Bought this truck from original owner and he still has all original paper work from the dealer along with window sticker. Truck has 100k on the clock he owns a body shop and he redid the body and frame and left the drivetrain stock besides a 6"lift.

Long story short the VIN and window sticker along with everything else say 5.3l. I tore it down today to install Ls6 cam and my LS1 heads and studs to get ready for turbo. Took first head off and well there is flat top pistons. Pulled the stock cam and its a 99 cam also. I trust the guy and i can almost garuntee he didnt swap the motor he had all service records ect.

Could be possible they put the wrong motor in the factory i guess...the look identical. Anyone ever hear anything like this before?

 

Know a guy who bought a truck which supposedly the same thing happened. First owner swore it was a 5.3 and had papers to prove it. Second owner ran the truck through a water puddle and the motor hydra-locked due to water splashing on the air intake. GM went to replace the motor and found that it was only a 4.8. Instead of investigating it further, they told the second owner they could only replace it with a 4.8. How terrible.

 

It happened with the 01-02 Camaros back in the day. Some cars came with the ls6 engine instead of the ls1 because of a mixup at the factories. Pretty cool for them, too bad you got a 4.8 expecting it to be a 5.3. Look on the bright side now you can boost it more lol

 

Yep im going to look for a 76mm turbo or just tell trick that i want to upgrade to a 76mm before he ships my kit and crank the boost up now. Im going to send foose a pm and get some pointers from his setup. Mine is pretty much the same.

 

I would be pissed if my truck had a 4.6 instead of a 5.4. Bet it's night and day difference between the 4.8 and 5.3.

 

Since you have the engine tore down, why not just convert it to a 5.3? All you need is 5.3 rods and a 5.3 crank with the right reluctor for your application. Heck, bore it out to LS1 bores size and use a LS1 rotating assembly for a 5.7.

 

Im going to stick with the 4.8 and boost it to 15lbs....... foose said should be close to 600 at the wheels. That is plenty for me for now.....

 

I wonder what the computer says. Anyone that you know that can read the tune off of it?

 

It was a factory 5.3l tune on the stock computer. Right now it is mail order tuned for a 5.3l also...

 

Kinda on subject my last truck was a 07 classic. The window sticker and vin said it was 3:73's. It turned out to have 3:42's from the factory go figure.