Hi Guys,heres some info for you regarding how & why timing & fuel octane effect power;
First some octane facts for you ,nice & simple no heavy reading or showing off;-
1) The higher the octane the slower the fuel burns
2) The slower burn means its shoving down on the piston for a longer period as opposed to a short jab. So more time is spent per cycle 'working', and a more controlled burn is achieved aswell.
3) Octane in the UK is rated as Ron
4)The Mon number is around 10 less than the Ron number
5) In the US their octane is the average of the Ron & Mon ,so their 92octane is the same as our 97Ron.
6) The highest octane unleaded fuel you can get is around 106 Ron (cool blue)
1) A higher octane fuel will benefit from an advanced (ie earlier) spark.Within reason if you dont advance the timing for the better fuel you wont gain any power,but then you wont hurt anything either.
2) A lower octane fuel requires the timing to be retarded,(ie a later spark where the piston is furthur up the bore),if you do retard the timing you lose power but the engine runs fine. If you dont retard the timing the engine pinks (the US boys say ping) this loses power too but also runs serious risk of an engine blow up if driven under high load for any period (eg nailing it in 5th or 6th)
3) The anti-knock sensors in theory retard the timing automatically when it pinks. In reality the car still pinks and this is not going to save you .Never rely on the Anti Knock Sensor. They are better than nothing ,but only just!
4) Pinking can be heard as a light 'tinkling' or 'rattling' under load. ;-Stereo off,windows closed, ear towards windscreen,use at least 3rd gear up a hill and floor the throttle . Try at 3000,4000,5000,&6000rpm. One tiny little 'tinkle' (only) under these conditions is usually ok. If you can 'never' get the car to pink then it begs the question 'Could this car use a little more advance?' -which would give more power in the process.
5) Assuming the knock sensor is not cutting the timing back ,you will not gain power merely by adding a higher octane fuel.
POWER UPGRADES (re-map)
1) The earlier 163bhp MCS
appears to have been mapped to run on very low octane fuel, they did this to ensure it didn't pink even on crap fuel.Hence as stock the 163 cars feel as flat as a pancake.
2) The later cars run more ignition advance , and would be more inclined to pink on the same crap fuel that the 163bhp cars can run ok on.This is where the 7bhp comes from. It makes the car more responsive low down too.
3) If we know the car will be run on a minimum of 97Ron, then one can advance the timing and reap the benefits. Earlier cars will gain more from just a remap than later cars. Effectivley they both end up with similar advance,but as the later car was half way their to start with it 'gains less'.
4) A remap only upgrade will not give anywhere near the power & torque of a pulley+remap conversion. Save your pennys and do it this way.
5) For power always use the highest octane fuel you can get (thats Tescos 99Ron at the moment) ,and map to achieve as much advance as possible but without it pinking.
Hope this helps ,Happy new year Roland GT Tuning