View Full Version : 5.3L L59 Flex Fuel to 6.0L LQ9 tuning help...what all to change??

January 16th, 2012, 07:22 AM
I have searched all over the internet and this forum for this...

I am about to swap a '03 L59 5.3L (VIN Z FlexFuel) engine out with a '06 SS Silverado LQ9 engine. I plan on using the 5.3 intake so i can retain the 33# Flex Fuel injectors and return fuel rail.

My question is: What all parameters will I have to change (or not change) to get this 6.0L working in a Flex Fuel vehicle?

Just Cyl Vol?, Main VE?, Spark High and Low Tables?

There are a ton of differences when I compare to a '03 SS tune. BTW the OS is 12579405

ANY help will be greatly appreciated...

January 16th, 2012, 02:59 PM
Hello 70LS Nova,

There are more than a few people out there, who have replaced their tired 5.3 L with a 6.0 L - and made no tuning changes. The vehicles don't run optimally, but often "good enough" for daily driving.

If this conversion is for a 2003 model truck / SUV - they were the last year for the return style fuel system - as you already know. This would necessitate using the the return style fuel rails - which was your intent.

As a start, copy the LQ9 High and Low Spark tables over to your 5.3 L tune (LQ9 has a higher compression ratio - needs less advance), and change the cylinder volume to 6.0 L (746 CC).

Once the engine is in the vehicle and running - tune from that point as necessary.