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ZDZ 80 twin

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Old 04-26-2002, 12:28 AM
  #1  
saddler
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Default ZDZ 80 twin

Anyone have any experience with the ZDZ 80 twin? I called rcshowcase and ordered the single yesterday and they said it would be here mid-may. I was thinking about the twin and just wondered if anyone had any comments on the engine. Any comments would be greatly appreciated.

Thanks
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Old 04-26-2002, 08:04 PM
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hat
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Default ZDZ 80 twin

Yes,
The twin weighs more than the single-
It is somewhat LESS powerful-It does
vibrate some----- And-
It COSTS more money!!

However, in balance its positive merits
must be considered:
It runs smoothler than the single-
it is more balanced.
It is easier to silence and runs fairly
quietly.
And it sounds neat!

Harvey Thomasian
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Old 04-26-2002, 08:56 PM
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kevin mcgrath
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Default ZDZ 80 twin

Wrong ,castor oil breath!The twin weighs1750grams and the single 1850grams,both without ignition.
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Old 04-27-2002, 12:43 AM
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Diablo-RCU
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Default ZDZ 80 twin

I've got both the single and twin because I couldn't decide either. I haven't run the twin, but my buddy HT had one and I put the tach on it. The ground rpm is about the same as the single. His turned a Mejzlik 26x10 - S prop at 6600 rpm on a B&B muffler(?) I know others claim the single is stronger than the twin, but I couldn't see it on the ground. The twin was a little bit stronger (about 100 rpm) than his 3W-80.
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Old 04-27-2002, 01:57 AM
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hat
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Default ZDZ 80 twin

Originally posted by Diablo
I've got both the single and twin because I couldn't decide either. I haven't run the twin, but my buddy HT had one and I put the tach on it. The ground rpm is about the same as the single. His turned a Mejzlik 26x10 - S prop at 6600 rpm on a B&B muffler(?) I know others claim the single is stronger than the twin, but I couldn't see it on the ground. The twin was a little bit stronger (about 100 rpm) than his 3W-80.
I don't doubt your results one bit. Your figures were in
transposition to ours.
Our engines were relatively new. Fuel used was out of
the same container and the same prop was used on both
engines.
But there were differences- airflow over and thru disimilar
cowlings, different levels of tuning, (good mechanic vs poor)
different muffler(s)and so on, which I know you realize.
Anyway, I appreciate your comments and possibly we'll
cross rubber swords again in the future!
Harvey
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Old 04-27-2002, 10:03 AM
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kevin mcgrath
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Default ZDZ 80 twin

Im primarily interested in scale applications .Would either of you who have run both the single and twin comment pls on idle smoothness, vibration,and rpm level,one vs the other? I assume the transition is as smooth on the twin as it is on
the single? I have a 60cc single but have had no opportunity to run a twin ZDZ.......
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Old 04-27-2002, 10:33 AM
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Default ZDZ 80 twin

I have both a single ZDZ 40 and a twin ZDZ 80. While the 40 is still being broken in on the test bench, it is quite smooth compared to the BME 44 I had. As for the ZDZ 80 Boxer, it is very smooth at idle, not a turbine but for a high compression engine, it is very smooth.

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Old 04-27-2002, 10:58 AM
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Default ZDZ 80 twin

A twin is always always smoother than a single because the opposed firing cancels out the firing impulses of one another. Normally a twin has less power than an equivalent size single but with proper port timing, that can be beaten also. Saito built a n alternate firing opposed twin which vibrated more than both a single and a twin. Needless to say, it wasn,t around long.
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Old 04-27-2002, 01:22 PM
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Default ZDZ 80 twin

Hello Flypaper:
In theory you are correct, but the devil is in the details. A BME 100 twin is typically not as smooth as a ZDZ-80 single, IMHO. A boxer twin and a single both have the same firing cycle, a big bang every 360 degrees of crank rotation. Each will produce a similar power pulse and reaction force (shake). As far as dynamic balance of the rotating and reciprocating components, a twin will be better but not perfect. The pistons on a twin are offset so you will not get perfect dynamic balance.
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Old 04-27-2002, 01:53 PM
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Default ZDZ 80 twin

FWIW-
I put a new 80 twin in my Bucker - also an 80 single - also a 40 single -.
Also ran the twin on pipes also the single 80'salso the 40's.
The 80 twin was very nice - and a 4 lbs flat - a great engine with excellent power for a four lb engine.
Here come the BUT!
BUT!! The 60 ZDZ on a pipe -was as almost strong -
using a MenzS 24x10 as a critera- turning 6400 rpm.
Same weight - much smaller -easier to mount, only one pipe rquired , one plug etc..
So - for me it is a no brainer -
I stick with their 40/60/80 singles as still being the best power to weight setups up to 100 cc , you can find.
the price be damned!
Now then -if you just gotta have a twin-- the 80 twin is a pip-
My only twin is the newest 160 ZDZ-and I have not yet set it up with the exhaust systm for checking performance.
based on power to weight and my past experiences - it should be what I was looking for.
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Old 04-27-2002, 03:18 PM
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Default ZDZ 80 twin

Diablo
On a single, the piston is going downwards forcing the crankcase upwards. on a twin these forces cancel each other out .The twisting force making the prop go one way and the engine nhe opposite way is the same for both. We're both thinking along the same lines. Ijust don't explain very well
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Old 04-27-2002, 03:42 PM
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Default ZDZ 80 twin

Don't forget the whirling forces - they tend to keep the crankcase from jumping about.
(prop/crank weight--)
The BIGGIE force tho is the rotational force.
The prop does not run at a constant rpm-If it did - there would be no need for the torque required to keep the prop moving.
This is where turbines really shine--lots impulses per each prop revolution.
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Old 04-27-2002, 06:26 PM
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Default ZDZ 80 twin

Also the reason a balanced plastic prop tends to run smoother than a wood prop. More flywheel effect .
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Old 01-14-2019, 01:26 PM
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chandley43231
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Default New zdz 80 is comming back

What does everyone think about the 80 twin comming back updates?
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Old 01-25-2019, 02:10 PM
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Default

Its coming back?
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