Hey guys, I'm getting a Blitz SBC-iD really soon and I was wondering what is the max boost level I can attain without having to dump more fuel into the car safely. Until I get my guages and AFR I'll have to play it safe. I may not install until I get everything but can't say for sure. I'm impatient

 

I was under the impression that most of the tuners are actually not using the SAFC to "dump more fuel" which would lead to a rich condition, but are instead leaning the mixture out as the factory fuel map is extremely fat.

Rich is certainly safer than lean,and that is why the factory map is calibrated that way.... it just doesn't run as cleanly and you leave some HP/TQ on the table. The trick is to achieve an air fuel ratio that is optimally leaner, without being so lean that you experience detonation.

The only safe way to tune your SAFC is to dyno tune your car or perhaps use a pocket-logger to determine knock. You can run a tuners base SAFC map, but differences in each car, the altitude, fuel quality, etc... will all have an incremental effect on tuning.

The factory boost controller(FBC) provides 19 psi then tapers to 16 psi at higher rpms. It seems like folks are posting the use of a boost controller set for 19-20 psi through redline.... even when using the SAFC to lean things out.I think I read that fuel cut for the EVO VIII is around 21psi.

So it would seem like setting your SBCid for 19psi through redline would be a safe bet with the rich factory fuel map. Since the SBC-id allows you to map boost against "speed", you could also run a variable boost with a higher boost (19-20psi) at lower rpms, and then maybe taper to say 18psi in the higher rpm range if you are really concerned about detonation.

When I get ready to install my boost controller, thats the track I will take.Opposing views?

 

Thanks for the post N10S. I knew the car ran ultra rich from the factory. I also didn't stop to think that even with upping the boost that most people were leaning the car out with the AFC DUH. I just want to push the power in this car at safe levels. I imagine if I went up to 20-21psi through redline it would actually be fine with stock fuel maps in place. Have to test and tune to see. Can't wait for all of my parts. I'm getting antsy wanting more power.

 

I think your main issue with running higher boost over 20psi may be running into fuel cut. I am also not sure how efficient the stock turbo is at holding boost at higher levels. After you hit that diminishing point of return, you start to really see a lot more heat as the turbo tries to spin its little heart out trying to push enough air. If you have an EGT gauge, you can keep an eye on exhaust temps and that can help avert problems as well.

Keep us posted on the SBC-id. I had an AVCR once upon a time, but really like the SBC-id better with its dual solenoids and ability to provide read-out in good old psi!

If you install it yourself takes some pics and post an install guide!

 

That's what the AFC is for.........dumping more fuel after 20 psi so that you dont hit the fuel cut or blow up your engine. Without a fuel controller, I would say on 91 octane 20 - 21 psi is good. 20 is safe. You might hit fuel cut at 21 in the higher RPM range.

 

If you use an AFC to dump in fuel, you will hit fuel cut sooner than you would if you left it alone. Fuel cut is based on mass-airflow. By adjusting the AFC to get the ECU to dump in more fuel, you are also telling the ECU that there is more air entering the engine than there really is. More airflow means a higher MAF signal. Higher MAF signal means you are closer to the fuel cut limit.

You will know when you hit fuel cut, btw. It feels like you just hit a 2 foot high brick wall.

 

on 91 octane HAHAHAAH

anyone ever tested for knock on stock boost with 91. Your timing falls flat on it's face. If you going to run 19-20psi you are going to need atleast 93~95 octane. I'd suggest running 91 with a can of octane booster and see where that puts you. I have tested several runs with various octane boosters and 2 of which I have noticed great results. CD-2 makes an off-street legal booster that boost 20 points (1 number = 10 points) which in turn would take 91 octane to roughly 93.
http://www.partsamerica.com/PartDeta...egoryCode=3235

There is also another booster by Gumout which is said to boost octane 7 numbers (1 number = 10 points)
http://www.partsamerica.com/PartDeta...egoryCode=3235

I have come to conclude that this booster completely eliminates knock however I feel the burn is slower then should be and fuel mileage reduces becasue of this. Remeber the higher the octane doesn't always mean the better then octane. Just as air fuel mixtures there is an optimal level.