420a injector size (help)

[Misterbeechy]

Goodafternoon DSMers,

im running a 12:1 FMU for my turbo 420a- T. i dont really want to run my stock (190cc i believe) injectors to 100% and probably still run lean at max boost ( 6 - 8 lbs)

what would be the biggest injectors i can run, using stock ECU?

also, would a thicker head gasket lower the compression for more boost?

thanks in advanced guys..

i tried posting in 420a but nobody got back to me. :/

any ideas?

 

[Nayannas_man23]

Goodafternoon DSMers,

im running a 12:1 FMU for my turbo 420a- T. i dont really want to run my stock (190cc i believe) injectors to 100% and probably still run lean at max boost ( 6 - 8 lbs)

what would be the biggest injectors i can run, using stock ECU?

also, would a thicker head gasket lower the compression for more boost?

thanks in advanced guys..

i tried posting in 420a but nobody got back to me. :/

any ideas?

The stock fuel injectors are 305cc. I have 550cc injectors in mine without an upgraded ecu. I believe 550cc is the biggest you will need on a stock ECU if you get a bigger ECU like AEM or MegaSquirt you can go bigger after that. Im getting the MegaSquirt 2 within a month and going with either 1000cc or 1200cc fuel injectors. So i would say on stock ECU 550cc is all u would need

 

[NYCRedlineTalon]

Goodafternoon DSMers,

im running a 12:1 FMU for my turbo 420a- T. i dont really want to run my stock (190cc i believe) injectors to 100% and probably still run lean at max boost ( 6 - 8 lbs)

what would be the biggest injectors i can run, using stock ECU?

also, would a thicker head gasket lower the compression for more boost?

thanks in advanced guys..

i tried posting in 420a but nobody got back to me. :/

any ideas?

i would get 550's that what i'm getting on a stock ecu. and i'm thinking yes it would lower the compression but not by much at all. I'd just get a cosmetic head gasket or HKS metal head gasket cause they are layered and super strong as far as holding boost

 

[Peej420a]

I know this Thread is Mighty Old, But are you guys sure this can be done? I have been almost killed for saying that im going to be using 460cc injectors on the stock ecu. People say that i would just be drowning my engine, and that I wouldnt even be able to start. Just saying what ive been told on forums and in vid comments.

 

[bryanwheat]

I know this Thread is Mighty Old, But are you guys sure this can be done? I have been almost killed for saying that im going to be using 460cc injectors on the stock ecu. People say that i would just be drowning my engine, and that I wouldnt even be able to start. Just saying what ive been told on forums and in vid comments.

Throwing in bigger injectors on the stock ecu without being able to tune will make the engine run very rich, get bad gas mileage and possibly damage the engine from fuel in the oil.

 

[Peej420a]

Throwing in bigger injectors on the stock ecu without being able to tune will make the engine run very rich, get bad gas mileage and possibly damage the engine from fuel in the oil.

Thank you for clearing that up for me. I dont if those guys actually did what they said they were going to do, but it kinda threw me off. So how big could i go before the ECU cant handle them?

 

[bryanwheat]

Thank you for clearing that up for me. I dont if those guys actually did what they said they were going to do, but it kinda threw me off. So how big could i go before the ECU cant handle them?

It has nothing to do with the ecu not being able to handle them. It's about the fact that the ecu is programmed from the factory to control a certain size injector (certain pulsewidth and deadtime) and when you put bigger injectors in they will spray more fuel at the same settings. With bigger injectors you have to scale them back so that they spray the same amount of fuel to keep the a/f ratio optimal.

 

[punxnotdead185]

I would never recommend upgrading injectors with a way to compensate for them whether that be a safc, messing with fuel pressure, or something. It will run horrible otherwise.

 

[Peej420a]

I would never recommend upgrading injectors with a way to compensate for them whether that be a safc, messing with fuel pressure, or something. It will run horrible otherwise.

So would an Adjustable fuel pressure regulator help with this any? Would it at leat help at idle and the FMU would only kick in under boost, right.

 

[LeeSD1]

So would an Adjustable fuel pressure regulator help with this any? Would it at leat help at idle and the FMU would only kick in under boost, right.

You would use the AFPR to adjust the base fuel pressure and the FMU to raise fuel pressure under boost Yes. But if you use slightly larger injectors as I mention in your other Thread 'Peej420a' you would also need to use a smaller FMU as opposed to most people using the 12:1.