So I'm going to port my stock 706 heads with a dremel and expect an increase in power? I can guarantee you it will hurt the flow. Just because something can be ported doesn't mean it's will increase power. I would like to see back to back dyno runs on a stock vs ported tb. It would be any easy swap and test. I'm sure it's been done, but those that did it probably found a loss in power with the ported tb and didn't want to post the negative results. Or someone prove me wrong with some hard fact #'s, until then my tb is stock.

I don't see how someone could notice a seat of the pants increase with such a small mod (if it was even proven beneficial) especially in these heavy trucks.

 

porting of stock parts has proven performance gains since the engine has been around...You may not get the gains on newer heads and such that you used to get on older stuff, but gain none the less. Now if you have joe blow down the street who thinks he can port heads and throttle bodies just because he owns a dremel, you might be in for a disappointment, but if done carefully it can definitely improve power. The new boss hoss bikes that i work on for a living have ls2's and ls3's in them, we have a very good engine builder do the major work on all of our motors and he always hand ports the heads and the tb's when he does any work. He also built our 632 ci big block that makes 922 hp on pump gas. These guys know what they are doing and i doubt they would do something to decrease power when they get paid to increase. He is also the guy that ported my heads and tb.

 

I think you are missing the point again. Until you open up the actual ID of the TB and increase the size of the opening you are not going to see much if any gain. What you are actually doing is "smoothing" the air path, this will improve the way the TB "processes" the air...but not how much air it will take in. What are you doing when you CNC a set of heads? OPENING UP THE INTAKE AREA!


You are NOT taking in any more air until you OPEN up the effective throttle area. Anything else is snake oil and will be a negligible gain at best.



But hey, I am an idiot.

 

I would have to say the noticed gain is probably more from cleaning the TB that anything else.


Agreed...

I agree with you. Until you open up the narrowest point, there will not be a significant increase in CFM through it. There will be a small increase from SMOOTHING the flowpath, and another small amount from grinding the throttle stop, so all told, YES, you may feel a slight difference, and a crisper throttle. However, what BlownChevy is saying is there is alot of potential for error when porting the TB, that the "risk vs. reward" is upside down here, and the money is better spent elsewhere. Now, if you are doing it yourself, then go to town, the result is free, whether its good or bad.

 

By doing the half shaft modification on the TB, you are increasing the cross sectional area at WOT. I did this, but I cannot say I noticed a SOTP improvement in hp, I think a side by side dyno comparison would have to speak for any power increase. But as you said, you would be taking in more air by increasing the effective throttle area, so I would imagine it would make more power.

EDIT: Just did some rough math: If you have a 78mm TB and the part of the shaft you remove is 3mm thick, you have increased the cross sectional area 5.6%, 4mm is 7.5%.

 

1-2hp gains are like splitting hairs. If you simply add the money you would spend to a BETTER mod, the better off you are.

The juice is not worth the squeeze with the TB "Porting" mod, sorry.

 

I better get the spiral one for my truck.. it should spin the air when im in boost..

 

in my case i kept the stock valves so i didnt change the actual size of the opening...i must not have gained anything from it?

 

I noticed an increase with mine, I don't really care what someone who hasn't done it says about it.

 

I really dont give a **** what you think Scott.