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Message
I think the cast iron manifold the 88-91 series are
pretty good, but they don't match up with a T4 turbo. The stainless steel
ones tend to be a bit $$ for my blood, but then I'm cheap {:>). Yes,
their are a number of good turbos that could replace the Stock ones with better
results with a different manifold. You can pretty much figure out which
compressor wheel would suit your needs simply by looking at your airflow and
matching it with wheel that gave you the boost you want with the airflow you
need.
However, the challenge is in getting the correct
turbine housing, one with the correct A/r ratio. I suspect you need one
that has an A/r closer to 1 than 0.6, but there are no formulas that I am aware
of that will tell you which one is best. Its often done by custom turbo
places by simply trying on different sizes until you get the response you
want. Needless to say even at only $250 or so a turbine housing that can
get expensive real quick.
You want to calculate your normal engine airflow
(normally the charts use either lbs of air or CFM, but most now use lbs of air)
and then you go looking at the compressor maps with that value at your target
boost (for the rpm that gave you that airflow) and see if the intersection of
your desired boost (as a ratio) on the vertical axis and your airflow (lbs or
CFM) on the horizontal axis. You would like to lines drawn from each point
meet in the middle (best efficiency) part of the chart. But, you need to
be careful, because if you are too close to the left line (often marked "Surge
line") at sea level, the changing pressure ratio as you go up in altitude (for
the same boost) can push your operating point over into the Surge zone - which
is not a good place to be.
Let me know your target rpm and boost level and I
can quickly give you your flow in lbs/minute which most of the compressor charts
use.
Ed
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
Sent: Wednesday, June 02, 2004 3:03
PM
Subject: [FlyRotary] Re: Power loss
diagnostics
Ed,
I
see allot of Stainless Steel turbo manifolds available to convert a 13B
to a T4 turbo. Would this be a good option ?
Steve Brooks
Thanks for the info, Grant
I had exchanged an e mail with Max asking
whether or not a core could be acquired in AU rather than me shipping
one. I assumed the cost of shipping (US) vs cost a core (AU) might be
compensated for by elimination of one way shipping cost. Max
stated he would check, but never heard back from him. But, I do think
that their mods are crucial for reliable long term turbo use at the higher
rpms we turn. I think folks are running into some challenges because
the Mazda Stock turbo was designed (split scroll, small A/r turbine housing,
etc) for that low - mid rpm "sports car" boost and not for power at
sustained High rpms. The modifications they offer is what is needed in
my opinion.
Welcome to the list
Ed
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
Sent: Wednesday, June 02, 2004 9:31
AM
Subject: [FlyRotary] Re: Power loss
diagnostics
Hi All,
Been lurking on the list now for a couple of weeks, actually got in
just when the discussion about turbo mods was hot. Since I'm
planning on using a '90-ish 13B turbo on my BD-4 project (actually have
the engine already), I wrote these guys about doing the upgrade.
Essentially his quoted cost for modifying the stock turbo was
$630AU. I'll attach his response to this message. Sounds like
a pretty good deal, especially when the exchange from AU to US is about
1.4:1.
Grant Schemmel
Penrose, CO
Hi,
A V2 compressor wheel
profile machined into the original comp cover will give you aprox 300 - 350 RWHP at 1 bar of
boost given fuel is aprox. 11.5 AFR
under load, exhaust 3", etc match. The wheel is heavily back-cut.
(see pix on website) I use 2 springs
on the backplate to strengthen the thrust. On a bench drill I just drill a
large enough hole to still leave a seat for
the flapper to sit on, I also keep drilling untill I drill through
the scroll in the centre of the
housing. Using a porting tool I further enlarge the hole until its as large as possible
but still retains a smallish seat. A
larger flapper "disc" can be welded on but I've found its not
necessary in most cases as the above
seems to fix the problem. There are other options for more power but the above will
adequately fill your requirements very
economically. If you find there is too much torque for your buggy
you could try a Series 5 turbine
housing which will transfer the power into the higher rev range but most people seem to love
the torque. The Series 5 housing has
2 flapper holes (Hitachi realised they had a problem) & the
mods are therefore not necessary to
the flapper hole, but the housing is more offset & consequently your engine pipe etc
will move to the side a bit. You need to
lay the 2 housings side by side to see what I mean or if you can't
email me back & I'll take a pix
for you. I would stick to the Sreies 4 & consider trying the Series 5 later if necessary.
I charge $630 (+ 10%
GST AU only) for the above including reconditioning the turbocharger but freight is obviously an
issue from here as they are quite
heavy. Hopefully someone nearby can help you at a reasonable cost.
I sometimes also get the comp cover
"power ported" or called "extrude honed"
in the States rather than change covers & backplates
which helps further increase
air flow & helps reduce inlet temperatures. Not so expensive here compared to the States I think, aprox. $180. You should also drill & tap a
1/8 Gas (NPT) thread hole into either the
turbine housing housing or exhaust manifold & test exhaustt
manifold pressure which should
roughly = boost pressure. You can put a 1/8 steel plug back in the hold after finished testing.
If you find exhaust manifold
pressure is too high (email me with results if you like) you can
machine a bit of housing away around
the turbine outlet blades, try about a millimetre to gauge the differance. Pressure drop
across the intercooler shouldn't be
more than 2 psi, a simple test & a permanent pyrometer is a
good idea with the probe mounted
about 2" behind the turbo in the engine pipe as rotaries can tend to run too hot. I don't like to
see much more than 850c for
reliability although many race at 950c. The pyrometer can also be
used to help you tune the engine as
we used to use pyro's for this years ago before Air Fuel Ratio Metres (AFR's) were
invented. Finally you'll
notice on the website pix I machine the exhaust housing outlet in a funnel shape (all above work
done on a lathe except drilling
flapper hole), to further help exit exhaust gas, the angle I use is
7 degrees which will still leave
enough room for the dump pipe to seal
although you may have to modify the gasket & dump pipe should
you find there
diameters are small than the turbine outlet diameter after
modifying.
Hope this helps & if you have
any further questions please fell free to ask.
Regards
Max Heywood ATS/Turbonetics
20a Assembly Drive,
Tullamarine, Vic.,
Australia, 3043.
Phone- 613 93351254
Fax- 613 93351264
www.turbonetics.com.au
----- Original Message
-----
From: "Schemmel, Grant"
<Grant.Schemmel@Aeroflex.com>
To:
<sales@turbonetics.com.au>
Sent: Wednesday, May 19, 2004
3:30 AM
Subject: 13B turbo
modification
> Dear Sirs:
>
> I was referred to your
website from a rotary newsgroup. I have a '90 13b
turbo engine which I plan to
install in an off-road vehicle, that will see
sustained 5000 - 8000 rpm use,
low rpm operation will not be a factor. I'm
hoping to set up the engine up to
run at around 220 - 250 HP. I understand
from the newsgroup that the stock
factory turbo will have a tendency to over
boost or creep. I also see from
your website that you offer turbo
modifications to take care of
this.
>
> So, could you give me an
idea as to the pricing of your services on an
existing turbo?
>
> Thanks!
>
> Grant Schemmel
> Penrose, CO USA
>
Let us know what you find out about them and what they can do for
you? And $$$? I'm interested too, just been too darn busy to contact
them myself.
S. Todd Bartrim
Turbo 13B
RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm
"Whatever you vividly imagine, Ardently desire,
Sincerely believe in, Enthusiastically act upon, Must inevitably come to
pass".
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