DIY_EFI Digest Thursday, October 14 1999 Volume 04 : Number 580 In this issue: Re: DIY_EFI Digest V4 #579 Re: marine engine FI Re: DIY_EFI Digest V4 #579 See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Thu, 14 Oct 1999 15:40:25 +0200 From: nhoj@xxx.se Subject: Re: DIY_EFI Digest V4 #579 You Espen Hilde wrote: > [About Yamaha HPDI] > To reduce the fuel to a fine mist the system uses high pressure, > 700psi , ficht uses (OMC) 300-400psi , DFI (Merc) 80 psi. Note that you cannot directly compare Mercury's 80 psi with Yamaha's 700, since Mercury uses direct air/fuel injection, and compressed gas contains much more energy than a pressurized liquid. Pressure is just a marketing figure. It atomization that is interesting. Has anyone seen atomization figures for HPDI? > The pressure is developed through a very small high speed pump. A large low pressure fuel pump pushes fuel into a liquid/gas separator to get rid of any bubbles, and then into the high pressure pump. > Yamaha uses the common sensors , crank position sensor.TPS,KNOK, > rpm sensor, water temp, air temp,MAP,O2.....o2.............?(patented 02 > sensors ) The fact that Yamaha can operate in a real closed loop mode was what struck me when I first read the specs. Yamaha already does this in the OX66 EFI system which is used on their 76 degree 3.1 litre engines, by the way. The reason for going with a 76 degree engine is that it allows them to stay within the form factor of the 90 degree engines despite the new hardware. > All manufacturers of theese dfi outboard engines has had some bugs > that develop..... To say it nicely. :) > Mercury delivers a high perf 200 dfi that took 2 place at paris ruoen 24 > hour (river) race.The ability to run lean burn conditions is great for > reliability as I see it. Do they really deliver it? Given that it has a lower unit that can't reverse, it wouldn't make much sense for anything but racing. And as a racer you get more power per cubic inch from an XR2, 2.5EFI or even a 300 ProMax. > I have 2 2.5efi high performance engines that I am reparing, line boring Are they any fun? I have very modified Yamaha 200 that will get an EFI system if it is still running when I can aford one (eg MADEFI) or find time to build something... Performance below 4000 RPM is not exactly stunning when using carbs. > new crank, one piston 70grams to heavy +++ 70 grams??? That's a lot of extra weight... > They have analog efi with old d-jetronic peek and hold injectors.(As > standard) Is this the 260hp version? > The new 2.5 efis has digital boxes ,Motorolabased. The 280hp machines? Regards, John Hornkvist ------------------------------ Date: Thu, 14 Oct 1999 15:21:46 +0200 From: nhoj@xxx.se Subject: Re: marine engine FI Stuart Hastings wrote: > > More like 200, IIRC. Also, Ficht's solenoid driven injector is not very > > precise; the pressure varies a lot. > > I suppose there is no way to really know without measuring it, and > this would be difficult. One imagines a small, closed chamber, filled > with an incompressible liquid, and a Ficht injector screwed in one > end. Perhaps you could repeatedly fire the injector until the pressure > stopped rising... That would only tell you the maximum pressure, not the sustained pressure through a burst. Pressure in itself is NOT a good thing in a gasoline DFI, though. OMC and Yamaha use the pressure to get atomization. If they could get that atomization with lower pressure, they would. The penetration rate (velocity of fuel entering the cylinder) is too high when the pressure is raised enough to provide reasonable atomisation. This is coped with by putting spray deflectors and bowls in the piston and cumbustion chamber, but these are all band-aids trying to slow the spray down and contain it near the spark plug to achieve stratified charge conditions (i.e. rich near the plug and lean elsewhere). Orbital does not have this problem, since it uses compressed air to shear the droplets. > > Note that compressed air contains far more energy than pressurized > > fuel, which means that Orbital gets by with a far lower pressure. > > Thus, they avoid a few of the drawbacks of DFI. > > Speaking as a potential customer, the extra belt and air compressor > used on the Orbital design look like additional parts to break. Of course. But a belt driven air compressor is not exactly rocket science... > The Ficht design has none of these parts. The Ficht has a whole lot of other parts to break. (And it seems to be doing so with gusto...:)) > My point was that DFI two-stroke engines are still blowing oil out the > exhaust. If the emissions have dropped by half, that's great, but it's > still disconcerting. True. They could have moved the precompression out of the crank case, using a conventional "wet" crank case, and a screw compressor instead. That would have given more efficient scavenging, and gotten rid of all oil in emissions. In addition, they would probably be able to get a fair bit more power out of the engines since the problem of piston overheating would not force them to run rich at WOT. At least one of the car manufacturers that worked on an Orbital engine did this. > More specifically, EPA is interested only in *air* pollution from > marine engines. When they mandated oxygenated fuel, they indirectly > required California fuel to incorporate MTBE, and nobody realized it > would contaminate the *water*. This may be true. I read somewhere that it is doubtful that a significant amount unburnt gasoline passes into the environment because of the high temperature of the exhaust gases. Since I'm not American, I won't claim to know how the EPA thinks or works, though. > Hello, EPA, most marine engines exhaust > *underwater*, even if most of their smog immediately bubbles to the > surface! That can easily be fixed with a holesaw, if you're worried. :) > I'll guess that EPA isn't yet concerned about oil emissions because > much of the oil stays in (or on the surface of) the *water*. That is possible. They may also be taking on one problem at a time. > OMC claims to have fixed their problems, and I haven't heard of any > Ficht owners out of warranty yet. Neither have I. Even if you are under warranty, it is quite frustrating to be left drifting on the ocean, though. That's one reason why it is a problem for OMC; they get a bad reputation out of the failures, and they have to pay for the repairs... As far as I know, its the 60 degree V6 engines that have caused almost all of the trouble, particularly the 175. The 90 degree V6 and V4 engines seem to do OK. An OMC rep told me that in order for your Ficht to survive, you should block the oil return line the first time you start it, as well any time it hasn't been running for a while. Otherwise there is a significant risk of hurting the rings and sleeves during startup due to oil starvation. Further, it is a good idea to give it some extra oil during the first few seconds it runs. The OMC rep suggested spraying fogging oil into the intake, or running a rich pre mix. Since many retailers (and hence customers) don't know about the startup procedure, many Orbital engines are severely damaged the first time they are started... The rep also claimed that OMC is having a lot of trouble getting mechanics to diagnose the (old fashioned) mechanical problems people are having with the engines. As soon as the built in diagnostic system can't tell what's wrong, mechanics tend to give up. The second generation Ficht system should take care of the problems, and OMC are upgrading the old engines, starting with the 98's, IIRC. The 97's have been less troubling, but there is or will be a kit out for them too. It seems that OMC are pushing Ficht onto new engines a lot faster than Mercury is pushing Orbital. It could be because Ficht is easier to retrofit than Orbital, but I suspect that it is because OMC are less scrupulous about testing than Mercury. > OMC has said as much on their website in the past. OK, I got the info from an Orbital engineer and an OMC rep. > They also listed a > bunch of problems they had with it, all problems that were adequately > solved by Mercury. This leads me to believe they prefer Ficht because > they were able to buy the technology outright and avoid paying > royalties. Another reason may be that they wanted a technology of their own, rather than being an "Orbital also ran"... Yet another may be that by the time OMC canceled their Orbital engine, it was clear that Orbital would not be a hit in the automotive world. Thus, economies of scale didn't look significanlty better for Orbital than for a home brewed system. Orbital is working hard on the (four stroke) automotive market these days, with the selling point that their DFI system runs unthrottled, which makes the engine more efficient at the low power levels where cars spend most of their time. Regards, John Hornkvist ------------------------------ Date: Thu, 14 Oct 1999 10:32:40 -0600 (MDT) From: Steve Ciciora Subject: Re: DIY_EFI Digest V4 #579 ------------------------------ End of DIY_EFI Digest V4 #580 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. 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