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Engine basics => Engine set up tips => Topic started by: Dennis Moritz on September 09, 2008, 07:15:15 AM

Title: OS SF-S 40
Post by: Dennis Moritz on September 09, 2008, 07:15:15 AM
What's the story about this engine? I've an opportunity to buy one nib. I'm curious.
Title: Re: OS SF-S 40
Post by: Robert Zambelli on September 09, 2008, 07:26:54 AM
Hey, Dennis - I knew one guy who used one and it seemed to do quite well. Ran fast and consistent with a low-pitch prop.
He bought it used and the seller claimed it was reworked but had no details.
His main complaint was the weight - he replaced a plain bearing engine and then needed lots of tailweight.
The muffler that came with his was huge and he eventually went to a tongue muffler.
If I'm not mistaken, a .46 version was offered in the same case.
Randy Smith will probably be more familiar with the engine.

Bob Z.
Title: Re: OS SF-S 40
Post by: Mark Scarborough on September 09, 2008, 08:12:08 AM
I thought I heard that the  SF .40 is a side exhaust version of the .40 VF? the picture of the one I am watching looks very similar to the VF except for the side exhaust
Title: Re: OS SF-S 40
Post by: Just One-eye on September 09, 2008, 04:39:01 PM
The SF was the high performance 40 in between the FSR and the FX.  The VF was concurrent with it, so perhaps they did share some features, but I'd never really thought to compare the two directly, and my VFs are locked up, inconvenient to get at just now, or I might offer to sit them side by side here (I have the SF right here in this room with me right now). 
Title: Re: OS SF-S 40
Post by: Andrew Hathaway on September 09, 2008, 05:44:44 PM
I've got some VF 46's, and some SF-S 46's, while they might share some parts (I say might, but you'd have to cross check the part number listings) the run and power output aren't the same.  If you're looking for a side exhaust VF substitute the FSR is a much closer match.  I'd consider the 46 SF-S as one engine I wish I'd never spent money on.  I've never gotten a good run out of mine, even after rework.  The S version has a different crank then the R/C version along with the venturi and nifty ST clone NVA.  I went so far as to check mine for the stunt crank, it's stamped with the S but still doesn't run well.  Last time I had it out it wouldn't stay running long enough to get out to the handle.