octane gas

[thedeadcivic]

what octane gas should i be using in my D16a6?
does higher octane give power?

[turtlecrxsi]

87... no power gained... ugh!

[Christ]

Myth: Higher octane fuel will give your engine more power...

Truth: Higher octane fuel will stop you from losing power and possibly your engine due to detonation. Basically, the higher the octane is, the longer it takes to explode, meaning that it's designed to stop pinging in heavily worn, high C/R and over advanced timing engines.

[FrodoGT]

Right, octane rating=resistance to combustion, if your engine was built, tuned and timed for regular, then 93 wont do a damn thing.

[Tony]

+2 on what Frodo said.

if the motor isn't tuned for it or a high c/r motor, you won't notice a thing. If you get it tuned for it, yes. If its a high compression motor you will gain power from higher octane.

[thedeadcivic]

is it possible to buy new pistons that are taller in order to get higher compression? if so, where would i start looking?

[Tony]

Yes, but there is more too it than just that. I don't want to get into it for fear of giving the wrong info.

[thedeadcivic]

mabye ill just make a new thread

[FrodoGT]

Just for a little tidbit of info..the reason you want a higher octane for your High C/R engine is because when the piston rises, it compresses the fuel and air (duh), when it does this, it gets hot, very hot..which is actually how a diesel engine operates, on compression alone, anyway..if it is too hot from too much compression, and if you have a low octane gas, that detonates easily, when that piston rises the fuel will compress and explode BEFORE the spark plug even has a chance to go off. By raising the octane, the fuel will resist detonating until spark is applied to it, so the engine will not knock, or ping etc etc..

Im bored and im sick at home..Felt like typing something :P

[Schister66]

Originally Posted by FrodoGT

Just for a little tidbit of info..the reason you want a higher octane for your High C/R engine is because when the piston rises, it compresses the fuel and air (duh), when it does this, it gets hot, very hot..which is actually how a diesel engine operates, on compression alone, anyway..if it is too hot from too much compression, and if you have a low octane gas, that detonates easily, when that piston rises the fuel will compress and explode BEFORE the spark plug even has a chance to go off. By raising the octane, the fuel will resist detonating until spark is applied to it, so the engine will not knock, or ping etc etc..

Im bored and im sick at home..Felt like typing something :P

93 octane + boost + GSR = me FTW....

good info though

[bambam89lx]

Originally Posted by Schister66

93 octane + boost + GSR = me FTW....

good info though

Using a higher octane doesn't equal more power. But, it allows you to pull more timing which does equal more power.

[FrodoGT]

Basically..detonation=BAD= GG new engine..

[Christ]

There are several ways to get more compression, one of which is buying new pistons... but in order to get higher topped pistons, you need to make sure that they aren't going to come up too high and contact anything else, like the valves or the cylinder head casting.

There is a strength issue too, being that if you use pistons from other car manufacturers, the wrist pins might not be in the right place for the stroke that your honda engine has (from a honda dealer in carlisle pa) which will cause unnecessary stress on your pistons and rods assy.

most people just get higher compression by having the head and block castings milled, usually b/c when you rebuild an engine, you wanna have it "trued" anyway, meaning that you wanna have it so that the head deck is parallel completely to the centerline of the cam bearing seats, or completely flat, and the block deck should be the same with the crank main bearing seats.

another good way to get higher compression is just to install a thinner head gasket.. like if you have a B2 engine, I'm pretty sure, (correct me if I'm wrong), you could use a y8 head gasket, and that would increase your compression to something like 9.4:1 instead of 9.2:1 (figures are pry wrong too.. it's been a long day so far)

if you're really into compression, then you could actually do a combination of all three, which usually requires blueprinting your build, b/c you have to then start making measurements of all the parts you're goign to use, to make sure that when they are under stress, they aren't going to beat the piss out of each other.

just b/c you have 1.1 thousandths clearance between your pistons at their highest point, and the valves, at their lowest point, doesn't mean that when you warm the engine up, and get to 4k rpm, they won't expand due to heat and stress, and slam into each other, causing the kind of marriage that only your local engine builder is happy to hear about... or at least his wallet.

so, that said, my personal option is to just leave the compression alone, if not lower it, and put boost into the engine... basically adding power by theoretically increasing the "displacement" of the engine, in that I"m adding compressed air instead of atmospheric air..

2.2 litre engine + 14.7 psi (1bar) = 4.4 litres of combustible mixture

Not precisely, since your engine almost never has 100% Volumetric efficiency (meaning that it doesn't actually pull in/push out 2.2 litres of air), but it's a good way to explain it to someone that doesn't know. (not saying you don't, personally, but alot of people don't, that might read this.)

Wow... I wrote a book.. any publishers around? I'd like to get paid for this. :P

[bambam89lx]

Originally Posted by Dr0pZ0n3

There are several ways to get more compression, one of which is buying new pistons... but in order to get higher topped pistons, you need to make sure that they aren't going to come up too high and contact anything else, like the valves or the cylinder head casting.

There is a strength issue too, being that if you use pistons from other car manufacturers, the wrist pins might not be in the right place for the stroke that your honda engine has (from a honda dealer in carlisle pa) which will cause unnecessary stress on your pistons and rods assy.

most people just get higher compression by having the head and block castings milled, usually b/c when you rebuild an engine, you wanna have it "trued" anyway, meaning that you wanna have it so that the head deck is parallel completely to the centerline of the cam bearing seats, or completely flat, and the block deck should be the same with the crank main bearing seats.

another good way to get higher compression is just to install a thinner head gasket.. like if you have a B2 engine, I'm pretty sure, (correct me if I'm wrong), you could use a y8 head gasket, and that would increase your compression to something like 9.4:1 instead of 9.2:1 (figures are pry wrong too.. it's been a long day so far)

if you're really into compression, then you could actually do a combination of all three, which usually requires blueprinting your build, b/c you have to then start making measurements of all the parts you're goign to use, to make sure that when they are under stress, they aren't going to beat the piss out of each other.

just b/c you have 1.1 thousandths clearance between your pistons at their highest point, and the valves, at their lowest point, doesn't mean that when you warm the engine up, and get to 4k rpm, they won't expand due to heat and stress, and slam into each other, causing the kind of marriage that only your local engine builder is happy to hear about... or at least his wallet.

so, that said, my personal option is to just leave the compression alone, if not lower it, and put boost into the engine... basically adding power by theoretically increasing the "displacement" of the engine, in that I"m adding compressed air instead of atmospheric air..

2.2 litre engine + 14.7 psi (1bar) = 4.4 litres of combustible mixture

Not precisely, since your engine almost never has 100% Volumetric efficiency (meaning that it doesn't actually pull in/push out 2.2 litres of air), but it's a good way to explain it to someone that doesn't know. (not saying you don't, personally, but alot of people don't, that might read this.)

Wow... I wrote a book.. any publishers around? I'd like to get paid for this. :P

Dont' forget about flat faced valves or welding chambers. Reducing the size of the combustion chamber is the best way to increase compression. For example, a GSR head has flat quench pads on the edge of the combustion chambers which is why it yields a higher compression than a B16 head, on the same block. Believe it or not, you want to run as flat as a piston as possible. You'll make more power with a flatter piston, and milled head to get a 12:1 compression ratio than with a higher domed piston without milling to get a 12:1 compression ratio. High domes are terrible for combustion, flame travel, and volumetric efficiency. High domes:

-tend to "split" the incoming air charge
-can lead to hot spots aka detonation due to the reduced surface area for detonation
-are usually heavier, causing more stress on the bearings/rings

[Christ]

wow, I"m surprised that noone caught that... the thing about turbos...

They ONLY increase your volumetric efficiency by adding air.. and just b/c you're running a 2.2 litre engine @ 1 bar of boost DOESN'T mean that you're gonna have 4.4 litres in there... I was really tired when I wrote that... but yeah... what I meant to say was this:

Provided your engine runs @ 100% VE all the time, and you're at sea level, and your turbo is 100% efficient all the time, pushing in air at the same temp as your surrounding area, you could effectively double your engine's efficiency, meaning that your 2.2 litre might become a 4.4 litre, without actually increasing the engine size... this, however, would probably lead to your engine not lasting very long, since being a street motor, it's safe to say that you're probably not going to get it tuned for double duty, nor are you going to have proper amounts of fuel.

BamBam, thanks for clarifying the dome piston thing... I actually knew that, but forgot about it... ya know how that goes lol.