1G throttle body on 2G...bolt on?

[Shpyder]

I know that the 1G throttle body is an upgrade for the smaller 2G tb's. Im thinking about getting one for my 97 turbo.

My questions:

1) is the installation a bolt on affair, or do I need any adapters/flanges or any other extra material?

2) any special precautions before/during installation?

3) will the stock 2G elbow fit?

4) any specific 1G year/model throttle body that I should search for?

One more thing...I have GReddy IC piping and BOV with my stock SMIC. Can I use the same piping for a Big GReddy FMIC or would I need the piping kit? In a nutchell, is a GReddy FMIC worth it, or should I look elsewhere? (Even though a larger SMIC would be ok once I get my EvoIII16G, i wanna front mount! just has to be large enough to cover a major portion of the front opening).

[kjewer1]

1) It technically bolts right on. All DSM TB bolt patterns are the same (I'm using a 1g NT for instance). The issue is that the hole in your 2g manifold is still 52mm, so the 60mm TB opening wont help you. Swapping to the 1g manifold requires a lot of porting to the head or thats completely ineffective (even detrimental), so you might as well then upgrade the head too. I Did all of them at once.

The best middle ground solution is to port the 2g manifold to 60mm. Its not hard at all, and if you like I can provide information on what carbide burs to use, where to get them, etc. But you need a die grinder, either electric (~80 bucks at sears, a pain in the ass), or pnuematic (~20 bucks at lowes/HD, badass, lots of control, but requires an aircompressor).

2) Not really. Its a straight froward swap. You will need to drain your coolant first though or you'll have a mess when you remove those lines.

3) The 2g stock elbow fits fine, most 1g guys upgrade that that one. Its not quite 60mm though, so it helps to enlarge that as well when you port the manifold.

4) You want a 91-94, since the vacuum line setup is very similar. The 90s are quite different, and the TPS is incompatible. You'll need to use the 2g Throttle Position Sensor since on a 2g it incorporates the throttle closed switch (hence the extra 4th wire) while the 1g uses an actual switch on the throttle arm (where the cable connects). Leave ths switch intact even though we dont use it, its also a throttle plate stop. It may stick shut occasionally if you remove that switch. Ask me how I know


I hope that helps!

[scottsee]

what kind of extra horepower could you expect from the full head, intake, tb swap? with stock internals?

[kjewer1]

Hard to say. Most poeple on 20g/50trim type setups log a 3 lb/min airflow increase, and using the standard 10 hP rule, thats 30 HP. I think the more air you are flowing, the more this upgrade is worth. Plenty of poeple make tons of power on 2g heads though, especially with a magnus 2g sheet metal intake manifold.

[Shpyder]

Kevin, that helped me to no end! Thanks for the info, this thread is saved.