chris-m

couple of questions if anyone can help, whats the stock Ls1 compression and also what (generally) is the grade of pump fuel in the USA out of interest that they run on?
trying to work out what octane rating fuel to run it on here in the UK, as our RON rating isnt directly comparable to yours i believe? i can get 95 octane, 97 or 98. dont want to see it detonating if i run our cheapest grade 95 octane thats all. i have an msd timing box with the 6 timing pills to use.
hope this is the right section for questions!
thanks
chris

mchdg86

iTrader: (3)

Stock LS1 compression is 10:1. In the US 91 is the recomended octane.

chris-m

thanks for that. i'll try and find out how 91 octane in the US compares to our 95 or 97 octane. we aren't as fortunate as you guys on petrol prices for these big v8s! :-)
98 octane near me is £1.12 /litre eeeek!

LS1Z28_98

Trust me, we aren't lucky with fuel prices anymore. Paid $3.39 a gallon for 93 the other day. Not what you pay, but we are creaping closer and closer to that.

chris-m

optimax (98 octane) good stuff has been £1.19 a litre recently in some parts. my Celica GT4 is mapped on that fuel, luckily i dont drive it daily. diesel tho is £1.09 a litre today- ouch!
do you guys run 93 octane in highly tuned cars,or just by choice for better fuel?

i've asked on the MSD ignition forum if they can advise what octane their MSD ign units are mapped to as standard
cheers

chris-m

ps i would love to be paying $3.39 for a gallon! :-)
last time i was in the US i think we paid circa $2.69 ish in florida on holiday. seems to have gone up a jump for you also.

RedWS6 00

Chris I'm here in the UK too.
I always run on Shell Optimax, they say is over 99 octane, but who really knows. I know if i run on regular unleaded of 95 RON I do get some knocking, but then the car learns from the knock and after a few miles doesn't show knock retard.
I think you'd be okay on 95 RON as the car learns, but saying that i always put in Optimax as a safe measure.
Optimax is £1.08 for me, but i guess it depends on where you are in the country.

chris-m

hi there! pm'd you!
my worry is the msd ignition unit is not mappable with the version i got, just the basic unit with 6 different curves via timing pills. i do need to know what fuel octane msd used for the timing tables to prevent det on friday. its going to be track use (and quite hard!) so its going to help if i can get away with cheaper fuel than optimax etc.
regards
chris

chris-m

bttt
anyone know what octane msd ign control units are mapped to for US fuels? been told it may be ok on equivalent to uk 95 octane if anyone can help?
cheers