Mercury 90 Fourstroke: Increasing Power

[timf]

Any experience or suggestions out there for increasing power output of a Mercury 90 FOURSTROKE made in 2015? It is the 2.1 liter version of the motor.

https://www.mercurymarine.com/en/us/eng ... 75-115-hp/

From what I can find, the control module is the only difference between the 90-HP and 11-5HP engines.

ECM (115HP) 8M0088063
ECM (90HP) 8M0088062

Could the ECM just be swapped out?

[timf]

Looking closely at the parts diagrams, it appears more than the ECM would be needed to convert a 90 into a 115. There are different air restrictor and camshaft part numbers. I'm guessing the cam is actually different having unique part numbers.

[Dutchman]

If it were as easy as an ECM, then everybody would buy the lower power model and change out the ECM No way Mercury or any other manufacturer will allow that to happen. You second post is probably more right with different cam.

[timf]

I agree, that would be too easy.

It looks like the parts would be ~$600 to buy the 115 HP version of the ECM and cam.

I'd be tempted to do it if the engine were older, but not sure about opening up a perfectly working engine less than a year old. The timing chain is on the bottom of the head, which might make it more difficult to unbolt the cam gear...

Head and Camshaft Diagram

https://xfer.mercmarine.com/pximages/partscatalog/COMMON/55131_x2.gif

Cam Shaft part numbers

18 8M0094684 1 CAMSHAFT ASSEMBLY 65 Jet, 75, 80, 90, 100 Hp
18 8M0098630 1 CAMSHAFT ASSEMBLY, 75,90 SeaPro -
18 8M0090775 1 CAMSHAFT ASSEMBLY 115 and 80 Jet
18 8M0098631 1 CAMSHAFT ASSEMBLY, 115 SeaPro -

[jimh]

Considering the EPA regulations that prohibit the tampering with any part of a regulated engine that can affect exhaust gas emission, it seems possible that you might not even be able to buy an ECM without demonstrating that you had the appropriate model engine for its use.

The easiest way to increase the power of an outboard engine of a particular rating to a different model with more power based on the same block is just to sell the lower power engine and buy the higher power engine.

Modifications like this might have been possible in the days of unregulated outboard engine emissions and simple carburetor engines with air flow restriction plates as the power limiting mechanism, but today I doubt there is any easy, simple, legal path to getting more power from an engine.

The only place I know this happens is at VERADO CLUB rendezvous held in foreign countries where the Mercury factory engineers pass out free horsepower upgrades to attendees by installing new firmware in their engine controller--well, at least, that is the legend that is told.

[JRP]

...
The easiest way to increase the power of an outboard engine of a particular rating to a different model with more power based on the same block is just to sell the lower power engine and buy the higher power engine. ....

This would be my advice as well. Even trading in with a dealership, you should be able to get very decent money for such a new and well-regarded engine.

And consider that down the road if you ever sell your boat, having an OEM 115 HP engine should yield higher re-sale value than a 90 HP outboard engine that has been retro-fitted and modifed to reach 115 HP. That extra re-sale value might make up for some of the up-front cost of upgrading to a 115 HP engine today.

[timf]

I agree and like that option of swapping the motor as well.

I'm guessing that might cost quite a bit, but maybe reasonable compared to the cost and added risk of modifying.

I'm not planning to sell for a long time, but would the larger motor likely be seen as added value to some buyers and not others.

Thanks for all the great responses!

[flymo]

Assuming this is on your Montauk 170, the more powerful motor would appeal to the very small subset of buyers who are willing to take the risk of operating a boat with a motor that is above the rated horsepower of the hull. All others will run away fast.

Having driven a Montauk 170 with the 90, it sure feels like it will handle the additional horsepower fine. However, it seems to me you are leaving yourself open to legal action in the event of any accident - if someone gets hurt, they go after after anyone and everyone they think they can squeeze money out of. The old forum has many discussions on this subject - try the search function.

F

[timf]

Good points!

I did read on the old forum a while back and lots of great information there. I agree I think [a Boston Whaler 170 MONTAUK boat] would handle [a Mercury 115-HP FOURSTROKE engine] fine, but the legal part seems pretty undefined from what I could find.

Thanks

[andystephcami]

The maximum horsepower rating--whatever the hull states--is really doing nothing more than stopping someone from putting a too heavy engine on the boat. I have a Mercury 75-HP FOURSTROKE made in 2015. [That engine is the] same as the 90 and 115. My boat hull says 90-HP maximum. Why not 115? They all weigh the same, right? And if you buy the same exact boat as mine that is three-inches longer you can run the 115? Makes no [sense]. There is an air restrictor ring in the intake, very easy to get to. Take that out and you will be getting too much air and not enough fuel. Check out simonmotorsports.com. They now, as of a few months ago, have the software to program a new Mercury engine ECM to deliver more fuel. All you have to do is send them your ECM, they program it, you plug it back-in, and you remove the intake restrictor. I spoke with them and by simply doing this they can make my 75 [into an engine that produces] around 124-HP. I would have [chosen] this right away if I hadn't already needed warranty work done--a $700 fuel pump replaced. Of course, there is the added cost of [changing to a different propeller]. I can promise you, in two more years I will be sending them my ECM.

[jimh]

The maximum horsepower rating is a required rating for the boat manufacturer as specified in federal legislation (the 1971 Federal Boating Safety Act). The maximum transom weight is a separate rating. It is not a required rating in any federal regulation that I am aware of. In the case of Boston Whaler boats, some models in some years have been given a maximum engine weight rating.

None of these ratings prevent a boat owner from exceeding them, unless some state or local regulations require they be adhered to. Please see the FAQ for more on this topic.

http://continuouswave.com/whaler/reference/FAQ/#Q6

[jimh]

EPA regulations apply, not only to manufacturers of engines, but to owners of engines. They prohibit tampering or modification that affects the regulated exhaust emissions. Refer to

https://www3.epa.gov/otaq/marinesi.htm

The EPA has prepared an FAQ, titled "Frequently Asked Questions from Owners and Operators of Nonroad Engines, Vehicles, and Equipment Certified to EPA Standards." This excerpt is applicable to the discussion at hand:

What requirements apply to owners and operators of certified products?

One of the most important part of the regulations that applies to you is the tampering prohibition—you
may not disable any emission controls installed on certified engines, vehicles, or
equipment. This would apply for removing emission control devices, adding or modifying hardware
or software that increases emissions (of any pollutant), reprogramming onboard computers,
or operating engines without any needed supplies such as Diesel Exhaust Fluid. Manufacturers
explain in their owner’s manual what type of emission controls exist for each model; they may
also specify some minor maintenance that must be done to keep emission controls working
properly. For restrictions and recordkeeping requirements that apply for rebuilding engines and
performing maintenance on certified products, see “How to Maintain or Rebuild Engines Certified
to EPA Standards,” EPA-420-F-12-052 (available at http://www.epa.gov/nonroad/).

Similarly, EPA regulations prohibit defeat devices—you may not make, sell, or install any part
that bypasses, impairs, defeats, or disables the control of emissions of any regulated pollutant.
Since manufacturers have the primary responsibility to meet emission standards for their products,
you generally have no requirements to achieve a certain level of emission control or to re-certify.

[Jefecinco]

A very long time ago a man for whom I had enormous respect told me it is never smart to make rules that you cannot enforce.

I believe it would be very difficult or virtually impossible to enforce the quoted rules pertaining to modifying a marine engine.

[pcrussell50]

Considering the EPA regulations that prohibit the tampering with any part of a regulated engine that can affect exhaust gas emission, it seems possible that you might not even be able to buy an ECM without demonstrating that you had the appropriate model engine for its use.

Never tried such a thing in the marine hobby, but in the automotive hobbies, you can buy all the ECM's you want at places like Rock Auto, including exactly what is talked about here... ECM's from the same family of motor but different horsepower, without having to present any "proof" of the exact model you have. Further, with modern, EEPROM-based, "flashable" ECM's, the equipment exists to flash any calibration you like to a particular ECM, including the calibration for the more powerful motor. This is obviously illegal for street driven cars from the perspective of the EPA, but nearly impossible to enforce, and quite common.

Modifications like this might have been possible in the days of unregulated outboard engine emissions and simple carburetor engines with air flow restriction plates as the power limiting mechanism, but today I doubt there is any easy, simple, legal path to getting more power from an engine.

Yes, you would have to change hard parts like heads, cams, intake paths, that will allow the motor to process more air in order to make more power, and the ECM would need to be recalibrated (or buy the one with the more powerful calibration), to give the proper fuel, and timing for the new airflow capability. It would probably be SUPER easy to not get caught by the EPA if you did this. But...

I agree with Jim, the amount of time, effort and warranty voiding would not be worth it to me. Just belly up and buy the power you want the first time.

-Peter

[jimh]

A very long time ago a man for whom I had enormous respect told me it is never smart to make rules that you cannot enforce.

In today's government frame of mind, the bureaucrat that regulates the most is the bureaucrat that is serving the nation the best.

[pcrussell50]

In today's government frame of mind, the bureaucrat that regulates the most is the bureaucrat that is serving the nation the best.

Yep. The more rules your bureaucracy oversees, unenforceable or not, the bigger your staff, your budget, your status, you power your prestige, the more prominent your seating location at official galas, the pick of prettier mistresses, etc.... Laugh if you want but these are the trappings of political power and they are not given up easily. Look at how those who seek to reduce such excesses are labelled as extremists?

-Peter

[timf]

Considering the EPA regulations that prohibit the tampering with any part of a regulated engine that can affect exhaust gas emission, it seems possible that you might not even be able to buy an ECM without demonstrating that you had the appropriate model engine for its use.

Never tried such a thing in the marine hobby, but in the automotive hobbies, you can buy all the ECM's you want at places like Rock Auto, including exactly what is talked about here... ECM's from the same family of motor but different horsepower, without having to present any "proof" of the exact model you have. Further, with modern, EEPROM-based, "flashable" ECM's, the equipment exists to flash any calibration you like to a particular ECM, including the calibration for the more powerful motor. This is obviously illegal for street driven cars from the perspective of the EPA, but nearly impossible to enforce, and quite common.

Modifications like this might have been possible in the days of unregulated outboard engine emissions and simple carburetor engines with air flow restriction plates as the power limiting mechanism, but today I doubt there is any easy, simple, legal path to getting more power from an engine.

Yes, you would have to change hard parts like heads, cams, intake paths, that will allow the motor to process more air in order to make more power, and the ECM would need to be recalibrated (or buy the one with the more powerful calibration), to give the proper fuel, and timing for the new airflow capability. It would probably be SUPER easy to not get caught by the EPA if you did this. But...

I agree with Jim, the amount of time, effort and warranty voiding would not be worth it to me. Just belly up and buy the power you want the first time.

-Peter

Peter--I agree with your comments. I would have been happy to pay a little more for the 115-HP rather than 90-HP version of this engine for the boat. Being the same weight, I don't think the few MPH maximum difference between the two engines would create a safety concern that didn't exist before.

I assume [assigning a maximum horsepower rating] is most all marketing in this case. And for example, if Mercury dropped the current motor line and replaced with a new 115-HP model, the boat maximum horsepower rating would rise accordingly :)

[pcrussell50]

Someone correct me if I'm wrong here, but I don't think BW has ever rerated it's hulls of a given size for more horsepower, even after doubling the weight for a given length, as with the classic 13 versus the current 13. Both rated for 40hp max. These pages are full of reports from owners of current 13's with brand new 40hp Mercury four-stroke-cycle motors, complaining of difficulty getting on plane with heavier but legal, loads.

So if you were hoping BW might one day rerate the modern Montauk 17 from 90hp to say, 115hp I wouldn't hold my breath. Obviously it's perfectly safe to do it, but check with your insurer if you do... Not for hull loss, but for liability. If you hurt someone with an overpowered boat, you might not have coverage for what is sure to be a million dollar claim against you. And maybe find a forum where they discuss such problems. In the car world, it is not unheard of for people to be dropped from coverage, just for asking if they could pay extra for supplemental coverage for risky things, like more power or track days.

-Peter

[dswatloski]

I talked to Mercury Support today March 29, 2016 and while the tech said they could not consult on modifications to engines, there was more involved than just the ECM in the differences between the engines. I said CAM shaft differences not just part number differences. I got an uhuh, (YES) response.

This could have been an intentional on the tech's part to not let the word out, but I didn't get that from the tone of the conversation.

To be clear, the cam shaft, 99% probability, has to be swapped along with the ECM. So $325 for the ECM and another $300 for the cam shaft plus your time or another $300 or so in labor. So $625 to $925 for the upgrade. Think Simon's Motor Sports for around $600 plus shipping.

I have this same post on the Hull Truth, where I was trying to get to ground truth on this in another forum.

[pcrussell50]

More thoughts:

The jump to 115-HP from 90-HP is more than a 25-percent increase. It is unusual that this can be accomplished with a cam and an ECM calibration alone, unless the 90-HP motor is rated at a low RPM, and the 115 is rated much higher, in which case it would be possible. If both the 90-HP and 115-HP are rated at say, 5,500-RPM, then there has to be something more in play than higher lift and longer duration camshafts. Something along the lines of better flowing heads or intake manifold, or both. Unless the 90-HP engine has intake manifold runner control that artificially stunts it down. It would pay you to take an exhaustive look at the parts diagrams at every part between the 90 and 115 models where air or exhaust flows, and make SURE that that the cam and ECM are the only differences. Because it sounds unlikely, unless again, there is an ECM controlled, variable restriction in the intake manifold that is artificially keeping a choke on the intake of the 90-HP version.

You should not have to buy an new physical ECM itself. I'll bet my dollar against your dime, that it's the same physical module, just that one is flashed with the calibration for the 90-HP and one is flashed with the calibration for the 115-HP. I'd bet that any certified Mercury repair facility could re-flash your 90-HP ECM module with the 115-HP calibration. The question is, would they? I bet some of the businesses that work in Mercury high performance and racing would have the equipment, the willingness, and most importantly, the know-how to do it and not steer you wrong.

--Peter

[timf]

I talked to Mercury Support today March 29, 2016 and while the tech said they could not consult on modifications to engines, there was more involved than just the ECM in the differences between the engines. I said CAM shaft differences not just part number differences. I got an uhuh, (YES) response.

This could have been an intentional on the tech's part to not let the word out, but I didn't get that from the tone of the conversation.

To be clear, the cam shaft, 99% probability, has to be swapped along with the ECM. So $325 for the ECM and another $300 for the cam shaft plus your time or another $300 or so in labor. So $625 to $925 for the upgrade. Think Simon's Motor Sports for around $600 plus shipping.

I have this same post on the Hull Truth, where I was trying to get to ground truth on this in another forum.

The differences are the ECU, cam, and an air restrictor per the Mercury parts listing for the motor.