I emailed with these guys because they rebuild the air intake and bore it out 1-2 mm.
Standard bore is 45mm.
"The throttle body is CNC machined to 46 or 47mm depending of the body?s condition. You can send your own throttle to be modified."

If you have had difficulty with a sticky butterfly due to wear and it lodges itself in the intake, this seems to be a good remedy. They replace the butterfly because they bore it out. $149 for a 914 2.0 intake. You have to send them yours or pay extra for core charge. Here is their temporary site.
http://home.att.net/~lonza/index.html/
You'll have to email to find out their deals.

Won't help much, if at all.

You are still limited to the diamter of the intake manifodls.

I think PB Anders did some testing and found the benefit negligible.

Money spent better on other things.

Karl

I have dyno'd them. Save your money or have yours rebuilt (they are starting to wear out).


B

I had mine bored out to 50mm, wow it made hardly any difference. What made a difference is I also had brass throttle shaft bushings installed. Now that made a difference with a smooth throttle and no lvacuum leaks around a sloppy shaft.

Geoff

So is $149 a reasonable rebuild price to fix that sticky butterfly? How come they never put a stop in the intake so the butterfly would stop instead of wearing and going in further?

I have no idea why they didnt install a stop (I think your asking because the big bore guys brag about their throttle stop setup). Honestly.. they lasted for 30+ years.. I dont think they need a stop.


B

I got my bored-out TB by picking one out at the junk yard. I got just the size I wanted and it was $15. I think it came off a Chrysler. It's a valve. It's the right size. That's all I care.

If that offends anyone, you should see my intake plenum. He he. I cut the end off and rotated the TB elbow 90 degrees, added about 5% to the volume, hammered it into shape and welded it back together. This was all in preparation for that turbo that I thought I'd have on it by now, but I've burned out on working on it and have just been driving it all summer ignoring things I should be fixing.

-Ben M.

I haven't heard anything from the big bore guys but mine tends to get sticky every month or so. I end up spraying some silicon spray and it loosens up. I spray it right in the intake. l\l instead of l-l is what the butterfly ius doing. If I can find another intake make that would fit and works good, I'd use it.

anyone ver used dual throttle bodies..... (just thinking hypothetically)

Not with Djet. CB Performance sells a dual TB set up.
Geoff