DIY_EFI Digest Monday, May 10 1999 Volume 04 : Number 273 In this issue: Re: Espen's Reed Valves Re: Espen's Reed Valves See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Mon, 10 May 1999 09:19:57 +0200 From: nhoj@xxx.se Subject: Re: Espen's Reed Valves You wrote: > 4,000 on a 175cc per cylinder engine (4 stroke). > As the air flow goes up your gonna need large reeds, inertia goes up, and > they drop in max rev effectiveness. > Or go to LOTS of little one, and then port volume goes to h---. > Again, the is just on th Yamahaha, and old info, but I haven't head of any > manufacturer going to reeds lately for auto use.... Crank case pre compression on a two stroke wouldn't work very well if the reeds stayed open. The key to performance at high RPMs is low weight, high stiffness and the proper shape. To get performance at low RPMs also, Boyesen's multi stage reeds can be used. Remember that 2000RPM is only 33Hz. Locking open at that frequency sounds improbable. 20,000RPM, sound more like it. Composite reeds, often using graphite, work well into the 9000's on outboards. The problem with composite reeds is that they don't last very long, however, the failure is not very dramatic. Metallic reeds, on the other hand, while long lasting, will tear an engine to pieces if they break at an inopportune moment. Maximizing reed cage area is important since larger reeds will give better flow. Now, anyone for a homegrown EFI system for 2-stroke outboard ? Regards, John Hornkvist ------------------------------ Date: Mon, 10 May 1999 10:10:25 +0200 From: "Espen Hilde" Subject: Re: Espen's Reed Valves The Honda vtec engine impresses me, 1,8l, 207hp at 8500rpm. Same torque as other 1.8l at lower rpm...... A poor mans Vtec for big cubes it could be something..... My consern is to have a engine that performs better i all rpms. Look at your torque curve, is it not flat does it stop to early? The arias that are low could probably be fixed with reeds or a system simular to what Alex describes.Its one thing that I think is a fault in engineering todays engines, and that is to use thiese heavy valves that can stand the combustion pressures to control a few psi......A valve that is to controll thise low pressures can be made much faster acclerating and have a bigger dynamic working aria. The reed way is a do it yourself way.If you do it this way you dont have to have a rollercam and heavy spring pressure to open and close the valves fast, and all the other items that you need to beef up your valve system, you need more timing on your camshaft but gentle movements. Offcurse you need to have the same size air path that you would use in your max hp effort. Please Fred , tell us more about your reed setup and your experiance with it. Espen - ---------- > From: FHPREMACH@xxx.com > To: diy_efi@xxx.edu > Subject: Re: Espen's Reed Valves > Date: 10. mai 1999 08:51 > > In a message dated 5/7/99 7:20:35 PM Pacific Daylight Time, > claresnyder@xxx.com writes: > > << All the idea of using reed valves would do is improve the low end torque - > exactly what we want, while staying open at high speeds to reduce > obstruction - which we also want. If they lock open at 2000 RPM on a 2 > stroke you should get some effect up to about 4000 RPM on a 4 stroker - > which sounds pretty good to me. >> > > Aren't you really just trying to compensate for having the wrong parameters > in your motor? If you are on the street, live with a low rpm torque motor and > if you race, design for that application. Stop trying to have everything, or > you will have a "cresent wrench" motor, one that fits everything on paper, > but can't fit into half the places it needs to. After you figure out how to > fit the reed blocks in, then you need to figure out how to get the fuel to > stop puddling in the way to big plenum volume. but then you will need to set > up a system to increase the octane as the RPM goes up. I applaud the > inventive nature of your work, but having gone down the road of this before, > I can say that you will find a lot of better ways to make a motor work. > Fred ------------------------------ End of DIY_EFI Digest V4 #273 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".