The best way to know is by datalogging......if no knock and afr is good then your basically good to go?

 

Stock 05 boost at 20.5 psi and is safe on 91 cali octane so 22 on 93 should be more than enough safe margin to run your car.

 

Personally, if I could get 93 or 94 octane pump gas I would just run 21# max with your setup. The tuner did all the research and makes his boost level recommendations tailored to the particular fuel trims and timing maps in your flash.

There has to be a certain margin of safety built into these flashes and the boost recommendations because as you yourself have noted...conditons vary. On a particularly hot day, with low relative humidity and at sealevel, you might wanna turn your boost knob down just a tad. Also, you could get unlucky and fill up on a really crappy batch of gasoline.

If you like running near the ragged edge then you may wanna invest in a digital knock reading device with memory recall and adjustable telltale light. This way you can do a test blast and afterwards hit the recall button and know right away if your knock readings are staying below the magical 2.00mv level. The Knocklite device is also supposed to work.

Many of the piggyback ECU's have knock logging capabilities. ECU+ and XEDE SMART come to mind. Even, an SAFC will indicate indirectly where and if your engine's knock sensor is seeing any knock. At the very least check your sparkplugs visually on a regular basis and be on guard for the telltale signs of detonation.

Dont rely strictly on your ear to detect detonation as even innaudible detonation can be destructive. If you want to run high boost levels on pump then invest in a knock monitoring device. Even an EGT gauge can be useful if you know what to look for.

Sometimes your particular combination of mods can influence your engine's propensity to knock. Any reduction in intake air temps is beneficial and has been proven to reduce knock. Lowering charge air temps via an upgraded FMIC or alky injection is helpful too. Something as inexpensive as a sparkplug change to a colder heat range is good.

If you reduce exhaust back pressure via removing the cat, going to an improved O2 hsg and porting the hotside and the manifold you will improve exhaust gas flow, reduce back pressure and should lower EGT's and combustion chamber temps. All this stuff'l probably help reduce your motor's tendency to knock on a given octane level.

 

I think they might pull a number from a hat

 

The reason they decided that boost is simple. It gives you more power and still leaves a good margin of safety.

Mitsu did not find the most powerful spot, they did the same thing.... find good power with plenty of safety.

You are removing more and more of the safety net the higher the boost you run. Im sure at 19psi our cars would live well over 100k miles of beating on em. At 33psi the same probably wont happen.

Honestly, it was kind of a stupid question regardless. Like travman said... you think they pull a number from a hat??? I mean come on... Im sure they just tuned one car and it worked out so they figured they would put thier reputations and businesses on the line and just hope it all works out. It seems pretty obvious (Or it should) that they are tuning cars so they DONT blow up. They tune cars that can be ran in winter or summer, high altitude/low altitude, decent gas or great gas, etc... Next time you get a car tuned ask them to tune it for a drag only car that never drives on the street and only uses C16. You will probably get a slightly different type of tune dont you think?

 

And this whole I listen for knock crap. Come on.....

Let me explain something simple. If your untrained (Because obviously most are) ear can honestly HEAR the pinging..... its already too late.

I have been driving these cars, tuning these cars, and building these cars for a long time as a hobby. I have had my cars knock extremely badly (Fuel pumps quit, nozzles clog, etc..) and I never heard this special pinging noise.... I heard a car misfiring, bucking and getting pissed but never a ping. But you never know... maybe that is how these tuners find the perfect boost... they floor it and listen. Screw datalogs, dynos, tracktimes, etc.... just floor it and listen.

 

I'd put your sarcasm where it belongs but you're not standing here. I truly wish you were.

You apparently need a reality check on the purpose of this type of forum so I'm your guy. To ask questions and share info in as civil a manner as possible.

If your two responses represent the closest you're able to come then give it a pass the next time you see a question I've posed.

 

for the definitive answer on your boost level. there is no safe boost leve. there is only safe air mass flow. that said you can't measure that very well, the maf will give you some indications of it and if the maf cut is still in place it will cut when it thinsk there is too much.

but that's no fun at all, you can't add power without more air, especially if you have the fuel to back it. so what to do?

wlel the only way is to receive a fully logged and very precise tune. but with that done you have to account for every condition you will ever face. so there is fudge room... your sweet spot for april 5th may not be the same for the month of november. so what do you do? let your 23 psi run amuck in winter and hope nothing goes wrong? turn your knobs every season? you can do many things, but unless you have the proper tools... don't.

proper tools? logging software, monitoring hardware. etc.

 

To add to this thread (and maybe adding more questions than answers), what safe level would you guys peg your EGT gauge before stepping off the gas? I've read somewhere that EGT is a more reliable indicator than than an A/F meter.

What about a Walbro fuel pump? How would that effect safe boost levels?

 

you determine it by knowin how to tune