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HelicopterSynergy R/COther › 8.4 Gear Ratio Now Available
01-27-2007 02:07 PM  10 years agoPost 21
Doug L

rrVeteran

Minnesota

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've run both with the SZ PS's.

The SZ SB18 produced better top end power and smoother midrange than the older SB18.

- Rob
Rob, Have you tried both on the Synergy? I'm running the SZ SB18 on mine, and I'm having a hard time staying on the pipe unless the headspeeds at a minimum of 1900. I've got the SZ PS, stock gearing 8.27, and Radix 710's. Would I be better off with the old style SB18?

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01-27-2007 05:03 PM  10 years agoPost 22
BPFlyer

rrApprentice

Wichita, KS

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Doug L

You hit it right on the mark, the SB 18 is for head speeds in excess of 1900 RPM. If you want similar power below 1900 on the SZ, use the SB 17 pipe. Both were designed specifically for the OS SZ motors, but with destinction of head speeds above or below 1900 RPM.

On a side note, the YS 91 rips with the SB 18 pipe! You have to use the SB 16 header due to the difference in OS/YS muffler mount spacing. I found tunability a little touchy as a down side, not the typical set it and forget it scenario.

Fly it like you stole it!

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01-27-2007 06:18 PM  10 years agoPost 23
the hitmaker

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LA

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so.. bpflyer

simply put if i wanna run a head speed of 1950 use the sz-sb18 or just the sb-18?

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01-27-2007 07:00 PM  10 years agoPost 24
Doug L

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Minnesota

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BPFlyer.. Are you saying that it's harder to tune the SB17 even at lower headspeeds or with the SB16? The hitmaker I found this thread doing a search, and also found THIS THREAD Jerry Sudimick does a great job of explaining the differences in the pipes. The SB18 SZ is designed for engine RPM's 15700 and higher 15700/8.27 = 1898 or higher head speed on the Synergy with stock gearing. The SB17 is for operating below 15700 RPM.

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01-27-2007 09:04 PM  10 years agoPost 25
BPFlyer

rrApprentice

Wichita, KS

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Clear as mud I guess?

SB 18 for rotor RPM above 1900 using the 8.27 gear. SB 17 for rotor RPM below 1900 using the 8.27 gear. The dividing line in choosing the correct pipe is based on maintaining engine RPM at 15,700 on the OS SZ series motors.

I only mentioned difficulty in tuning the SB 18 when I used it on my YS 91 engine. I used the SB 18 as a option to crank up the YS RPM and see what kind of powerband it would provide. It made more power than the SB 16, but was harder to tune.

I have not tried the SB 17 on any motors.

My current set up is the OS 91 SZ-H PS and a SB 18FH at 1930 Head RPM. It makes VERY good power!

Fly it like you stole it!

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01-27-2007 10:44 PM  10 years agoPost 26
the hitmaker

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LA

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thanx doug

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HelicopterSynergy R/COther › 8.4 Gear Ratio Now Available
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