ESE's works engine tuner

[peewee]

hey guys do you know of any good links where i can learn more about velocity through a duct ?

for example if you have X (high) amount of pressure at the duct opening and Y (low) amount of pressure at the exit, and lets assume the duct cross area is the same from entrance to exit, you will have Z amount of velocity.

now if we keep the pressure differentials the same as the above scenario (high pressure at entrance and low pressure at exit), but change the duct so the cross area converges (gets smaller) as it goes toward the exit. how does that affect the velocity , mass and energy of the air delivered to the low pressure space ?

reason im asking is because some people say you need a huge transfer opening in relation to the small exit at the window. but i thought it was better to have a opening about eqaul or only slightly larger than the exit. but then again the window is partially covered most of the time so maybe its ok to even have the entrance smaller than the exit ?

[TZ350]

... reason im asking is because some people say you need a huge transfer opening in relation to the small exit at the window. but i thought it was better to have a opening about equal or only slightly larger than the exit. but then again the window is partially covered most of the time so maybe its ok to even have the entrance smaller than the exit ?

That is a very interesting question, I would be interested in the answer too.

[adegnes]

Quick question for you TZ; have you modified the rotary "valve seat" with grooves or similar for less drag between it and the valve itself? If so, any measurable gain from doing so?

[peewee]

wob what you think of this. im just gathering the required info for engmod. in the process i put some playdoh in the B port for the hell of it. im sure your familiar with the front wall of the B port and how it twists ( at the entrance its the red line, then as it gets closer to the window it twists back to a trajectory straight across the piston like the green line)

do you see any reason i shouldnt use some epoxy and eliminate that twist so the wall runs straight up from entrance to exit like the orange line ? blue line is bore center

[TZ350]

TZ; have you modified the rotary "valve seat" with grooves or similar for less drag between it and the valve itself?

No sorry, mine are standard Suzuki, alloy plate engine side and fiber?? carb side.

[adegnes]

No sorry, mine are standard Suzuki, alloy plate engine side and fiber?? carb side.

Ok, thanks!
Same fiber stuff on the ts100 cover, looks like cork. I have a Tomos a35 moped engine with what looks like the same stuff, lining the wet clutches!

[cotswold]

I spotted this on a classic 50 racing forum, a pretty radical disc valve.

[husaberg]

I spotted this on a classic 50 racing forum, a pretty radical disc valve.

If I only used my powers for good

The Kreidler engine shown by TZ350 was cutting edge technology in 1962, but I do not think any of you want to copy transfer passages that, together with twin rotary disks and a twelve-speed gearbox, produced all of 10 HP out of 50 cc.
In case you wonder: the transfer timing was 142°; the single exhaust was way over 200°. Don't try this at home....
Below are some more pictures of the same engine, showing the twin carbs and the screwed-in caps that gave access to the transfer ports for easy modification.
You can also see the hand-operated three-speed gearbox behind the foot-shifted four-speed box.

[F5 Dave]

I agree it certainly won't be easy but I found this on BDKs webpage, they recon just under 20hp at 10K, and 98 mph, here: http://www.bdkraceeng.co.uk/Bike5.html

A program I have that predicts top speed 1/4 mile etc also seems to think 21hp may just do it (with no wind on a nice day with no slope ) It also uses a predicted Cd.

Dave

Dave

Just. Thread dredge from July last year re Practical Sportbike mag 100mph moped. They didn't make much past 90mph and then went quiet on the subject. Not sure if any more info on Farcebook I don't dabble there.

[TZ350]

For something different, tonight its from the dark side.



Blue is where we started, Red 23.47hp is the best and Green is where we finished up after fitting a longer bell-mouth.



But for real hp, 2T's are where its at.

[Frits Overmars]

I spotted this on a classic 50 racing forum, a pretty radical disc valve.

It is, but then you need to know what kind of engine it came from.
Your picture, repeated a little larger below, shows the Kreidler 12V 6x2-engine, which means twelve speeds, 6 foot-operated x 2 hand-operated.
It was the successor of the engine shown above in Husabergs pictures, the 12V 4x3, 4 foot x 3 hand, which drove the riders crazy when they had to brake, shift down and keep count. Suppose you are in 10th or 11th gear and you brake for a hairpin. Was it three times down with the foot and twice up with the left hand that also has to operate the clutch, or was it twice down with the foot and once down with the hand, or... f*ck, wrong again! And reading the notes written on the gastank wasn't good for health either because it could easily make you miss the corner. And we're talking 1960-circuits here, like the Nürburgring with 184 corners over 24 km.
The 6x2 was a lot easier to ride than the 4x3, although still not as easy as the Suzuki 12-speed and 14-speed machines, with just foot-operation.
Suzuki lost out however in downshifting: changing down 13 times for a hairpin simply took too much time.
OK, back to the disc timing. The Kreidler 12V 6x2-picture below left shows one normal disc, from the roadracing engine, and one crazy disc that hardly closed at all because it came from the compressor-blown land speed record engine.

[goose8]

For something different, tonight its from the dark side.



Blue is where we started, Red 23.47hp is the best and Green is where we finished up after fitting a longer bell-mouth.



But for real hp, 2T's are where its at.

Is Avalon doing the two hour ?

[Gigglebutton]

For something different, tonight its from the dark side.



Blue is where we started, Red 23.47hp is the best and Green is where we finished up after fitting a longer bell-mouth.



But for real hp, 2T's are where its at.

Thanks for all your help Rob & Cully

[trevor amos]

Frits,
I recall reading a magazine article about the fun and games Hugh Anderson had with the 50cc Suzuki in the Island. In the end he gave up trying to compute the actual gear he was in and changed down in groups of three at a time. After that the numbers were a little easier even if racing the bike wasn`t!

Trevor

[Frits Overmars]

Frits,
I recall reading a magazine article about the fun and games Hugh Anderson had with the 50cc Suzuki in the Island. In the end he gave up trying to compute the actual gear he was in and changed down in groups of three at a time. After that the numbers were a little easier even if racing the bike wasn`t!

It still doesn't pay to know which gear you're in, as long as the engine is in the powerband. But knowing how many gears you need to change down for any particular corner, does pay.