posted 08-10-2011 01:34 PM ET (US)        

Fueling is tough to mess with, because mixture less than ideal--you can cut power by fueling over rich, but that will ruin you emissions status. 

You can mess with timing--a little--but not enough to create a 25-percent difference in power and still have it run acceptably.  

The only other thing I can think of is possibly building the motors really peaky, with a big wallop of power at the very top, and put a rev limit on the lower powered motor, denying it the big slug of power at the top. 

I suppose they could combine that tactic with the paperwork slop allowed in claiming a certain horsepower.  Maybe the (hypothetical) 115-HP is allowed to make 120-HP and the 130-HP is allowed to make as little as 125-P, then you can fudge out the remaining 5-HP with tuning.

posted 08-10-2011 04:08 PM ET (US)            

Feel free to talk specifics with me. I do my own ECM tuning on my race car motors.

Dgoodhue. A 90-HP difference on a 425-HP-class car, just by ECM tuning is on the order of 20-percent. I do not see how that is possible unless the factory calibration was way off, which it wasn't if the car was emissions compliant when it left the factory. You are talking about a 20% increase in power from a PCM calibration that cannot hold a valve open longer, or higher, and cannot make an intake or exhaust port larger. If the motor was totally, 100% stock when your people changed the ECM tune and it picked up 20% more power than an emissions-compliant, professional tune, I'm just gonna have to remain skeptical. Do you have dyno sheets you can scan and show me? Tuning notes from tuner? Who was the tuner? It also seems a little unusual that someone would pay for a custom tune on a bone stock motor, when there are already many off the shelf aftermarket tunes for that same, bone stock motor. Usually people who rent dyno time for custom tunes are trying to optimize mods they have performed, (meaning the motor is no longer stone-stock).

posted 08-10-2011 08:13 PM ET (US)            

I believe the supercharger and its boost setting is the primary factor.

posted 08-10-2011 09:21 PM ET (US)            

The Mercury VERADO L6 is sold from 200-HP to 275-HP with what I believe is the same mechanical configuration. The power output is likely influenced by supercharger boost pressure. (And the more power the shorter engine life, as far as I can see.)

posted 08-10-2011 10:29 PM ET (US)            

And Butch, if you wanted your 135hp Verado to become a 200hp Verado, you could not get there on an ECM change alone... unless the blower had a magnetically variable drive that the ECM could control the boost output with.  Otherwise, you are looking at changing the pulley, belt, and (probably) injectors.

Unless Jim is somehow right and you can simply vary the fuel tables to your hearts content, and the correspondingly appropriate airflow somehow be there.

Somebody's got to bring more meat to this table. Jharrell? You've got to know this stuff. Nick? You too, mate.

posted 08-11-2011 09:21 AM ET (US)            

I believe the Verado has a boost controller to bleed off boost. So those would be easy to control.

As I mention above timing can control the hp.

I don't know if any outboard motor has a variable intake. Which basically is plate that opens up at higher for high end hp. The lower rpm has smaller passages that promote low end torque. My daily driver has it. The switch normally open up at 4800 rpm. If I disable it my engine is winded by 5500rpm (instead of going strong to 7000rpm) and is down a good 30-40hp.

Obviously any motor is cam timing control by a computer could easily affect the hp.

posted 08-11-2011 10:06 AM ET (US)            

Skip 10% of the bangs and you'd drop 10% in power, right? Actually you'd maybe drop more than 10%, because you'd have to be compressing the air, but getting nothing for it.

posted 08-11-2011 10:35 AM ET (US)            

For more information on the HP increases available on the Gen 2 Verados by simply changing the ECM search veradoclub.com. As stated, I believe boost control is the key.

If anyone has a Gen 2 Verado L4 200 HP ECM they'd like to get rid of let me know. Please.

posted 08-11-2011 11:39 AM ET (US)         

Superchargers can have variable waste-gate like valves to control boost. I believe the Verado has an electronic boost controller based on this.

With a boost controller you can pulley the supercharger for higher boost at lower RPM's and have the boost controller bleed off boost based on conditions. This almost gives you the equivalent of a variable displacement engine.

So boost control along with EFI or DFI and some VVT can give you quite a lot of computer control over the engine parameters.

Whether a stock Verado 135 can become a 200 with just different software I don't know. Usually a engine manufacturer will take advantage of the lower horsepower using less expensive, and lighter weight components. So even if the 135 and 200 have the same specs, if you ran the 200 programming on the 135 it might be more likely to blow, maybe the crank is cheaper or whatever.

If they truly are the same then the 135 is a very overbuilt engine for it's horsepower, which can be a good thing, usually companies avoid overbuilding though as it cost them money.

The trend is definitely more electric control over all aspects of the engine, there is already work being done on electric valves which would provide infinite valve timing per cylinder.

posted 08-11-2011 12:53 PM ET (US)            

It's technically feasible, by placing the air meter after the BOV, but so complex and inelegant that I'm not sure any OEMs actually use it.

The first issue with that approach that comes to mind is that with a positive displacement, (PD) supercharger, you will be heating the daylights out the intake charge air, to levels you would get with high boost, and only using a little bit of it. It's so inelegant, factory auto engineers basically don't do it, (unless something like it is being done VERY recently with some kind of modern technology DFI system. If so, I haven't heard of it. The Caddy CTSV has a PD supercharged powerplant. Somebody can correct me if I'm wrong, but I'm pretty sure it does not employ this tactic. The wildcard with the Verado is, it's cooling system. With virutally unlimited access to cool water, I suppose its feasible to cool the superheated intake charge air with sea water. But how much space is available after the BOV and before the air meter to put in a water-to-air, charger-air cooler? Sounds HUGELY complex, if that is what they do.

Anywhow, the Verado is unique in this class and should not be the focus of our discussion.

Dgoodhue is on boarD here now:

quote:

---

pcrussell is correct that you just can't change the fueling without doing other change. Just taking away fuel will create a Lean condition.

---

I'm interested in how you make a 75hp and a 90hp E-TEC, (say) out of two mechanically identical motors, with only a change in ECM calibration. Specifics please. We've heard of simply injecting less fuel, but that doesn't account for or reduce the amount of air the motor is ingesting.

-Peter

The only thing I can think of is if there is something about the nature of DFI where you can stratify or packetize a large wad of air, and have only part of it get mixed and burned, (at the correct air fuel ratio). Could this be done? Is stratified charge technology far enough along that this is feasible to create 20% differences in power using this technique alone? Skeptical.

posted 08-11-2011 02:41 PM ET (US)         

These are typically bypass valves in the case of a roots, and if fully open will simply "freewheel" the supercharger not heating up anything dropping parasitic loss off. With centrifugal superchargers it's basically the same as a turbo BOV, still taking power off the engine. Some are simple on off, but they are doing modulated variable boost regulation as well

Mercury mentions their system all over the place but I can't find much detail:

http://www.mercurygovsales.com/technology/verado.php

quote:

---

Unequalled Torque and Acceleration
Verado is equipped with a patented supercharger, charge air cooler, and electronic boost control system that delivers better low end torque and acceleration than not only other four strokes, but most two strokes as well. Its mid-range acceleration exceeds any other outboard in the world.

---

posted 08-11-2011 03:38 PM ET (US)            

http://en.wikipedia.org/wiki/Blowoff_valve

As for the Verado, maybe. They must have some kind of magnetic decoupling of the supercharger drive system that the ECM is in control of. But DAMN! What extraordinary, eye-watering complexity for an outboard motor. This cursory description of the Verado's variably boosted PD supercharging makes it look considerably more sophisticated than say, that for the Corvette ZR1, whose PD blower's BOV system is pretty much on or off. Makes you wonder if there will be ANY 2011 Verados still running in 35 years, like there are old Evinrude v4's still running today.

My amazement at the apparent complexity of the Verado's supercharging system aside, I still don't know how (say) Evinrude does it between the (supposedly) mechanically identical 75 and 90 E-TEC.

posted 08-11-2011 03:58 PM ET (US)            

Perhaps the exhaust system on the etec 75hp and 90 hp are tuned differently. Back when the etec first came out I remember reading about some type of exhaust valve that Bombardier had patiented for some of their other 2 cycle engines.

Ahhh, my memory is old, I'm old, the information is old.

posted 08-11-2011 04:15 PM ET (US)            

With ordinary EFI, skipping firing would be a recipe for all kinds of trouble, from HUGE cylinder wear, to HUGE increase in emissions (if done through timing). But with DFI, you can avoid the dangerous cylinder washing that occurs when you have fuel not ignited, washing the lubricating oil off the cylinder walls... IF the E-TEC can selectively not fuel a cylinder, but still spray a jet of lubricant into it, this trouble would be avoided. Otherwise, each non-fire cycle will have the rings sliding up and down a dry cylinder wall. Sooo, if they can do this, the only thing left to worry about is the rough running you would get from each intentional misfire. In my 3 years as a boater, I have noticed that outboards tend to have very soft rubbery motor mounts that do an amazingly good job of smoothing out misfires from the perception of the people in the vessel. It seems extraordinarily inelegant, but certainly possible.

Knot, you are suggesting small mechanical differences that add up to relatively large changes in performance. That is how they made the difference between the old Evinrude 9.9 and 15. The 15 had different carbs, a different exhaust manifold and tuning pipe, and made the rest of it's power difference at higher rpm. There were some other small mechanical differences, too. These of course means that the 9.9 and the 15 are NOT mechanically identical, even if the basic naked powerheads are identical.

posted 08-11-2011 05:53 PM ET (US)            

The different motors have to be flowing the same amount of air, as they have the same displacement, the same RPM, and the same induction system.

They can't be monkeying with the throttle butterfly opening; that would make the throttle control feel different, as most of these motors are still directly cable-controlled.

The fuel / air mixture can't vary much without causing other problems, such as pre-ignition or smoke, which neither the 2 or 4-stroke variants of this technology exhibit.

The rev-limiters already have the means to chop off injection / ingition cycles, so it's cheaper to use that and to reprogram it rather than adding something else.

They can't just be cutting out the ignition cycles and flowing the fuel - even though it wouldn't cause fuel washing problems due to the separate DFI oiling, that would result in motors of different power using the same amount of fuel, and blowing unburned fuel out the exhaust. Neither of those things happen.

So I am betting on skipping fuel injection cycles, on a rotating basis across cylinders. It probably does not matter whether they are skipping ignition cycles too, as it's not going explode clean air.

posted 08-11-2011 06:11 PM ET (US)            

from the wikipedia article on wastegates:

quote:

---

A wastegate is a valve that diverts exhaust gases away from the turbine wheel in a turbocharged engine system. Diversion of exhaust gases regulates the turbine speed, which in turn regulates the rotating speed of the compressor.

---

They are a fabulous way to control boost in turbo systems, which is why PCM calibration changes, (chips, if you will), are so very effective in turbo cars/trucks.

I'm pretty sure J was talking about Mercury's (apparently little understood, and neccessarily hugely complex), variable boost system they use in their Verado.

Tim, I'm totally following you. You make a convincing argument. I think a system like that is ugly, (personal opinion), and would think that other engineers would too, but I won't swear you wrong.

Over on the fast outboarders forums a discussion got going on the difference between the E-TEC 130 and the E-TEC 115HO. They appear to be identical, same weight, same external parts, same dual-path exhaust bypass. Some over there are claiming that the 130 produces a nominal 130hp, and that the 115HO produces a nominal 127'ish. Now this IS believeable from two different ECM calibrations, and is the going theory over there. They say the two different calibrations produce a different ramp or shape of the power delivery curve from each other. One even said that the 115HO felt quicker than the 130, even though he admitted it was more a seat of the pants sensation rather than verified by instrumentation. Note the 115HO (high output) is NOT the regular 115. It looks different and weighs more.

-Peter

posted 08-12-2011 12:06 AM ET (US)            

quote:

---

Fueling is tough to mess with, because mixture less than ideal--you can cut power by fueling over rich, but that will ruin you emissions status.

---

posted 08-12-2011 12:07 AM ET (US)            

quote:

---

Fueling is tough to mess with, because mixture less than ideal--you can cut power by fueling over rich, but that will ruin you emissions status.

---

posted 08-12-2011 04:34 AM ET (US)            

BUT throttling is very bad for economy, because a throttled motor suffers from large "pumping" losses. IOW, it's harder to turn a motor that is throttled than one that is not, because of the restriction. That is in fact a secondary benefit of EGR systems in street cars. By introducing spent exahust gas back into the induction side, you not only cool the combustion, (producing less NOx), but you also displace some air/fuel mixture, so that the driver has to open the throttle more, to get the same amount of power he would have gotten had there been no EGR. This has the effect of actually improving fuel economy, because for any given speed, the throttle opening is greater, when EGR is flowing, and thus, the pumping losses are less.

Not saying it isn't done the way you describe, because it certainly can be done that way, but having the lower powered motor of the two, running around at "full power", with a partially closed throttle is ugly and inelegant, (right, Jharrell :)

posted 08-12-2011 04:59 AM ET (US)            

Whats still a mystery to me is, how is it done by ECM alone in the 75/90jp E-TECs? IF indeed it IS done strictly by ECM.

What do you think of 'niner's theory, that the lower powered motors run around partly throttled, at "full power"?

posted 08-12-2011 08:02 AM ET (US)            

With respect to the dropping injection / ignition cycles, it actually seems like an elegant solution to me. Consider the eTec 75 / 90 triples. To go from nominal 90 to nominal 75, you might want to drop 1 in 8 cycles (12.5%). The cylinder firing map would look like:

123123123123123123123123
1234567X1234567X1234567X

which neatly rotates across the cylinders for even wear; since it's a very regular pattern, you wouldn't even notice the skipped cycle.

I did check my F70 manual, and it does cut out both ignition and fuel injection to do the rev limiting - so the technology is there, they just have to change the software.

posted 08-12-2011 01:35 PM ET (US)            

But if it's a true "drive by wire" setup and the throttle butterfly is controlled by an actuator, then the easiest way to achieve the reduction would be to just back off the gain on the actuator. It would also suggest that a mechanical or electrical amplifier on the actuator would gain back the "lost" power - I have a hard time believing they'd make it that easy.

posted 08-12-2011 02:48 PM ET (US)            

How do two mechanically identical outboards make 20% difference in horsepower to each other, just from different ECM calibrations?

posted 08-12-2011 05:11 PM ET (US)            

I think most agree to substantially increase power output to an engine's maximum potential at a given rpm requires more fuel and air. That's how it's always been done and electronic/computer controls don't change physics.

Easiest example to help explain would be motors with electronic throttle control like Verados. Same motors with different control units and produce different hp at the same rpm. The Verados are also motors that have supposed been confirmed to only require the ECU/ECM to upgrade power. Verado L6 & L4 + 33%. L4 75-90 + 20% same rpm and 75-115 + 53% max rpm + 400.

On the lower hp models the ECU/ECM will under some power demand situations limit the amount of throttle valve travel to limit the amount of air entering the engine. Primarily this keeps the mixture correct but also is one part of the system that prevents reaching it's potential higher hp rating. Programming will keep the mixture correct up to a predetermined position. To prevent tampering with the throttle to get more air in an attempt to trick more power output the programming will prevent more fuel from being added even if it senses further opening and more air. It would eventually go into a safe mode or shut down. Obviously MAP, OAT and several other sensors are also sending info to the ECU/ECM and affect fuel flow and mixture.

On the highest hp models the programming will allow further opening of the throttle which allows the additional air needed to increase power. The higher hp controller will increase the fuel flow and maintain mixture up to it's higher max power rating at the same rpm.

Peter's original topic/inquiry was how can a simple box change and it's programming vary the hp output of two base motors by 25%. I don't profess to have all the answers or detailed knowledge of all these engine's controls, sensors and programming. Attempt to put into terms we understand of how a relatively simple engine is controlled by complex electrical/electronic components and a computer controlled processor.

posted 08-12-2011 08:21 PM ET (US)            

I understood you the first time. There is a rather significant efficiency issue when a power valve is only open part way. Take any yard tool you have, and pull the rope start with the throttle fully closed. Then do the same with the throttle fully open. It is much easier when the throttle is fully open. Now imagine how much harder it would be a 5000 rpm, with a rapidly moving column of air. The rampup in pumping loss is non-linear with rpm. Thus, while you could very easily keep power down by having only a partial throttle opening, and have the ECM fuel appropriately, you would be incurring significant pumping losses, and hurt fuel economy significantly. A quick google search on "pumping losses" would be a good read for most here.

Again, not saying they don't do it the way you describe, but it's a pretty sucky way to do it, from an efficiency standpoint.