Question for Don, Redline or other tecs

[esdbass]

Hey if you look at this whole video you'll see they ran the E-Tec with out the Cowl and put the coals to it and it didn't blow

http://e.blip.tv/scripts/flash...=true

My understanding is if you tried this with an Optimax it would blow for sure. Now I have learned from another board that the ""Bomb & Yammy have typical DI, which compensates for air density & temp. The opti does not use typical DI, instead injects a pre-emulsified mixture. It's very flow sensitive. Change air flow in an opti & go kaboom."

They went on to say a "Typical DFI injection is directly into the combustion chamber (or port of 4 stroke). The Opti injects into air compressed by compressor, and this mixture is injected into the motor. Pre-emulsified mixtures are more homogenous than any direct injection. This also means more HP on less gas as the gas is more thoroughly burned, thus more HP form less gas. But you are so close to the edge, it doesn't take much modification to ruin a good motor.

Now this guy I know knows his stuff but can you guys from here help explain to me a little differently so I can better understand it?

I thought the Yamaha DFI which uses a very high pressure injection system would atomize the fuel best over the Opti's which use a lower pressure. Do the Hammer and E-Tec each also have 3 star environmental ratings and if so it would seem the Merc Optimax is yet even cleaner burning than the Bomb and Hammer? Guess that's why they run so strong but on the edge????


Modified by esdbass at 7:26 PM 12/3/2008

[EuropeanAM]

Your video link is bad... tried to access it.

In "general theory" direct injection simply means that fuel is DIRECTLY injected into the combustion chamber. That's where the Opti, HPDI and E-Tec are similar.

HOW that fuel is delivered is where they differ. The HPDI (High Pressure Direct Injection) is just what it says. The E-Tec is obviously not identical, but does use high pressure injection. The Opti, on the other hand, injects the fuel into pressurized air, to better atomize the fuel mixture as it is injected into the cyl. Hence, cleaner combustion, and MUCH lower injection pressures (other DI motors can range from 500-1100 PSI at the injectors, while the Opti's range from 90-108 psi).

I've worked on many of the HPDI's and E-Tecs, and though I'm not nearly as familiar with them, will say that they still are operating on a "Speed-Density" system. There is no sensor or means for the engine to "learn" a new airflow. That being said- any one of the three engines will run for some time with no hood- believe it or not, "No-Hood" is actually less of an airflow change than a "scoop".

Don't take me wrong here... I'm not recommending that you go out and race somebody with your hood off... with any of the brands. What I am saying is that there are several means of "altering airflow"... such as hood modifications that result in higher air pressure at high speeds (inside the cowling), larger throttle plates, reeds, bore size, cyl. head modifications, etc. etc. Any of these items CAN result in a leaner condition- on ANY CURRENT PRODUCTION direct injection engine- ANY BRAND.

I did see a video of injector comparisons between the E-Tec, HPDI, and Optimax. There is a HUGE difference in the spray pattern, and in the pressure used. All three engines are shooting for that "perfect combustion 14.7:1 air/fuel mixture"... and they're all very close to it. The primary difference is that the Opti's already "atomized" air/fuel blend can be injected at a lower pressure, in a cleaner spray pattern, and is as such, more efficient on fuel.

Hope that explanation answers your questions......

[esdbass]

Don: Try this link instead

http://e.blip.tv/scripts/flash...=true


Don't know if this changes any of your remarks but at least you'll see what I'm saying

[EuropeanAM]

Not much to change on my comments....

If you listen closely, there's a statement about that being a 2010 year engine...

We run Opti's without the hood (for diagnostic purposes, of course) on a fairly common basis... single runs and the likes. I don't recommend it as a "regular practice", of course.

The whole key to changing airflow/ compensation for changes is that the engine must be equipped with EITHER an airflow meter (or oxygen sensors), and well as PCM programming to utilize the sensor to adjust mixture accordingly. It's coming... probably by 2012 or 2013. Of course... there will be "pre-programmed (and mechanical/logistical) limits" even then.

[esdbass]

Don: Jimmy B from Merc had the following take which is different but several other guys have had mixed feelings.

Here is what Jimmy B said:

"no, the motor wont blow up... However the engines are calibrated with the cowls and intake systems in place, so all the air flow calibration is based around the cowls and intake being in place. Removing a cowl and running might gain you 5 hp on a 300 and it wont gain you anything on lower 200-225 hp because those motors are not airflow limited when making their HP"

Now I think running it on a bench dyno where it's standing still is far different than running at WOT down the lake, which is further different than the scoop effect a properly louvered cowl could bring into the equation.

This is interesting stuff to me, hopefully it is to others here

[redline]

Geez, I don't know about that Eli. I would question the extra airflow giving the Opti's more power. I agree with Don wholeheartedly. Think back to the situation where we calibrated your TPS and throttle plate. Moving the plate alone does nothing at all. As a matter of fact, you can move the plate from "idle" to "WOT" BY ITSELF, and the motor will not gain ANY rpm. What does that tell you about intake volume? Unless you are to mechanically "enrichen" the fuel in the correct stoichiometric ratio {14.7:1}, the extra airflow does zip......

[20xdBake]

I am just trying to figure out why Don is playin on BBC at 3AM? If I am on the internet at 3AM I am probably looking at something I shouldn't be and not giving a dam about boats

[esdbass]

Red: Thanks for your thoughts! However my motor was standing still when we did that, not getting air stuffed down it's throat at WOT speeds. Wouldn't that increase the intake volume?

By the way Red I'm not saying it's going to give an Opti more power but I am questioning why the heck a opti which is darn lean, seemingly even more so than a Bomb or Yamaha DFI motor due to the use of the air comprssor means of injecting a fuel air mixture to the motor, won't just lean out and blow up with the extra air if the ECU can't adjust the fuel amount up to compensate for the extra air.

I think it all boils down to at least from the Bomb and Yamaha side of things that they don't blow because their means of DFI injection is different than the use of the DFI system in the Optimax which uses the air compressor to mix both fuel and air before it is introduced into the motor?

In regards to the Opti's it's a great conversation and I hope guys like Eric Simon might chime in with their experiences as well

[EuropeanAM]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by esdbass &raquo;</TD></TR><TR><TD CLASS="quote">I think it all boils down to at least from the Bomb and Yamaha side of things that they don't blow because their means of DFI injection is different than the use of the DFI system in the Optimax which uses the air compressor to mix both fuel and air before it is introduced into the motor?</TD></TR></TABLE>

Man, Eli... you just had to go and , didn't ya?

Don't matter if it's an HPDI, E-Tec, Opti, Simon, Worthy, chainsaw, weedeater, moped, or any other two stroke. Run it lean, it's gonna start throwing pieces out of the block, eventually. It's just the way it is, and the way it's always been.

Expect that over the next 5 years this will get worse... and not better, especially as EPA regulations/requirements tighten. Yes, we'll eventually see Oxygen Sensors even on outboards... but there will be pre-programmed parameters in the PCM, and when the engine falls outside of these parameters, it will set faults and cause "Guardian". If it's like the automotive systems, they may even have the ability to detect "aftermarket" improvements, and will set a fault to indicate that this has been done.....

The solution is likely gonna be- buy a bigger motor.... or two of them!

[esdbass]

Don: Wasn't meaning to stir any Bomb, Yamaha, or Merc people, just trying understand why the E-Tec it also being a DFI motor didn't lean out and blow when it was run hard with the cowl off. What I was saying that their DFI system is different than the Opti's and that's why it didn't blow.

Now in regard to what an Opti would do if run with out the cowl that's where this thread has gone and it's an interesting discussion. Jimmy B seems to have a different conclusion than others here. I assume Eric and Wayne Worthy are most experienced in seeing what happens when you dump more air into the 3 L DFI's so was hoping to hear of their thoughts and experiences

[redline]

Well Eli....I wouldn't be surprised if the Opti's ran richer on the top end without the cowl. The intake is pointed up and back, and may actually create a vacuum at high speeds...think carb venturi and low pressure. Bottom line is that even if the air was "forced" into the plenum assy, and the motor is already on the lean side of stoichiometric, it will not make more power, but perhaps lose some. To compound the issue, when the combustion temps skyrocket due to the added air, and no way to compensate for it, we will be looking at a catastrophic failure, what I like to term as a "thermal event". These new "green" motors are calibrated to run on the edge for fuel economy and emissions, and they do so eloquently. Remember what we said about the "three stars"?, If we wanted more performance, lose the rating, fatten up the mixture, and we would perhaps be able to extract more power....but.....it comes at a price, and that is everything the new motors stand for....economy, clean, efficient. Remember the good 'ol days of the first v-6's? They were rude, obnoxious, drank fuel like it was endless, smoked up a storm, but were PERFORMANCE animals. They started out as a 2.0 litre / 122 cu in 175...and those 1976 engines actually made closer to 210 prop shaft horsepower...now.....you need 3 litres {or a supercharged 4 cylinder Verado}, to get comparable power.....{with the emission controls in place} and lest we forget, they weighed only 370lbs!!!!! You want technology, we now have it, and we get the best of both worlds....performance AND "green"...

[esdbass]

Red: Outstanding stuff there And I guess we have plenty of experience with "thermal events" in our history and that's with the stock cowl ON

Based on what you are saying though if you could increase the amount air and fuel into the motor you could generate more HP while keeping emissions the same ? or is that an over simplification ?

One other thing though is that that 2.5 L 335+ HP prop shaft motor we love so much doesn't have nearly the torque of the 3L and bigger blocks so while they weigh more and put out less HP per Liter of displacement the cubic inches of the bigger heavier engines produces a lot more torque that is so important to run a bass boat to it's potential. As you are well aware even on arelatively light very efficient hull like my Stroker we're talking about 1200 lbs of hull weight which is quite a lot more than a 750 or 500 lbs hull Ally race boat which dose fine with the lesser torque of the 2.5 but as high or higher HP. That 2.5 on a Z9 or a Ranger would be a disaster in comparison to the modern 3 L motors

[redline]

Based on what you are saying though if you could increase the amount air and fuel into the motor you could generate more HP while keeping emissions the same ? or is that an over simplification ?

That's exactly what we are saying. Your motor is nothing more than an air pump....but.....fuel AND air must be introduced at the correct ratio....as long as stoichiometric is maintained, emissions should follow closely.

[EuropeanAM]

Here's a key for you to think about, Eli.

There's essentially an air "wall" in the 3L's... and once they hit about 5900 RPM, the power band starts to fall off, no matter how much fuel (or air) you dump at it. That's why the limiters have moved up... to allow some more RPM's (don't ask... it's a touch-and-go thing, you turn more RPM's, but the "torque/horsepower curve" is falling off too).

My suspicion is that this air wall is actually the sleeve. The air runners are essentially wide open... air packs into the runners, and hits the "essentially flat" outer diameter of the sleeve. Some of the air travels through the intake ports, but only so much can make it through. Think of it this way... take a carboard box, cut a 1" x 1" hole in one end, then put a fan in the other end. Measure the air that comes through the 1" hole. Now, replace the fan with a leaf blower... and remeasure the air coming through the 1" hole. Not a whole lot of difference... certainly not as much as you'd expect!

I think you'll find this is why Merc went to a 3.2L "stroked" version for the 300. The 3.0L had "essentially" reached it's horsepower/torque "peak" (as an emmissions rated DFI) at the 250 XS/ProXS.

I passed a theory to address this issue on to Eric Simon... I just don't have the time, or equipment to get into it... but it should work... when he get's the time.
That "ball is in his court now"... to do with as he wishes.