90 Engine

[Sar]

Alright, free cash moving up and I have a second Raptor I want to start doing some conversions to. It's setup as a 60 right now, it will eventually be an extended 90.

With my current flying R60, I blew the OS60, now it has a 70. I wanted to go to a 90 and LATER do the 90 upgrade to it, but was convinced by several people it would be a bad idea and should do it all at once or not at all. For a few bucks extra I could have had the 90.

So, can I throw a 90 in an R60 with 680CF and standard boom and fly it, and then stretch it later? I plan on running a Gov on it, the worst I can see happening is that the 90 may not see full throttle for the most part. I know the gear ratio is different once you go for the longer blades and tailboom, but do I need to change it to run 680 blades?

Totally scratch all personal opinion out of is, I want to know from a purely technical standpoint, will there be a problem doing this that can't be overcome?

[Al Magaloff]

Jon, I would do 8.27 gears and run the 680's. What motor are you thinking of going with?

[Sar]

A lot of the local guys say to go with the YS, the local shop has OS C-specs w/pump for $300 ATM, so one of those is tempting as well. I haven't decided which to use yet, still researching. It's hard to find hard data that isn't soaked in personal frustration :D

[pookie8]

ive been flying a short boom 90 with 680's and its a rocket no bogging at all the only thing i changed is the gear ratio to 8.27 so far so good

[Splattt]

Sar,
I run vblade 690's and 105 tails on the 90 boom. But I started out just running 680 vblades on a stock 60 boom with a ys91. All u need to do is get an 11tooth pinion and a 91 tooth main(8.27 ratio) and u should be ready to rock. U might want to upgrade the fuel tank to the 550cc on to extend your flights alittle bit.

As for which 91 to get the YS is nice plenty of power and runs sweet on a sb16. the 91ps might put out a bit more power and is certianly more tolerant of either the sb-16 or MP2. But alot of people end up doing the kline reg mod and end up putting a viper head on it to smooth it out and add power. Personally I just chose the ys91 as it was already pumped and Im certianly not going to miss the little extra power that the big dogs need.

Good luck and have fun with the larger bird. BTW I run 1550normal and 1780 idle up and my 91 seems happy.