DBB6776RH Turbine Housing

[MikeL.]

Has anyone run this turbo with the 0.85 A/R turbine housing inplace of the standard 0.63? Since these spool lightning quick, maybe trade a little spool for more top end power? I'm wondering if a 3400 stall would still be enough or would you need to jump to the 36-3800 range

 

[RUQWKNF]

The 6776dbb with the .63 combo needs a converter that can flash to 3200, or at least zero psi at 3200. If it were me, and I was going to run an .85 A/R on this turbo (which is the same turbo I currently run but with the .63) I would make double sure that the converter would flash to at least 3500, and be able to foot brake up to 3600 to make it spool up quickly. I'm sure Dusty could get you straight with a converter upgrade.

IMHO, I would not sacrifice the bottom end and tight converter setup, for the slight gain you would see with an .85 A/R housing up top. There are guys who are running very low 10s with the .63 A/R housing on this turbo. If you're trying for 9.80s on a built stocker or stroker motor, then I would say yes, do the .85.
Hope this helps a little.

Patrick

 

[MikeL.]

Thanks Patrick. Are you running the RH version with the 63 housing? Looks like that is the 4 inch in/3 inch out and didn't know if folks running a 3in THDP had any issues with the DP flange creating a "hurdle" for the exhuast to exit? hopefully that makes sense.

 

[Brer Rabbit]

I just swapped my .63 housing for an .85

Interesting that this came up. I originally tried to buy my 6776DBB turbo with the .85 housing but at the time there was a back order on them at Precision. Since I was impatient I just had them put the .63 housing on. The spool up is so crazy that I changed the gearing in the rear end to a 3.08 (experiment) and I just put the .85 housing on since the spool is a lil too fast in my opinion. The car is apart but so I cant know for sure yet what the difference is yet. If the gear change didnt hurt the spool up then I cant see a lil bigger exhaust housing hurting at all.

 

[MikeL.]

Keep us posted

I'd really like to see the difference between the two housings. Like Patrick and yourself menioned, the spool is insane quick so just curious to hear the flip side and see how it affects the top end and what the trade off is in spool up.

Maybe enough to crack the 140mph barrier I'd like to see that on 93 and meth with this turbo.

 

[Brer Rabbit]

140mph!

Maybe downhill with a tail wind.

 

[RUQWKNF]

With Sarah's trans being shot at the moment, I have yet to get any real passes on my new combo yet. But it did feel good at 27psi and C16. Good enough to fry the trans after two passes.

I have a PT6776RHP, the Ported Shroud H cover with a .63 A/R housing. The wg hole has been opened up as large as I can go with my current 3" THDP.
I will be running an Art Carr 16930 9" 3200-3400 stall converter with the new trans and she should scream.
I'm only wanting 11.30s.

Definitely keep us posted Brer on your progress. If only this dang snow would hold off a little longer.
Sigh.....

Patrick

 

[MikeL.]

Ported Shroud

Patrick, no doubt you'll hit and surpass that 11.30 easy once the tranny is up to snuff. Before the trans went out, what differences did you notice, while cruising or street encounters, with the ported shroud versus your old turbo? I'm guessing your old turbo didn't have the ported shroud on it.

I think you're the only board member I know of running a PS turbo and I'm veerrryy close to buying this turbo with all the specials that are going on right now and I hadn't considered it until you mentioned it. Is the surge completely eliminated with it? How much more, approx, for this upgrade? I hear both sides of the coin on this issue and I'd like to hear from someone who actually runs a PS turbo.

Thanks
Mike

 

[RUQWKNF]

I need to get my Art Carr 9" installed when I get the new trans. Then I will really be able to see what the spool up is going to be like. You are right, the turbo I had before this one was a standard journal bearing PT6776S. With my 10" l/u 3000 stall, spool us was horrible. But I knew going into it that the converter was not right for it, I just dealt with it with the intentions of upgrading the converter. Then I got a smoking deal from Don on his PT6776RHP turbo that I couldn't resist. I can tell you that with the standard S cover, I did have some slight surge issues, but now, with the Ported Shroud H cover, I have absolutely zero surge. The turbo from a roll punch from say 35 comes up on boost instantly once the trans kicks down. And it does sound like a jet. In all my years with the Turbo Buicks, this turbo is absolutely the loudest, shriekiest turbo I've ever owned and I've owned 10 different turbos in Buicks since '94.

The only downside to running any comp cover with the Ported Shroud option is, that a small amount of intake air is always diverted back onto itself under WOT. This translates into a very small loss in total HP. But!!! If you are wanting to make 600-700 flywheel hp and have very good spool up with a true 3200 stall converter, in my opinion, this is absolutely the best turbo I have ever owned. The ported shroud compressor cover option from the last time I checked was no extra charge from PTE.

Personally, after running this turbo for awhile, I would recommend the PS option for anyone that likes to really hear their turbo and not worry about surge. Next season, I will be doing a track test of the HPS cover vs a standard H cover to see if there is really any track difference between the two. In the Turbo Supra world, I got reports of anywhere from 15-25hp difference between the two compressor covers.

Hope some of this helps.

Patrick