Anyone ever tried a "polished" throttle body?

[many944s]

As I start taking data on the flow bench for the port matched heads, I am throwing around other ideas for subtle low buck HP gains. Of course all of these ideas will be tested in about a month when the dyno engine is up and running.

So the question is: Has anyone ever used a throttle body where the interior "lip" has been taper polished? Basically, the throttle plate sits in a reduced diameter duct in the throttle body. If you take into account the existing taper of the TB, there is no reason that the forward lip can't be polished. It does not change the diameter of the path around the throttle plate, but so far in testing it does increase overall air flow (not by much) but the difference is measurable. As soon as I have a WHOLE day to run parts on the flow bench, I will have some real numbers to post. Here in Indiana the Humidity changes everyday, so I must run all these parts in the same day to make sure the data is accurate!

Below is a stock throttle body:


Here is one in the first stages of polishing:


Final polished and assembled:


And a side by side comparison:


Just curious if anyone has any "butt dyno" information on small DIY mods before it goes to the real test!

Thanks,
Nick

[bland vanilla]

I will be following this post closely. I am thinking of pulling the head off my 84 over the winter to have a nice valve job and possibly cam done. The lower end was balanced in Atlanta by the PO and I have done a lot of other mods. With the headers and Lindsey Rail, etc, I have done the head is next. I also have a power perfect MAF set-up in a box that I am seriously going with after the head is back.

Steve

[speedracing944]

I will be doing this as well. For turbulent flow through a pipe, the mass flow is a function of surface finish and the more gentle the transition from the large ID to the smaller ID the less disturbed the streamlines are.

Speedy

[Schumi]

many944s- for that race car I told you about, we are always looking for little things like that to help out since hte engine is restricted. One of our guys did a lot of hours of flowbenching. By swapping throttle bodies for a newer kind with a thin blade and a nice polish and port matching radii with the restrictor, we picked up 2 CFM or so. Not a lot, but it all adds up eventually.

steve-
I can't wait to see your results from the MAF upgrade. I'm kinda gray on how the fuel tuning side of those work. I saw one on a european 944 site a company that sold a bosch MAF upgrade that had a built in converted that was plug and play to the old AFM cable. No external computer tuning required. I think if someone could make the circuitry to do that it would be a much more viable option for many of us. There would not be as big of horsepower gains but the throttle response gain would be worth the $200 a Bosch OEM MAF costs.

[bland vanilla]

Mike:

A guy I know pretty well here in town owns a dyno / tune shop down off Hampton that specializes in Viper SC installs. He always has 3-4 of them sitting around. He has agreed to do the 944 for me out of begging, pleading, paying, etc. Joe is a very good tuner and I have total confidence. We shall see what happens. Hopefully I can get the head done and back on by winter and take it down to be gone through. If I could get another 30-40 horse out of it I would be happy, at least until I want another 30-40.

Steve

[fast924S]

Yes, Infact I have tappered the inner lip and also cut down the rod and bolts that hold the butterfly valve in hoping this will increase air flow at WOT, As far as but doyno, I did so much at one time I cant really tell because the car fells alot faster, so I think all mods worked together very well. Also you may want to try port matching the TB to intake, That has a HUGE lip and doesnt match up well, I must have remove at least a 1/4-1/2 inch of metal to get it smooth.

I think If your doing head work/intake work it would be a good thing to do. I know the stock setup does not out flow the AFM even at WOT. SO you got some room to play with.