Throttle body Knife Edge / Polish

[Woodyman84 3]

Anyone ever done this, Noticed any differance?

[Lowlifedubber 9]

I will be doing this very soon.All i can think is it wont hinder anything so why not.

Ive got the conical bits and pieces to do it now as they came last week so will crack on with it this week and post a couple of pics if you like.

[Woodyman84 3]

Ah yeh that would be ace if you can!

i might be obtaining a spare so i figured itd be a nice little project for lunch times!

[Woodyman84 3]

Ok just thought id do a little update on this

Thought id do some research before i took to the TB with a grinder, and boy am i glad i did

There are some major differances in the OB1 and OB2 Throttle bodies

Mainly being that the OB2 is cast and sealed for life!

You can still get the butterfly out as usual but i cant see anyway to get the shaft out

Secondly after a lot of research it seems you cannot deramp OB2 as it totally screws the idle and the ECU cant cope with it

After reading many many different threads from various forums i did find one or 2 positive results from polishing and porting OB2 TB

It seems that you can port an polish but you cannot reduc the lip on the ramp

That is to say you can widen and polish befor and after these lips and smooth them but not decrease there size

So ive decided as its easier to take off more later im going to go with very subtle port polishing for now in the hope that i dont totally screw it

Im also in two minds as to weather i will remove half of the shaft holding the butterfly, this would increase airflow a fair amount but i dont know if half the shaft will hold in the long run (although it looks fairly solid)

Ive taken a few pics before i have done anything, there are some really harsh casting lines so at least i can smooth these out!

Comments welcome, and yes i realise i will get little or no gain from this but its laying around doing nothing but it keeps me busy and atleast i know my TB is all clean an lovely

As you can see the lines from casting are very rough. i intend just to smooth these very carefully

im going to completely leave the area where the butterfly is situated while at idle as i dont want to screw it up

Anyway i will add updates later and let you know if i screw it up

[FishWick 21]

If you unclip the motor cover mate, you will see the end of the shaft has a spot welded disc / flange type end on it, so removing it looked pretty impossible to me.

The main reason you can't shave off the ramp is because the casting isn't thick enough at that part. You'll see the external side of the ramp is indented. I would imagine if you take the metal off inside, you'll create a nice big hole?

It's just speculation from what I remember of OBD2 throttles. I never actually did one.

And yeah, the increase in airflow may upset the idle control because the ECU might not be able to close the blade enough to bring the rpm down. It's only open ~ 4% if I remember, to hold the stock 680rpm.

And speaking from experience, the only real gain from modifying VR6 throttles comes from fitting a larger butterfly. Impossible on OBD2, but the OBD1 can go 3mm larger iirc.

Sorry to put a dampener on your little project, but you may be wasting your time

[Woodyman84 3]

That's ok mate. I pretty much knew I wasn't gonna achieve much but figured least it will be nice an clean. Plus I'm one of those stubborn people who has to learn the hard way :-).

One point I would say tho is there is not indent on a ob2 throttle body so it would be entirely possible to deramp it leaving plenty of material. It's just that everything ove read has said not to do it due to the idle.

[Woodyman84 3]

Another little update,

After many hours with some 1500 grit (very fine) sandpaper and some soft wire wool i took all of the sharp edges off of the ramps and smoothed out any imperfections.

Again i am only going very minor on this attempt as i would like it to work. then if i feel like it ill modify the one i take off the car and push things a little further

After removing the imperfections i went round it all with a dremel with polishing brush

Its far from perfect but its alot smoother than it was at the beggining

now intend to give it a polish and then a clean through with some alcahol cleaner

Any criticisms / questions welcome

[Woodyman84 3]

Another update (boring day in the office!)

As i am not cutting the shaft down at all

i decided i would recess the screw heads flush and cut down the threads so they where flush at the back too.

Think im pretty much done on what i wanted to achieve for my first attempt.

Time to put it on the VR i guess :S

One small not i think is relevant,

When tightening the screws i didnt find there was a fraction of a mil play in where the butterly sat so i tried my best to centre it an leave even spacing the whole way round

[Woodyman84 3]

Some results for you good people!

After electrocuting myself and fitting the new throttle body. Which was suprisingly quick and simple

I noticed the original TB was covered in oil an crap, and was sticking at close and was all rough and horrible

Also noticed the Gasket between TB and inlet is obscuring the flow slightly but didnt have time to match this up which i would have liked to do.

So started her up, idled like a bag of cack and continued to run a bit lumpy for around 30mins. then settled fine

Throttle is definately a little quicker to respond, i havnt noticed any real performance gain although ive not driven it hard yet.

Final verdict. it was free so i dont regret doing it and it feels a little nicer to drive now.

Gonna give it a run down the motorway tonight so ill let you know on top end performance as WOT is where i would expect to feel any differance

[WaynesVR6 2]

So what was the end result, did it help in any way?

[Woodyman84 3]

I really want to get this on the rolling road to find out. I think it picks up a little better on the mid range. An there is definitely less lag on the throttle response. Thanks for the reminder by the way lol.

[RBPE 198]

Anything that helps improve laminar flow is always a good idea and in return responsiveness. One of the problem with MAF's is the turbulence created and why you see Bosch one's with mesh grilles in front of them now. Have to say that when I looked into throttle bodies I was quite impressed with the US cars (Mustangs/Vette's etc) throttle bodies, they have a completely flat edge to them now. Defo worth a few ponies methinks.

[FishWick 21]

How do you find the low rpm manners just off idle? The ramp whilst blunting off idle response a little, helps smooth out any snatchiness when crawling along in traffic etc. That's the trouble with the 24Vs which have full bore TBs. They are pretty savage at part throttle.

Good skills though!

[Woodyman84 3]

Idle is absolutely fine it was all over the place for about half hour then stuck on800 been fine since. I was told u can smooth the ramps but do not remove any material or it will never idle again! So that's what I did.

I concentrated more on other areas like the shaft an disc, removing excess screw thread an countersinking the heads. I then removed material from anywhere that wasn't the peak of the ramp or around the throttle disc.

Before I did this the car felt sluggish when flooring it from low speeds. It definitely snaps alto more now but not annoyingly so.

I've yet to venture further with the tb I took off, I was goin to go more extreme with my second attempt