Gm Turbo differences

[Will L.]

Gm 6 & 7
I think about everyone knows each bigger number is the newer turbo which was an upgrade from the previous.
But what ACTUAL changes were made?
Anybody ever put anything together?

I remember reading somewhere the gm7 is supposed to be a 3% improvement in power over the gm6. But I know they take the same wicked wheel. Housing enlargement maybe?

 

[THEFERMANATOR]

GM 1-3 were all manual spring loaded waste gate actuators, GM 4 was a GM 3 with a vacuum actuated waste gate, GM 5 changed the waste gate so it pulled upwards instead of forward for improved boost control, GM 6 was the center mount, and GM 8 was the last model used on trucks. As to other differences, I believe the intake side was supposed to be the same on all models(except vans), but there was supposed to have been some small changes to open the exhaust side up with each revision. The same center section is listed for all models(excluding vans), same impellers, but the housings did change.

 

[Will L.]

Both gm6 and 7 are centermounts used on vans and hummers. But the source that spoke about the 7 being 3% better than the 6, I have found to have a bunch of other misinformation. So idk what the real differences are.

My personal plans are to eventually loose my gm6, but think it would be nice if we can learn differences for those wanting to choose them.

 

[THEFERMANATOR]

For the 5 vs 8 the difference was in the elbow coming out of the exhaust side of the turbo. The 5 was supposed to be flatter and have a sharper turn forward coming out. I would guess the 6 vs 7 is similiar.