10.8:1 + boost? (mad or what?)

[EC8]

iv'e been getting alot of info from different sources relating to high compression and boost, assuming all internals are up to scratch what do you with detonation? Where and how do you get rid of that excess heat generated by the large ammount of air and fuel being hugely compressed and ignited?

My project... Stock compression on b16b ie 10.8, small turbo small boost t28 running 6psi and a 10k revlimit, forget the 10k for now, need to get the high compression + low boost theory correct before I blow a large hole in those nice molybdenum covered pistons, all theories and toughts are welcome.

 

[Shiznit]

you need a higher octane fuel..

 

[potatobiker8]

you need a higher octane fuel..

maybe suggest how high of octane to go?but im sure u cant run that on pump gas

 

[EC8]

not the technical answer i was expecting... but higher octane fuel is not an option over hear its good luck that we currently are running something in the 93 octane range. I've been told that I can forget to run above 9 or 9.5 compression max, I want to know why, and what I can do to overcome the difficulty.

 

[tricked_civic]

alcohol injection, that would be a way to go

 

[Shiznit]

not the technical answer i was expecting... but higher octane fuel is not an option over hear its good luck that we currently are running something in the 93 octane range. I've been told that I can forget to run above 9 or 9.5 compression max, I want to know why, and what I can do to overcome the difficulty.

okay... one way to use a lower octane fuel is to get lower compression pistons for your car. If fuel octane is too low for a given compression ratio, the fuel ignites too early and the fuel charge EXPLODES rather than BURNS resulting in incomplete combustion. The effect is a loss in power and possible engine damage. Even though you say your compression is 10.8:1 dont forget the fact that youre throwing compressed air into your engine also. Your knock sensor will recognize detonation and throw a code if it happens

i dont know where malta is but there are additives that you can add to your fuel to raise the octane if you have to resort to that kinda thing.

EDIT: the reason people say lower compression motors are better for boost is because of this reason. most people believe that your engine will blow up if you have a high compression and thats just not true. the truth is your engine will perform better with higher compression, but you will need a high octane fuel so that it the fuel burns the way it supposed to. most people just assume that oyu can use any fuel for any compression and be okay, and they blame the engine blowing on the high compression, when in reality it was the incorrect fuel that they were using that caused it.

but the way to stop detonation since you dont have access to high octane fuels is to lower your compression, and to do that you can get a thicker head gasket or you can get low compression pistons.

 

[King Bob]

okay... one way to use a lower octane fuel is to get lower compression pistons for your car. If fuel octane is too low for a given compression ratio, the fuel ignites too early and the fuel charge EXPLODES rather than BURNS resulting in incomplete combustion. The effect is a loss in power and possible engine damage. your knock sensor will recognize detonation and throw a code if it happens

i dont know where malta is but there are additives that you can add to your fuel to raise the octane if you have to resort to that kinda thing.

right !

think of how a desiel engine works compression = heat, to much compression and heat will "detonate" the fuel. you will need to lower the comp the easyest and cheapest way is to replace your head gasket with a thicker one. Weather or not this will be enough is a question for a more knowledgeble person

 

[Inigo Montoya]

search for tonyt or something like that on HT.. he is running 10+ compression at 10psi on a gt30 (i think), although he is using forged internals.

 

[Handlebars]

stock type r motors take well to boost. a good, conservative tune is the key to running high compression on boost. that means something in the neighborhood of an 11:1a/f ratio at wot, and pulling .8-.9* of timing per psi until brake max torque, then holding that timing across the top of the rev range.