Jett .40 Or Jett pipe?  
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Jett .40 Or Jett pipe? - 7/11/2007 3:54:19 AM   
Destiny-RCU


 

Posts: 103
Joined: 6/29/2003
From: Ft. Lauderdale, FL, USA
Status: offline 		I'm sorta in a sticky spot. Maybe i'm looking for opinion also. Well My Viper is under Firewall repairs and now ending up getting a full make over. I had about 15 flights on the stock TT40. I think the reason i'm uneasy is because the flight before the firewall decided abandon ship, a Kobra with an OS .46 + Ultrathrust was giving me a run. Not pylon racing just sunday flying.

My question is..How much extra top end can be gained just from adding the pipe? Is it enough to keep those pesky patriot/kobra type planes away?. I mean this guy was within 5mph of the Viper. Should I put the $70 towards an engine?
What type of speeds would the SJ .40 give over the TT and pipe combo?

Thanks Russ

P.S. The guy with the Kobra walked up to me after that flight and says "what engine do you have on there???"...Now I must go faster..

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RE: Jett .40 Or Jett pipe? - 7/11/2007 2:23:31 PM   
bob27s



Posts: 4588
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		A kobra is a .25 size plane with the .46/ut combination..... slightly smaller wing and such. Hard to really compair. But I bet your viper flys better

The TT40 is a good engine. Trick is not to over-prop it.

Bolting on the Jett-stream muffler will help a bunch. The engine resonds very nicely.
First flight on that combination with a standard 9x6. This prop will be a little small, but set the engine just slightly rich - let the engine turn up in flight.
Then move to an APC 9x7 and perhaps then to a 8.75x8W




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Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to Destiny-RCU)
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RE: Jett .40 Or Jett pipe? - 7/25/2007 2:03:04 AM   
Destiny-RCU


 

Posts: 103
Joined: 6/29/2003
From: Ft. Lauderdale, FL, USA
Status: offline 		What's up Bob,

I ended up buying the Jett stream pipe. I wanted to ask you before I go flying with it. How will the engine behave? Will I need to make any low speed needle adjustments? Is the engines starting procedure the same? I don't want to get to the field and have to start making adjustments.
Sorry, i'm a newb with these fast things

I started it for a minute just to hear it but that's about it...I Love it!

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RE: Jett .40 Or Jett pipe? - 7/25/2007 2:59:19 PM   
bob27s



Posts: 4588
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Looks nice

The engine will basically run the same. Depending on the prop you choose, you may have to tweek the low end mixture ever so slightly. Chances are you will not have to touch it.

The jett-stream will provide more tank pressure than any of the stock mufflers, and also provides a good balance of backpressure. You will probably have to reset the top end - do this first
---- start with the needle out about a half turn further than normal - start engine, go to full throttle - all the engine to warm up for 30 seconds or so. Then lean it out slowly.

Use a tach as a reference, or just do it by ear. Find approximate peak rpm, and then back the needle out so you can hear the engine drop off just a bit (usually 500-600 rpm will do). Should be good to go there.

And once the top end is set, maybe adjust the bottom end just a little to get the transition and idle perfect if needed.

Starting is the same. Engine will not behave any different. Just will hit a few more RPM than normal

Bob


_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to Destiny-RCU)
       Post #: 4

RE: Jett .40 Or Jett pipe? - 7/26/2007 1:10:08 AM   
Destiny-RCU


 

Posts: 103
Joined: 6/29/2003
From: Ft. Lauderdale, FL, USA
Status: offline 		Thanks very much. I've been into slow stuff and Extra's for a long time. Always seen these but never paid much attention except when they fly, trying to avoid mid-air's..hehe. I asked because I started it yestarday at about 3 3/4 turns out and it seemed to run so smooth. Where as with the stock muffler it would have been running like a pig. Even throttled decent. I'll give it a shot.

Thanks Russ.

(in reply to bob27s)
       Post #: 5

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