ESE's works engine tuner

[husaberg]

http://www.thunderproducts.com/u_f_o.htm

The marketing bullshit with the parts like UFO and Quad Torque Wing are the products of a very fertile imagination but in the case of the old VM round
slide carb the improvements are repeatable and for sure worth having - where you are forced to use them due to tech regs.
There may be cases where the flow disruption of the stainless X insert may offset any gain in response, but in a TZ350 this isnt a limiting factor.
I thought about this seriously after doing the TZ400 with 40mm HV Lectron flat slides ( period legal in Pre 82 ).
This setup had such superior throttle response on the dyno, when compared to the shitty Bwwraap Bwwraap stumbling against any applied load, of the VMs, even when tuned as well as possible.

Looking at that pic made me think of something Cameron wrote that Ev Kanemoto (I think) had been told about the slide cut away on some GP bike by one of the Japanese techs.
it went along the lines of "FFS don't touch that cutaway" it took us 2 months to get just right..........

[adegnes]

Your questions about the inlet are interesting, I would like to know too.

Please keep posting pictures and reports as your build progresses.

Will do, and thanks for the fast reply and warm welcome!

It's hard to tell from just one picture, but I get the impression that you aimed the inlet upwards more than just a bit.
Put a piston in a cylinder at BDC; then put that cylinder on your crank case and look through the inlet hole. Chances are that the piston is right in the way of the flow path, so you may want to lower that path. Remember that the flow must be able to reach the opposite transfers. If you need a 'kicker' at all, the crank web bevel will do that for you.

I haven't used E85 yet; you could be right. You'll just have to find out by trying.

Thanks for your fast reply to! My phone is running out of juice, I'll post when I come home.

[seattle smitty]

About ten pages back, I offered up a "speed secret" (heat-cured moly coating on the inside of rotary valve cases). I did this somewhat tongue-in-cheek, but later thought this might not have been clear and that someone might take the idea too seriously and then be disappointed if they didn't see a tire-shredding power increase (or any power increase). So I went back and edited it.

An old friend of mine, Bob Wartinger, who has been racing outboards with great success since we were both in college in the mid-'60s, has a fine judgement on the supposed "speed secrets" we all simultaneously laugh at and covet. Of the ones that actually work at all, the vast majority come under Bob's category of,

"Well, it can sometimes help a little . . . but it won't make up for a bad start."

[jonny quest]

I had a half hearted attempt at running E85 on a 4 stroke.... it makes power. From what i remember it likes 7:1 instead of 14:1 air to fuel. One peculiar thing about that fuel, even though it made more bottom end power... it wasn't crisp and snappy down low. But again. .. i didn't spend a ton of time getting jetting just right. On a 250cc 4strk single it was 2hp better than 93 pump

[adegnes]

It's hard to tell from just one picture, but I get the impression that you aimed the inlet upwards more than just a bit.
Put a piston in a cylinder at BDC; then put that cylinder on your crank case and look through the inlet hole. Chances are that the piston is right in the way of the flow path, so you may want to lower that path. Remember that the flow must be able to reach the opposite transfers. If you need a 'kicker' at all, the crank web bevel will do that for you.

Yep, more like quite a bit, or a fair bit... And as you have predicted flow is aimed straight at the piston. Out with the kicker.

I haven't used E85 yet; you could be right. You'll just have to find out by trying.

Try I will!

[adegnes]

Forgot the picture...
Is shaping the intake so the valve opens the whole side at once good practice, or should I keep it as is(just mached to how the hole is shaped on the valve cover)
I've never built anything rotary valve before...

[Frits Overmars]

I had a half hearted attempt at running E85 on a 4 stroke....From what i remember it likes 7:1 instead of 14:1 air to fuel.

Here are some numbers to help you on your way.
We need 14,7 kg air to burn 1 kg petrol. We call this the stoichiometric ratio. A mixture with this air-fuel ratio is also called "Lambda=1". But for maximum power we make the mixture a bit richer: Lambda=0,86 is best for power. That means: 1 kg petrol for every 12,64 kg of inhaled air.

The stoichiometric ratio for ethanol is 8,4. E85 fuel is 85% ethanol and 15% petrol. Completely burning one kg of the stuff would require 0,85 x 8,4 kg air + 0,15 x 14,7 kg air = 9,345 kg air in total, so its stoiciometric ratio is 9,345.
And since we want power, we go for Lambda=0,86 again, so we feed the engine 1 kg of E85 for every 8,04 kg of inhaled air.
Conclusion: E85 needs 1,57 x the amount of petrol.

[Frits Overmars]

Is shaping the intake so the valve opens the whole side at once good practice, or should I keep it as is(just mached to how the hole is shaped on the valve cover) I've never built anything rotary valve before...

I seem to remember that Martijn Stehouwer posted a rotary-building-manual on www.emotracing.nl.

[adegnes]

I seem to remember that Martijn Stehouwer posted a rotary-building-manual on www.emotracing.nl.

Great! Thanks!

[Flettner]

Something odd happens with ethanol, at approx 70 degrees C ( engine temp ) you will need to up the ratio a little, make it richer.
I have had no end of trouble with my air cooled twostroke, carburetored, You will get a few laps in then suddenly the engine goes lean. Or you set the engine up rich and suffer for the first few laps. Thats one of the reasons I run EFI, there is a temp graph for changing the fueling as temp changes. I run E90, you will need a small petrol squirter to start the engine on cold days, ethanol doesn't light up as well as straight petrol. You will use more compression, a high squish head is important also I think.

[seattle smitty]

So apparently have some youngsters in Thailand (where Jan Thiel happens to live nowadays ): http://www.youtube.com/watch?v=ybpdNcMPs8s

I rode on a couple of the Thai klong-boats in 1970, but I don't think they were being formally raced then as they are now. Having the props spinning out at the end of a gimble-mounted eight-foot shaft would certainly put a damper on competing drivers wanting to get close enough to be "trading paint;" it could become a Thai version of "Texas Chainsaw Massacre."

Actually, in the US northwest we have had a similar thing going on for something over fifty years: "Indian war canoes." Back in the days when we were racing fuel-burning crossflow Mercury engines with open megaphone exhaust on hydros and runabouts, members of one of the coastal indian tribes procured some of the two-cylinder, 322cc Mercs, and mounted them on the dugout canoes that they were already building (as a hobby). They modified the canoes by scabbing on a flat area at the back of the boat for planning purposes. Whether the canoes already were flat-bottomed when this experiment began, I don't know. If they started with round-bottom canoes, they would have learned the inadvisability of that on their first test-run. Even with the flat bottom, they are canoes, very long and very narrow, and quite tricky to drive when on-plane. In our local club races, the indian "war" canoes showed up and ran as a special event, and were very popular with everyone. All these years later, the same tribe and maybe other tribes on the Washington State coast, are still racing the canoes, though they haven't come to our outboard races in a long time. Nowdays, instead of the open-pipe Mercurys, they use engines that come from Japanese pari-mutuel outboard racing, which is another zany (but very profitable!!) form of boatracing.

[wobbly]

One thing I learned from playing with the KZ2 and 125 open kart engines is that having a "bend" of any sort in the intake tract
seriously affects power.
Now this relates to reed engines and I suspect that much of the effect is to do with flow bias thru the petals as we have spent countless hours
trying differing petals and backup stiffness to try and find the best flowing combinations.
But now the intakes are dead square to the flow path thru the reeds and no power is to be had with differing petals, but the overall stiffness and backup configuration
is even more critical.

In the CPI Cheetah cylinders, having the reed 5mm offset to one side in the reed box is a loss of around 5Hp, simply due to the asymmetric flow into the transfer tunnel entries.

Many years ago though I built a Rotax 256 with CNC valve covers that angled the carbs upward 10* on the manifolds and from memory
that simple change was worth 3 Hp in mid 70s by simply angling the flow slightly before it hit the chamfered edge of the flywheel.
When working at ZipKarts I tried a back to back test on Hines brand new engines for his SuperKart title shot ,by grinding the inlet port with straight angled sides ( but with quite big top corner radi ).
That made several Hp more, and we kept the idea on the qualifying engine only as the case began to wear quickly.
I figured this was due simply to the increased STA of the port - as the engine made better power with 2mm bigger carbs ( it didnt previously ) but they lost too much mid power to use on track.
Then I wasted 2 weeks trying a huge number of rotary valve leading/trailing edge angles/curves - nothing I did made any better power, but I read a while ago
than Jan made the comment that an angled leading edge helped reduce wear around the port - no mention of any power advantage I am aware of.

[adegnes]

One thing I learned from playing with the KZ2 and 125 open kart engines is that having a "bend" of any sort in the intake tract
seriously affects power.
Now this relates to reed engines and I suspect that much of the effect is to do with flow bias thru the petals as we have spent countless hours
trying differing petals and backup stiffness to try and find the best flowing combinations.
But now the intakes are dead square to the flow path thru the reeds and no power is to be had with differing petals, but the overall stiffness and backup configuration
is even more critical.

In the CPI Cheetah cylinders, having the reed 5mm offset to one side in the reed box is a loss of around 5Hp, simply due to the asymmetric flow into the transfer tunnel entries.

Many years ago though I built a Rotax 256 with CNC valve covers that angled the carbs upward 10* on the manifolds and from memory
that simple change was worth 3 Hp in mid 70s by simply angling the flow slightly before it hit the chamfered edge of the flywheel.

Good info! I'll reduce my intake angle from more than a bit angled to just a tiny bit.

[adegnes]

I seem to remember that Martijn Stehouwer posted a rotary-building-manual on www.emotracing.nl.

Link wont work for me. Tried looking around at a few of the other EMOT sites but no luck...

[Frits Overmars]

Link wont work for me. Tried looking around at a few of the other EMOT sites but no luck...

Here's something that will work: http://www.emotracing.com/rotary-inlet-making.html
But I thought that somewhere there was also a written how-to. Can't find it though. Maybe you should write Martijn an email; he is extremely helpful.