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FIRE 90L "Staging"?

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Old 03-26-2010, 07:37 AM
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klhoard
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Default FIRE 90L "Staging"?

I have read the instructions for my FIRE 90L and ran it three times on the stand. After working out several little issues (like forgetting the zip ties on the coupler - duh!!) I can get 15.2K consistently with a 12x6 Top Flite wood prop. I'm getting ready to start leaning the engine down a little and get it set up to put in the airplane. . . Other than tightening a few bolts and maybe 1/2 turn on the high speed needle, I haven't touched anything past where Dub did the test run and pipe tuning at his shop. So, I know the engine is set up and ready, the issue is with me. . .
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My question concerns the term "staging". I understand that the pipe increases the engine power at a certain RPM. How do I tell when the engine is "staging"? Is it by sound? Is it a non-linear jump in RPM towards full throttle?
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Thanks for any help and sorry for the simpleton question. . . I'm really looking forward to getting this engine in my plane. If everyone keeps their fingers crossed, I think I'm on the way to keeping the plane in the sub-8 pound range which should make for some really interesting flight performance!!
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Old 03-26-2010, 09:41 PM
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resourcecapital
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Default RE: FIRE 90L

there will be a noticable increase in rpm when properly set.
why are you using an old style wood prop. while it is a good prop you should see better thrust and rpm's with an apc.
you may need to adjust the length of the pipe by 1/4 inch at a time to achieve the best performance.
if you have them put an extra head gasket into the motor to help prevent blowing plugs while you set the motor up.
do not run it to rich as it needs the heat to properly expand the sleeve.
when it comes ON you could see as much as 1500 to 2000 rpm increase.
note with the rpm increase you should richen up the needle so the engine does not lean out.
richen it up just to the point where it drops off of being ON the pipe. this is where you want to fly it. as the engine unloads in the air especially in a dive the engine will come ON the pipe and you will be suprised at the extra performance.
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Old 03-27-2010, 09:11 AM
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Default RE: FIRE 90L

If the pipe and header setup was already done by Dub Jett, instead of cutting anything he should be using props that get the engine into the ground rpm range suggested by Jett and setting the needle appropriately.

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Old 03-27-2010, 09:23 AM
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Default RE: FIRE 90L


ORIGINAL: MJD

If the pipe and header setup was already done by Dub Jett, instead of cutting anything he should be using props that get the engine into the ground rpm range suggested by Jett and setting the needle appropriately.

MJD
ZACTLY.......i'd email Dub with the question on when the 90 stages. he'll explain it in detail and especially since he set the engine up, he'll be happy to suggest the best props.

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Old 03-27-2010, 04:29 PM
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Default RE: FIRE 90L

Thanks for the replies, gentlemen. . . I was hoping that I could get an answer on the forum so that others could see also. .
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I was going to use and APC prop, but the instructions said that wood props are safer. I'm assuming that the APC's are good up thru the higher RPM ranges?
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Old 03-27-2010, 07:25 PM
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Default RE: FIRE 90L

The APC rule on their sport props is they are safe up to 190,000/diameter in inches. So, 10" prop - 19k for example. They don't instantly fly apart when you exceed that by a small amount, but be aware of it.

In any case, don't go trimming anything or messing with the setup until you talk to Dub directly or wait until Bob can get on line here. Did you not get any direction on ground rpm, prop choices, that sort of thing..?

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Old 03-30-2010, 08:46 PM
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Default RE: FIRE 90L

I got the standard instruction package that covers all of the FIRE engines, but nothing specific to this 90L. . . I got my prop size and RPMnumbers from the web site. .
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ORIGINAL: MJD

..<snip>. . Did you not get any direction on ground rpm, prop choices, that sort of thing..?

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Old 04-06-2010, 12:34 PM
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Default RE: FIRE 90L

Sorry for the delay !!

Yes, staging was explaind properly here. It is a midrange step where you will hear the engine jump a bit onto the pipe effect. Generally happens around 12,000 rpm with your setup (about 1/2 throttle position - then takes off from there. But it should be pretty smooth. You will not hear or see a monster jump in RPM with this setup. Throttle and transition should be outstanding.

If you have too much prop on the engine, the stage point will be later, engine will struggle to get on the pipe, and it will be difficult to find a needle setting.

As far as adjusting the pipe DON'T !!!! Mike noted, change the prop, not the pipe. Much easier. If you think the pipe is a bit long yet, put more prop on it. If it runs well, great. If it misbehaves, go back a prop size.

For the 90L FIRE setup, 11x8, 11x9, 12x6, 12x7 are where you want to be. APC is good, Wood is good. If you get a chance to try the Vess props, I really like those too.
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Old 04-08-2010, 12:01 AM
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Default RE: FIRE 90L

Vess!! I didn't think of those props. . . I had one on my DA-50 and loved it. . . I didn't know they made smaller props.
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And 15.2K is where I want the RPM, right?

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Old 04-10-2010, 08:07 AM
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Default RE: FIRE 90L

if that is set up properly, YES you are right on the money. Anythign between 14,500 and 15,500 ground rpm is perfect. Thats a LOT of power there
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Old 04-13-2010, 12:46 PM
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Default RE: FIRE 90L

Call the Tool Man!!!
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Got my Vess's in over the weekend. . . can't wait to get some numbers with those props. . .
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ORIGINAL: bob27s

. . .<snip>.. Thats a LOT of power there
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