Chris69

If i said the AFR of my car was 11.5/1 wot would u say??
I have a PE printout that says this as a side note when my car is on full load, is this the compression ratio if so is it ok cus from wot i've read it seems very high and would explain why my car boosts so early
just wondering tis all thanks for any help

Christian and Beccy

iTrader: (14)

If your engine had a Compression Ratio of 11.5:1 it would be non-existent by now!!!

The AFR is the 'Air/Fuel Ratio' and is a term to describe exactly that, the ratio of Air to Fuel. The higher the number, the leaner the mixture. So, for example, 12.5:1 is leaner than 11.5:1.

11.5:1 is safe.

Chris69

thanks alot christian shows how clued up i am doesn't it
How can i find out wot compression my car is running then?? i've see the compression testers in halfords do u know how they wrk or are they crap??
glad that my fuel/air mix is ok that puts my mind at ease cheers

Christian and Beccy

iTrader: (14)

A Compression tester doesn't test Compression Ratio. The only way to do that is to measure it and that really isn't easy.

A standard RST is over 8.0:1, but needs to be lower than that to run big boost. 7.5:1 or lower. The higher the Compression Ratio, generally the more responsive the engine, but you won't be able to run as much boost before detonation occurs, so its a fine balance. Most people opt for low comp to be safe.

Compression ratio isn't something that changes or is better or worse on a good/bad car. Consider it an 'immovable' factor that only changes when you make a change, like having the Head skimmed if the Head gasket fails etc (this raises the Compression Ratio, which is generally a bad thing for a Turbo engine).

A Compression tester will test for loss of Compression (pressure) due to things like Head Gasket failure/Piston ring problems/Valve seating problems etc.

Chris69

thanks for clearing that up christian i think its about time i had my car setup as i think alot of the questions i still wanna ask will be more answerable when said rs turbo is in front of the tuner
thanks for ur help though i appreciate u humouring someone trying to learn about there rs turbo

Christian and Beccy

iTrader: (14)

Where in the world are you??

Chris69

I'm in bristol mate and will most probably be visiting the nearest PE place to get her setup as i want to make sure shes sweet- i'm just trying to find out some info for myslef- educate myself as it where because my rst didn't come with much history and wot it did come with is sketchy at best

paconassa

11.5:1 is too rich, you are most probably wasting fuel and power...
try, on rollers, to get afr between 12:1 to 13.5:1 to obtain max power

but like Christian and Beccy said 11.5:1 its safe...

good luck

paconassa

chunt69

chunt69 wrote:
If i said the AFR of my car was 11.5/1 wot would u say??
I have a PE printout that says this as a side note when my car is on full load, is this the compression ratio if so is it ok cus from wot i've read it seems very high and would explain why my car boosts so early
just wondering tis all thanks for any help


11.5:1 is too rich, you are most probably wasting fuel and power...
try, on rollers, to get afr between 12:1 to 13.5:1 to obtain max power

but like Christian and Beccy said 11.5:1 its safe...

good luck