Mach1Latus

My Feedback: (3)

I heard somewhere that you can increase the performance from the ZDZ-100 by replacing the stock carb. I have the 100NG with AMT tuned pipes running a Menz 26x10. Can anyone suggest a replacement carb that would work with this setup?

Thanks
Stephen

Antique

My Feedback: (4)

Why a manufacturer would use a small carb when performance would be better with a larger one is beyond me....
Increasing performance with a larger carb is mostly an urban legend, especially on the larger engines...Maybe on a weedeater conversion.....I once put a Walbro SDC 80 on a G62, no difference at all...A G26 runs the same with a 11.1 carb as with a 14.7 carb....A GT80 runs the same with an SDC 80 as it does with a the WJ64 the engineers put on it....Before you spend $$ on a new carb you might find someone with a larger one and try it, there are only 2 bolt patterns on all the carbs we use on gassers......I have the largest Walbros made, WB39, 28.3mm, on my 289 methanol racer...It works just as well with 23mm carbs..5mm larger made no difference at all...

rmh

All of the 100NG engines come with the right sized carbs -
for most cases - the WJ38 is a perfect match - with smaller prop and tuned pipes .the WJ71 seems a bit better .
anything larger is futile.
The difference in matching exhaust setup and prop -to the model -is far greater than any power difference in carb size
The AMT pipes set at aprox 72-75" from exhaust outlet to end of the pipe (the band around the end) seems good .
Best prop with this combo -so far - Mejzlic 26x10.-fuel Mobil 1 at 32-1
The reason we like this setup -is that it gives best vertical performance here at 5400 ft elevation --on a model which is almost 30 lbs all fuel up .
We did this setup for a local friend Dave Fox-in a Katana model .
the setup works very well.
At this altitude - static rpm is 7000rpm.-It unloads very nicely in the air . Not really noisy as most flying (he flies Advanced IMAC- and wins)) is throttled back- power is used on demand.
That's about as much info as I can provide about the setup.

Mach1Latus

My Feedback: (3)

Dick & RCIGN1:

Thanks for the info I just figured that with a better breathing exhaust it might benifit from a different carb.

72-75" shouldn't that be cm? On the length measurement do you count the small exit pipe at the end, the one that curves down?

what effect dose lengthening or shortening have on the setup?


Stephen

rmh

yes cm- I use pipe length- from referrence points - exhaust flange to -in this case - the large seam around the end of the pipe
All tuned pipes are not the same in measuring the "tuning point".
On the AMT-- a header of aprox 10" will give this length.
As to correct length----this depends on what rpm band you choose to use .
I find that the engine performs best if propped at upwards of 7000 rpm-so I used the 72cm
shortening the header will theoretically inrease power - Actually -it simply increases the operational rpm band and in some cases the combination of prop load and pipe length is so mis matched --that the engine would actually run faster with NO pipe .
When it is right --the engine will run up quickly -evenly -from an idle to max rpm.
in a hover -the engine will be easily throttleable- nice even changes in rpm.
The charts and endless volumes on "how tuned pipes work" typically are addressed to max power available - NOT best performance throught entire power band.

hobdean

My Feedback: (11)

I have a AM yak 33% with a 3w 80cs on cans . It pulls it ok just does not jump out of a hoover.
I saw the weight of the zdz 100 ng and it weighs less than the the 3w 80cs.
I am interested in keeping the weight down since all i do is 3d.
Seems logical that a zdz 100 NG with amt pipes would fit the ticket.


Does this sound logical and would I still be in the power band with the zdz 100 on pipes for toque rolling and hovering or just use the super sonic pitts muffler and save some weight?

Thanks
Hoby