How much boost on 91 octane???

[ZUL8R]

Hey guys this is my list of mods and i was wondering what u guys think the best boost would be for a daily driven 91 octane gas?? here r the mods

TOPHAT Performance Crate motor Supertech 8:4:1 compression, 89.5 Coated Pistons, Supertech performance Piston rings, Cometic MLS Head Gasket, ARP Head studs, ARP Main Studs, ARP Rod bolts, Brian Crower Springs & Retainers, Timing Kit (tensioners guides, chains, and gears), Oil pump, Water pump, Clevite main and Rod bearing, Freeze plug Kit, Mr Gasket Copper exhaust gasket, Enthalpy ECU, APEX'I SAFC-II, Greddy Profec-E Boost controller, XS Engineering power pack, B&M short shifter, ACT Street Extreme Clutch/Pressure plate, New clutch slace cylinder W/Steel braided line, Gredy TD-06/20G turbo, Greddy Type-S BOV, Greddy FMIC, Greddy catch can, Walbro Fuel pump, RC 750 Injectors, 300ZX MAF, Fue pump regulator, NEX GT Fully adustable Coilovers, 300ZX Brake swap, Kouki front lip, Kouki Side skirts, HID headlights

thanks alot fellas
Modified by ZUL8R at 9:45 AM 1/12/2007

[ZUL8R]

Bump, whats going on guys no one knows around how much psi i should run with this Setup on 91 octane. I had the car for like two weeks and dont know what best. Any replys would kinda give me an idea. Thanks

[ZUL8R]

Hey guys this is my list of mods and i was wondering what u guys think the best boost would be for a daily driven 91 octane gas?? here r the mods

TOPHAT Performance Crate motor Supertech 8:4:1 compression, 89.5 Coated Pistons, Supertech performance Piston rings, Cometic MLS Head Gasket, ARP Head studs, ARP Main Studs, ARP Rod bolts, Brian Crower Springs & Retainers, Timing Kit (tensioners guides, chains, and gears), Oil pump, Water pump, Clevite main and Rod bearing, Freeze plug Kit, Mr Gasket Copper exhaust gasket, Enthalpy ECU, APEX'I SAFC-II, Greddy Profec-E Boost controller, XS Engineering power pack, B&M short shifter, ACT Street Extreme Clutch/Pressure plate, New clutch slace cylinder W/Steel braided line, Gredy TD-06/20G turbo, Greddy Type-S BOV, Greddy FMIC, Greddy catch can, Walbro Fuel pump, RC 750 Injectors, 300ZX MAF, Fue pump regulator, NEX GT Fully adustable Coilovers, 300ZX Brake swap, Kouki front lip, Kouki Side skirts, HID headlights

thanks alot fellas

Modified by ZUL8R at 9:45 AM 1/12/2007

[Bronze MFP]

might get a good answer in the KA-T forum, but i'd say to be safe, no more than 5-7lbs. Depends on what turbo you are running and how aggressive a timing map you are running too. Ewww just read you are running an safc-II, be careful that its only used to fine tune an existing chip tune on the ecu, if you adjust the fuel maps too much it affects your timing maps, and thats bad. The lower compression pistons help though. Can you not get anything better than 91 octane in AZ?

[ZUL8R]

I

might get a good answer in the KA-T forum, but i'd say to be safe, no more than 5-7lbs. Depends on what turbo you are running and how aggressive a timing map you are running too. Ewww just read you are running an safc-II, be careful that its only used to fine tune an existing chip tune on the ecu, if you adjust the fuel maps too much it affects your timing maps, and thats bad. The lower compression pistons help though. Can you not get anything better than 91 octane in AZ?

I can get 101 octane but its $6 a gallon.

[Cabezcoco]

you can try to spike it with some avgas if you want to bump it up a few points. Im not recomending that but hey cant hurt to bad

[ISUJinX]

How much boost you can run depends a lot on piston shape (and material/coating) as well as combustion chamber design and final static compression ratio. With a forged dish piston like you have and a moderately low CR at 8.4 (if I read that correctly) you should be able to run 8-12 safely. With 93 octane you can usually safely run up to 1 atm. (14.7 lbs.)

On 101 you should be able to run about 16-17, with 105 about 20. Octane is a measure of "resistance to detonation", thus the higher the octane, the higher final compression ratio (including boost) you can run without detonation. Keep in mind that this means more heat, and will need a stronger spark.

On a side note - if you are running dome pistons (in a hypothetical situation) you will need to run a lower final compression ratio because the tips of the domes create "hot spots" which will lead to detonation, and eventually a hole in the piston. Same goes for Nitrous.

P.S. Don't mix it with AVgas. Its a different weight and will settle in the tank causing erratic firing and unpredictable octane. Plus its bloody expensive :-p.