Does anyone have any experience with these specifically? Are there any issues that are different than a regular 5.3? I know they have larger injectors, but what else is different?

 

What kind of supercharger? I turboed the 5.3 that I put in my dads 72. It was from a FF truck and am running 5 lbs on the stock FF injectors so far.

 

I ran my 03 flex fuel tahoe for a year with a whipple on its stock injectors. I was stretching it a little lean on top, but had no problems.

If you had even larger injectors, you could run a mix of E85 which is excellent fuel for forced induction. Your PCM would adjust to the fuel mixture automatically.

 

I've been looking at a procharger. I would like to run 8psi with it. The truck is internally stock.

 

Flex fuel injectors are 38lbs. and they have a higher capacity fuel pump.
They also run at lower fuel pressure than regular gas engine. My manual says
48~to 54 lbs. for flex fuel and 55~62lbs. for regular gas engines. Don't know if this will work with 8psi. pro-charger as I only have experience with a Radix.

 

That's interesting to know. I wounder if you could put a regulator spring in them out of a non FF truck and bump up the pressure and get a bit more out of the FF injectors?

 

To run a procharger, I'd expect you'd want larger injectors. I think there is a larger FF injector but not sure of the price or part number. You could run some standard truck injectors or car injectors if you swapped the harness clips. If you did this, just don't run pure E85 all the time as the seals and o-rings on the other injectors aren't going to last as long with E85.

On the 03 I have, you'd need to swap the fuel rail. The regulator on my hoe isn't the same as a non-FF model. It doesn't appear to be removable and doesn't have the security torx adjustment screw in the center. Not sure about the in-tank regulated FF models though.

 

Did you have to do anything out of the ordinary to used the Radix?

 

radix sells a kit for flex fuel models. there just like the regular kits just you dont get the injectors in the kit. I was told 9psi with a radix was max with FF injectors. i dont understand though why the flex fuel kit that doesnt get new injectors is the same price as the kit that comes with injectors. I would figure they would be a couple hundred cheaper.

 

Magnuson FF kit also does not come with a fuel pump or injectors so it should be
several hundred $ cheaper. Don't know why it's the same price as regular fuel vehicles. If I was buying new, I would buy the regular fuel radix kit to get 42lb. injectors and fuel pump (to save for future upgrades)and just get a retune on my westers PCM. You would already have to have a mail order tune or need one because the regular fuel programmer will not work with FF engine.