TRD3000GT Posted July 21, 2005 Share Posted July 21, 2005 After a bit of a search on Supraforums, (Our US brothers) I came across with this... It seems as though they are safely running much higher boost levels than us. I know CJ has / was running 1.8 bar on his without any problems and I have seen as much as 1.65 on mine without any leaning out or det. I have converted all the PSI values to Bar as well... ********************************************************** After running many different mixes of race fuel in my Supra's over the years, i would like to share my opinion on octane requirements. All my info is backed up with close monitering of the engine's a/f ratio, EGT and timing. Keep in mind that the size of the turbo, intercooler, and many other things will effect your octane requirement but i feel these numbers are on the safe side of things. 91 octane pump fuel(~87 Motor octane): Good for 14psi / .96 Bar max in a car with stock twins/16psi single turbo before a signifigant amount of timing is pulled. 96 Motor octane pump fuel(Unocal 100 r+m/2, Trick 101): Good for all the stock twins can blow, good for 22psi / 1.5 Bar on a single turbo car. 99 Motor octane fuel(Sunoco GT 104): Good for 26 psi / 1.8 Bar on a single turbo car. 105 motor octane fuel(Powermist, Trick 112): Good for 28psi / 1.93 Bar in a single turbo car. 108 Motor octane(VP C12/VP C16 mixed down): Good for 32 psi / 2.2 Bar on a single turbo car. Please note these arent requirements that i feel that you can get by with, as you may be able to get by with more boost/lower octane and not hurt parts, rather these numbers are for maximum performance... My personal favorite mix is to mix VP C16 down to 108 Motor octane(3.5 C16 to 1.5 91 pump gas). However, if i were to run more or less boost or nitrous, i would simply dilite the C16 more(or less) with pump. I can honestly say i can feel a SOTP diffrence with C16 mixed down vs. strait C12(C16 pulls harder). Feel free to ask me any questions.. BTW my Supra has seen 28-32 psi every weekend for almost 2 years now with no engine damage and the same compression #s as when i started. Link to comment Share on other sites More sharing options...
Digsy Posted July 21, 2005 Share Posted July 21, 2005 BTW my Supra has seen 28-32 psi every weekend for almost 2 years now with no engine damage and the same compression #s as when i started. Apart from the compresison bit, that's a difficult claim to justify. I would read "no engine damage" as "its still going so far". Link to comment Share on other sites More sharing options...
RobSheffield Posted July 21, 2005 Share Posted July 21, 2005 dont they use a different octane rating to us? if im right we use reswearch octane number (RON) and they use Motor Octane Number (MON) im sure im right, but im far from being an expert! Link to comment Share on other sites More sharing options...
Alex Posted July 21, 2005 Share Posted July 21, 2005 You're right Rob, Our 98 is about their 93... To be honest their fuel will be different from ours, we actually seem to be able to run more boost than them on our 98 (their 93). Link to comment Share on other sites More sharing options...
normore1 Posted July 21, 2005 Share Posted July 21, 2005 91 octane pump fuel(~87 Motor octane): Good for 14psi / .96 Bar max in a car with stock twins/16psi single turbo before a signifigant amount of timing is pulled. 96 Motor octane pump fuel(Unocal 100 r+m/2, Trick 101): Good for all the stock twins can blow, good for 22psi / 1.5 Bar on a single turbo car. 99 Motor octane fuel(Sunoco GT 104): Good for 26 psi / 1.8 Bar on a single turbo car. 105 motor octane fuel(Powermist, Trick 112): Good for 28psi / 1.93 Bar in a single turbo car. 108 Motor octane(VP C12/VP C16 mixed down): Good for 32 psi / 2.2 Bar on a single turbo car. QUOTE] It might be useful to note that the octane numbers listed are based on USA standard Pump Octane Numbers (PON = R+M/2) and/or MON. In the UK Reasearch Octane number (RON) is used. For pump gas RON is typically 8-10 points higher than MON and therefor 4-5 points higher than R+M/2. In the above examples 91 PON would therefore be approximately UK 95 RON (preminum unleaded) and 96 MON would be about 105 RON which I have yet to see here. UK SuperPremium (BP Ultimate and Shell Optimax) are supposedly ~98 RON so about 88 MON or 93 R+M/2. Personnaly I have run 18 psi (1.25 BAR) on 93 PON (98 RON) with no signs of detonation or retard. However, I do have a 3-row GReddy front mount which I think helps in this departmant. If you interpolate, then about 1.1 BAR on 98 RON would seem reasonable. derek Link to comment Share on other sites More sharing options...
Ian C Posted July 21, 2005 Share Posted July 21, 2005 I've run 1.4bar on optimax without having to pull any timing so far BL T67 turbot. I think a lot depends on your intake charge temps... So pushing the boost limits should be done on a hot day -Ian Link to comment Share on other sites More sharing options...
Guest Usmann A Posted July 21, 2005 Share Posted July 21, 2005 no more than 17 psi on pump for us. 98/99 whatever is is called these days. I found last year that 29 psi with 74 with stock head will be fine on race gas - 114MON sunco stuff I used. No big detonation occurance, with iridums aswell. The MON afaik is the actual rating given when using the single cylinder testing chamber .. O how Id like to have one of those in my garage ... Chris, are those with a stock 8.5:1 comp, or lower? Link to comment Share on other sites More sharing options...
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