why are you so sure of this? did you do a dyno comparison too?

I made three pulls total, first two were with the ported tb. The first two pulls were within 1 or 2hp of eachother. 20 minute cool down after each pull. The TB was the only variable that changed.

We can continue this discussion once I have the graphs in front of me and post them up on here. I was surprised with the results too, but I have learned that not everything makes sense in this world.

 

I really don't see how lowering the restriction of air intake flow would drop the power level anywhere in the power band. Air = power (in a gasoline application anyways)

 

I'm speculating that it has to do with the velocity of the incoming air

 

the air coming through the throttle body has to go all the way to the back of the intake and then up and around the center section. Nothing in the air intake tube should honestly effect the power output in a negative way if restrictions are being removed. The only thing I would think that would lower engine torque would be shorter intake runners (think truck intake vs ls1/ls6 style intake). An increase in air velocity from the ported throttle body should only help the numbers.

Were your dyno runs on the same way, with the same weather conditions? If they were during the same day did you drive the truck around for awhile to allow the computer to learn the right fuel trims for the increase in air?

 

By porting a TB, you are increasing the size of it, and when an intake port is too big to provide the necessary velocity, the result will be a loss of power until the engine is sucking in enough air to create the adequate velocity. Meaning you can lose horsepower by putting a set of heads with valves that are too big over too small of an engine. I don't know if this is why you lose tq, just my speculation.

For example, when you put your thumb over the end of a water hose, you aren't really changing the water volume of the hose, just forcing it through a smaller opening, so the water must now come out at a faster rate to keep up the same volume coming out as before.

 

Taking a few thousandths of an inch off of a throttle body is much different than putting in heads with too big of runners or valves. How much torque did your dyno charts show it lost? And you didn't answer if it was done on the same day and if you drove it to let the computer relearn.

 

And the dynos were all done back to back to back. The truck was strapped down the whole time, hood open and fan blowing on high for all three pulls. 20 minute cooldown after each run. The only thing that changed was the ported to stock TB. I will post up the comparison graph as soon as I get home, I'm in Tulsa right now and don't have the graphs in front of me, otherwise I could quote you the actual hp and tq differences.

 

I did it to my Z and for sure it helped.
I was sittin right about 320-330 rwhp at the time.It was ported to the max meaning porting was done till we blew through the outside of the throttle body.Pops welded it up and cleaned it off and called it good.

 

I don't claim to be some engineering guru or engine savant, I am just telling you what the graphs showed and speculating as to why they are what they are.

 

IIRC, when tdrumm swapped on his ported tb, he gained HP but lost some torque also. This swap was done while the truck was still strapped to the dyno at TTP.