Performance numbers for Firewall Forward Horsepower Plus

[adverseyaw]

I've got a 1978 M20J with the Firewall Forward "Horsepower Plus" STC SE2741NM. This is an IO-360-A3B6D with the stock dual magnetos and no other engine performance upgrades of note. I do have GAMI injectors which got me to a spread of 0.2GPH and reduces tendency to run rough, especially at altitude. This STC limits propellers to the stock McCauley so that's what I'm running.

This engine has about 350 hours on it since overhaul by FF. No real issues with the engine so far.

The airframe only has a couple of speed mods, notably flap/aileron seals, but it still has the multi-piece belly.

 

Usually I fly this airplane at Economy Cruise (low altitudes, up to about 9000 feet) and Best Power Cruise above that. Ram air is open on all runs. I keep the cowl flaps closed and make sure the CHTs don't get out of hand, and in all cases below I've let the airspeed and temps settle for at least 20 minutes before recording numbers. I haven't been writing down degrees ROP/LOP. Weight on these speed runs is around 2500 pounds so I'm averaging the 2300 and 2740 speeds in the POH. RPM, MP, and fuel flow are measured with a JPI 800. I've got more runs than this but picked 4 that I could match to the POH.

The TL;DR on this performance for this STC is that starting around 9k feet, it gives me lower fuel burn, and sometimes better speed. Below that, it performs like a stock engine: at or slightly below factory numbers.

 

[carusoam]

Same invite for @Sandman993...

Best regards,

-a-

[Sandman993]

On 3/26/2020 at 10:40 PM, carusoam said:

Same invite for @Sandman993...

Best regards,

-a-

Plus I’m cheating... fine wire plugs and power flow exhaust.

[carusoam]

23 hours ago, Sandman993 said:

Plus I’m cheating... fine wire plugs and power flow exhaust.

Have you considered an electronic mag yet, Sandman?

The data is starting to flow around MS lately...

Best regards,

-a-

[Sandman993]

17 hours ago, carusoam said:

Have you consider an electronic mag yet, Sandman?

The data is starting to flow around MS lately...

Best regards,

-a-

Yeah, I’ve drooled for two (2018,19) years at Oshkosh. I’d love to have one. Have kept a spare dual mag I share with another j owner. We’ve sworn an oath to red label it to wherever the other gets stranded for a quick swap. So if they ever stc an electronic mag... I can think of three dual mags that will come up for sale pronto quick.

 

i kick myself every time I board for not spending the extra 9k to buy a different accessory plate and mags at overhaul. I didn’t get 75hrs run time on the new engine before I had to overhaul the Siamese twins (again) because of condenser failure. Not to mention it ruined a nice trip. Thankfully I was still within 60miles of base so, turn her around, pucker up and go home.

 

I’m still waiting on the “phantom” autopilot too. I wish we hadn’t been so hard on pro pilot... my friend has one in his 182... that thing is great!

[Rotorhead]

Bringing it back from the dead...

Anyone else have experience with this STC? @adverseyaw, still happy sad indifferent about having done the mod? 

I'm interested but I'm sending my engine in for an overhaul and contemplating about doing this mod or the electronic ignition for my Dual mag engine.

-KC

[Niko182]

55 minutes ago, Rotorhead said:

Bringing it back from the dead...

Anyone else have experience with this STC? @adverseyaw, still happy sad indifferent about having done the mod? 

I'm interested but I'm sending my engine in for an overhaul and contemplating about doing this mod or the electronic ignition for my Dual mag engine.

-KC

why not just go the IO390 route.

[1980Mooney]

2 hours ago, Rotorhead said:

Bringing it back from the dead...

Anyone else have experience with this STC? @adverseyaw, still happy sad indifferent about having done the mod? 

I'm interested but I'm sending my engine in for an overhaul and contemplating about doing this mod or the electronic ignition for my Dual mag engine.

-KC

I contemplated this about 23 years ago on my J.  The engine runs higher compression pistons. - 10 to 1.  Maybe with the new GAMI G100UL it will be safe to boost compression on all engines but at the time I was concerned about detonation on 100LL..  As a result I went with the Missile 300 HP conversion.

From the sales brochure:

The H.P. increase is accomplished by the installation of Lycoming built pistons for the 360 engine that raise the compression ratio from the stock 8.7:1, to 10.0:1.

[Niko182]

35 minutes ago, 1980Mooney said:

I contemplated this about 23 years ago on my J.  The engine runs higher compression pistons. - 10 to 1.  Maybe with the new GAMI G100UL it will be safe to boost compression on all engines but at the time I was concerned about detonation on 100LL..  As a result I went with the Missile 300 HP conversion.

From the sales brochure:

The H.P. increase is accomplished by the installation of Lycoming built pistons for the 360 engine that raise the compression ratio from the stock 8.7:1, to 10.0:1.

wasn't the company also an absolute nightmare to deal with. I feel like I've heard firewall forward around here and don't remember it being great things.

[ArtVandelay]

why not just go the IO390 route.

It requires a different prop so it’s additional money above the engine cost.

A good thread to read:

https://mooneyspace.com/topic/2503-pireps-on-firewall-forward-hp-stc/

[aviatoreb]

On 3/25/2020 at 11:30 PM, adverseyaw said:

I've got a 1978 M20J with the Firewall Forward "Horsepower Plus" STC SE2741NM. This is an IO-360-A3B6D with the stock dual magnetos and no other engine performance upgrades of note. I do have GAMI injectors which got me to a spread of 0.2GPH and reduces tendency to run rough, especially at altitude. This STC limits propellers to the stock McCauley so that's what I'm running.

This engine has about 350 hours on it since overhaul by FF. No real issues with the engine so far.

The airframe only has a couple of speed mods, notably flap/aileron seals, but it still has the multi-piece belly.

 

Usually I fly this airplane at Economy Cruise (low altitudes, up to about 9000 feet) and Best Power Cruise above that. Ram air is open on all runs. I keep the cowl flaps closed and make sure the CHTs don't get out of hand, and in all cases below I've let the airspeed and temps settle for at least 20 minutes before recording numbers. I haven't been writing down degrees ROP/LOP. Weight on these speed runs is around 2500 pounds so I'm averaging the 2300 and 2740 speeds in the POH. RPM, MP, and fuel flow are measured with a JPI 800. I've got more runs than this but picked 4 that I could match to the POH.

The TL;DR on this performance for this STC is that starting around 9k feet, it gives me lower fuel burn, and sometimes better speed. Below that, it performs like a stock engine: at or slightly below factory numbers.

 

Is that in knots or mph?

[Rotorhead]

8 hours ago, Niko182 said:

why not just go the IO390 route.

Because AMU's unfortunately 

[KSMooniac]

9 hours ago, Rotorhead said:

Bringing it back from the dead...

Anyone else have experience with this STC? @adverseyaw, still happy sad indifferent about having done the mod? 

I'm interested but I'm sending my engine in for an overhaul and contemplating about doing this mod or the electronic ignition for my Dual mag engine.

-KC

If it's either/or, I'd go for the dual electronic ignition upgrade to delete the D3000 siamese mag.  I just bought the kit, but haven't installed it yet.  It should be a performance and efficiency boost, easier start, more redundancy, and better reliability.  I'm very much looking forward to it, but my installation is getting pre-empted by a paint job soon.

[adverseyaw]

On 3/15/2023 at 1:48 AM, Niko182 said:

wasn't the company also an absolute nightmare to deal with. I feel like I've heard firewall forward around here and don't remember it being great things.

The company changed hands in the 2010s and reports were that the customer service problems were resolved. I've dealt with Firewall Forward a couple of times on minor topics, things like questions on STCs and AD'd parts, and they were professional and responsive.

 

On 3/15/2023 at 6:32 AM, aviatoreb said:

Is that in knots or mph?

Denominated in knots.

On 3/14/2023 at 11:04 PM, Rotorhead said:

Bringing it back from the dead...

Anyone else have experience with this STC? @adverseyaw, still happy sad indifferent about having done the mod? 

I'm interested but I'm sending my engine in for an overhaul and contemplating about doing this mod or the electronic ignition for my Dual mag engine.

-KC

The choice is a personal one based on what you value. My aim here is to present the data as I see it so everyone can make a decision. Some additional considerations: 1) G100UL has reportedly better detonation margin than 100LL, so risk of detonation due to high compression will likely trend lower in the future. 2) Some A&Ps are not fans of stacking engine STCs on each other, so putting an upgraded prop or exhaust on this engine could be an issue depending on the mechanic. 3) The data shows that the increased power and efficiency at altitude is bona fide.

All that said, the only regret I have with this engine is the decision the prior owner made to keep the duplex magnetos. I would much rather have a single traditional magneto and a single electronic module. There are a lot of other threads on what's involved in that upgrade.

[1980Mooney]

On 3/20/2023 at 5:18 PM, adverseyaw said:

The company changed hands in the 2010s and reports were that the customer service problems were resolved. I've dealt with Firewall Forward a couple of times on minor topics, things like questions on STCs and AD'd parts, and they were professional and responsive.

 

Denominated in knots.

The choice is a personal one based on what you value. My aim here is to present the data as I see it so everyone can make a decision. Some additional considerations: 1) G100UL has reportedly better detonation margin than 100LL, so risk of detonation due to high compression will likely trend lower in the future. 2) Some A&Ps are not fans of stacking engine STCs on each other, so putting an upgraded prop or exhaust on this engine could be an issue depending on the mechanic. 3) The data shows that the increased power and efficiency at altitude is bona fide.

All that said, the only regret I have with this engine is the decision the prior owner made to keep the duplex magnetos. I would much rather have a single traditional magneto and a single electronic module. There are a lot of other threads on what's involved in that upgrade.

I assume that you read the PIREP from a 5 year owner that was in the link that @ArtVandelay attached. 
 

“No appreciable gain in performance (climb or cruise”

”Excessive vibration”

And numerous comments that it accelerates case cracking (an existing Lycoming weakness)

 

[adverseyaw]

I saw that but did not experience any of those issues