Compression question

[JASON ROSARIO]

I have just purchased wiseco 9:0:1 pistons. My question is since I'm changing the static compression ratio what changes would I have to make to the fuel or plug gapping. I have 550cc injectors and 255lph pump. Im just wondering if i would have to adjust fuel pressure and if 550cc would be enough injector for 25lbs and that kind of compression ratio. Any ideas would greatly be appreciated.

 

[kpt4321]

Injector sizing does not really change with compression ratio.

550's aren't enough for 25 psi on any compression ratio.

 

[bigjangin]

what kind of turbo, and any turbo that will hold 25psi will laugh at 550's. Get some bigger injectors. You wont be able to turn the fuel pressure high enough to make the 550's work.

 

[sonicnofadz]

Don't try it. You will destroy your engine. Go with 650 cc or above. The larger the better. The nice thing above injector sizing is if you go too large you can just either turn down the pressure or you can just adjust the SAFC and just lower the pulse. But if you accidently go a little bit too lean (too small of an injector) then you very well could be screwed and will be looking for a new motor.

 

[JASON ROSARIO]

ok well I was throwing 25 psi out there as a high boost level, just in case. Um as for a turbo im going to be running the good ole big 16g for a bit. Im going to be broke for a bit after my engine gets built. As far as low boost levels with the 550's between 10-18psi would i be able to get away with that. Im trying to work with what I have for now. My main concern was if i needed to upgrade the injectors right off the back.

 

[JASON ROSARIO]

I have to add a bit of info. On this motor I will be using a mitsu 4 layer which I measured .074 compared to the stock one which is .054 so my compression might even be lower not be much.

 

[kpt4321]

550's will be fine for a lower boost level, to at least 15 psi.

Beyond that, I can't tell you anything.

Pressure is almost meaningless; the required injector size is mainly dependant on airflow, which changes a lot depending on what mods you are running.