ESE's works engine tuner

[RomeuPT]

Attachment 282886

........ found it.

Already have built some pipes in part based on those formulas.

Dunno if is good or bad, what I can say is that gives low header angle, header ends at 34% and difuser ends at 68%. Tail pipe restrictor seems to low compared with others, but maybe because that is just the restrictor.

Not complaining about it, it maybe in fact be very good...

[Haufen]

Yes, the chambers were polished too, but I think the main goal here was to avoid carbon deposition which could cause glow ignition.

Thanks, Frits. I am wondering, what would be the best way to keep the edge of the squishband sharp when polishing the combustion chamber?

[senso]

I think that you want to keep the sharp edges, to promote turbulence in the combustion chamber.

[RomeuPT]

I think that you want to keep the sharp edges, to promote turbulence in the combustion chamber.

promote turbulence, or to not promote coanda effect?

[senso]

I would say turbulence, has the combustion occurs in small pockets of burning gas, more turbulence means a better spreading of the initial flame and thus achieve a more even/complete combustion.
That or I'm totally wrong.

[ief]

Although very interesting it seems to totally miss the essence of the question posted by Haufen

[TZ350]

Tillotson HL-360A 24mm carb

Posted as someone was asking about using a pumper carb because they have clearance problems with a conventional carb and they also want a shorter inlet tract.



Adapter, the shorter pumper carb can be mounted hard up to the case or cylinder as it does not need a rubber vibration mount. It also does not need the add-on bell-mouth to make good power. I think, on this carb the bell-mouth is just a handy place to attach an air box.



Set up like this, the pumper made 28hp on the dyno and did not make anymore with the add-on bell-mouth and a little less with a KT100 air box.



And ran well at Taupo.



But on the track it needed a wind shield like the rubber one on this OKO carb.

[twotempi]

As positioned as per the photo the "wind shield" is going to act as a venturi and will REDUCE the available air pressure at the carb inlet .

You won't see the difference on the dyno but on the track with air-flow past it you would. Did you try turning it around 180 deg so faced the other way. Some form of still air box would probably be better.

[TZ350]

As positioned as per the photo the "wind shield" is going to act as a venturi and will REDUCE the available air pressure at the carb inlet .

You won't see the difference on the dyno but on the track with air-flow past it you would. Did you try turning it around 180 deg so faced the other way. Some form of still air box would probably be better.

This way when I crashed it folded over the carb and protected it. I had thought of fitting it the other way but expected it would act like a scoop and fill the carb with gravel in the event of a crash which happens a lot in F4 at Mt Wellington.

Although with the regulation KT100 cart air box it made about 2hp less, I agree, your right, a proper still air box would be the story.

[F5 Dave]

So I'm still thinking about the somewhat irrelevant reason that my dirt bike for example will stutter through the first few gears despite a little warming up at least. Once its run through the gears it will pull cleanly, but not before.

How would a drag bike cope with this as they often run from cold?

[TZ350]

I have been trying to figure out where to place the injectors. My EFI setup calls for two injectors, one small and one big so its a bit of a puzzle to figure out where best to put them.



I needed a fuel rail and got this Honda Civic (D16Y8 engine) rail with 240cc saturated high impedance injectors and fuel regulator off Trademe. All sorts of injectors will fit this rail and it can be shortened up to suit my engine.



A bit of info on injectors and spray patterns.

[twotempi]

This way when I crashed it folded over the carb and protected it. I had thought of fitting it the other way but expected it would act like a scoop and fill the carb with gravel in the event of a crash which happens a lot in F4 at Mt Wellington.

Although with the regulation KT100 cart air box it made about 2hp less, I agree, your right, a proper still air box would be the story.


That's always the quandary. It will work better BUT becomes very vunerable to damage when/if things go pear-shaped. A combination still-air box / carb protection fairing may be a good option. A bit like the "riders boot fairing" as on a Britten may work, and look real cool as well. But not pink !!!

[Rick 52]

New Carb is bolted on and the pipes for the pulse are fitted, one into the in let port and the carb diaphragm pipe moved, now all I need to do is make a bracket for the throttle cable.

[TZ350]

Crankcase Compression Ratios Revisited

Primary or crankcase compression ratio is determined by dividing the full crankcase volume including transfers with the piston at TDC by the crankcase clearance volume with the piston at BDC.

For a 125 the ratio will probably be some where between 1.3:1 and 1.5:1, also according to Blair it is very difficult to get a 50 above 1.4:1 and a 500 below 1.55:1.

Pic, the good old Suzuki GP125

Using EngMod2T I simulated up some of the numbers Bucket came up with when he measured the GP's crankcase volume.



Blue line is 1.3 primary compression ratio and Red is 1.4 to 1, no other changes.

1.4 is a crankcase volume including transfer ducts of 517cc using a 105mm rod, 1.3 is 621cc with a 110mm rod.

I remember Frits suggesting using the crankcase as a plenum and Speedpro talking about the crankcase as a place to store air/fuel untill its needed. I guess I will be looking to add some more crankcase volume to the Beasts engine.

[TZ350]

New Carb is bolted on and the pipes for the pulse are fitted.

Good work Rick, I am looking forward to getting it onto the dyno.