ESE's works engine tuner

[husaberg]

I had a hunch that this would be it:My feeling was that they only used the piston pump to draw air through the carburettor and then dumped the mixture in a huge vessel, from where the engine could breathe as if it were the atmosphere. You know, the bigger the vessel, the smaller the pressure drop when the engine inhaled (did someone say 24/7?)
I was surprised that they could get away with a 5 Gallon volume. I would have expected the fuel to drop out because of the almost stationary state of the mixture in the vessel.

I was rather surprised it was that big, My own theory was that at lower rpm the tank was actually storing some pressure as well as mixture and as you said providing a large volume to breath from. It could have some very good emissions if used as FI engine, if it was storing unused low RPM pumped volume that might other wise be sent out the pipe.

[Muciek]

Hello Everyone!

Frits and Wobbly,

i want to modify a Simson Cylinder (40mm Bore, 44mm Stroke) for daily use (not looking for big hp) and have 2 Questions regarding that:

1. Is a Combination of 150° Inlet Duration (Piston Port), 125° Transfer Duration and 170° Exhaust Duration okay or is there a Mismatch?

2. I will use a 20mm Carburetor, meaning a 314 square mm cross section area. the inlet port is 10,6 mm high and 28,6 mm wide, meaning about 303 square mm cross section area.

is it necessary or better if the inlet port area is bigger than the carburetor area? and if so, how much? i am asking because i could just shorten the piston inlet skirt to achieve the 150° duration and leave the port and it`s area alone. But what is better in your opinion? enlarging the port or shortening the piston? one could think enlargening the port is better but on the other hand shortening the piston skirt makes the edge of it stay away longer from the port and thus not disrupting the flow (if there is a flow) when the piston travells down from TDC.

Thanks in advance! (as usual, opinions of all other forum members highly appreciated!)

But what are the rpm's that are You aiming for? You are want to use 2 transfers or more? Around 500 page there was link for Porting calculator You could use it for calculating STA's if You cannot afford engmod. As for pipe since You want very broad powerband I would try to play with origninal pipe but change the cone position and volume behind it to match the tuned lenght (the origninal DDR pipe it's vevey type, later ones and those made right now are other design as far I have seen)

[lodgernz]

As the Ex height has a big influence upon the trapped dynamic com, I use the trapped ratio.
For your air cooled 125 on AvGas a ratio of 7.4 will work reliably no matter where the port is.

Wobbly, can I assume the trapped ratio you refer to is the CR calculated from exhaust closing rather than the simple geometric CR based solely on swept volume?
If so, do you have a guideline for a water cooled 100 on 98 pump gas?

[wobbly]

The trapped ratio takes account of radical differences in Ex port height, but when dealing with your normal race engines
the Ex port is usually in a fairly small window of timing.
Thus your 100 on Avgas could quite happily go around 16.5 full stroke CR, 98 pump would be pretty much maxed out at 15.5.

Re Martins engine details, again I reiterate that without actually doing a proper analysis its all just wild gestimation that would serve no one any good at all.

[41juergen]

It will be interesting to see where you get too Juergen.
I'd love to see 80+ from my TZ250 (not TZR); while I have a few spare TZ barrels, much rather tinker (likely destroy) some of the 3xv sp barrels (given they are not rocking horse shit).
While you say the parts are exactly the same - there is a number of differences in the port layout and time areas.

Of course most of the parts are (slightly) different, but if you go into EngMod you will get a good advise were to look into. Most power you will get when following what Wob and Frits are praying about the exhaust duct, next is (surprisigly at least for me) the reed setup and finaly a bit the exhaust incl. the venturi at the end of the conus. The sim predicts a plus of 5 HP on that....
But finally only the dyno will tell you the truth.

[lodgernz]

Thank you Wobbly. Useful advice as always.

[TZ350]

On my way home I saw this pile of junk put out for the rubbish collection. I recognized that the crank was from a two stroke and grabbed it.



Center main reed valve and split big end bearing and deflector top piston. My guess is, its from an old 2T Mercury V6 outboard.



There had been an old Lola fitted with a 6 cylinder 2T boat engine, well it went pretty good so it was Banned of course ......

Possibly the most unusual T294 to have competed is Pietro Raddi's car, HU81, which is powered by a 2-litre Mercury engine from a powerboat.

http://www.lolaheritage.co.uk/histor...di/t294_01.htm

FEDERACION ESPANOLA AUTOMOBILISMO: the first year they were looking, but the year after decide to change the rules, and write a new article in the GR6....ENGINE HAS TO BE 4T!. Because many drivers were claiming against me and the 2T's power."



More on the the stepped piston concept, looks like an existing 2T could be adapted to it Ok.

R&D of the novel concept of the stepped piston engine.

The primary objective of this project has involved a demonstration of the low oil consumption characteristics of the stepped piston engine. The support enabled the design and build of a single cylinder 150 cm³ SP engine and this is shown above as a modification to an existing motorcycle crankcase and gearbox assembly. The original 125 cm³ crankcase scavenged "base" engine can be seen below.

http://users.breathe.com/prhooper/mcycle.htm

[peewee]

finished the exh roof tonight

[Grumph]

There had been an old Lola fitted with a 6 cylinder 2T boat engine, well it went pretty good so it was Banned of course ......

There was a single seat special built here in NZ, I think for our domestic 1500cc formula. OMC V4 powerhead from memory.
I never saw it run but i've seen it written up, I'm sure Husa could find the info. Car may have been called the Spider...

[husaberg]

There was a single seat special built here in NZ, I think for our domestic 1500cc formula. OMC V4 powerhead from memory.
I never saw it run but i've seen it written up, I'm sure Husa could find the info. Car may have been called the Spider...

Id rather post pics of Colin Listers V engines.

[Flettner]

Attachment 313911Attachment 313912Attachment 313913Attachment 313914


A “ROUGH AS GUTS” EXPERIMENT Part 2

4. So there’s no influence due to extraneous cylinder connected volumes in the upper cavities of the blocked off transfer passages (1 * A & 2 * B), we fill these flush with Silastic
5. Then we bolt it all together with a carb, but with no exhaust system
6. Crank it over with a few squirts of oil into the crankcase, check it out and it is all nice and oily, as one would expect with a wet sump.
7. Fill the carb with fuel only (no oil), ignition on and crank it over.

Simple really and I did say “rough as guts”.


WODDAEWESREKKON happens then?

Well what? Bets please, on what the outcome might be

[Flettner]

On my way home I saw this pile of junk put out for the rubbish collection. I recognized that the crank was from a two stroke and grabbed it.



Center main reed valve and split big end bearing and deflector top piston. My guess is, its from an old 2T Mercury V6 outboard.



There had been an old Lola fitted with a 6 cylinder 2T boat engine, well it went pretty good so it was Banned of course ......

Possibly the most unusual T294 to have competed is Pietro Raddi's car, HU81, which is powered by a 2-litre Mercury engine from a powerboat.

http://www.lolaheritage.co.uk/histor...di/t294_01.htm

FEDERACION ESPANOLA AUTOMOBILISMO: the first year they were looking, but the year after decide to change the rules, and write a new article in the GR6....ENGINE HAS TO BE 4T!. Because many drivers were claiming against me and the 2T's power."



More on the the stepped piston concept, looks like an existing 2T could be adapted to it Ok.

R&D of the novel concept of the stepped piston engine.

The primary objective of this project has involved a demonstration of the low oil consumption characteristics of the stepped piston engine. The support enabled the design and build of a single cylinder 150 cm³ SP engine and this is shown above as a modification to an existing motorcycle crankcase and gearbox assembly. The original 125 cm³ crankcase scavenged "base" engine can be seen below.

http://users.breathe.com/prhooper/mcycle.htm

Yes, they might well want to ban twostrokes, especially now with the new found clean burn and LOADS of HP!
I think that's a straight six (your parts you found)

[TZ350]

Straight six, yes I think you are right.

[seattle smitty]

The crank in the photos is from a Mercury inline six, but (guessing) about fifteen years and one design-generation newer (early '70s) and with 40-50% more displacement than the red Mk78 (about 1958) in the photo. The car has a V-6 that's a good ten years newer yet. If you're into this old stuff, the last generation of crossflow Mercs was called "Direct-Charge;" google that term for photos of the somewhat unusual piston.

On Pg. 78 of The Bucket Foundry thread is some talk about an oddball outboard project; Flettner, I think the crank you picked up might well be the one that Dick Austin is using in his homebuilt motor (which however is loop-scavenged, not crossflow).


(LATE EDIT) Oops, not Flettner, TeeZee!!!! Sorry!

[Lef16]

Hello guys
Frits has already explained about port directions and axial angles.
Aprilia A-ports had about 28* axial angle and B ports had 7*.What about the opposite?
I was watching old Yamaha cylindes(B ports directed upwards and A ports are perpendicular) I was wonderining what effect will these axial angles have with A ports having more duration (no exhaust power valve).
Cheers!