Question about turbo housings...

[wannawangan]

I am about to purchase a .70 ar Turbonetics turbine. It's got a divided inlet and a V-band outlet. I intend on using the turbine to replace the .63 ar one on my Turbonetics T3/TO4B 5-bolt. My question:

My turbine exhaust outlet measures 5cm and the .70 ar unit measures 5.8 according to the seller. In what way(s) will the difference in size affect the exhaust flow? Please provide your input.

Thanks!

[KATwo40]

The size would indicate a small increase in spool time (turbo lag). However, they've designed it with a twin-entry housing, to help combat the lag.

The only problem is that, unless your manifold is designed to accomodate the twin entry housing (split outlet on the manifold), you won't see the benefits of the split housing. In fact, it will add a small amount of lag, since the gas must make and abrupt split when it hits the housing divider.

You might at least port the divider with a dremel so that the surface is sharp (like the intake ports on the head) to decrease exhaust gas disruption.

In the end, I doubt you'll see a significant increase in turbo lag. Maybe 200-300 rpm.

[wannawangan]

That is good to know. Makes me feel a bit more confident in my purchase. I just like the fact that it has the V-band outlet. Fabrication of an outlet/downpipe should be much easier.

Your input is definitely appreciated!

[hannibal]

Not too familiar with an 0.70 A/R housing. Is it a T4 turbine? If so, you need to make sure your manifold the larger T4 flange and is tapped for it.

[KATwo40]

...Turbonetics T3/TO4B 5-bolt.

[Chezedik]

I am not aware of a T3 turbine that had the divided flange.

[KATwo40]

There are a few "other" market housings. The CHRA and compressor are likely Turbonetics, and the turbine housing is something else. I've seen them before.

[Chezedik]

Yeah, just because I am not aware of them doesn't mean they don't exist. I did not mean to sound arrogant, I just didn't think they made them.

[hannibal]

Never heard of a V band T3 turbine either...

[KATwo40]

They're happening more and more, especially on the turbonetics stuff. A very good friend of mine has the Turbonetics T3/T04b V trim and it has both V-band and Twin Entry on the exhaust housing. This is on an FC body RX-7.

[Chezedik]

Like you say, that would be great if you have a divided setup.

[KATwo40]

Yup. I'd love to run one, but I'm not gonna pay for the fabrication of a manifold, with so many other options out there that are much more affordable.

[wannawangan]

I don't believe a custom fabbed manifold is necessary. Coincidentally, I was thinking about how a v-band topmount turbo manifold may be a great idea. As far as custom fabrication is concerned, I will need to have a v-band outlet pipe and down pipe made. I will more likely do a one-piece design with an O2 bung. I anticipate that it should not cost any more than a custom 5-bolt or 4-bolt flanged set up.