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Message
Ed,
I wish
I knew the answers to your questions. I think that I want to run at about
5800 RPMS, and I only want to run about 7-8 lbs of boost. I really don't
want to stress the engine too much, or consume lots of fuel doing
it.
I've
seen several SS manifolds on E-bay for about $200. They even have them for
the stock turbo, which may save some weight. The one for the T4 turbo has
an external waste gate flange.
Steve
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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