Author Topic: Bugatti Typ 50 1/4 Scale model  (Read 40048 times)

Offline michelko

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #270 on: July 02, 2018, 01:37:17 PM »
Hi guys, would like to hear your opinion…

If i crank and hold the carburetor closed with my thumb, should i feel some vacuum at the finger?
I think so but i am not sure with a multicylinder engine like the Bugatti.
The Background is i had to open up the idle Setting for a (in my) opinion very large ammount and i am not feeling its sucking. .

 Michael
« Last Edit: July 02, 2018, 01:57:31 PM by michelko »

Offline Roger B

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #271 on: July 02, 2018, 02:58:12 PM »
Assuming that there is some valve overlap (inlet and exhaust open together) then on an 8 cylinder engine the vacuum will probably be lost that way. If you can remove the inlet manifold and try the individual cylinders I would expect some suction.
Best regards

Roger

Online Vixen

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #272 on: July 02, 2018, 05:19:13 PM »
Hello Michael

At any moment, in an 8 cylinder engine, one of the cylinders should be sucking and the other inlet valves should be closed.

Low suction may be a symptom of leaking piston rings as would excessive blow-by into the crankcase.

How fast do you need to crank the engine to get it to start?

Regards

Mike
It is the journey that matters, not the destination

Offline michelko

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #273 on: July 02, 2018, 07:40:46 PM »
Hi Mike,
this was my first thought, but i can feel strong compression when i turn it over by Hand. It also holds the pressure for a while and snaps back if i release the flywheel.
Here is a short Video.



So i think its not ring related. Maybe the timing changed? i think i will open it and take some meassurement on the valve timing.

Michael

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #274 on: July 02, 2018, 10:18:56 PM »
Hello Michael

Yes the compression looks strong so the rings should be OK.

You have overhead camshafts, so how do you adjust the valve clearance? Could it be the inlet valves are not opening fully?

Got an idea, e-mail the engine to me and I will have a look.   :Jester:

Mike
It is the journey that matters, not the destination

Offline Roger B

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #275 on: July 03, 2018, 07:19:35 AM »
If I remember correctly this engine was very sensitive to the exhaust system which is a sign of quite 'wild' valve timing. I would suggest that you try to measure the actual valve openings using a dial gauge and a degree wheel on the crankshaft and then plot them to see what is really going on.

Without delving back through the thread, can you easily adjust the timing of each camshaft?
Best regards

Roger

Offline AlexS

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #276 on: July 04, 2018, 06:59:38 PM »
Hey Michael. Perhaps another idea to simply figure out the opening and closing moments of your valves.

Using the following CDI ignition:
https://hobbyking.com/nl_nl/replacement-cdi-ignition-for-rcg-50cc-engines.html

And then with the help of the following tuning of the ignition:
https://hobbyking.com/nl_nl/gas-engine-cdi-ignition-test-and-timing-setup-tool-includes-crankshaft-degree-wheel.html


This test set can, in addition to adjusting the ignition, also provide a kind of pulse generator. This is to test your ignition at a certain rpm.

Currently I use this method for my engine. If you connect this to the spark plug, I think you are good when the valve opens or closes. Simply seen that the ignition is quite loud, and if the valve is open the sound becomes louder. At these moments I note the value, by reading the angle measuring device supplied.

Personally, I find this a quick and simple way to find out the valve timing. Of course you can not find a valve opening and the course of the profile.



Or an idea is the reading of angular displacement and linear displacement sensor with an arduino.

https://nl.aliexpress.com/item/WDD35D4-5K-conductive-plastic-angular-displacement-sensor-cheap-angle-rotary-encoder-of-high-precision-linear-0/32815107213.html?spm=a2g0z.search0104.3.1.37037fc7bvfHVe&ws_ab_test=searchweb0_0,searchweb201602_3_10152_10151_10065_10344_10068_10342_10343_10340_10341_10696_10084_10083_10618_10304_10307_10820_10821_10301_10843_10059_100031_524_10103_10624_10623_10622_10621_10620,searchweb201603_32,ppcSwitch_5&algo_expid=d4f7c338-c36f-4cc7-b968-64c2a1d6378e-0&algo_pvid=d4f7c338-c36f-4cc7-b968-64c2a1d6378e&priceBeautifyAB=0

https://nl.aliexpress.com/item/KTC-50mm-series-Linear-displacement-sensor-resistance-scale-electronic-scale-The-packing-machine-Rod-electronic-ruler/32648160463.html?spm=a2g0z.search0104.3.14.37037fc7bvfHVe&ws_ab_test=searchweb0_0,searchweb201602_3_10152_10151_10065_10344_10068_10342_10343_10340_10341_10696_10084_10083_10618_10304_10307_10820_10821_10301_10843_10059_100031_524_10103_10624_10623_10622_10621_10620,searchweb201603_32,ppcSwitch_5&algo_expid=d4f7c338-c36f-4cc7-b968-64c2a1d6378e-2&algo_pvid=d4f7c338-c36f-4cc7-b968-64c2a1d6378e&priceBeautifyAB=0

I am also curious or someone else's options!
« Last Edit: July 04, 2018, 07:03:32 PM by AlexS »

Offline AlexS

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #277 on: July 04, 2018, 07:11:19 PM »

Offline michelko

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #278 on: July 04, 2018, 08:27:03 PM »
Hi alex,
I hadthis idea also. At first i used an ecu to control spark. This ecu has an map sensor on board. I will hook it up to the manifold and make some measurements.
Michael

Offline AlexS

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #279 on: July 05, 2018, 07:47:18 PM »
Okay! May I ask what kind of ecu you have used?

Offline michelko

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #280 on: July 05, 2018, 08:01:05 PM »
sure, its called speeduino and is Arduino mega based.

Today i hooked it up to the throttleboddy. I saw realy low fluctation while cranking the Motor with ca. 1600 rpm.
It Shows the same result as testet with the finger tip. nearly no vacuum :thinking:

Michael

Offline Admiral_dk

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #281 on: July 05, 2018, 09:42:11 PM »
Hi Michael

I must admit that I can't remember if you has done any compression test previously in this thread ....  :noidea:

But if you have and all where good => then there must be a leak between inlet valve(s) and the carb somewhere.
If the compression test fails on one (or more) cylinders, that might be why .....
If all have about the same compression, but it is somewhat low - you might have a blockage between the carb and the valves - but probably not the most likely scenario, since it can run ....

Hope this might inspire / help. Best wishes

Per

Offline AlexS

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #282 on: July 06, 2018, 07:02:10 PM »
I'm a bit brainstorming. I do really like your engine and progression.

Maybe an idea to extort the incoming side of the intake powder. This can be realized with a bottle with a nipple to mount an air hose.

First spray into the inlet nozzle as the first brake cleaner or wd40. And then mount the air hose and pressurize the whole.

It seems to me that somewhere liquid / vapor escapes from possible leak paths. However, the inlet flaps must remain sufficiently closed. I do not know how strong the valve springs are. It could give a distorted picture. To remedy this, you could possibly bring the cylinders under the same air pressure (through spark plug hole).

And for the cylinder you could pressurize the cylinder with the same principle. This could also go along the piston rings. If necessary, put oil in the cylinder, which could provide a bit of a seal.

For me, the use of water was enough to determine which position my valve / valve seal was leaking. This was considerable!

Offline michelko

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #283 on: December 02, 2018, 07:37:55 PM »
Hi,
started a new batch on plugs. Since i converted my mill to ballscrews this is the first production run


The isolator on these is again of corian. Maybe i will reduce the compression ratio a bit.

Michael

Offline michelko

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Re: Bugatti Typ 50 1/4 Scale model
« Reply #284 on: December 06, 2018, 12:46:50 PM »
So here are some more pics of the Progress i made.

1. plug bodies


2. forming the electrode using a grinding Wheel


3. first one piece Isolator made complete out off corian.


The very first set of plugs i made last much longer than the later ones. I thought a lot about this. the major difference was the Isolator from corian and the center electrode  from stainless welding rod.

I think i will try again the welding rod instead of the tungsten center electrode.

Regards Michael