normality78

Ok, im not sure wat im asking here make any sense but hell, without asking i wont know does it make sense.

Most of us know force induction engine mostly running in low comp ratio or to any bolt on application, piston need to be change to low comp to withstand average boost. Some bolt-on owner choose to use thicker gasket or retard ignition as the boost grow to avoid knocking.

my question is what is the different from retarding ignition over utilising low comp piston? For example, an engine was having 10:1 ratio with bolt on turbo. As boost building, ignition get retarding. Will this engine make the same power compare with an engine with 9:1 ratio compression? Taking it exact same boost level, engine capacity and turbo size

rprznt

oh god. learn the difference between compression and timing, ---- a duck noob :1

CivicOCD

I can't even begin to explain the things wrong with that paragraph but I think i know what you want to know.

A lower compression ratio will allow you more "room" for error/tuning. It will allow you to run more boost generally speaking before you start detonating. other factors contribute as well, octane of fuel/ignition

I wont try to explain the difference between static and dynamic compression ratio, google it.

your other question: comparing 2 identical engine's, the one with the higher compression ratio is going to make more power. with or without a turbo..

normality78

CivicOCD ,
Ok, i'll google it. Tks for the reply anyway.

juce

---- it his question makes sense. Both are legitimate methods of preventing damage to your engine although the two are not always related. 13:1 compression, not matter how retarded your timing is going to blow up under high boost. 40+ degrees of spark advance no matter the compression is going to give you issues at high boost.
WHERE THEY ARE RELATED is that the higher your compression ratio, the more the air fuel ratio is compressed and thus heated during the compression stroke, and the faster it will burn once ignited by the spark. As a result you want to run less spark advance at higher compression ratio's. This is very theoretical, and in practice the amount of timing you need to pull to compensate for compression is doesnt account for much of your total timing curve.

normality78

Tks for the reply Juce. I get better picture now. Can i say that should i decided to run with low boost application (engine with 10:1 ratio), i could get away with retarding ignition instead of investing into low comp piston to achieve boost friendly compression? I think the trick here is how to find out the max boost press can that engine torerance.

lilpooh21186

not true juce 13.2 cpr 25 psi lsvtec it all comes into tuning and weather conditions. cooler air - chances of detonation hence +1 for methenjection and race fuel with higher octain content also increases your det threashold. Im sure he runs extreamly retarded ignition timing with all that boost but there are too many little things that can change the way a tune must be setup. On my personal setup i just wasnt happy with my part throttle performance rembering my compression was 9.0 with my .030 headgasket i went and jacked up my timing by 3 degrees in my vac tables like night and day. My afr were all off but i could feel the diff in the way the car pulled it actually moved after retuning i went from using a half a tank every 3 days to half a tank every 5 driving about 10 miles to work so about 20 miles a day. Heres the lsvtec setup