SJ50 Fire vs. BSE50 Fire  
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SJ50 Fire vs. BSE50 Fire - 8/12/2003 3:02:49 AM   
MCR-RCU



Posts: 73
Joined: 2/2/2002
From: South Haven, Michigan
Status: offline 		I have a new Whiplash and am looking for the best engine for it. In looking at these 2 engines, there specs. appear to be the same. What is the difference between the 2 engines besides the way the case is made?

What would be the recommendation for a whiplash setup? I called Jett today but got a answering machine saying they are closed until thursday. I'm want to order a complete tuned setup, but don't know which one would be best.

Also, I have several gallons of Wildcat YS20/20 fuel. Would there be any problem with running this fuel in the Jett?

thanks,
Marty Ridner
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SJ50 Fire vs. BSE50 Fire - 8/12/2003 5:42:17 PM   
bob27s



Posts: 4821
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Hi Marty....

Thanks for writing

Yes, Dub is on vacation this week. I am sure I can assist you in the interm.

The BSE FIRE 50 and cast case FIRE 50 have essentially the same performance. The main difference we see with the bar stock case is the consistancy from engine to engine. Where in the past we noted test rpm varience of +/- 400 rpm with the case case, the BSE machined case engines seem to hold a tigher tolerance.

Having said that, the BSE configuration allows Dub to make small case and porting refinements over time. The cast case is, litterally, fixed in stone by its shape and tooling. So I will say at this time the BSE will outperform the cast case engine by a few hundred RPM (on average)

Dub has a fairly standard Whiplash/DD set-up we have provided to many the past few years, and he can provide a similar one for you as well.

It consists of a BSE 50 FIRE and a pre-tuned, welded pipe and header combination. You have a choice of the standard pipe or muffled pipe. The pipe is tuned for higher RPM (above 17,500) and must be propped accordingly. Specifics are provided with the engine. The engine comes standard with Jett's remote needle valve.

If you wish, you can place the order on the jettengineering.com web site. Simply place an order for the BSE 50, your pipe selection, and specify Whiplash configuration.

As for the fuel, you should have no problem running the 20/20. Jett engines run just fine on 10 to 15 % nitro fuel, but a bit more nitro won't hurt them. The oil content is fine.

(for others reading this, more nitro than about 20% is not needed or recommended for Jett sport engines)

I hope this has been helpful. Feel free to write or email with any other questions.

Bob Brassell

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SJ50 Fire vs. BSE50 Fire - 8/12/2003 8:12:29 PM   
MCR-RCU



Posts: 73
Joined: 2/2/2002
From: South Haven, Michigan
Status: offline 		Thanks for your prompt reply. I have placed a order via the website as you suggested.

Do you know what prop works best for this setup?

Thanks again,
Marty

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SJ50 Fire vs. BSE50 Fire - 8/12/2003 10:53:14 PM   
bob27s



Posts: 4821
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		I would start with an APC 9x8

If you ask around on the Extream Speed board, Gene and some of the other DD and Whiplash guys can give you some good examples.

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Prop Selection - 8/13/2003 10:55:02 AM   
hooaa



Posts: 197
Joined: 6/29/2003
From: Cambria, CA,
Status: offline 		Bob,
I noted your recommendation of 9x8 in the above thread. I just received my 50 FIRE and on the invoice was hand written "APC 8.75 x 8W to 9W
8.8 x 8-9
18-20K range peak"
Please interpret this for me. I just ordered some 8.75 x 9W based on Dub's comments while taking my order. I have some 8.75 x 8W that I use for pylon. I was planning on using one for break-in, then switching to the 8.75 x 9W after 30 min. or so. Your help deciphering would be appreciated.


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SJ50 Fire vs. BSE50 Fire - 8/13/2003 5:49:17 PM   
bob27s



Posts: 4821
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		hooaa,

Sorry if I caused any confusion.....

Start with the props recommended by Dub. The pipe is tuned to run in the RPM range he specified, and the props he listed will all run in that range. As I noted in my original post above, the specifics on tuned RPM and recommended props to run at that RPM are provided with each engine.

The Q-500 pylon props (which Dub suggested) all work great in the application.

Some of the guys out there found they had good results with the standard blade APC 9x8 and 9x9.

I prefer the pylon props because the hub and blades are well proven to run at the higher RPMs, and perform well at higher aircraft velocities.

The 8.75x9W is my personal prop of choice for the Whiplash and Diamond Dust applications. The engine likes it, it unloads a ton in the air, and the speed is excellent.

Yes, start with the 8W until the engine gets some time on it.

I have not yet flown an 8.8x9 on a whiplash, but I think in the long run that is going to be 'the' prop.

You can experiment with props as you wish. The key being, make sure the prop/engine will peak out over 18K rpm on the ground, and launch no lower than 17,500.

< Message edited by bob27s -- Aug 13 2003 12:55PM >

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SJ50 Fire vs. BSE50 Fire - 8/13/2003 7:23:41 PM   
hooaa



Posts: 197
Joined: 6/29/2003
From: Cambria, CA,
Status: offline 		Bob,
Thank you for the feedback. I'm glad that the props on their way will be useful. For 10 years I have been running K&B 6.5 FIRE. I have high expectations for this new setup. I only hope my knees hold up on the maiden flight.


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SJ50 Fire vs. BSE50 Fire - 8/13/2003 8:21:35 PM   
bob27s



Posts: 4821
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Well, the nice thing about the FIRE50 is the throttle and transition are outstanding.

You can throttle back on that first flight.... get the plane trimmed out properly...then open things up once things are dialed in. I even suggest you launch at about 1/2 throttle. Save the knees for the 2nd or 3rd flight

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SJ50 Fire vs. BSE50 Fire - 8/13/2003 8:48:44 PM   
hooaa



Posts: 197
Joined: 6/29/2003
From: Cambria, CA,
Status: offline 		I am definetely looking forward to having the ability to throttle back. I'll be using the Whiplash launcher. I think I must launch with full throttle, up and right elevons, then quickly throttle back to 1/2. If that's incorrect let me know.


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SJ50 FIRE - 8/15/2003 7:33:57 AM   
hooaa



Posts: 197
Joined: 6/29/2003
From: Cambria, CA,
Status: offline 		Bob,
I ran it today for the first time on the bench. I didn't follow the part about starting with a prop one size under (i.e. 9-6). Instead I used an 8.75-8W, ran it very rich for a minute, peaked it at 19,300, then richened it to 18,300 and ran it for 15 minutes. It ran smooth as silk constantly, RPM never wavered. Have I started off in a manner that will result in poorer performance? I want to graduate to an 8.75-9W when the RPM's pick up. Should I mount it and fly now?
As an aside, it makes more noise than I ever imagined. It will scare some, and thrill the beejeezus out of others!


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SJ50 Fire vs. BSE50 Fire - 8/16/2003 1:29:20 AM   
bob27s



Posts: 4821
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		yeah...at that RPM, it will generate a lot of 'energy' A great deal of what you hear is prop noise too.

If the engine is turning 19K, you dont have to worry about a small break-in prop. You are running about 1000 rpm down, and that is good.

Take that 8W up to about 18,800 or 18,900 on the stand for one tank... up closer to peak rpm.

Then back the needle out a half turn, and try the 9W. Find peak on that, back off 500-600 rpm, keep note of that RPM. You may notice the combo will run in the 18,500 range. Run this setup for a tank (3-4 min). This will give you an idea of how the setup will run when installed in the plane.

After that, put it in the airplane... and hold on tight to those sticks

Always run it 500-600 rpm down at launch, and the engine will remain smooth and reliable.

Have fun
Bob

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SJ50 Fire vs. BSE50 Fire - 8/16/2003 3:41:45 AM   
hooaa



Posts: 197
Joined: 6/29/2003
From: Cambria, CA,
Status: offline 		Bob,
I'll proceed as you suggested. Thanks once again for the guidance.
BTW, the gardner in the backyard, following the break-in session, said that he'd been to a lot of Rock concerts but that his ears had never hurt like they did after the shutdown.



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SJ50 Fire vs. BSE50 Fire - 8/18/2003 6:04:50 PM   
bob27s



Posts: 4821
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		the quiet pipe is a ... little.. better. nitro pipes really bark

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SJ50 Fire vs. BSE50 Fire - 8/19/2003 7:21:11 PM   
hooaa



Posts: 197
Joined: 6/29/2003
From: Cambria, CA,
Status: offline 		Bob,
Yesterday I began what was to be my final breakin session before mounting. In the previous sessions I had burned 24 oz., using an 8.75x8W, peaking 19,200. Yesterday the peak was 18,500, all other condx unchanged. I ran it at 18,000, stopping three times to tighten the mount while burning up 8 oz.
Two questions popped into my mind.
Why the 700 rpm drop in peak, and secondly, when the engine is mounted in the Whiplash is vibration less of a factor compared to being mounted hard to a sawhorse?

My well worn piped K&B 6.5 FIRE turns 19K on the ground so I'm anticipating that this combo will produce much more between loosening up and unloading in the air.


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SJ50 Fire vs. BSE50 Fire - 8/19/2003 8:15:30 PM   
hooaa



Posts: 197
Joined: 6/29/2003
From: Cambria, CA,
Status: offline 		Bob,
I forgot to mention an important point, the pipe slipped at least 1/4" in the coupler at some point. This might explain the 500 rpm drop. I'm going to introduce a little contact cement in the coupler assy process.


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SJ50 Fire vs. BSE50 Fire - 8/19/2003 10:50:35 PM   
bob27s



Posts: 4821
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Thanks for the update.

Be very certain to balance the prop. Having experience with other engines, I'm sure you are aware of how critical that is at these RPMs.
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