TeamSwift

i already know 3 cyl engines vibrate pretty bad (compared to a v8) is there any way to get them tostopthst or reduce it?

Yeah , turn off the ignition

Even if you have the engine balanced it will still vibrate. It is a 3 cylinder engine not enough pistons to balance out the firing pluses. That is why 4 or 6 or 8 cylinders run smooth. Even numbers are smoother in general.

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Cars and Harleys

The 1.0 litre 3's all vibrate, in my opinion, in a soothing ''magic fingers'' massage-like way, at idle.

A three cylinder inline engine has primary balance, but suffers an imbalance called a rocking couple. This type of vibration should diminish above idle, and the exhaust sound as raspy and nice as a V6 under acceleration.

A three's idle vibrations can become more pronounced as a motor mount becomes worn, or if the exhaust system pipes become bent, which can place stress on the rubber mounts' ability to suspend the engine and reduce the vibration to an acceptable level.

Four cylinder engines without balance shafts or hydraulic motor mounts can suffer from vertical shake type of vibration, which is why you notice buzziness in fours that are not as harsh in a three. 4 cylinder automatic transmission cars can be particularly annoying when you are in Drive and stopped with foot on brake.

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according to the bosch engineering handbook, which is a very good reference, a 3 cylinder inline engine is one of a few "inherently balanced" design types.

i have a very good guy with a spectacular vibration analyzer who has zero balanced the rotating mass on the last 2 g10t engines i have built. they are amazingly vibration free and "turbine-like" in operation.

if you are experiencing the typical "bounce" on a 3 banger you probably have out of whack compression along with clapped out power unit mounts. in my experience the automatic transmission cars are worse, especially when sitting in gear at a stop.

on my "special" cars i have gone to great lengths to lighten and balance the rotating assemblies. it's expensive and time consuming and not something you would normally do on a 3 banger but if you put the effort into it the little engines respond very well. i don't do this kind of work on every g10 engine but believe me, the vibration and bouncing you describe indicates some problem you can address and get rid of.

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1991 Blue Geo Metro Convertible highly modified 1.0L Turbo3 5 spd. - 1991 Red Geo Metro Convertible customized with a Twincam 5 spd.

My Turbo3 Project
My Cardomain Page -Ol' Blue
My YouTube Channel
My Photo Gallery
SAAB Sonett II

I humbly agree with our Moderator.

Here's 64 seconds of a normal 3 cylinder idle:

https://vimeo.com/5456921

The camera isn't nearly as stable as that engine!

If yours 'vibrates' more than that (and is stock) you don't have it dialed in. Compression has been mentioned. Fuel delivery (leaky injector, carburetor) and vacuum leaks should also be included as you chase down the cause of 'vibration at idle'. Of course, faulty ignition might also contribute.

Inline 3, 6, 9, 12 (etc.) cylinder engines are inherently stable and vibration 'resistant' due to the throws on the crank (120, 60, 40, 30 degrees). You balance them (see my thread on the topic) and the engine will be rock solid at idle.

mine doesnt vibrate too bad, its mostly th le exhaust rattling on the swaybar

im getting the engine rebuilt soon

most engine rebuilders will just assemble parts. you want to get some reasonably accurate digital scales and take each part on the rotating assembly to the exact weight of the lightest piece of their matching parts.

that does wonders.

getting as much mass out of the rotating assembly (within reason) by removing material from stategic locations improves throttle response, too.

it's all the little things that you do during a rebuild that increase reliability and durability as well as performance. as a matter of fact, when an engine is designed by automotive engineers they rely on a certain amount of "detuning" to occur from the spec blueprinted engine to the factory's mass production engine. that is the safety margin that allows the manufacturer to offer a warranty and it can be as much as a 20% change in delivered power. you can do some very simple things like cleaning up burrs in the intake manifold passageway to improve air flow or taking the time to trim gaskets on the intake and exhaust interfaces so that they don't protrude into the air flow. those things make the difference between a good engine and a great engine.

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1991 Blue Geo Metro Convertible highly modified 1.0L Turbo3 5 spd. - 1991 Red Geo Metro Convertible customized with a Twincam 5 spd.

My Turbo3 Project
My Cardomain Page -Ol' Blue
My YouTube Channel
My Photo Gallery
SAAB Sonett II

im considering knifeedging the crank lol

not much if anything to be gained there.

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1991 Blue Geo Metro Convertible highly modified 1.0L Turbo3 5 spd. - 1991 Red Geo Metro Convertible customized with a Twincam 5 spd.

My Turbo3 Project
My Cardomain Page -Ol' Blue
My YouTube Channel
My Photo Gallery
SAAB Sonett II

Run it through a QRX 6500 with lots of gain:

http://en.wikipedia.org/wiki/Knife-Edge ... er_song%29

6 - way speakers won't hurt, either.