fitted a slightly larger t25 turbo on the astra ,and did a day of testing on the chassis dyno ,it seems to be quite good ,
i did a bit of experimentation with timing and mixture ,and thought it might be of interest...
bearing in mind its on lpg ,so around 5 to 10% less powerful than petrol,i would say it would make 170 to 180 on petrol .
i went through various steps....
heres a boost log ...pk boost at pk bhp is 10 psi.
firstly tried a multitude of mixtures ,here are a couple...
then a test on ignition timing ..there may be a little more to get here , but im playing it a bit safe ,and remember ,boost rises from 7 to 10 psi but most of the time its between 7.5 and 9.5.
then a comparison between turbo's and over the days progress scaled to show max detail..
lastly power and torque on a 0 scale to show real smoothness levels .
boost log for last runs ...psi bit higher at 10.477psi.boost control seems erratic!
then i had a play with low rpm torque i raised and lowered timing to see what i'd gain .turns out to be around 6 lbs/ft at 1800 ,noice.
phew .lots of runs... 35 in total .. engine stayed cool throughout ,and today i might have a go at economy tuning .. i did an experiment yesterday where i held the car at 75 mph ,and changed throttle opening to replicate cruise vacuum .i did it at 10'' and 5'' hg ,and got 7 bhp and 22 bhp .so that's my range .i plan to vary settings ,and watch injector pulse width ,lower the better for the same bhp .
regards
robert.
thanks for posting 