SupraKiller

I was wondering how much boost I can go from stock with pettit ecu and upgraded fuel pump? do I need a ported injector? or fuel control ? I am hoping to run 13 pounds max with my pettit ecu which is good for15 and my upgraded fuel pump, is it possible?

zooq

i'm running about 15 psi with C12 race gas. i have a fuel pump and the pettit ecu also.

Mahjik

iTrader: (1)

You are going to have people that tell you that the duty cycle of the stock injectors will be too high over 13 lbs. Is that bad? Some people agree, some people disagree.

However, there are two versions of the Pettit ECU, limited and unlimited (really, just a higher limit). The limited will be fine for 14 PSI while the unlimited is good to I think 17 PSI.

Johnny

forget duty cycles for a moment...the stock turbos lifespan are going to be seriously compromised at 15 pounds of boost

Want2race

thats a rumor...

goodfella is running 15psi and his are still runnign strong!

I would say you max out your injectors LONG before you hit 14psi... so I wouldnt go over 13 unless you raise the fuel pressure rate..

Trexthe3rd

Let's look at this from an engineering point of view.
First, the injectors. The injectors are nothing more than a solenoid. It opens when energized and closes when the current is cut off. To provide more fuel for higher boost, the ecu simply tell it to stay open a little longer by altering the current pulse train (Higher duty cycle). The major determining factor in the life span of a solenoid is the number of operations (open/cloes), which in this case would stay the same.
Now for the turbos. The only thing that touches the turbine and compressor is air, nothing else. Wether you are running 2 psi or 200 psi. That in itself will not damage the turbos. The only way to shorten the life span of the turbine and compressor is if there are foreign particles in the intake air or exhaust gas. Now for the connecting shaft. The connecting shaft is suspended and lubricated by a thin film of oil, if the oil is dirty (having foreign particles) or there is a problem with the oil supply, then the turbo will be damaged. In another words, not changing your oil frequently will shorten the lifespan of your turbos a whole lot quicker than running 15 psi. Theoretically is there is a steady fresh supply of oil and no foreign particles entering the turbine and compressor, a turbo has an indefinit life span.
Final note, improper care and lack of maintenance will kill your car a whole lot faster then running higher boost. Hope this helps.

Johnny

That's ok....he days are numbered..I dont have a doubt.

Wade

iTrader: (1)

If everything on your car works properly (fuel injectors are clean, fuel pump works and maintains proper pressure, fuel pressure regulator hose is connected, etc.) then the unlimited Pettit ECU should give you enough fuel to run all the bolt on mods with stock based turbos and about 15psi of boost. Your a:f should be in the 11:1 range with this setup. It is possible you could run even more boost and still have a good a:f ratio.

Yes you will be hitting 100% duty cycle with the stock injectors if you want to run about 15psi of boost. Personally this doesn't bother me, I've been doing it for about 3 years, but some people are really concerned. It's up to you.

The only way to be sure about the fuel is to check out our your fuel components and pray, or use a wideband lambda meter to make sure your air:fuel ratio is correct.

Your bigger problems would be dependent on the rest of your modifications, for instance if your intake charge is too hot you may have knock, your local gas might not be good enough to run 15psi safely, etc.

Wade

j9fd3s

iTrader: (3)

actually there is one more part. the compressor blades move x amount of air per revolution. to move enough air for say 10psi they have to spin at a certain (y) rpm. if you raise the boost (airflow) you also have to raise the shaft speed; the only way to raise the airflow out of the turbos is to spin it faster. x(amout of cfm per revolution)+y (rpm)=cfm airflow. the problem is that the turbos are only designed to spin so fast, if you spin them faster than they were designed it will shorten their life.

mike

SpecFIB18

A little off topic but, does the petitt unlimited ECU eliminate the bucking that sometimes people have problems w/? I've heard the PFC does a great job at this but does the petitt do the job as well? My goal is a reliable rx7 and am not doing to be boost crazy is this ECU suitable?

Mahjik

iTrader: (1)

Do a search for "3000 hesitation" and you'll find TONS of threads on it.

It seems to be caused by different things for different cars. For some cars, it seems to be more of a grounding issue, and simply adding more grounds (or getting the Pettit grounding kit) helps it.

For others, it wasn't solved until they switched to a re-programmable ECU like the Power FC (to help with the primary -> secondary injector switching).

However, I really don't believe that any of those actually "cure" it, just make it so it's not noticable.