Is there any performance diff in the 5.3 LMG vs LY5
 

There are 2 5.3L choices when specing a 2008 Chevy Silverado RC. Is there a downside to the one that runs ethanol?

Engine,
Vortec 5.3L V8 SFI FlexFuel, with Active Fuel Management, capable of running on unleaded or up to 85% ethanol, (315 hp [234.9 kW] @ 5200 rpm, 338 lb-ft of torque [456.3 N-m] @ 4400 rpm), iron block (LMG)

Engine,
Vortec 5.3L V8 SFI, with Active Fuel Management (315 hp [234.9 kW] @ 5200 rpm, 338 lb-ft of torque [456.3 N-m] @ 4400 rpm), iron block (LY5)

I am toying with the idea of selling my CTS-V and getting a RC and pumping it up to 420 or so RWHP. Supercharged of course.

I believe the only difference is in the tuning, the flex fuel has different injectors. Other then that I think there the same..

John

Go with the flex fuel truck because the stock injectors will support your power goals.

yeah i've heard the flex fuel engines have bigger injectors.

Plus the E85 loves BOOST!

But if he uses E85 with boost, he will have to upgrade injectors...

why is that?....explain

I would not use the Flex Fuel truck for FI....I would get the gas motor.

Why not because of the dual tune or what? Larger injectors and larger pump.

E85 requires more fuel flow. Those 38(?) lb injectors that the flex fuel trucks have will support his power goals with gasoline; but to make that same power on E85, he will likely need 50-60lb injectors.