Very interesting, but can you actually buy a unit? Their web site is under construction. I'll see if their email works.Originally Posted by husaberg
Lohring Miller
Hardcore Biker
Very interesting, but can you actually buy a unit? Their web site is under construction. I'll see if their email works.
Lohring Miller
Forum whore
Did he loan you a crank seal???
Lets go Brandon
Forum whore
and I thought my Husky 460 Rancher was the business...
https://www.youtube.com/watch?v=so2N2PAtzgs
Lets go Brandon
Forum whore
Not a lot of feathering the throttle there.
No8 Wire Extraordinaire
Pretty sure I replaced that. Or bought you a beer.Did he loan you a crank seal???
Or drank one in your honour. It's a fuzzy reality at best.
Don't you look at my accountant.
He's the only one I've got.
Hardcore Biker
Because when you throttle off, the airflow collapses and so does the pipe resonance.
How about an unrestricted reed valve at the inlet, control the airflow (engine speed, rates of accel & decel) with metered fuel delivery and maintain pipe pressure & temp for instant response by throttling the chamber outlet. Forget about asking it what it really wants, instead, just tell it what you want it to do! ....
Cheers, Daryl.
Forum whore
I think you just invented the Diesel Daryl.
Hardcore Biker
The unrestricted inlet and the exhaust brake are Dieselly...
The ability to out compression brake 4-strokes is a bonus, plus a great new 'noise' to frighten the horses.
The rest is still Otto.
There might be a couple of cycles of (potentially) exhaust contaminated or lean mixture on transition back to accelerate mode.
The FI could perhaps inject a little extra fuel initially, to manage this. (Just like an accell pump does)
A retarded spark or two and the rich mixture might quickly put some heat & pressure back into the pipe, to fire it up again.
The stinger throttle should not be direct by cable to the twist grip. It will really need its own control circuit monitoring things like:
Throttle position, RPM, pipe temp & pressure, brake activation & pressure , decell rate (G force) etc. (A fart by wire system).
Cheers, Daryl.
Hardcore Biker
Exhaust throttles were once common in model boat race engines. The throttle was usually located at the beginning of the header. Sticking and leakage were problems. Recently stinger throttles were also tried. They seem to be equally effective without the header throttle problems. Users claimed that the throttle response was better than with conventional carbs. These engines run alcohol based high nitro (60+%) fuels so the exhaust temperatures are low. As far as I know they haven't been tried on gasoline engines.
Lohring Miller
Hardcore Biker
Thank you for your interesting input Lohring.
I'm pleased to know that i'm not just 'brain farting' into the wind.
Cheers, Daryl
Scooter boy
TZ350 - this is probably a totally dumb idea, but what about using a pressure signal from the intake or exhaust to control fuel flow by manipulating the fuel pressure regulator? The collapse of resonance would reduce intake vacuum and reduce pipe pressure. If you could feed that pressure event to the regulator, wouldn't it help add another dimension to the fuel mapping? Of course, these would be average pressures so some sort of buffering would be needed to apply the average pressure to the regulator. Although it wouldn't be a complete solution, it might help some problem areas of the EFI tuning.
Forum whore
That is not a bad idea.
It turns out that the collapse of pipe resonance allows the intake, crankcase and average pipe pressure to all increase to near atmospheric (0.95 bar or so). When the pipe is resonating well everything is at a lower working pressure (0.8 bar or thereabouts). The two stroke inlet manifold situation is totally different to a four stroke. When the pipe is not resonating and sucking air through the motor atmospheric pressure flows back in via the exhaust stinger and any other hole it can find. Piston pumping on a high performance two stroke (or any 2S) is virtually non existent compared to a four stroke.
Hardcore Biker
OK, I see that with regard to braking.2S is just compressing and expanding 'gas' above the exhaust port.
No matter what the actual pressure, the effect is pretty neutral.
A compression release on a 2S is effective because the compression work is lost, not returned.
In a 4S engine on overrun, the pressure is lost out the exhaust valve.
Probably even more effective as a brake with an open throttle and the ignition killed.
Cheers, Daryl
Forum whore
My plan is to measure the difference between the highest and lowest pressure in the crankcase each cycle and use the difference between these readings as an indication of relative changes in airflow through the motor. The more air, the bigger the difference.
Following pointers from other people, I have found that the pressure sensor transmits the pressure reading in discreet 1 ms steps, ie; every ms it transmits the current value for 1 ms. I thought it was going to be a continuous analog signal but nope, I was wrong about that. 1 ms steps it is, not sure but this might be quite a common approach.
Checking with a scope near maximum rpm I am able to see a distinct high and low pressure reading for each crank cycle, so good to go with my plan.
Because the pressure transducer and TPS have relativly high output resistances I need to use an OP AMP voltage follower to supply enough current quickly enough to charge the capacitors in the analog input of the EFI's CPU for the CPU to read.
The EFI CPU reads an analog signal by allowing the analog voltage to charge a capacitor up and the CPU then times how long it takes to discharge. These capacitors have very little forward resistance so the signal source also needs to have little forward resistance to be able to charge the capacitor up in the time available. TPS's and MAP sensors don't, they have relativly high forward resistances and low current so I will need something like an OP Amp to follow the sensors signal voltage and output a low resistance high current signal to the CPU.
My first efforts with an Op Amp were a bust. It took me a while to find out that an OP Amp has limitations. It is unable to completely swing to the extremes of the supply voltage. So a 0 to 5 Volt power supply is not good enough for a 0 to 5 Volt analog output. To get a zero Volt signal out you need a negative supply rail to the OP Amp. I have been able to find some tricky little DC DC converters that take +5V and converts the output to -5V so now using the bikes 12Volt system I will be able to jack up a -5V to + 12V supply for the Op Amp and get a good 0V to 5V analog signal out. Hopefully get to bench test this over the week end.
This is Buckets, you take a simple idea like EFI, leap in boots and all, find out how complicated it is to implement then learn a shit load along the way trying to make it work........... Love It.
Hardcore Biker
Website under construction, no phone, no reply to email; I think they are not in business. I've checked out several other small two stroke throttle body injection systems as well. So far, no luck. I suspect they don't offer enough advantage over carbs and are higher cost.
The small IC engines are also in danger of being replaced with battery electric systems. That's pretty much happened in the under 15 cc model engine area and is creeping into even larger sizes as battery costs and weights go down. We'll see what happens with larger, low weight, high power applications.
Lohring Miller
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