anything of the sort.
You can PM me if you have any questions about anything I said as it's late and I'm not sure if I'm making mistakes as to details.
Has nothing to do with your compression. Has to do with your compression ratio. The higher the octane numbers, the harder it has to be compressed to spontaniously combust (like how diesel engines work, they use high combustion to squeeze it until it detonates rather than use spark plugs). When the fuel detonates, it can "preignite" if your octane isn't high enough to match your compression ratio. So if you put high compression pistons and valves in there to up your compression, then maybe you'd have to go with 89, 87, or 91 octane due to the compression ratio being raised to the point where it'll preignite before the piston hits TDC (top dead center) (where the gas is the most compressed and the spark plug fires).
The Y8 head does have more compression than the Y7 I do believe, but it's not much, not enough where you're going to preignite anyways. All the stuff you hear about putting higher octane in your car to make it run better is all bullshit. It's all how high your compression ratio is, like diesel trucks have compression ratios of like 18:1, so obviously diesel fuel (if in the form of gasoline) would have a really high octane rating..but your civic's got like a 9.5 compression ratio...and raises to like a 9.5001 with the new head. The difference is too null. I don't know the compression ratios exactly, but you get the idea. I think Honda recommends 87 in their engines, in a Y7 or a Y8 though, it won't matter, continue putting your 85 octane gas in there and you'll be fine. And 10 years from now if you still have the car it'll last just as long as the guy that said he had to treat his car right and continued putting 97 octane in there, only difference is his wallet would be a lot lighter than yours :-P.
EDIT:
What you measured was the compression, that just tells you the compacity of the combustion chamber at BDC (bottom? dead center...where the piston is the lowest). Obviously you want it to be the same accross but doesn't have anything to do with octane - that's your compression ratio. The compression ratio or "CR" basically means (using the example 9.5:1 CR) that when the piston is all the way down you have 9.5 volume in there (not an actual measurement of anything, just a ratio). Then when the piston's all the way up it makes the volume 1, so it's basically a fraction, 9.5:1 means you had 9.5x more volume when the piston is all the way down, then if you bump the CR, to say, 11:1 CR, you'll have to use higher octane gas b/c now you have 11x more volume when the piston is all the way down...and it usually starts to preignite around that area on a civic and you'll neeed higher octane. You don't really need to understand CR's completely, just know that you can continue using 85 in your car and you'll be absolutely fine and your car won't run less or anything of the sort.
You can PM me if you have any questions about anything I said as it's late and I'm not sure if I'm making mistakes as to details.
08-16-2006, 10:48 PM
#4
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Re: (Syndacate)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Syndacate »</TD></TR><TR><TD CLASS="quote">That's completely false and incorrect. You can continue putting 85 octane in there.
Has nothing to do with your compression. Has to do with your compression ratio. The higher the octane numbers, the harder it has to be compressed to spontaniously combust (like how diesel engines work, they use high combustion to squeeze it until it detonates rather than use spark plugs). When the fuel detonates, it can "preignite" if your octane isn't high enough to match your compression ratio. So if you put high compression pistons and valves in there to up your compression, then maybe you'd have to go with 89, 87, or 91 octane due to the compression ratio being raised to the point where it'll preignite before the piston hits TDC (top dead center) (where the gas is the most compressed and the spark plug fires).
The Y8 head does have more compression than the Y7 I do believe, but it's not much, not enough where you're going to preignite anyways. All the stuff you hear about putting higher octane in your car to make it run better is all bullshit. It's all how high your compression ratio is, like diesel trucks have compression ratios of like 18:1, so obviously diesel fuel (if in the form of gasoline) would have a really high octane rating..but your civic's got like a 9.5 compression ratio...and raises to like a 9.5001 with the new head. The difference is too null. I don't know the compression ratios exactly, but you get the idea. I think Honda recommends 87 in their engines, in a Y7 or a Y8 though, it won't matter, continue putting your 85 octane gas in there and you'll be fine. And 10 years from now if you still have the car it'll last just as long as the guy that said he had to treat his car right and continued putting 97 octane in there, only difference is his wallet would be a lot lighter than yours :-P.
EDIT:
What you measured was the compression, that just tells you the compacity of the combustion chamber at BDC (bottom? dead center...where the piston is the lowest). Obviously you want it to be the same accross but doesn't have anything to do with octane - that's your compression ratio. The compression ratio or "CR" basically means (using the example 9.5:1 CR) that when the piston is all the way down you have 9.5 volume in there (not an actual measurement of anything, just a ratio). Then when the piston's all the way up it makes the volume 1, so it's basically a fraction, 9.5:1 means you had 9.5x more volume when the piston is all the way down, then if you bump the CR, to say, 11:1 CR, you'll have to use higher octane gas b/c now you have 11x more volume when the piston is all the way down...and it usually starts to preignite around that area on a civic and you'll neeed higher octane. You don't really need to understand CR's completely, just know that you can continue using 85 in your car and you'll be absolutely fine and your car won't run less or anything of the sort.
You can PM me if you have any questions about anything I said as it's late and I'm not sure if I'm making mistakes as to details.</TD></TR></TABLE>
when i did that compresison ratio calculator thing it said i had a 10.25 compression with dual layer HG and with just a reg y8 HG says 9.9.
http://www.zealautowerks.com/dseries.html or am i supposed to base it off teh effective ratio?
Has nothing to do with your compression. Has to do with your compression ratio. The higher the octane numbers, the harder it has to be compressed to spontaniously combust (like how diesel engines work, they use high combustion to squeeze it until it detonates rather than use spark plugs). When the fuel detonates, it can "preignite" if your octane isn't high enough to match your compression ratio. So if you put high compression pistons and valves in there to up your compression, then maybe you'd have to go with 89, 87, or 91 octane due to the compression ratio being raised to the point where it'll preignite before the piston hits TDC (top dead center) (where the gas is the most compressed and the spark plug fires).
The Y8 head does have more compression than the Y7 I do believe, but it's not much, not enough where you're going to preignite anyways. All the stuff you hear about putting higher octane in your car to make it run better is all bullshit. It's all how high your compression ratio is, like diesel trucks have compression ratios of like 18:1, so obviously diesel fuel (if in the form of gasoline) would have a really high octane rating..but your civic's got like a 9.5 compression ratio...and raises to like a 9.5001 with the new head. The difference is too null. I don't know the compression ratios exactly, but you get the idea. I think Honda recommends 87 in their engines, in a Y7 or a Y8 though, it won't matter, continue putting your 85 octane gas in there and you'll be fine. And 10 years from now if you still have the car it'll last just as long as the guy that said he had to treat his car right and continued putting 97 octane in there, only difference is his wallet would be a lot lighter than yours :-P.
EDIT:
What you measured was the compression, that just tells you the compacity of the combustion chamber at BDC (bottom? dead center...where the piston is the lowest). Obviously you want it to be the same accross but doesn't have anything to do with octane - that's your compression ratio. The compression ratio or "CR" basically means (using the example 9.5:1 CR) that when the piston is all the way down you have 9.5 volume in there (not an actual measurement of anything, just a ratio). Then when the piston's all the way up it makes the volume 1, so it's basically a fraction, 9.5:1 means you had 9.5x more volume when the piston is all the way down, then if you bump the CR, to say, 11:1 CR, you'll have to use higher octane gas b/c now you have 11x more volume when the piston is all the way down...and it usually starts to preignite around that area on a civic and you'll neeed higher octane. You don't really need to understand CR's completely, just know that you can continue using 85 in your car and you'll be absolutely fine and your car won't run less or anything of the sort.
You can PM me if you have any questions about anything I said as it's late and I'm not sure if I'm making mistakes as to details.</TD></TR></TABLE>
when i did that compresison ratio calculator thing it said i had a 10.25 compression with dual layer HG and with just a reg y8 HG says 9.9.
http://www.zealautowerks.com/dseries.html or am i supposed to base it off teh effective ratio?
08-16-2006, 10:59 PM
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Hrm, I did it too and got the same numbers, I don't know if that's right or not, I mean I don't think it's wrong but maybe we're plugging something in wrong or it's reading it wrong or something. I dont' know anything about that really, maybe you do have a 10.25CR, regardless, all I can tell you is that you can continue using 85 octane with that setup, if you wanna step it up to 87 be my guest, it is your car. Until you have preignition due to misfire (your car starts misfiring) I wouldn't worry about upping the octane.
08-16-2006, 11:04 PM
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Re: (Syndacate)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Syndacate »</TD></TR><TR><TD CLASS="quote">Hrm, I did it too and got the same numbers, I don't know if that's right or not, I mean I don't think it's wrong but maybe we're plugging something in wrong or it's reading it wrong or something. I dont' know anything about that really, maybe you do have a 10.25CR, regardless, all I can tell you is that you can continue using 85 octane with that setup, if you wanna step it up to 87 be my guest, it is your car. Until you have preignition due to misfire (your car starts misfiring) I wouldn't worry about upping the octane.</TD></TR></TABLE>
awesome thanks man, sometimes when my car is idling i notice it seems to have a little missfire but other than that there is none, guess ill got for 85 and see how things go
awesome thanks man, sometimes when my car is idling i notice it seems to have a little missfire but other than that there is none, guess ill got for 85 and see how things go
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08-16-2006, 11:10 PM
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Re: (Syndacate)
According to that site, my engine should have a 15:1 CR (a b7/z6 mini-me), which would be amazing, since I'm using 93 octane pump gas with no problems. Either I'm doing something blatantly wrong, or the calculations aren't accurate.
EDIT:
oops! I was doing something blatantly wrong! I got 10.22:1 now, which sounds just about right. Try it again. I forgot to tell it I'm using a D15 crankshaft (default is D16), which screwed it up.
EDIT:
oops! I was doing something blatantly wrong! I got 10.22:1 now, which sounds just about right. Try it again. I forgot to tell it I'm using a D15 crankshaft (default is D16), which screwed it up.
08-17-2006, 06:28 AM
#10
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Re: (elguluso)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by elguluso »</TD></TR><TR><TD CLASS="quote">yeah 15:1 sounded a lil insane 
</TD></TR></TABLE>
yeah thats a little off wonder how long that would last on pump though
</TD></TR></TABLE>yeah thats a little off wonder how long that would last on pump though
08-17-2006, 07:20 AM
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Re: (modifyORdie)
Yes and if his c/r is 10.2:1 he requires premium gas. My si and a 10.2:1 c/r and it requires premium gas. Why not spend the extra $2 now? Use it.
08-17-2006, 07:23 AM
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Re: (cambopheonix56)
hmmm strange they make them so different...you know my dad always made a good point...you only see one tanker when they come to fill the stations up 
but back on topic....i would spend the $2 anyways for premium...cleaner burning, better milage, cleaner for your engine
but back on topic....i would spend the $2 anyways for premium...cleaner burning, better milage, cleaner for your engine
08-17-2006, 07:53 AM
#14
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Re: (modifyORdie)
Yeah in new mexico and the southwest where oil is abundant and oil fields are paying like 20.00 and hour for nothing jobs we can only get 91 octane 
.
.
08-17-2006, 09:26 AM
#15
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Re: (sauceja)
Yes they make 91 octane. That's pretty much the highest you can get in most of CA.
If your compression ratio is 10 or higher, then you should be running 91 or higher. Your compression ratio is most likely between 9.1 - 9.5, so 87 is fine. I don't know if I trust those compression ratio calculators. What pistons did you enter in?
Don't run 85. 87 is the minimum.
If your compression ratio is 10 or higher, then you should be running 91 or higher. Your compression ratio is most likely between 9.1 - 9.5, so 87 is fine. I don't know if I trust those compression ratio calculators. What pistons did you enter in?
Don't run 85. 87 is the minimum.
08-17-2006, 11:07 AM
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Re: (suspendedHatch)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by suspendedHatch »</TD></TR><TR><TD CLASS="quote">Yes they make 91 octane. That's pretty much the highest you can get in most of CA.
If your compression ratio is 10 or higher, then you should be running 91 or higher. Your compression ratio is most likely between 9.1 - 9.5, so 87 is fine. I don't know if I trust those compression ratio calculators. What pistons did you enter in?
Don't run 85. 87 is the minimum.</TD></TR></TABLE>
P2E pistons
and the grades here are 85, 88, and 91 the altitude plays a major role
If your compression ratio is 10 or higher, then you should be running 91 or higher. Your compression ratio is most likely between 9.1 - 9.5, so 87 is fine. I don't know if I trust those compression ratio calculators. What pistons did you enter in?
Don't run 85. 87 is the minimum.</TD></TR></TABLE>
P2E pistons
and the grades here are 85, 88, and 91 the altitude plays a major role
08-17-2006, 02:42 PM
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Re: (pumpkyn)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pumpkyn »</TD></TR><TR><TD CLASS="quote">P2E pistons
and the grades here are 85, 88, and 91 the altitude plays a major role</TD></TR></TABLE>
damn maybe i wont leave tn....no inspections, better octance, and cheaper gas
and the grades here are 85, 88, and 91 the altitude plays a major role</TD></TR></TABLE>
damn maybe i wont leave tn....no inspections, better octance, and cheaper gas
08-17-2006, 08:22 PM
#19
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Re: (modifyORdie)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by modifyORdie »</TD></TR><TR><TD CLASS="quote">
damn maybe i wont leave tn....no inspections, better octance, and cheaper gas</TD></TR></TABLE>
If I hit the lottery I am moving back out there. Just too damn much rain. I also like the one tag in the back and no state income tax if not mistaken. Not crazy about dry counties either but yeah I liked Tennessee.
damn maybe i wont leave tn....no inspections, better octance, and cheaper gas</TD></TR></TABLE>
If I hit the lottery I am moving back out there. Just too damn much rain. I also like the one tag in the back and no state income tax if not mistaken. Not crazy about dry counties either but yeah I liked Tennessee.
08-17-2006, 09:24 PM
#20
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Re: (modifyORdie)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by modifyORdie »</TD></TR><TR><TD CLASS="quote">
damn maybe i wont leave tn....no inspections, better octance, and cheaper gas</TD></TR></TABLE>
here its 2.99 for regular
damn maybe i wont leave tn....no inspections, better octance, and cheaper gas</TD></TR></TABLE>
here its 2.99 for regular
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