differences between gm turbos??

[Big Blue dsl]

i recently aquired a gm-3 turbo that is in need of seals for my project, can anybody explain to me the differences between the turbos, aside from the wastegate, if there is a difference is it possible to upgrade to gm-8 spec save the vac wastegate?
thanks


chris

[gmctd]

No chance - the turbine wheel, shaft and compressor wheel are similar, but the catridge and both housings are totally different than the GM-5 and -8.

The split is -4 down, -5 up.

GM-5 and -8 are identical but for length of wastegate pivot shaft and bushing.

[gmenor]

I went from a GM4 to a GM8 and did not notice any earth shattering difference. IMHO the GM4 had more power on take off than the GM8 but, at passing speed at 55-70 mph the GM8 had more guts. This is my experience and I know there is alot more experienced people who can shed more technical value to this than I can.