My Victa 167CC turbo BMX
- Thread starter SP2333
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Sigh...
This is not a turbocharger. It is a supercharger or blower and follows much the same design as the blower bentleys (4, 4 1/2 and 8 litre varieties) one of which I was lucky to see outside my parents house one day.. but I digress.
The idea is with a supercharger and why they were used more in the early days is that they were more simple because you dont need to meter the charge as you do with a turbocharger. All you are doing is pushing more of the same mixture charge into the cylinder at one time - a similar effect that either a reed kit or a tuned pipe is intended to have in a 2 stroke motor.
In this case it is true that unlike the supercharger on the Bentley motors (which used up to two massive carbs between the front wheels of the car and ran off spur gearing from the crank) it looks like its driven by exhaust pressure the concept is the same and will have the same effect - whereas a turbocharger is specifically designed to raise the compression of an engine by orders of magnitude to obtain the same general effect.
This motor therefore should provide good performance and should be able to spool the supercharger fairly progressively without too much problem since the engine will always operate in a pressurised state - thus the cfm from the exhaust will therefore be higher and further assist the charging of the intake.
Its also a good thing to have a free flow muffler fitted since that reduces backpressure and helps provide the best flow past the exhaust rotor and out.
Re the lubrication... as this engine is two stroke it should have enough lubrication in the mix to run ok - my only worry is if there are two bearings, one to the front (inlet air) and another to the back (exhaust side) - in that case the exhaust side bearings could cause problems unless the oil in the mixture can percolate through or there is some sort of manual oiler...
Now... all I ask is can you make up a kit for this that'll fit a schwinn cruiser
. I am also curious as to a ballpark figure for building something like your setup 
I think its the best and most creative machine I have seen on here so far
Jemma xx
This is not a turbocharger. It is a supercharger or blower and follows much the same design as the blower bentleys (4, 4 1/2 and 8 litre varieties) one of which I was lucky to see outside my parents house one day.. but I digress.
The idea is with a supercharger and why they were used more in the early days is that they were more simple because you dont need to meter the charge as you do with a turbocharger. All you are doing is pushing more of the same mixture charge into the cylinder at one time - a similar effect that either a reed kit or a tuned pipe is intended to have in a 2 stroke motor.
In this case it is true that unlike the supercharger on the Bentley motors (which used up to two massive carbs between the front wheels of the car and ran off spur gearing from the crank) it looks like its driven by exhaust pressure the concept is the same and will have the same effect - whereas a turbocharger is specifically designed to raise the compression of an engine by orders of magnitude to obtain the same general effect.
This motor therefore should provide good performance and should be able to spool the supercharger fairly progressively without too much problem since the engine will always operate in a pressurised state - thus the cfm from the exhaust will therefore be higher and further assist the charging of the intake.
Its also a good thing to have a free flow muffler fitted since that reduces backpressure and helps provide the best flow past the exhaust rotor and out.
Re the lubrication... as this engine is two stroke it should have enough lubrication in the mix to run ok - my only worry is if there are two bearings, one to the front (inlet air) and another to the back (exhaust side) - in that case the exhaust side bearings could cause problems unless the oil in the mixture can percolate through or there is some sort of manual oiler...
Now... all I ask is can you make up a kit for this that'll fit a schwinn cruiser
. I am also curious as to a ballpark figure for building something like your setup I think its the best and most creative machine I have seen on here so far
Jemma xx
Please elaborate. I see a wrapped exhaust pipe entering the exhaust turbine side..........
As far as I can tell the Victa motor has the same piston ported style setup as one of the Chinese motors. Ie. No exhaust valve. Timing is determined by the location of the ports in the cylinder. If I am mistaken and the Victa has a rotary exhaust valve or something please let me know as I have never seen a Victa motor in person.
On the Chinese engines the transfer ports overlap the exhaust port which is open to atmosphere. This is the overlap that Jak was referring to. Jburr36 posted a nice picture of a cylinder. I have posted it below. The exhaust port is at the back and the transfer ports are on the side. See how they are open at the same time and the transfer ports close first? (as the piston rises toward tdc and ignition) This means that any boosted air/fuel mixture will flow into the cylinder from the transfer ports and right out the exhaust port. No boost for you!
It may be possible to create a boost condition with an expansion chamber. Ie. The returning pressure wave created by the expansion chamber acting as a valve to hold the boosted air/fuel mixture in. This engine doesn’t have an expansion chamber. Just a pipe from the exhaust to the turbo. In any case this type of arrangement would have a hopelessly peaky powerband since it only makes boost in the power range of the expansion chamber. The only way to make use of a powerband like this would be to employ a CVT (like in a snowmobile). This allows the motor to be run at a constant rpm and the transmission varies to adjust for the load and acceleration.
Before someone else brings it up I will mention that there are 2 stroke boosted diesels. They are however of a completely different design. The airbox is not part of the crankcase so they require boost to run. They also have exhaust valves.
I know that this bike was mostly an experiment for you and that you are having fun. We are having fun too watching you build it. Even if it doesn’t make boost it should still run and be a whole lot of fun. It may be a bit difficult to start however due to the large intake manifold and the restriction caused by the turbo.
Once again I would like to congratulate you on your excellent craftsmanship and your chutzpah for trying something new!
On the Chinese engines the transfer ports overlap the exhaust port which is open to atmosphere. This is the overlap that Jak was referring to. Jburr36 posted a nice picture of a cylinder. I have posted it below. The exhaust port is at the back and the transfer ports are on the side. See how they are open at the same time and the transfer ports close first? (as the piston rises toward tdc and ignition) This means that any boosted air/fuel mixture will flow into the cylinder from the transfer ports and right out the exhaust port. No boost for you!
It may be possible to create a boost condition with an expansion chamber. Ie. The returning pressure wave created by the expansion chamber acting as a valve to hold the boosted air/fuel mixture in. This engine doesn’t have an expansion chamber. Just a pipe from the exhaust to the turbo. In any case this type of arrangement would have a hopelessly peaky powerband since it only makes boost in the power range of the expansion chamber. The only way to make use of a powerband like this would be to employ a CVT (like in a snowmobile). This allows the motor to be run at a constant rpm and the transmission varies to adjust for the load and acceleration.
Before someone else brings it up I will mention that there are 2 stroke boosted diesels. They are however of a completely different design. The airbox is not part of the crankcase so they require boost to run. They also have exhaust valves.
I know that this bike was mostly an experiment for you and that you are having fun. We are having fun too watching you build it. Even if it doesn’t make boost it should still run and be a whole lot of fun. It may be a bit difficult to start however due to the large intake manifold and the restriction caused by the turbo.
Once again I would like to congratulate you on your excellent craftsmanship and your chutzpah for trying something new!
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Yes you do... that doesnt automatically mean that this is a turbocharger in a turbocharger application.
The reason I think it has more in common with a supercharger arrangement is that in an engine that has a size relative turbocharger the turbo doesnt take power from the motor indirectly or otherwise.
In this case, because of the relative size of the motor and turbocharger - there would be a percentage power loss caused by spinning the unit and the resultant backpressure (admittedly reduced by the free flow exhaust aft of the rotor) which means the engine is using some of its power to produce the power gain from the increased intake side pressure.
While it is true that generally (as is the case with the bentley, R-R Merlin/griffon etc) a supercharger was run off the crank - there are many car engines nowadays that use a supercharger run from exhaust gases - in which case the major difference between the two is that of boost pressure and complexity.
Since this engine is using a large size compressor/rotor for its size it would act more as a supercharger than it would a turbocharger simply because it couldnt provide the high boost pressures available to larger displacement engines.. since boost pressures from a properly sized and set up turbo would be higher and might result in engine failures... which is not to say that this may not - although from looking at the engine it seems based on some of the villiers stationary motors (maybe a licence built variant?) and they have a reputation for being fairly bombproof in the UK.
All in all to be honest its swings and roundabouts as to whether this is one or the other since it seems to use the parts from one to create a similar effect to the other..
gonna need a helmet and nerves of steel to pilot that death trap. i am so very impressed at the quality alone. very good work, you must have a really nice selection of tools to do that level of work.
Ms Jemma, Any other type of air compressor other than a turbo is driven by gear or belt. I only know of Tanks, Blowers, Supers, and Turbos. If there are other types of compressors, let me know. On this one, If you look close, you will see neither a belt or gear drive. This is an exhaust driven compressor. That means it is a turbo charger. But then again. These are pictures only and I have not seen it in person to determine if there is a hidden gear or belt in there somewhere. My Postulate is that this particular 2 stroke does not have nor is it able to facilitate a belt or gear drive system. I must say, I have turbo charged a lot of Gas and Diesel engines in my day..And..This sure looks like a Turbo to me. Looks like an oil line going to the Center of the Turbo as well. And..I was wondering how the oilier was going to work. That was my Q. Enjoy the ride..
Jemma I know what you are saying that the heat energy really won't be driving the turbine in this app, but methinks the nomenclature still fits.
I just wanna see him ride that thing!!
I just wanna see him ride that thing!!
i think jemma means in fnction it is technically not a turbo chargered vehicle. However the thing attached to the motor by many peoples standards would be considered a turbocharger. i mean really if you go to the autoparts store and ask for a supercharger they are not likely going to hand you what you see attached to that engine.
Fabulous fabricating, a work of art. I have a pic of a super charged two stroke engine from the 30's I think. One problem you have with an other than valved two stroke IE Detroit Diesel, is that you are putting pressure on the crankcase not packing extra charge in the cylinder. What happens is that it will push the seals out of the side of the engine with the extra pressure, and it is true that the ports overlap and any extra charge just blows down the exhaust. He still has to solve the oil problem for the Turbo also. It could be he is using a small pump to supply oil, but remember there are no bearings in a Turbo is depends on the oil to keep the parts from touching, the shaft just spins on oil with special seals to keep the oil in. Have fun, Dave
Bump.
The pedantic gibberish about "this is for show, not go," "this won't work" and "this isn't a turbocharger" notwithstanding...
Amazing build. Just amazing.
Curious, what did you do to oil the turbo?
The pedantic gibberish about "this is for show, not go," "this won't work" and "this isn't a turbocharger" notwithstanding...
Amazing build. Just amazing.
Curious, what did you do to oil the turbo?
There are different types of turbos. There are ones that do not require oil and ones that do have bearings. It just depends on what he has.
Also, it seems a turbo or supercharger could work on a 2-stroke engine, but it would require a burst valve of some sort on the exhaust side that held pressure up to a certain point, but would open under the high pressure of the exhaust cycle. I could be wrong of course, but this makes sense to me.
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^ its tiny but still to big to work lol. There's no way it will work lol. I mean sweet fabricating, looks amazing. turbo looks sweet. But i highly doubt it will have any effect. Everything that could be said, has. Like to see a vid. theres so many reasons why it wont work lol. To me, its a waste of time. Even IF it did run.. you couldn't even ride it. You have skills. Take it to a car.
Oh for crying out loud its a turbo! the turbine (exhaust end) induces exhaust air to turn! Centrifugal super chargers do not have a turbine wheel! only a compressor wheel turned by a belt.
Relative to the size of the motor that turbo is gigantic and wouldnt spool a psi, shaft speed would be so low an oil feed/return and a pump would be pointless.
Relative to the size of the motor that turbo is gigantic and wouldnt spool a psi, shaft speed would be so low an oil feed/return and a pump would be pointless.
