But would I get any gains from putting on the bigger 6.0 tb?

 

only if you add a throttle body spacer.

 

and drill some holes in it for some spray... lol

 

I think your measured the casting at the back of the TB bore, correct? If you look at it again, you will see that the back side of the throttle body knecks down about 5-6mm behind the blade, which would equal your measurement of 72mm vs. the actual blade/bore diameter of 78mm.

Search on here for ported stock throttle body or words like that and you will find several hits. I posted pics in sort of a how to format if you search for throttle body and my user name.

 

yes I measured the back as that is the smallest opening and therefore the area of the greatest air restriction.


Thanks for the information.

Everyone is referring to these stock TB's as 75mm or 78mm and I find that misleading as the smallest opening at the rear is 72mm.

Thanks, I have noted the part # appears to be the same for the 4.8/5.3/6.0 so it appears that they are all the same bore.

I quess the next obvious question is will I see any difference in performance if I go to a modified TB such as 80mm and change nothing else?

The reason I ask is because my 2003 is a drive by wire.
If the stock TB that is used is large enough for the 6.0L motor, it is certainly more than enough for the 5.3L
I assume because it is drive by wire, the TB will only open up to what the engine can match for the proper Air/Fuel mixture.
That being said, it would seem pointless to use a larger TB unless I also purchased a tuner to take full advantage of the extra CFM's available.
If a larger TB is used and a tuner is then used to modify the settings, will the stock injectors be sufficient or do they need to be upgraded also?

Is my thinking correct on this?

LIFE WAS SO MUCH EASIER WITH MECHANICAL TB'S

 

I believe the tb will open to whatever the pedal tells it to.

 

Gains of 7-8 HP is pretty typical with a properly ported TB on LS1's, though I've never seen anyone dyno it on a DBW truck. Most people note improved throttle response and I've seen about 7% in MPG. A ported stock TB will net more flow area than an aftermarket 80mm TB and cost you a LOT less.

To answer your question, your DBW TB works just like a cable TB does. Mat it and the TB is wide open.

The stock injectors are good with a few bolt ons, but are sized a little small for much more than that. Ported TB will not put you over the edge.

 

Thanks, I am on the hunt for a ported TB.