how to do 25psi on 91 octane?

[The Pope]

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Originally Posted by speeduphoria Also personally I think the AMS car dyno was skewed. Like Ondonti said every car is different, 12.5A/F with high boost on race gas is Ok, or low boost pump gas(15psi max). Pope if the computer controlled boost works so well then why are you changing it to a MBC at the track??

The AMS could be a bad example. Normally this subject is like many that causes a war because so many love to use a MBC. Myself I have used them in the past my self, on one car I have one set low on the street.

On the CSX it uses the SBEC and a non IC 2.5 computer, I run the MBC on it with an intercooler. But eitherway the car is a turd and just not making any power. The CSX has all of its supension ripped out right now. It is getting brand new 11" brakes with drilled and slotted rotors with rebuild calipers. I also have the whole suspension in poly and bought a new set of Konis for it. Lastly I have a SBEC 2.5 trim cal that is going into it, 4 boost setting with a high of 22 PSI. It also gets a new 555 with econo PG and crome diff retainer, then a T3 PP, aluminum flywheel and carbon fiber pro half puck disk. In bad need of some love and will be getting a real computer.

My old set up on my GLHS from years ago had a MP stage 2 computer and only a max of 13 PSI. Mopar computers are junk for racing, very hard to launch the car with the wastegate opening and shutting during launch making for a "boost bounce" I also ran +20s with the MP cal made for 32 lb injectors. I melted 2 engines and tore up bearings in a 3rd by using the MBC. But it was a race car. Currently the car has a lot changed now coming to the end of a 3 year long build up. I have no intention to run the car on the street or tract with a MBC, and with an FWD computer I won't have too. Will I use one on the dyno to find different AF ratios at different RPMs and boost levels? Sure, they are required for correct tuning.

10 years ago life was like it was a month ago for my CSX. Without a MBC you were hosed and there just wasn't anything out there safe that worked. FWD, ND and the others didn't sell computers that were safe yet. People would blow up there engines on a custom cal and flood there engine and be safe with a MBC. Many are still stuck in the past. TODAYS computers are not much different than a MBC for fell when you drive them. 99% here have street cars, not drag cars. 99% still want to get some amount of gas mileage. 100% don't want to lose any real power at the same time. Guys like shadow run 11.0 @ 133 at the track and drive home on street tires. Is his car really that slow at 18 PSI on the street? The thing is a missle at 18 PSI I'm sure and will hook up better and won't eat the fuel. FWD isn't the only one making good cals now, TU does too. BUT I can get a cal from cindy normally in a couple weeks, not 2 years or never. FWDs computers are also dirt cheap really. You constantly here people with problems on TD. Gas mileage and issues with making them last. Drowning your engine with fuel destroys your rings and compression, it also destroys your oil so it doesn't do its job. Engines can be detonating and most of it can't be heard with yours ears and a MBC. People need a good computer and let the thing do its job on the street, where most of us end up.

[The Pope]

Quote:

Originally Posted by Ondonti 13.2:1 is NOT the best for turbocharged horsepower..let alone n/a horsepower. That is just wrong.Low/mid 12's depending on your engine. Every engine is different, therefore there is no concrete rule. Also, giving advice for people running 91 octane that is based on an AMS car that is running 100% C16 racing gas is a very bad idea. 1 bad batch of gas and say goodbye to your motor. Its pure luck if you survive bad gas and you were running irresponsible setups.

Lean is mean and it doesn't matter if the car has a turbo or not. Unless you think oxygen really doesn't make gas burn hot? Go for a ride with some one with D cal and a wide band and play with the AF ratio. Below 11 the power just goes away fast. If your car doesn't run right at 12:1 AF with boost your not setting up your timing right. On my V8s going from 12 to 13:1 AF is 43 HP on a mild 11 second build up. Is 13 scary on a turbo? Sure, I push there with racing gas not pump. A SRT 4 is just going to do a better job than an older TD, the fact one here has run 21 PSI and 13.2:1 AF around town on the street for 25,000 miles doesn't count.

Pig rich drowning your engine with fuel in the 9-10 range isn't good for your engine either. Sure you don't detonated but you do wash all the oil off the cylinder walls and contamiante your oil with fuel. Your causing your rings to ware faster and you need to change your oil twice as aften at least. At this point your chewing fuel and power.

[speeduphoria]

Quote:

Originally Posted by The Pope Lean is mean and it doesn't matter if the car has a turbo or not. A SRT 4 is just going to do a better job than an older TD, the fact one here has run 21 PSI and 13.2:1 AF around town on the street for 25,000 miles doesn't count.

Ok Rob not trying to argue with you, but can we discuss with out all the side chatter about na V8's and the other miscellaneous info that you love to throw in that doesn't pertain to the questions/rebuttals please.

Yes lean is mean but a turbo compresses air which creates heat, so unless your intake charge is equal to ambient temps on a cool day then I dont think you can compare apples to apples. This would imply that ambient temps and intake temps dont play a role in detonation thresholds.


Can you please list more details on the SRT4 you refer to. Is it spiking 23psi or holding that to redline(as SRT4 guys like to use this terminology with stockish turbos). Also is this a stock PCM controlling it? Or what tuning devices are being used to lean it out? Also what brand wideband is this?

[The Pope]

Quote:

Originally Posted by speeduphoria Ok Rob not trying to argue with you, but can we discuss with out all the side chatter about na V8's and the other miscellaneous info that you love to throw in that doesn't pertain to the questions/rebuttals please. Yes lean is mean but a turbo compresses air which creates heat, so unless your intake charge is equal to ambient temps on a cool day then I dont think you can compare apples to apples. This would imply that ambient temps and intake temps dont play a role in detonation thresholds. Can you please list more details on the SRT4 you refer to. Is it spiking 23psi or holding that to redline(as SRT4 guys like to use this terminology with stockish turbos). Also is this a stock PCM controlling it? Or what tuning devices are being used to lean it out? Also what brand wideband is this?

there are a few things to discuss. Is your intercooler big enough and doing the job of cooling the air? If not don't turn up the boost in the first place, nothing over 20 with a stock type IC should be a rule.

Then comes who is doing what with a MBC. This means are you running a boost cut out riser on a stock computer? A stock computer pulls less timing than a performance cal because many hit cut out early. Then a 2 bar cal running 25 PSI? Thats 10 PSI of boost PAST the timing curve. Many have done this for years.

So "if" you have the right FMIC and 3 bar cal the engine should run 25 PSI at 12:1 AF no problem. Running a stock IC with a tiny turbo and a 2 bar cal? You can but I won't ever say it is ok and feel free to drown the engine

The SRT 4 in question is the one from the 12 SRT threads I've done.

Clays black car. Tire dynos and holds 13:1 AF. It has a BFMIC, not a stocker. A stage 1 MP computer that controls boost. Stock exhaust, not a typo. K&N Typhoon CIA. AGP wastegate can, no other power mods. 12.71 @ 111 MPH on drag radials.

The problem is that he added the AGP wastegate. Clowns that build the SRTs think they need them, they do because the ICs are super restrictive. The stock WG can't hold the boost because of massive exhaust back pressure. Cure the problem and a new one comes up, way too much boost. My brothers car would hold 17 PSI to redline stock and did for 60,000 miles. Why? BFMIC, same spearco on clays car. This IC also really helps the lack of fuel. wideband info is from the dyno guys machine, to give the AF during the RPM range. It has been this way for 3 years or more, time flys I'm going to be 40 in a couple years