[Diy_efi] This turbo assist stuff, suggestions

[Grant Beaty]

> Ie a Garrett plain bearing with T3 60 comp and a T25 79 trim exh wheel
>     a Garrett ball bearing with T3 60 comp and a T25 79 trim exh wheel
> The BB DOES spool quicker.

How much quicker? Just transitional response, or does it lower the boost
threashold as well?

> I think that the real advantage is going bigger on comp wheel and with a
BB
> core still having the same or similar low drivability, with the  big
> increases up top.

In our experience, the size of the compressor wheel hardly effects spool at
all, its all about the hot side. I've line up 3 cars at 3k RPMs with
compressor exducer sizes 76.2mm, 84.2mm, 91.0mm (60-1, PTE63, T66,
respectively). All 3 cars had T04 .70 P-trim exhaust wheels. The results was
no noticable difference in spool. The tuning of all 3 was more or less the
same (if I owned my own dyno, maybe you'd get more scientific data, but I
don't, so you won't).

Perhapes there is a difference in transitional response, but its nothing
very noticable (although the MBC on my T66 probably spools better than most
EBCs).

> The friction itself is enough to point to advantages.. Ever heard a plain
> bearing turbo spin for about 40 sec after shutting down from idle??

I'd sure hope not, since plain bearings need oil pressure to work, and
hopefully oil pressure drops when you shut the car off! Are all GT-series
turbine wheels ceramic?

Grant

> On 1/1/03 4:54 PM efi student wrote
>
> > How about apples to apples.  Same wheels, same housings, BB cartridge
vs.
> > plain.  Do you have experience with this?  Our experience with 3 liter
I-6
> > Supras says BB is just a fashion statement as do a number of reputable
> > sources in the industry.  Do you have hard data that suggests otherwise?
>
>
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