hosrom_951

Skunk: I was also told that the BB are a nightmare if not impossible to rebuild if the bearings fail???

evil 944t

true, horom

serial_modder

nah, me and Skunk are going all the way with full customization of the entire engine.

the turbo is a GT76 BB Q2 trim.

Skunk Workz

That's right...there is NO rebuild kit. You'd have to buy a whole rotational assembly...which is just about as expensive as buying 2 stock turbos....so most guys I know use the single BB/plane bearing option,as it seems to withstand the rigors of hard use better.

Mike S

I got my turbo from them, TO4E non ball bearing and was fairly happy. I ordered the turbo with standard housing and it came polished (bonus!!!). Other than that, the turbo has done really well with about 5k on it now.

Skunk Workz

So...it's not 2.75",it's 4".

hosrom_951

hmmmmmm......maybe i should stick to a standard bearing turbo then........

But again, i would like some more input from Turbonetic's turbos on the 951's (using the KKK hotside).

mochman

tony ran a full garrett as far as spool realize he was running a #3 milledge cam and had extensive head work. As far as BB turbos singles tend to leak while duals are lesss prone too. As far as spool-up between BB and nonBB turbos BB sweep faster, ie ident turbos exc for the bearings say 0-5 psi would be about the same above that BB build boost quicker also BB turbos tend to stay spooled between shifts quicker than nonBB turbos.

Skunk Workz

You are safe running a single BB 60-1...the single bearing helps spool,and they very seldom fail. (that I know of,from my experience.)

Porsche-O-Phile

Thanks for the explaination. Wouldn't the rotating shaft tend to stabilize itself naturally though (especially at higher speeds) due to gyroscopic action? I'm assuming the assembly is balanced properly.

Skunk Workz

Yes,it does that,but when you have massive surge the air lets go/stalls on the compressor "wings" and this makes a "buffeting" action the Dual BB cannot dampen. If you've ever run without a dump valve,I guess you've heard the "Wooooosh-cha-cha-cha-cha" when you let go of the throttle...these "cha-cha-cha" noises is air stalling on the blades,and literally going backwards. If it goes on for too long/hard on a DBB,either the bearings will break or the compressor or turbine blades will move out due to axial pressure and touch the housing walls. Big ouch,if it has 108.000 rpm at that time.

ehall

Good post Hosrum. Thanks for asking the question. Hopefully you'll get an answer from someone that addresses your specific question. Either way, the info here has been awfully helpful to others. Thanks E

fast951

Guys, did any of you actually test the spoolup between 2 identical turbos with standard and 2-BB turbos?
I think you will be surprised!!

Jfrahm

TEC is in Golden, Turbonetics is somewhere else.

-Joel.

Skunk Workz

Yup,I've done that on my bike...