more LT8 questions
 

now, i know i could have asked this through irc, but i figure there would be some ppl in a similar situation that have similar questions...

it is my understanding that the stock FC ECU is mainly hindered by the fact that it can only run the injectors at 58-63%DC, and it is my understanding that it's the reason increasing boost on our cars is pretty touchy. using a piggy-back (a la S-AFC) remedies this a tad bit with larger injectors, but still can't overcome the ECU's max duty cycle.

so are larger injectors really necessary for those with a stock turbo, only seeking maybe 11-12PSI boost max?

i guess my REAL question is how does the LT8 control the injectors?

ya throw ya AFM as far as ya can it uses a MAP sensor to control fuel

which brings in another question...has anyone ran into problems running a vac line through the firewall? im worried about it getting caught or something, or just getting bad readings cause the line is too long...

No problems at all here. The MT is not the first peice of car electronics to do this. Alot of boost controllers also require this, not to mention all mechanical boost gauges.

What is blowing alot of motors with stock turbo/ECU cars is a problem on the primary injectors not the secondary. As you said, the stock ECU can only drive the injectors to about 60%. Common proactice on a stock turbo car with full exhaust, intake, ect ect ect is to replace just the secondary injectors with larger units. The problem with this is that the grossly undersized stock turbo can build a significant amound of boost below 3800rpm especially in lower gears. Ever notice alot of TII motors blow just cruising on the interstate, you ever go to pass a car on the highway and give it a little in 4th or 5th and watch your boost gauge? The Microtech (or most any standalone) solves this, as you can stage the injectors as you like.



Daniel

Nope, zero problems. Before you do it, you think "This is going to suck." Then once it's done you realize just how not-bad it is :) It's nice and clean; you usually just run the vac line next to the harness.

Brandon
BR7 Racing

I sliced the length of the rubber boot that held the factory harness and reused it for the firewall. That's the only place that'd I'd worry about for the vacuum hose.

So, running the 550s would still be ok with the stock turbo at average boost levels (12psi max), since you'd be able to run them at a higher DC. Please correct me if I'm wrong.

The only way you could know that would be to hook the car to a wideband. Fuel pressure, fuel pump, air temp, VE and everything has a large effect on what kind of fuel flow you will need. It is impossible to make that general of a statement.

However with 550/720's I am almost sure you would be fine, with adequate flow from the pump of course.

Daniel

Why would you have to run a vaccuum line into the cabin?

The MAP sensor is integrated with the actual ECU housing. :)

Brandon
BR7 Racing

Hmmm, that sounds kind of cheap. I was seriously considering a Microtech, but now I'm having second thoughts.

You would change your mind over this little fact? That seems kind of strange to me since Wolf uses the same system and there is no real problem or difference doing it this way.

if your worried about the map sensor in the housing get a 3 bar map sensor and fit it where you want it