How much more power in 1g throttle and intake manifold?

[Race94]

I want to know if it's worth a swap on this items to a 2g engine?
What about the 1g head?

 

[blackGSX2g]

The throttle body swap is worthwhile, but you can't put a 1g intake manifold on the 2g head without doing some MAJOR port work on your head. I'd only use the 1g manifold on the 1g head. If you are using just the 1g TB, you need to port out your 2g intake manifold to 60mm. Just use the 1g gasket and a die grinder.

I'm not sure how much of an increase you'd get by swapping out to a full 1g head...the intake ports are alot bigger, but there are pleanty of arguements ont his site about velocity vs more air. My uneducated guess would be that you would lose a bit of low end responsiveness, but gain more in top end. This could be why stock for stock, 1gs do a bit better at the track.

Also, the 1g MT cams have a bit more duration and lift than 2gs, so they are an upgrade in themselves.

 

[4geze63]

I heard that 2gs w/ 1g tb,intake manifold gain around 20 hp

 

[karbon]

Everyone I've heard from and everything I've read and seen claims at least 40 horse for a 1g head with intake mani and throttle body. You have to consider that the cross section of EACH runner is maybe 40% bigger than on the 2g, and consider that the head is matched to flow it as well.

 

[DSMeclipse4G63]

the 1g throttle body is more then worth it. the best bet is to port the opening of the 2g manifold to the 1g size or bigger. This combo does wonders for your top end and boosts hp a good bit withoutn loss of low end grunt...
Andrew

 

[DSM mechanix]

Nobody can tell you how much power youll get from switching to the 1g manifold/TB, it all depends on how much of a restriction the 2g parts are to your setup.

 

[karbon]

the 1g throttle body is more then worth it. the best bet is to port the opening of the 2g manifold to the 1g size or bigger. This combo does wonders for your top end and boosts hp a good bit withoutn loss of low end grunt...
Andrew

Don't forget the throttle response. I did this, and didn't notice much if any higher top-end power. Throttle response increased and boost lag decreased a little. Probably wouldn't notice much on a small turbo though. I think it's a good modification though, as long as you got the TB cheap.