ScionFred

iTrader: (1)

So I bought this cheap Chinese-made Kawasaki rotary tool to replace my prematurely-deceased USA-made Dremel and wanted to test it out. Why not port and polish my TB thought I and having OCD, I had to do it. Removing the TB is easy enough although you will lose a little coolant. Be sure to plug off the coolant lines for the TB when you remove them. I used some spare bolts. If you need a DIY to remove the TB, you probably shouldn't attempt this mod.

Upon examining the oem TB up close, my OCD idea seemed like a very good one. The TB bore is very rough except for a machined strip about 3/4" wide at the throttle plate seat area. There are also distinct raised ridges at the junction of the rough finish and machined finish. Apparently the TB is cast with a raised section in the middle which is then machined smooth for the plate but left higher than the roughly surfaced bore above and below it. Obviously it's done this way for cost reasons but that doesn't equate to good airflow.

The goal here is to eliminate the raised ridge in the TB bore and smooth the rough finish to a smooth, polished finish. The more material you remove, the higher the airflow but I didn't go nuts with it. I just wanted to smooth the bore for a modest increase in air flow without any potential high-idle issues. Many people "knife-edge" the throttle plate but I opted just to sand the edge smooth with 400 wet and polish it. I also left the screws alone although they are rather long and could be ground flush with the plate shaft for better WOT airflow.

*NOTE: It is very important that no material is removed from around the throttle plate seat area or you could have high-idle issues from too much air getting around the closed throttle plate.

Let's get started...

Step 1) Grind down the edge of the raised ridge with a cutting bit. Use a shop vac often during all grinding and sanding steps to remove metal particles and do your best to keep them out of the plate shaft pivot points.

Step 2) Grind down the rough bore surface with a stone bit and blend smoothly into the raised center section at the plate seat area.

Step 3) Start smoothing the surface with a coarse sanding drum followed by medium and fine drums.

Step 4) Continue smoothing surface by hand with 150 grit paper followed by 400 grit wet. Be careful not to use too much water or allow water to get into the shaft pivot points. Just rinse the paper often and shake off the excess while sanding.

Step 5) Polish the bore surface using a polishing wheel and your favorite metal polish until it's shiny and very smooth. You can take this as far as you want but I settled for smooth and left some sanding scratches still visible.

Step 6) Thoroughly clean the TB with the solvent of choice and lint-free rags. Brake cleaner, carb cleaner, etc. Don't over-do it and get any solvent into the drive-by-wire module! Be sure to remove any metal particles and polish from the vacuum opening and tube.

Step 7) Reinstall TB, disconnect negative battery cable for several minutes, re-attach battery cable and start engine. Let it idle for 10-15 minutes so the ECU can re-learn the A/F with all the extra air flow you now have.

Step 8 ) Take a test drive and be amazed at the new throttle response and seat of the pants whp gain!

Man I wish I had easy access to a dyno! I'm gonna get on one soon but I won't have any before runs to show what each mod has done. It sure feels a lot quicker and sounds so much better than stock. For now the best way I can quantify the results are to say that I noticed a bigger improvement from the TB P&P than when I installed my NST UD pulley.

*NOTE: I don't want my post-mod enthusiasm to give the wrong impression. TB P&P is a small HP gain mod that can feel like a high HP mod because of the much-improved throttle response, especially off-idle and into the mid-range. In terms of actual whp dyno results, a properly P&P TB should gain 0-5whp on a N/A engine and 5-10whp on a F/I engine but it depends a lot on the engine, TB and other IFE mods. I've seen dyno results showing gains of 6.5whp on a Cobalt SS and 10whp on a Vette. YMMV.

Before





Ready for final sanding and polishing



After

FromTheOld

Is there any way you could post pictures "before" and "after"? I'm curious as to what it was really like in stock form.

AcidDrop

iTrader: (4)

watching...

ScionFred

iTrader: (1)

Sure! I'm gonna get them up tonight. The only problem is that I took the pics while I was working on it and didn't preview them until after. The before pics don't really show how rough the surface was but if you ever remove the intake and stick a finger into the TB bore, you'll feel just how rough it is. It is also very evident when you start grinding it and see the texture.

DREWxB08

iTrader: (1)

WOW I would have never thought about P&P the throttle body. Def a great DIY,I cant cause ill proble mess it up LOL. I can always get it sent out I guess

ScionFred

iTrader: (1)

It's not that hard really. You just have to go slow and be careful. The walls are pretty thick on our TB so you don't have to worry much about cutting too much away. If you don't already have a rotary tool and the required bits, it might be better to send it out. I did a lot of research before doing mine and there are a lot of places that do it. I haven't dealt with any so I can't recommend one.

Here's a pretty good link I found on the subject. This guy gained 6.4whp from a TB P&P. I've seen Corvettes gain over 10whp but I doubt a N/A XB would see more than 5whp and probably more like the 2-3whp. The throttle response feels much better in any case.


http://www.cobaltss.net/forums/showt...adgames+ported

Here is a place that will port your TB but the price is a little steep IMO.

http://www.maxbore.com/

TrevorS

iTrader: (1)

Thanks for the tip Fred -- I just did mine.

In case anyone's interested, a couple $2 spring clamps from Home Depot do a nice job of pinching off the two coolant lines. Then just put a shop towel or something under the nipples so when you remove the lines, the little bit of residual coolant doesn't make a mess.

ScionFred

iTrader: (1)

Cool. How's it feel?

Good tip on the spring clamps. I suppose vise grips would also work.

TrevorS

iTrader: (1)

Haven't reinstalled it yet but probably will over the weekend. I was planning on installing eyelids as well, but my order has been delayed -- apparently a problem with the paint job. I did a fair amount of porting on my Eclipse recently, so it just occurred to me I might as well tackle your idea as well (my first TB )!

Closing off small lines has always been a nuisance and after exposing the TB and studying the layout, I decided it was time to find a better solution. I didn't even know there were such things as spring clamps, but found them in the hardware department and bought a couple of each of the smallest sizes. The smallest would probably handle typical vacuum lines, but the next size up were needed for those coolant lines. So, now I'm prepared !

By the way -- which series Dremel did you have die on you? I've had two series 300 fail, both appearing to be switch problems. One just stopped in mid rotation (brushes were fine -- tool about a 1-1/3 years old, but not much use) and the other failed after just two days by becoming dual speed -- off and high !

ScionFred

iTrader: (1)

I'm gonna pick up some of those spring clips the next time I'm at Home Depot. They seem like a much better idea than my usual method of finding a bolt to plug the hose.

I forget the model number of my Dremel but it was a 7.2V cordless and the charger died. It was several years old but barely used. I bought the Kawasaki rotary tool mainly because of all the great accessories it came with but I think the 2A Black and Decker might be better.

TrevorS

iTrader: (1)

Well, took it for a good run, during the last half of which I hit some serious rain (naturally -- I just washed and waxed it )! Seems like the ECU took this change in stride (had to reset it for the CAI). The butt dyno registered a significant uptick in go, and the throttle sensitivity has increased yet again. Throttle is getting to the point where it's hard to make a pedal adjustment below fifth gear small enough to not cause the engine to react noticably -- kinda like a step.

Something else -- the stock behavior when I let off the gas and press in the clutch is a very noticable jump in RPM. Adding the CAI and AP pulley had no affect on that (wouldn't expect them to). However, I could swear that behavior has been reduced by the TB port. It's still there, but the spike didn't seem anywhere near as high and the duration seemed significantly shorter. I've always had to try to remind myself to let off the gas a moment before clutching in order to avoid the "roar", but I never even noticed the issue this time. I'm wondering if the OE TB turbulence resulted in a response lag that the port has seriously reduced. (Or am I just on drugs ?)

I'll have to take it out again and try to verify my impressions (especially that last one), but off the cuff, I'd say yes, the TB port works !

TrevorS

iTrader: (1)

Took it for a longer run today and am satisfied the "roar" following closely synchronized throttle release and clutch press has definitely lessened. However, I'd say the duration is the same. The driving difference for me is that before, the noise of that RPM jump bothered me when shifting normally (closely synchronized throttle/clutch action -- like in my Eclipse and previous manual shift cars), now I can just relax and shift .

ScionFred

iTrader: (1)

I'm glad you like the results. It sounds like your throttle plate is closing faster but I can't imagine why a port job would do that. Personally I don't care for our drive-by-wire throttle setup. I'd prefer good old mechanical linkage. In any case, it's good to hear that you got some extra benefit in addition to better TB air flow.

Chaos_Being

I'm probably going to do this to my tC. I already have a dremel, I just need to find the time to pull the throttle body and work on it. How long did it take you to polish it up? It doesn't look like that big of a job.

ScionFred

iTrader: (1)

I took about 4 hours but I was in no hurry. It could be done in half that time.

TrevorS

iTrader: (1)

I've decided I specifically don't like drive-by-wire. Or else, the stepper motor needs at least an additional divide by two gear reduction.

Any time I'm looking to hold a steady vehicle speed, the very slightest throttle adjustment results in a very noticeable response from the engine, and that seems true even in fifth gear. Since I've never experienced that before with analog accelerator linkage (ie. mechanical), I can only interpret it as one more misguided (or misapplied) application of digital technology.

ScionFred

iTrader: (1)

The only thing I like about our DBW is that the cruise control is the best I've ever seen. It holds my speed to within 1mph under all conditions. Other than that, it sux.

jmila1901

Did this a few days ago and love the results, i also ground down the butterfly screws a little bit. I noticed a bit more torque throughout the entire RPM range, that could also just be the better throttle responce, anyhow its a nice FREE upgrade!

Along with this i went ahead and removed that HUGE useless pipe that leads to the intake box, two screws and a little finagling and it came off. It coupled with the the TRD side vent (Or just removing it all together) gave me a really sexy roar! Not quite like an intake but still nice and once again FREE! Probably colder air too since it doesnt have to flow through that hot black pipe all over the place!

What would also be great is a NISMO like bumper "ram air" vent like they use on the 350z's... Its basically a hole cut in the bumper with a garnish directly connected to the intake that rams air in through the factory air box...

I was also thinking about picking up some of that black carb vent piping, cutting a hole in the bottom of the box and routing it to one of the vents, just an idea

ScionFred

iTrader: (1)

Glad you like the results from the TB P&P. You've got some excellent ideas there on oem intake improvements. My first mod was to remove that 3' long silencer hose. I think it breathed a little easier and the sound was nice. I recall seeing how someone re-routed that long silencer hose to clean air behind the lower grill. The diameter of that hose is a bit small but IMO if you made a duct for the end that captured all the air coming through the TRD side vent, that would be a great ram-air CAI. If you do something like that, just be sure that water can get out. I used some 4" vinyl intake hose to make a semi-ram-air CAI for my Dodge Dakota and it worked great. I routed it just behind the grill and drilled some extra drain holes in the bottom of the hose and airbox. I had no problems from it in 30K+ miles.

Zsanz

yeaaa im gonna do this over the weekend. nice write up.