A bored out exhaust or ported housing has no effect on reliability. Its the divider wall exposed to heat that is the issue. the divider wall is not machined or cut during stock frame builds. so reliability does not change one way or another. road racing itself would be very hard on that divider wall.

I would go with BBK full. proven best turbo for the job.

second choice would be HTA71. loads cheaper than BBK lite. same flow rates. ported shroud available for 71 and it will still be cheaper than BBK.

 

above is correct on the turbine housings-

fatigue from heat is fatigue regardless of whats installed in the housing- its the inlet side of the turbine housing into the volute with the divider that cracks---

cb

 

That is correct spark. Zero issues

Mikey

 

I understand what your saying and all. But talk to the guy who owned my car before I did. He beat the **** out of this car and tracked it for 2 straight years every weekend on top of daily driving it before he sold it to me without a problem. I know what the guy is looking for and I wish him well on whatever he decides on but honestly I just don't buy it.

 

very well put-

you can save me from posting LOL!

cb

 

The 10.5 housings crack on stock 9 turbos. So the BBK lite isn't going to make a difference in "reliability" of the hot side.

 

It is not theory. Think of it this way: It is all about airflow. Perhaps it is easier to understand that fitting a larger compressor wheel into a given compressor housing allows the turbo to flow more air. Take for example, the difference between the 68 CFM flowed by the FP Black's compressor and the 58 CFM(?) flowed by the FP Red's compressor. The Black shares the same comp housing as the Red, however the higher flowing Black is configured internally with a larger comp wheel than that of the Red.

In much the same way that a larger compressor wheel allows any given compressor to flow more air, likewise a larger exhaust turbine wheel allows a turbine to flow more air(aka exhaust). The larger turbine wheel drives the compressor wheel harder, and at the same time the larger turbine wheel produces less back pressure between the turbine inlet and the exhaust valves. The only advantage of a smaller turbine wheel is that it can spin faster than a larger, higher inertia wheel.

Now, let's take for example the BBK-Full versus the BBK-Lite. It is a fact that the Full produces more power than the Lite. Notably the Full and the Lite share the same, exact compressor wheel. The only difference between these two turbos is the different size of their turbine wheels. The Full which produces more power and less back pressure is fitted with a larger turbine wheel. The Lite meanwhile, flows less air through the same exact compressor but spools faster. In light of the above observations, to what factor(s) would you attribute the power difference between the two turbos? Please explain why.

HINT: The answer has something to do with pressure ratio differentials as well as back pressure. Incidentally, on turbocharged cars, turbine pressure is usually about double the charge air pressure. A good rule of thumb for when there is too much back pressure is when the pressure in the exhaust manifold exceeds more than half the pressure in the engine's cylinders. The smaller the turbine wheel...the higher will be the turbine pressure produced resulting in proportionally higher exhaust back pressure.

As a practical matter, I would say that the BBK-Full would be a better choice than the BBK-Lite for your particular application. If you want faster spool than the JB BBK-Full, then go with a BB-Full and not the BBK-Lite. AFAIK the turbine housing as used on the BBK-Full is not exhibiting any more issues than a sampling of stock MHI 10.5cm housing would. The turbine housing on the BBK-Full is bored on a computer controlled mill and all the clearances are held to highly exact standards.

 

is it true that the TME turbo's with the titanium shaft and wheel have a higher temp rated steel exhaust housing?

 

I had a JDM VIII RS turbo with a TiAl turbine wheel. It came from the factory configured with the 9.8cm housing. AFAIK, it was a standard 9.8 housing, nothing special.

The TME 6.5 turbo came with the 10.5cm housing. But, I understood it to be a standard metallurgy casting. However, I never actually saw one personally. So, I am just assuming. Wish that I could be more helpful Mike.

 

thanks for shedding some lights. i starting to wrap my head around it now. with a larger turbine wheel, there's more surface area for the exhaust gas to push against and larger diameter is like a longer torque arm of a wrench, easier to turn.

so in the case of BBK Full vs. BBK Lite, both have same compressor wheel. so the resistant at the shaft is the same for both at any given PSI on compressor side. but with larger turbine in the BBK Full, less exhaust pressure is required but more flow to turn the shaft compare to the smaller turbine which requires more pressure but less flow.

it would be interesting to see a dyno comparison between BBK Full vs. BBK Lite at 20 psi peak and 30 psi peak. there shouldn't be a huge difference with the 20 psi graph (besides the quicker spool) but there should be a substantial difference with the 30 psi graph.

 

Yup exactly!

 

As high pressure exhaust gases are forced through and past the turbine wheel, the turbine wheel itself becomes a "reduced flow area", within the overall flow path of the exhaust system. This exhaust flow restriction(reduced flow area) causes localized back pressure to exist between the turbine wheel and the combustion chamber. This resident back pressure produces a measurable loss of engine power.

There exists an inversely proportional relationship between turbine wheel size and back pressure. The back pressure between the turbine wheel and the combustion chamber increases if the turbine size decreases, and inversely, back pressure decreases as turbine size increases. Thus, a larger turbine causes a smaller loss in engine power all else remaining equal.

The basic size of the turbine wheel will be determined by the airflow requirements of the compressor wheel. The important element in determining maximum flow is the extruder bore size, i.e. the inner diameter of the turbine outlet.

The above info was plagiarized by me from the author, "Bad *** Bre", from an online article found on Custom-Car.us. Hope this helps.

 

very well thought out responses--

cb

 

Does anybody know the size of the turbine wheel in the following turbos:

- BBK-B-BB
- BBK-C-BB

The FP Green 73HTA has a 65mm and the FP Red a 67mm turbine wheel according to FP's website.

I'm really curious how the new ball bearing turbos from CBRD compare...