How far can a 5.7 be bored

[peter cain]

Hi Folks,

Does anyone know how far a 2011 5.7 can be bored out before fuel delivery issues occur? Or in other words, how much additional displacement can a 2011 fuel injection system handle without problems? Thanks!

 

[mondo]

Are you talking to make power? If so, if you are spending money to bore it and go bigger, why not upgrade the fuel system to handle the power?

 

[peter cain]

No, I’m not looking for more power. I’m rebuilding a seized 5.7, and assuming there is cylinder damage. I haven’t pulled the engine yet. Hoping that happens this weekend.

 

[charonblk07]

Your concern shouldn’t be whether fueling becomes an issue, it’s whether the water jacket thickness is sufficient to not crack under the heat cycling. The largest the 5.7L can be bored (without sleeving it) is 3.937”, and you’d need aftermarket pistons. If you can get away with boring it to 3.922” then I’d have no problem saying just drop a new piston in and it’ll be fine but if you have to go to 3.937” then you should be looking at boring all the cylinders.

Stock bore is 3.917”, CR is 10.72
3.922” CR is 10.75
3.937” is 10.82.

I’m using the numbers from Manley’s flat top pistons which are the closest to stock that I know of but are -1.5cc to the chamber.

Sent from my iPhone using Tapatalk

 

[peter cain]

I get that part, thanks!. I was concerned with the fuel system though.

 

[chrisp2493]

I highly doubt adding about 3cc to the motor will effect the fuel system at all.

 

[peter cain]

Thanks chrisp, that’s more or less what I was thinking. Nice to hear it from someone else!

 

[charonblk07]

The fueling will be able to keep up to the expanded chamber size, but just keep in mind that will be your lean cylinder and I'd be checking your plugs in that bank more often. Your O2 sensor on that bank may show a bit leaner and add more fuel to the other cylinders which will cause them to run a touch richer. It should all still be in spec for the engine but since it's a net AFR for the bank that will be the limiting factor.

 

[peter cain]

I wouldn’t actually bore just one for that very reason. If one needs boring, they’ll all get it.