[Abubaca]

So while I AM looking at supercharging, with everything else in life right now, I dunno. May or may not happen. Still....reading about the fueling systems, I've found I'm a little out of the loop with the fuel systems on these cars. I'm very experienced with engines and fuel injection, and built and installed the 383 sbc in my Iroc and tuned the Holley HP system. I understand how the engine needs fuel, and the basics of how superchargers can really expose any fueling deficiencies. I keep reading about the high pressure and low pressure pumps, and of course I realize the LT's are direct inject engines. I'll admit I don't fully know all the hardware involved.



Any real quick rundown or links to info on our fuel systems would be appreciated.

[Trochoidal]

When I purchased my car I also wanted to know more about fueling. This is what I read and it helped with understanding better. I saved the link in my “Procharger folder”.

https://www.hotrod.com/articles/unde...stem-swapping/

[Abubaca]

Wow, that's awesome! Just was I was looking for!
Thanks!

[Juiced1]

An easy break down is that there is an extra high side pump. Normal fuel systems operate around 58psi these days. Direct injection operates from 800-3000psi. This is what the high side pump is for. It is a cam driven pump that takes the standard fuel line and highly compresses everything.



The issue here is the high side pump can be limited and the aftermarket injectors are crazy expensive.

[Abubaca]

Thank you!

[KingLT1]

This FI forum has a lot of good info shared over the years.

The short version is our fuel systems have a high and low side. High side has a mechanical cam driven pump that operates upwards of 2400psi for the LT1 pump and 3000psi for the LT4. The low side which consists of a standard in-tank pump runs around 50psi. We also have a computer module in our cars called the FSCM controller that controls the fueling on these pumps.

While our fueling systems are complex and fairly expensive, the stock LT1 fuel system will support about 575whp(dyno may vary) on 93. The Full LT4 fuel system from the Injectors, High and Low side is a popular upgrade and will support 750whp on 93 octane. The problem is our engines are too high of compression to reach 750whp on 93 octane. The octane wall on 93 is around 620whp(dyno may vary). So that opens up another can of worms. Most usually end up running meth to supplement octane and cooling because it's cost effective. E85 is also a good way to go but it limits the fuel system headroom substantially. However if you mix it down into the E50-60 range then you gain back a significant amount of fuel headroom and you can make more power without fuel pressure dropping. E60 is about the sweet spot for running Ethanol to achieve optimal timing and fuel system headroom on these engines.

This should get you headed the right direction, now I would start reading threads pertaining to fueling.

[EDFHOBBIES]

Originally Posted by KingLT1

This FI forum has a lot of good info shared over the years.

The short version is our fuel systems have a high and low side. High side has a mechanical cam driven pump that operates upwards of 2400psi for the LT1 pump and 3000psi for the LT4. The low side which consists of a standard in-tank pump runs around 50psi. We also have a computer module in our cars called the FSCM controller that controls the fueling on these pumps.

While our fueling systems are complex and fairly expensive, the stock LT1 fuel system will support about 575whp(dyno may vary) on 93. The Full LT4 fuel system from the Injectors, High and Low side is a popular upgrade and will support 750whp on 93 octane. The problem is our engines are too high of compression to reach 750whp on 93 octane. The octane wall on 93 is around 620whp(dyno may vary). So that opens up another can of worms. Most usually end up running meth to supplement octane and cooling because it's cost effective. E85 is also a good way to go but it limits the fuel system headroom substantially. However if you mix it down into the E50-60 range then you gain back a significant amount of fuel headroom and you can make more power without fuel pressure dropping. E60 is about the sweet spot for running Ethanol to achieve optimal timing and fuel system headroom on these engines.

This should get you headed the right direction, now I would start reading threads pertaining to fueling.

Spot on...

This is why I tell people to put a PD on an SS vs a centri they will all max out the octane and fuel long before some jerk off says a centri creates less heat.. Most shop will agree the pd makes for a better driving car if not going all out.. now if this was a LS setup with fore pump and ID1300s plus then hell yall centri time!

[TJay74]

Originally Posted by EDFHOBBIES

Spot on...

This is why I tell people to put a PD on an SS vs a centri they will all max out the octane and fuel long before some jerk off says a centri creates less heat.. Most shop will agree the pd makes for a better driving car if not going all out.. now if this was a LS setup with fore pump and ID1300s plus then hell yall centri time!

Honestly it depends on the driving experience you are after as well. Knowing what I know now, I wish I had went the PD route over the Procharger Centri route. There are pro's and con's to both systems.

The centri drives like a stock N/A car until you get into the throttle, then after around 4k RPM it turns into an animal. The downside is the centri does require some modifications to the airflow system in the front of the cars, that is where had I known that I would have went the Whipple route.

[Glen e]

To continue the “DI for dummies“ discussion:

I understand that now it’s under a lot more pressure, why do that?

Is it because it needs more pressure to enter the cylinder versus the manifold? What’s the end benefit to the consumer?

I was under the impression that DI was an advancement because the Injection mixture could be better timed…True/false?

[KingLT1]

That is true. The window to inject fuel is much narrower but also much more efficient. It also aids in cooling which allows more compression with the same octane fuel compared to PI.

[JeffFox]

and links. Thank you.