DIY: Porting & Polishing a Throttle Body (Video Tutorial)

[ProStreetDriver]

http://www.youtube.com/watch?v=2Lxa-GHEQo4

Video tutorial on how to port and polish a vehicle's throttle body. In order to do this procedure, you must remove the throttle body from the engine so you can probably polish and port the throttle body and the material shavings do not enter the engine. This isn't much of a horsepower increase if any, but it does help with throttle response and reduced the build up of residue on the surface of the bore. Do not remove any material from around where the throttle plate touches in the bore either. Also when doing this procedure, I would recommend purchasing a new throttle body gasket so you won't have any vacuum leaks once reinstalling. Make sure you don't take off too much material either where it will affect the structural integrity of the throttle body. When doing this type of work, make sure you wear safety glasses for your own person protection.

Procedure:
-remove the throttle body from the vehicle
-clean any oily build-up inside of the throttle body
-remove the butterfly from the throttle body, most are held in with 2 screws that go into the shaft
-if you can, also remove the shaft and linkage (some shafts are pressed into bearings, other are not)
-if you can't remove the shaft, no big deal you just have to work around it
-tape around the shaft or the hole where the shaft was so no metal shavings get into that area and cause premature wear for the bushings or bearings
-depending on the finish of the throttle body's bore, there may be edges which you can to smooth out
-in order to smooth out those edges, you can use grinding stones for either a drill or rotary tool such as a Dremel
-when using a grinding stone, it's best to use WD-40 penetrating oil with it so the aluminum material doesn't plug up the stone and it'll no longer cut away any material
-once you are satisfied with the sharper edges being ground down, you can down move onto sanding drums for the rotary tool
-you can also flare out the bore where the air enters slightly so it has a smoother air flow into the throttle body
-you can even port match the throttle body to the intake if the throttle body is smaller
-if you don't have access to a rotary tool and sanding drums, you can also use flap wheel drum sanders that can be used on a drill
-the flap wheel drum sanders are available in a variety of grits such as 40, 50, 60, 80, 120, 180, 240, and 320
-when using the flap wheel drum sander, you can add water to help with finer sanding as to keep the dust down
-if the surface isn't too porous such as what is shown in the video, start out with a finer grit like 120 and move your way up
-once you have reached the highest grit in a flap wheel drum sander, you can now do some sanding by hand with 400 grit and add some water for lubrication
-once satisfied with your product, you can now move up to an abrasive like Scotch Brite
-depending on the color, will depending on how course the abrasive pad material is
-I started out with green and then moved onto the red pad for the finest compound
-you can also use water with this too to help finer sanding and to keep the dust down
-again once you are satisfied, you can now move onto a metal polishing compound
-the metal polishing compound I would recommend is Eagle One
-apply the polishing compound paste and rub until highly mirrored finish (multiple coats can be applied to achieve a higher polished surface
-once you are done with the bore, you can now move onto the throttle plate
-most throttle plates are smooth to begin with so you can skip directly to the Scotch Brite stage using the same procedure and finally move onto the metal polishing compound
-once done, you are ready to reassemble the throttle body
-make sure you peen the thread of the screws on the other side to ensure they don't come out or apply Lock Tight thread sealant
-install new throttle body gasket along with throttle body to your vehicle

[Kurty]

I read that this is not really a good move in the long run.

 

No doubt more inputs but the internal mechanism still the same and may overstressed. Plus ecu reading...

 

Nowadays, aftermarket throttle body like s90 are selling relatively cheap

[ProStreetDriver]

I read that this is not really a good move in the long run.

 

No doubt more inputs but the internal mechanism still the same and may overstressed. Plus ecu reading...

 

Nowadays, aftermarket throttle body like s90 are selling relatively cheap

 

Thank you for your response :) I've done a fair amount of reading on it and I know there is a huge variation between options of whether it's good or bad to port/polish a throttle body. I've done this on past vehicles and have never had any issues. All of which has been on the postive side whether it's smoother rpm, better throttle response, sometimes a slight increase in power, not having that oily residue build up. Even on carburated engines, I've seen the bore being polished/ported too.

 

There shouldn't be any stress on the assembly at all if you don't grind away too much material from the bore. Considering the area where the throttle plate still sits, that remains to be the same diameter so it should affect the reading on the ecu either.

 

Lol, that is very true! There is definitely a load of aftermarket support depending on the manufacturer and I agree that it's probably a cheaper route just to buy a custom one rather than trying to improve the original. But then again, not all vehicles have aftermarket options available such as my vehicle, which is why I took this route.

[Kurty]

 

Thank you for your response :) I've done a fair amount of reading on it and I know there is a huge variation between options of whether it's good or bad to port/polish a throttle body. I've done this on past vehicles and have never had any issues. All of which has been on the postive side whether it's smoother rpm, better throttle response, sometimes a slight increase in power, not having that oily residue build up. Even on carburated engines, I've seen the bore being polished/ported too.

 

There shouldn't be any stress on the assembly at all if you don't grind away too much material from the bore. Considering the area where the throttle plate still sits, that remains to be the same diameter so it should affect the reading on the ecu either.

 

Lol, that is very true! There is definitely a load of aftermarket support depending on the manufacturer and I agree that it's probably a cheaper route just to buy a custom one rather than trying to improve the original. But then again, not all vehicles have aftermarket options available such as my vehicle, which is why I took this route.

 

i see, what ride you driving, may i ask.

 

cause i did consider of changing to bigger throttle body too..

but for the inlet, i also need to change, being not very savvy.. i don't dare to proceed

 

[ProStreetDriver]

 

i see, what ride you driving, may i ask.

 

cause i did consider of changing to bigger throttle body too..

but for the inlet, i also need to change, being not very savvy.. i don't dare to proceed

 

 

I have a 1997 BMW 540i with a 4.4L V8... The tuning company Dinan has an aftermarket large bore throttle body but it's on for the newer engines which started in 1999. They also want $900 for it too. I had a 1989 Ford Ranger long long time ago with a 2.9L V6 and that was the first vehicle I modified the throttle body on. With that, I could purchase an older throttle body from and older model 2.9L from the mid 80s. I believe that was 10mm larger, direct bolt on and didn't even have to chance the size of the intake tube. I also polished/ported it too.

 

Yep I know what you mean... I had one vehicle like that in the past. I had a Volvo 850 turbo and the throttle body off a Volvo 6 cylinder had to be modified but would bolt onto the stock intake manifold. But the problem was with the intak tubes and the design it's very hard to retrofit something in. If your vehicle has a direct route from the airbox to throttle body, you would probably be better off doing a full custom cone filter and intake. So you not be only opening up the the throttle body, but also be able to support that extra air demand. My BMW, I will be replacing the stock air box with a custom setup when spring comes around.

[Kurty]

Wow, all nice rides.. and powerhorse

I guess you don't locate in Singapore? Do you? cause those cars that you mentioned, I don't think Singapore will or ever have them.

[Djdp]

If u do not hv any other supporting mod, bigger tb could perform worst

Bigger does not always means better

[ProStreetDriver]

Wow, all nice rides.. and powerhorse

I guess you don't locate in Singapore? Do you? cause those cars that you mentioned, I don't think Singapore will or ever have them.

 

Thank you :)

Nope, I'm not in Sinapore... I'm actually from Ontario, Canada.

 

 

If u do not hv any other supporting mod, bigger tb could perform worst

Bigger does not always means better

 

 

That is only if you install a larger throttle body. But with this modification this is just improving the stock setup and reducing drag on the intake flow. The computer will be able to compensate for that change. When I installed the larger throttle body on my truck, I already ported the intake manifold and had free flowing exhaust on it as well.

[Discoburg]

Does anyone still do port and polishing of their TB here?