[Half-Inch Stud]

So, WHAT-IF carbon-fiber Vee Reed Valves were set in the Manifold Runner, or stranger yet; within the Head (Divider chomped away like a 301 head). Individual Reed Cage per runner probably most effective.

Would CYL filling, or overall broad RPM power be increased? Greatly increased? HIS

[BruceWilkie]

I think your better off with proper runner length/csa and plenum sized for the application.

Space might be the first issue... a typical reed cage between a 38mm(1.496" throttle bore) mikuni and port is probably at least 3+ sq in. and maybe 1.5" deep. (havent seen or had my hands on any in ten years).

FWIW a 38 Mikuni flows somewhere around 98 cfm @1.5". Typically on modern two stroke(1 per cylinder) it can support 50-60 hp (per cylinder). Depending on engine size 7500-9000+ rpm to make that power. Keep in mind a 4 stroke would have to double that rpm to have as many intake strokes.

IMO if you want to run reed valves find a way to make your Pontiac motor into a 2 stroke.

[gtofreek]

We[Jeff and I] actually thought about this years ago, and tried flowing different reed valve assemblies to see what they would flow. The best one we tested only flowed around 200 CFM, and it was pretty big[bigger than a rec port BBC port], so we gave up on the idea. If you could get a reed assembly to flow good air, then I think it would work great. Just think, you could run a much bigger cam, without it affecting the signal to the carb, from the reversion pulses.

[Jack Gifford]

You might look into the few 4-stroke bikes that have had reeds. There were only a few examples, and I didn't pay much attention to the details. (Honda XR250 back around 1980?)

[Craig Hendrickson]

Mark (HIS): I have to give you credit, you think outside the box as much as anyone on this forum. But reed valves? That's way outside.

However, keep it up, as I enjoy your posts.

[tpssonic]

V-Force reeds- they've been around for many years. Using 38mm Mikunis slide-valve carbs and the V-force-style reeds (4-reeds per cage,w-shaped and double the surface area) my mild 3-cylinder Polaris 1000cc engine makes 220hp on the dyno (73+ hp/cylinder) at 8600 rpm and engages ("stalls") at 3500 rpm. It is a pump gas trail sled ("street-style") that you could putt around at 10 mph all day long without loading up, overheating, etc. Although the reeds would open/shut at less than half the speed (4-stroke as compared to 2-stroke), my concerns (as well as possibly-messy packaging issues) would be reed longevity and the ability for the 4-stroke to ingest reed particles in the event of reed failure. A 2-stroke can do this; I don't have any experience with a 4-stroke. We might need to get a bigger box...

[steve25]

So in a 4 cycle motor what happens to refective pulses of the 3 orders of magnitude that can be used to tune the motors peak power rpm?

[Half-Inch Stud]

Originally Posted by gtofreek

We[Jeff and I] actually thought about this years ago, and tried flowing different reed valve assemblies to see what they would flow. The best one we tested only flowed around 200 CFM, and it was pretty big[bigger than a rec port BBC port], so we gave up on the idea. If you could get a reed assembly to flow good air, then I think it would work great. Just think, you could run a much bigger cam, without it affecting the signal to the carb, from the reversion pulses.

The reed cages I've seen are probably the V-Force units: 4 CF reeds. as- tall, and 2X wider than an individual PMD runner.

[tpssonic]

In modern two-cycle sled applications (as well as 4-stroke motorcycles, automobiles -think Viper), the airbox operates as a Helmholtz resonance chamber, already encompassing resonance to enhance performance, sometimes negating altogether the need for a reed valve. With regard to reflective properties, this is usually seen on the exhaust-side end of the IC cycle (in a 2-stroke application) whereas a reflected pressure pulse in a properly designed header/divergent cone/center section/divergent cone/stinger exhaust pipe is used allow to "supercharging" of the cylinder. I think there is a couple of psi free "boost" in these systems.

[BruceWilkie]

Originally Posted by tpssonic

V-Force reeds- they've been around for many years. Using 38mm Mikunis slide-valve carbs and the V-force-style reeds (4-reeds per cage,w-shaped and double the surface area) my mild 3-cylinder Polaris 1000cc engine makes 220hp on the dyno (73+ hp/cylinder) at 8600 rpm and engages ("stalls") at 3500 rpm. It is a pump gas trail sled ("street-style") that you could putt around at 10 mph all day long without loading up, overheating, etc. Although the reeds would open/shut at less than half the speed (4-stroke as compared to 2-stroke), my concerns (as well as possibly-messy packaging issues) would be reed longevity and the ability for the 4-stroke to ingest reed particles in the event of reed failure. A 2-stroke can do this; I don't have any experience with a 4-stroke. We might need to get a bigger box...

Maybe of interest to the topic... Liquid cooled 1980 Kawasaki 340cc 2 stroke stock made 65 hp around 7400 rpm(3.13 hp per cu in)... Piston port motor with NO reeds(32 round slides).(340 fan was about half the power) The bigger bore 440 made 72-75(slightly larger mikunis) and the LTD 440("442" 4 plugs, 4 transfers per cyl, twin pipes) was around 85 (Keighin(sp?) carbs) None of them liked to idle below 3000 rpm. You could set them to idle low(1000 ish) but throttle response was horrible. Cold starts required both primer and choke to start with idle that high. (choke only would work with low idle).
No question reeds would have helped low speed operation.
IMO reeds might have hurt top end power if they were used on those motors.

I could see possible benefit on a 4 stroke with individual isolated throttle per cylinder. Typical 48 Webers on a 350 SBC are big carbs for stock ports/displacement under 7000 rpm(over 2000 cfm total) . They need to be that big or larger to deal with reversion at upper engine speeds in that range.


I was going to mention my old 680 triple(97 Polaris Ultra SP)... similar mods(SLP triple pipes V-Force reeds) as yours was making 155(about same rpm as yours). A tid weak with engagement under 4000 but 1000 plus trail miles every year. With 4800 engagement long trail riding was still very tolerable.(5400 engagement was my drag setup...I couldnt hook with higher and slow trail riding sucked). The V force reeds were a nice overall improvement over the CarbonFiber reeds both mid and top end.(The CarbonFiber reeds were a good gain over stock but when the V-force reeds came out they made a big difference). Too bad the sled was so heavy.

I still have my 340 Invader(stashed in NY still). I had an LTD 440 in it with the LTD twin pipes(put 38 round slide Mikunis on it) but the center seal went bad. I still have motor just never got around to rebuilding it.(Shocked a few modern 5-600cc sleds with it beforehand.) I put the 340 back in, added a pair of Mikuni 34 mm flats from a Yamaha, and had the pipes from the LTD reworked... made 72 hp at 7800 on his dyno(89 octane fuel). There is more in it if I port it and bump compression. Light and fun on smooth trail or lake, but old leaf front suspension pounds you on bumps you wouldnt know were there with modern sleds.

[tpssonic]

BruceWilkie,

The porting on those Kawassaki engines were ultra conservative; that is why the reed valves were not needed (although they certainly would have helped the soggy low end the Kaws were infamous for). The hp figures you give are a bit optimistic as well. The 1978-80 440cc Invaders (piston port) were 65-66 hp. (dynoed a bunch of 'em), The Invader 4/6 (1980 440cc 4-into-6 transfer port- the 2-plugs per cylinder was just gimmicky) and 440 LTD (1981 440 cc) were a bit stronger. I also had a limited-production, 1982 only (they went out of the sled business in 1983) stock 550 Interceptor (Keihin carbs and piston port) and that would only dyno at 85hp (corrected brake horsepower) on a good day. Due to the very conservative port timing, I agree that reed valves would just hurt top end flow. If low-end performancewas not an issue, I got 92+hp out of a 1979 Invader 440 piston port, but that needed porting and twin pipes to accomplish that.

[Half-Inch Stud]

If i could upload a Reed Cage photo from my IPAD...

So, the purpose would be to auto-slam the Intake path shut, so let's assess the desired benefits;

AutoMatic volumetric efficiency management vs RPM Inhale.
Probably improvement in CYL VE uniformity (no charge robbing ;1 robs 2, 7 robs 5, etc)
Anti-Reversion management
Probably improvement in fuel-air balance across CYLs.
potential development path to improved Street/Strip performance.
potential development path to improved Street/Strip manners.

Maybe a challenge to each of these claims will make clear the pro/con on the Reed Cage notion.

[Jack Gifford]

Found a little info on Honda's use of reeds in 4-stroke: it was the XR500 in about 1979. It solved a throttle-response problem at low engine speeds.

[cutrone]

Originally Posted by Half-Inch Stud

If i could upload a Reed Cage photo ...

.

[gavin]

Half-stud is not that far off the wall as jim fueling tried using reed valves in the exhaust headers of a racing VW engine.It worked but burned out in a short space of time.The next thing he used was the A-R cone a design that did work (older members will remember them).I found out about them in a david vizard article from 1980 and decided to try them on the FE we were building at the time.The middle ports were arkward and I had to use a separate plate to spread the bolts for access.The end result seemed to be very good with instant thottle reponse and a very good idle.Since the cam was 108 degree (but queit small) I did not expect such a mild engine.While I dont remember the exact jeting I do remember it seemed to need less jetting than expected.

[gavin]

When I built the headers for my 63 lemans I decided not to use full cones and just use a small shelf on the bottom of the exuast flange as it was a lot easier to do.It seemed to work well as the 400 had a very good idle and was very reponsive with the same small 108 degree cam and t11 that had been on the FE rail.It would hit the stock converter and make it flash to queit a high stall speed.To look at the manifold and intake ports after a lot of street driving you do not see overt signs of reversion.It does have a spacer wich can some times help with reversion but the particular design may make it worse.I think if you played with shelf angle on a flow bench you could bring the shelf up higher with out loss of flow wich may help on cast heads as they tend to have a dead floor on the exuast.Please excuse my spelling.

[Half-Inch Stud]

the metal AR cones were to be kept quiet. I mean to promote quieting. Yea that's it.

Round Ports may take the AR cone per port a bit nicer. Hope to try AR cones in the Collector to see effect on Cruise, then ET.



That VFORCE4 differs from the Vee I've seen. No outer plastic, no thick flange.