Twin gurus

eman1200

eman1200

Touchdown! Greaser!
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Mar 10, 2013
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Bro do you even lift
anyone know the APPROXIMATE fuel burn of a turbo seneca II ? very approximate, like within a 1/4 gph is plenty close. jk, rough estimate if anyone knows.
 
Turbo Seneca II uses TSIO-360s. At a reasonable power setting above 10,000ft, those are going to burn 11-12gph each. Down low, probably more like 13/each. You can dial back the power and probably get it to under 10gph/side, but you didn't buy a Turbo Seneca to go slow...
 
labbadabba said:
That sounds like a lot. Doesn't it use IO-360s?
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Displacement means little. What's the power rating and what power setting (horsepower) are you using in cruise? Without getting into other factors involved, the horsepower used is going to drive the fuel rate.

I'd probably figure 24-26gph for a Seneca.
 
A week ago you had to intention to ever mess with twins, what gives?
 
TRocket said:
A week ago you had to intention to ever mess with twins, what gives?
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Some local hooligan mentioned a deal on multi rating so I was just kickin around the costs and whatnot. But that dude is mostly made of money, for me it's just a pipe dream.
 
I probably wouldn't pay much attention to local hooligan if I were you. And that local hooligan most likely only wishes he was made of money...
 
two-sadhu-or-holy-man-in-pashnupati-temple-kathmandu-nepal-a591yf.jpg
 
bradg33 said:
Turbo Seneca II uses TSIO-360s. At a reasonable power setting above 10,000ft, those are going to burn 11-12gph each. Down low, probably more like 13/each. You can dial back the power and probably get it to under 10gph/side, but you didn't buy a Turbo Seneca to go slow...
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You don't buy a Turbo Seneca to go fast either...:) ;)
 
mondtster said:
Isn't that like the pot calling the kettle black coming from an Aztec driver? :)
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I can understand people are easily fooled by the svelte and racy lines of the Aztec, mistakenly thinking they are Millennial Falcon speed transport machines, but I am here to help correct such misconceptions. :D

If the Aztec is the GA equivalent of an F150, the Seneca is a Ford Ranger, the 310 a Country Squire, the long body Baron a Thunderbird, the short body Baron a Mustang, and the short body Barons with big engines (IO-550 conversions) are Shelbys. ;)
The Grumman Cougar is an AMC Gremlin. :eek:
 
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For the record, I ain't buying no twin. That is, unless some of the local Charlotte peeps got their sht together but I was just curious about costs. The local Seneca rents for $208 dry.
 
Max horse power divided by two give you ruffly the pounds per hour at 100% power

Divide by 6 to convert PPH to GPH

Multiply by percentage of power used.

IO-520, 300HP
150PPH at 100%
Or 25GPH
.6 or 60% power
15GPH at 60% (cruise power)
 
eman1200 said:
anyone know the APPROXIMATE fuel burn of a turbo seneca II ? very approximate, like within a 1/4 gph is plenty close. jk, rough estimate if anyone knows.
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Pop on over to the Red Board and ask Dr. Bruce Chien. I believe he transports his wallet around with a Seneca II turbo 320 engines*. -Skip

* engine size from distant memory....
 
Skip Miller said:
Pop on over to the Red Board and ask Dr. Bruce Chien. I believe he transports his wallet around with a Seneca II turbo 320 engines*. -Skip

* engine size from distant memory....
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Seneca II is 200hp nominal, can be up to 215hp at certain altitudes and thus still requires a HP endorsement. TSIO-360s, about 12gph/side in cruise.

BTW, there's no such thing as a "Turbo Seneca." The Seneca I was normally aspirated, the Seneca II through V are all turbo, every one of 'em. It's just a "Seneca."

Now, I like the way the Seneca flies, but like many twins, it's kind of a pig. Burns twice as much fuel as the Mooney to go slower. Carries more, but with the LR tanks I've had to go with less than full fuel just to have three good-sized people aboard. That big back door (similar to B58) is sure nice tho.

BTW, any of the turbo Senecas (II-V) are terrible things to use as multiengine trainers. They use a fixed wastegate type setup, so the turbos are always going no matter what altitude you're at, and when you cut them off suddenly, you're probably going to coke up the oil that's in the turbo at the time. Doesn't take long before you need very expen$ive maintenance. IIRC, you're supposed to idle the engines for five full minutes prior to shutdown to keep this from happening on a normal shutdown.
 
Seneca II at 65% burns 21 gallons per hour and at 55% burns 18 gallons per hour. Both figures are rich of peak.
 
James331 said:
Max horse power divided by two give you ruffly the pounds per hour at 100% power

Divide by 6 to convert PPH to GPH

Multiply by percentage of power used.

IO-520, 300HP
150PPH at 100%
Or 25GPH
.6 or 60% power
15GPH at 60% (cruise power)
Click to expand...

Doesn't work that well on turbos though.

TSIO-520-M, 310HP
25.8GPH
In real life, it's 31GPH at 100%.
 
Senecas with NA IO-540s 250hp would have been a much nicer and cheaper blend imo. Plenty of NA Aztecs running around just fine. "Turbo or nothing" was kind of an odd solution to the supposed Seneca I "problem". I wonder why Piper dismissed the rather self-evident choice of just installing higher HP NA motors?
 
mtuomi said:
Doesn't work that well on turbos though.

TSIO-520-M, 310HP
25.8GPH
In real life, it's 31GPH at 100%.
Click to expand...

Nor turbines, NA piston, I shoulda said that
 
James331 said:
Max horse power divided by two give you ruffly the pounds per hour at 100% power

Divide by 6 to convert PPH to GPH

Multiply by percentage of power used.

IO-520, 300HP
150PPH at 100%
Or 25GPH
.6 or 60% power
15GPH at 60% (cruise power)
Click to expand...

Hmmm. Never heard of that before.

For me: 280hp/2=140pph/6=23.3 gph (close-ish: 25 actual).
*.65 = 15.2 gph (12.2 actual).
 
hindsight2020 said:
Senecas with NA IO-540s 250hp would have been a much nicer and cheaper blend imo. Plenty of NA Aztecs running around just fine. "Turbo or nothing" was kind of an odd solution to the supposed Seneca I "problem". I wonder why Piper dismissed the rather self-evident choice of just installing higher HP NA motors?
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Might have had something to do with the additional certification requirements and costs, once committed to the 200 nominal hp 360 motor in the Seneca One? Adding 35 to 50 more sea level hp to a plane originally certified at 200 sea level hp is probably not trivial (things like single engine operation asymmetric thrust rudder authority start coming into the equation) , although I will admit Piper seemed to play that game well with the myriad of simpler single engine Cherokee derivatives. ;)

I am actually surprised how many airplane's start off life clearly underpowered when first introduced. Even Cirrus can be accused of that with the poor selling SR-20 that now, finally, has an minimally acceptable new engine for the size and weight of the airframe.

There's a bunch of reasons I bought an Aztec instead of a Seneca II or III, but the bulletproof NA Lyc IO-540s was one of them. The lack of useful load in the Seneca, mentioned indirectly by flyingcheesehead above, is another.

Following up on flyingcheesehead's post above, if one is contemplating a Seneca II or III, the Merlin upper deck controller and aftermarket intercoolers are highly desirable upgrades to look for installed on them.
 
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GRG55 said:
I can understand people are easily fooled by the svelte and racy lines of the Aztec, mistakenly thinking they are Millennial Falcon speed transport machines, but I am here to help correct such misconceptions. :D

If the Aztec is the GA equivalent of an F150, the Seneca is a Ford Ranger, the 310 a Country Squire, the long body Baron a Thunderbird, the short body Baron a Mustang, and the short body Barons with big engines (IO-550 conversions) are Shelbys. ;)
The Grumman Cougar is an AMC Gremlin. :eek:
Click to expand...

Need to continue this. I want to know what the TravelAir is in this analogy. ;)

And the Seminole. LOL.
 
jbrrapa said:
Seneca II at 65% burns 21 gallons per hour and at 55% burns 18 gallons per hour. Both figures are rich of peak.
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This is correct. I figure 21-22gph total and never run above 65% except takeoff. You need the Merlyns for engine life (wastegate controller). It has a different mission than the mooney as someone posted. I get 165 KTAS at 10k and 173 KTAS at 16-18 running 65%. If you want a single engine service ceiling of 18k, known icing and an extra fan if you need it, it's a great airplane. There are many many faster and more economical airplanes out there.
 
In the 100k range or less you might be able to find a Miller conversion Twin Comanche (200hp per side).

The one I did my multi rating in would do 170 knots on about 17gph combined. The engines are 4 cylinder lycomings, low cost to operate. Good useful load and great single engine climb... I think it would climb better on one engine than some low power singles.

While a bit more cost to operate I do like the Seneca II's. They do make up for it with the club seating, big doors and many have deice.
 
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