I was just reading the PH website and this guy (8Tech) did some good work. Have a look

http://www.pistonheads.com/gassing/t...f=70&t=1591564

 

I looked into doing that a few years ago. Reached out to a company that did the job for me on another car (a built '05 STi). Their response:

"We've been offering the service because our customers want it. In theory, it should smooth out the airflow, but we haven't been able to show any noticeable difference on a flowbench."

And the thread discussing intake setups:
https://www.6speedonline.com/forums/...e-airflow.html

If the guy got 10.7 HP out of porting the throttle body, that's pretty impressive. The TBs on our cars are already very, very large. Once air flows through them, there's still a ton of disturbance between the TB and cylinders for the air to deal with - much more than what's found in the TB itself.

I considered doing the work myself (I street ported a rotary engine to great results, which is FAR more involved than a TB), but the results didn't seem promising enough without doing the TB *and* intake manifold.

 

Telum01,

Do I read his graph properly, he shows 447.4HP (I assume it is at the wheel as he drove the car to let the ECU adjust) and over 420ft/Tq ??

 

Sorry! Just realized that's on a DB9, not a V8V.

I'm not sure what the output of a DB9 would be with exhaust and tune, let alone how TB porting would affect the results.

 

I got to believe most all of the 10hp he saw was from the secondary cats.. I think there's other dyno information out there showing 10-12hp from the exhaust alone is pretty much expected.

Still a pretty trick little mod that I can certainly see myself taking on some long cold night next winter.

 

Reminds me of an article on NASCAR engine builders preparing an engine for Daytona. The shaft holding the throttle plate was made thinner and the screws holding the throttle plate filed down so that they would not interfere with the air flow. Hp gains were minimal at best and only in the 7 to 8 thousand rpm range.
I don't believe you can get that much hp from this modification. It's what I call a feel good project. It's looks good and it helps.

 

I'd think it'd be a combination of a couple HP, and a touch more throttle response. Neither may even be perceptible to the driver, and only worthwhile if super-competitive. To get anything meaningful for most of us, you'd have to smooth flow and port match through the TB, intake manifold, and heads. Just my own speculation, though.

 

Just from smoothing out the transition you should not get 10hpm. That dyno variability could be from weather alone, without back to back on same day it's hard to compare.

Now if you bore out the entire throttle plate and remove half of the half shafts and gain a good 4-6mm then yes you can pick up a good 10-15hp and much more throttle response. Unfortunately nobody really does that.

I wonder if aftermarket ford throttle bodies should work. Somebody should look into that

 

Being on the outside looking in on this topic, I can add something as the 928 also has a large TB. In speaking with a fellow PCA 928 owner, on this subject, he went into his goody bag and gave me a polyurethane $10 JC Whitney velocity stack which had been cut down & the lip shaved. I was instructed to insert it into the TB as the gentle angle & glossy poly would be more conducive to airflow.
Once installed I did in-fact notice smoother response from idle. No perceived HP increase, just smoother throttle response. After my next service, it mysteriously disappeared. Moving on...