which unit is a better turbo? gm-5 or gm-8?

[asabadin]

i am buying a drop in unit and am wondering if there is a difference between gm-5 and gm-8? which unit is better? which is more reliable and delivers more power? i heard that the gm-8 was discontinued, is this true? i am a newbie and am trieng to gather some intel!! thanks guys!

[gmctd]

They are identical, but for improved wastegate shaft and bushing in the -8.

GM-5 and -8 are discontinued, as is the 6.5L - in GM's light truck lineup.

[Kennedy]

I need to go out and check the physical config, but I have some new units that fit all applications for side mount. GM4, 5, and 8. I had one out the other day, and noticed the wastegate actuator was horizontal, but did not notice the exhaust config...

[Docfranco]

will the GM-8 bolt up to the manifold in place of the GM-5?

[gmctd]

Yes - they are identical.

[gmenor]

I replaced my turbo from a GM4 to a GM8 this past year. The only difference was the wastegate actuator vacuum line on the GM4 was routed under the turbo as opposed to the GM8 over it the turbo. Other wise it was a clean fit.

There was no earth shattering performance between the two. The GM4 seemed have to have quicker take off than the GM8. The GM8 had a noticable power increase at 55-75 mph when passing.

[RT]

Anyone know if a GM-8 can be fitted with a mechanical wastegate controlled like the Turbomaster? RT

[TJ]

Yep...I have one on my 98 w/GM-8.

TJ