Thanks for the rapid response....Actually, we still carry the 6157 turbo. The new school list only included the newer billet compressor wheel and HP series model turbos. Not the ones that have been sold under the GT series nomenclature the past few years.
Thanks for the kind words. Honestly, the only difference between those three models, are turbine wheels.
HPQ turbine wheel measures 3.111" inducer, 2.693" exducer with 75 trim.
HPS turbine wheel measures 3.228" inducer, 2.956" exducer with 84 trim.
The turbine wheel used in the Billet HP4271, (or what is now known as the HP7175) is an 82mm turbine wheel with an 84 trim. (aka GT42)
Spool up would increase going from the HPQ on up. Exactly how much, is going to be combination specific. In the Buick world, it can be as much as 300-400 rpms. The dual ball bearing cartridge, would dramatically help alleviate the difference.
The Billet 76 compressor wheel, is available with the HPQ or HPS turbine wheel. The cast 72mm HPQ, cast 74mm HPQ and both cast and billet 76mm HPQ were left off the list because, this New School list best represents what 90% of the Buick market currently runs in a 3-bolt turbine housing configuration.
For the record, we still carry Garrett parts and turbos.
Hope this helps.
I doubt it caused any vendors a BIG problem. In fact I doubt it caused ANY vendors ANY problems. Lets not blow what John said out of the water here.This is the type of misinformation that starts rumors and causes big problems
for vendors. Even worse when is comes from someoone like you John that people look up and believe.
What about a rebuild on the older units, will precision still be doing those? Or once our old turbo is shot, they are trash???Since the housings will need to be remachined (if possible) and the backplate is different in most cases a Conversion/upgrade will have about the same cost as a New unit, may be most cost effictive to sell the old and buy new.
Check this outIs a TA-49 the only choice for a stock appearing upgrade ? It seems like there would be a good market for that crowd..