Too Much Horsepower

[donkaye]

It's always been said that you can never have too much horsepower.  Over the past week I found that personally not to be true.

The student, who just got his private a couple of weeks ago, purchased an Acclaim Type-S that had the 310 HP upgrade.  I've got a lot of time in Acclaims, but hadn't flown one with the 310 HP conversion.  We flew it from near Oklahoma City (KOUN) to San Jose, California last Sunday.  Because it had air-conditioning and TKS, it was load limited.  We did the trip with a 10 knot headwind most of the way and 2 fuel stops in a little under 7 hours.  I trained him all week and being a young 28 years old I was able to sign him off on his High Performance and Complex Endorsements by the end of today.

At full power you're pushed  back into the seat and the vibration is more than I like.  We used full power for the short Palo Alto and Livermore short runway, but a more comfortable power setting was about 30" MP or about 90% Power.  On takeoff with full power its burning 38 gal/hr, and in cruise its about 20.5 gal/hr.

If you're thinking about doing the upgrade, I might think again.

[Z W]

Does the 310 HP require excessive right rudder on takeoff, such that it feels unstable or dangerous on takeoff?

Sometimes I like the idea of an extra 100HP over what I've got in a 262. But I've wondered how that really feels on essentially the same airframe. And at 38 GPH take off / climb and 20GPH in cruise I feel like I would often be flying around with range anxiety, or be effectively limited to 2-hour legs unless flying solo and light.

[Schllc]

No. It does not require much more rudder than one without the upgrade, and it has never felt unstable or dangerous. 
in fact when you are taking off from an airport like north Perry in Florida, where there is NOWHERE you can land and survive if you lose an engine, you are grateful for every single hp. 
IIRC, the extra ho is only supposed to be used in takeoff, not cruise. 
the difference between the 280 and 310 is definitely noticeable, but it is not as if it’s going from a Camry to an F1 car. 
I do agree with Don however, in that is certainly not a necessity in an acclaim.  It is absolutely something I would want in an ovation.  And if you bought an acclaim with the mod, you do not have to use it, but I don’t believe it is worth what it costs to add. 

[donkaye]

1 hour ago, Schllc said:

No. It does not require much more rudder than one without the upgrade, and it has never felt unstable or dangerous. 
in fact when you are taking off from an airport like north Perry in Florida, where there is NOWHERE you can land and survive if you lose an engine, you are grateful for every single hp. 
IIRC, the extra ho is only supposed to be used in takeoff, not cruise. 
the difference between the 280 and 310 is definitely noticeable, but it is not as if it’s going from a Camry to an F1 car. 
I do agree with Don however, in that is certainly not a necessity in an acclaim.  It is absolutely something I would want in an ovation.  And if you bought an acclaim with the mod, you do not have to use it, but I don’t believe it is worth what it costs to add. 

The 310 HP on the Ovation seems different to me than the same on the Acclaim.  I recommended it to a student who lived in Truckee.  He got it and it really makes a difference at the higher DAs.  Not so with the Acclaim.  Regarding the rudder, I was surprised that it did not make as much of a difference as I thought it would.  However, my student did not like the rudder trim nor do I on the later model long bodies.  When trimming with it, it doesn't stop when you release the trim switch, but overshoots.  He actually found he liked just trimming the rudder to neutral on takeoff.  On my Bravo the trim works as expected, and stops when you release the switch.

[exM20K]

I disagree with my friend @donkaye here.  I did the conversion and find it very worthwhile for my needs.

The excess power is all about getting off the runway and climb performance. Since I operate half the time from a short, 2500ish foot runway, runway performance matters to me.

Since my 90% trip is -740 NM, the ability to jump up to 16-17,000 at a much better rate saves significant time and offers the benefit of well out climbing the dead-stick sing rate. Of course this is not meaningful coming off a short strip with a full bag of gas, but otherwise it is. At MGTOW, the 310 will sustain 1200-1500 FPM at 130 or 120 KIAS. That is 2-300FPM better than book. Excess power means better ability to climb in icing conditions, another safety plus.

AC+TKS is unusual.  Is that Fizan’s old plane?

There should be no excessive vibration. Your student should start with a dynamic balancing of the prop and dig deeper.  This is one of the smoothest piston engines I’ve flown.

If an unconverted plane has the Type-S prop, the SCT costs something like 1% of hull value. To me, that’s a no-brainer.

-dan

[exM20K]

48 minutes ago, donkaye said:

However, my student did not like the rudder trim nor do I on the later model long bodies.  When trimming with it, it doesn't stop when you release the trim switch, but overshoots.

Agree.  I re-trim to the middle after clearing the runway and set takeoff trim by holding it for a count of “Four.”

I was advised to actuate the rudder trim only when rolling to reduce the loads on the linkages. This seems to help with the overshoot.

-dan

[M20TN_Driver]

9 hours ago, donkaye said:

It's always been said that you can never have too much horsepower.  Over the past week I found that personally not to be true.

The student, who just got his private a couple of weeks ago, purchased an Acclaim Type-S that had the 310 HP upgrade.  I've got a lot of time in Acclaims, but hadn't flown one with the 310 HP conversion.  We flew it from near Oklahoma City (KOUN) to San Jose, California last Sunday.  Because it had air-conditioning and TKS, it was load limited.  We did the trip with a 10 knot headwind most of the way and 2 fuel stops in a little under 7 hours.  I trained him all week and being a young 28 years old I was able to sign him off on his High Performance and Complex Endorsements by the end of today.

At full power you're pushed  back into the seat and the vibration is more than I like.  We used full power for the short Palo Alto and Livermore short runway, but a more comfortable power setting was about 30" MP or about 90% Power.  On takeoff with full power its burning 38 gal/hr, and in cruise its about 20.5 gal/hr.

If you're thinking about doing the upgrade, I might think again.

Might be the first person I e ever heard say that.  That said, I have the type S and never felt any need to get the etc.  

[aviatoreb]

12 hours ago, donkaye said:

It's always been said that you can never have too much horsepower.  Over the past week I found that personally not to be true.

The student, who just got his private a couple of weeks ago, purchased an Acclaim Type-S that had the 310 HP upgrade.  I've got a lot of time in Acclaims, but hadn't flown one with the 310 HP conversion.  We flew it from near Oklahoma City (KOUN) to San Jose, California last Sunday.  Because it had air-conditioning and TKS, it was load limited.  We did the trip with a 10 knot headwind most of the way and 2 fuel stops in a little under 7 hours.  I trained him all week and being a young 28 years old I was able to sign him off on his High Performance and Complex Endorsements by the end of today.

At full power you're pushed  back into the seat and the vibration is more than I like.  We used full power for the short Palo Alto and Livermore short runway, but a more comfortable power setting was about 30" MP or about 90% Power.  On takeoff with full power its burning 38 gal/hr, and in cruise its about 20.5 gal/hr.

If you're thinking about doing the upgrade, I might think again.

Thanks very interesting Don,

I bet you have flown in the rocket. Do you feel the 305hp is too much for that airframe?  I am entirely used to it and like it but I do not have any other mooney time in a different mooney to contrast it to like you do.  Anyway I like it a lot.

[donkaye]

3 hours ago, aviatoreb said:

Thanks very interesting Don,

I bet you have flown in the rocket. Do you feel the 305hp is too much for that airframe?  I am entirely used to it and like it but I do not have any other mooney time in a different mooney to contrast it to like you do.  Anyway I like it a lot.

Yes, I've flown a number of Rockets.  I even did a couple of instrument ratings in them.  For some reason the 310HP Acclaim SEEMS to have much more power.

[donkaye]

7 hours ago, exM20K said:

I disagree with my friend @donkaye here.  I did the conversion and find it very worthwhile for my needs.

The excess power is all about getting off the runway and climb performance. Since I operate half the time from a short, 2500ish foot runway, runway performance matters to me.

Since my 90% trip is -740 NM, the ability to jump up to 16-17,000 at a much better rate saves significant time and offers the benefit of well out climbing the dead-stick sing rate. Of course this is not meaningful coming off a short strip with a full bag of gas, but otherwise it is. At MGTOW, the 310 will sustain 1200-1500 FPM at 130 or 120 KIAS. That is 2-300FPM better than book. Excess power means better ability to climb in icing conditions, another safety plus.

AC+TKS is unusual.  Is that Fizan’s old plane?

There should be no excessive vibration. Your student should start with a dynamic balancing of the prop and dig deeper.  This is one of the smoothest piston engines I’ve flown.

If an unconverted plane has the Type-S prop, the SCT costs something like 1% of hull value. To me, that’s a no-brainer.

-dan

No, Fizan did not have a Type -S Acclaim.  I flew his airplane back East to him from Santa Barbara when he bought it, and did his training in the middle of winter in Chicago. Brrrrrr.  Yes, for short runways it would be better.  We flew down to Hawthorne today in 1.5 hours, 15 minutes better than my plane.  He'll be commuting back and forth from Texas to LA.

[aviatoreb]

1 hour ago, donkaye said:

Yes, I've flown a number of Rockets.  I even did a couple of instrument ratings in them.  For some reason the 310HP Acclaim SEEMS to have much more power.

I wonder why.  Rocket was an after thought mod but was purpose built.

[Wingover]

On 3/1/2025 at 6:54 AM, donkaye said:

Because it had air-conditioning and TKS, it was load limited.

Don,

What is the useful load with AC and TKS?

[donkaye]

14 minutes ago, Wingover said:

Don,

What is the useful load with AC and TKS?

Empty weight is 2,544.  Maximum gross weight is 3,368.  Useful load is 824 pounds.

[Jeff Uphoff]

On 3/1/2025 at 1:54 AM, donkaye said:

We flew it from near Oklahoma City (KOUN) to San Jose, California last Sunday.  Because it had air-conditioning and TKS, it was load limited.  We did the trip with a 10 knot headwind most of the way and 2 fuel stops in a little under 7 hours.

This past weekend, I flew my 310HP Ovation from Salem, OR to Roanoke, VA at 15k' in under 11 hours, with one stop. Burned 125 gallons total. (A bit of tailwind helped.)

Damn but this plane is efficient; I was LOP burning 11 GPH and truing low/mid 170s.

(This was my first transcontinental round trip since selling my 231 years ago, which I used to commute CA<->VA in. It was my 25th transcontinental run overall.)

--Up.

[NickG]

On 3/3/2025 at 1:14 PM, Jeff Uphoff said:

This past weekend, I flew my 310HP Ovation from Salem, OR to Roanoke, VA at 15k' in under 11 hours, with one stop. Burned 125 gallons total. (A bit of tailwind helped.)

Damn but this plane is efficient; I was LOP burning 11 GPH and truing low/mid 170s.

(This was my first transcontinental round trip since selling my 231 years ago, which I used to commute CA<->VA in. It was my 25th transcontinental run overall.)

--Up.

Jeff, I regularly fly my 310HP Ovation from Las Vegas to Houston. About 6 hours  or so in the air, although I like to make a leg stretch stop in Roswell. anywhere from 12-17k altitude, true in the mid 170's between 10.5 and 11.5 GPH. Great birds. I've always wondered about the Fuel efficiency of an Acclaim S - perhaps the acclaim drivers can shine some light on it. Agree with @donkaye- the 310 HP makes a big difference in the Ovation in terms of T/O and climb particularly when its hot, high and heavy.

I'm assuming that one could fly an Acclaim S in the low teens and similar settings to an ovation or does the turbo make it much more thirsty? West to east, getting into the FL's would be great, but certainly not the other way.

[exM20K]

43 minutes ago, NickG said:

Jeff, I regularly fly my 310HP Ovation from Las Vegas to Houston. About 6 hours  or so in the air, although I like to make a leg stretch stop in Roswell. anywhere from 12-17k altitude, true in the mid 170's between 10.5 and 11.5 GPH. Great birds. I've always wondered about the Fuel efficiency of an Acclaim S - perhaps the acclaim drivers can shine some light on it. Agree with @donkaye- the 310 HP makes a big difference in the Ovation in terms of T/O and climb particularly when its hot, high and heavy.

I'm assuming that one could fly an Acclaim S in the low teens and similar settings to an ovation or does the turbo make it much more thirsty? West to east, getting into the FL's would be great, but certainly not the other way.

Close, but the lower compression cylinders on the TN are inherently less efficient. Book speed at 16,000:

-dan

[Jeff Uphoff]

10 hours ago, NickG said:

Agree with @donkaye- the 310 HP makes a big difference in the Ovation in terms of T/O and climb particularly when its hot, high and heavy.

I like it because I'm based at an airport (KROA) that's literally in a bowl, surrounded on all sides by mountains--and with continued unfriendly terrain to most points southwest, west, and north. I want max climb capability to at least 5-6k to get clear and gain options. The 310HP is outstanding for that.

--Up.

[NickG]

19 hours ago, exM20K said:

Close, but the lower compression cylinders on the TN are inherently less efficient. Book speed at 16,000:

-dan

Thanks! That's really got a wide operational range! 173KTAS for 2300/19 between 10.5-11.5 all the way up to 19 GPH and 218 KTAS..... fantastic.