tconn

For those with experience, what are your thoughts on removing the balance shafts for a street engine?
Will it effect long term durability ?
Is there more vibration?
Thanks

special tool

No way, dude.
Don't do it.
There is only one known street engine in the universe which is said to be smoothe - David Floyd's.
But he is no mere mortal.

rhesus

No experience but you might get some help from these:
https://rennlist.com/forums/944-turbo-and-turbo-s-forum/194490-blance-shafts-or-no-balance-shafts.html
https://rennlist.com/forums/944-turbo-and-turbo-s-forum/318325-how-bad-is-it-without-balance-shafts.html

tconn

I've ridden in Davids and it feels stock. That's what got me thinking about it.
Yes the attention to detail on Davids car is incredible. I don't like opening my hood when the cars are together.


Thanks for the links!

gt37vgt

the formula for successful balance shaft removal is this:

replace factory monster alternator with one half the size otherwise it shakes off the block .

Plan to spend very little time at 2800 to 3600 rpm as this is the speed at which its shaky.
next.
next when your distributor cap and rotor self destructs convert to multi coil .

M758

No reason on street car motor and very little reason on a race motor.

All it leads to are problems and gains you what 3 hp.

David Floyd

Is it the proper thing to do ? probably not, but I do have 50K miles and counting with zero problems.

I will give Tim @ SFR full credit for the quality machine work on the internals of my engine.

Tim, I have not had time to search for the oilfilter housing I promised you, but I will.

ST, your the immortal one, 600 rwhp, I have yet to bust 400

tconn

David, I'm in no hurry. Thanks again!

I read through the old threads and there seems to be different opinions, but it looks like that on a stock engine
it would not be a good idea. On an engine that has a lightened, properly balanced bottom end, like David's, removing them would not be an issue.

ehall

the real question is, "what will you gain?"

tommo951

Don't do it, have a look at Chris Whites website. There is a picture of a fractured oil pick up pipe caused by the harmonics of not having the balance shafts fitted.
David Floyd is the exception, we salute you David, you have proved it is possible. I would not be as brave!!

tconn

Ehall, what you stand to gain is less complexity, fewer potential problems and less weight.
After reading Scott Gomes posts on the subject it makes perfect sence as to why you would remove them for an engine that has it's lower end lightened and balanced properly.
I'm not saying I'll do this, because at this point I'm not sure how far I'm going with the new engine.
I'm gathering info so I can determine how far I want to go with the new engine.

Chris White

Harmonic balance has nothing to do with static balancing. You can achieve perfect static and dynamic balance and you will still have a harmonic issue – its an inherent part of an inline 4 cylinder design. That larger the displacement the bigger the problem. You will not feel the harmonic issue unless you put your hands on the engine at mid range rpms – then it will feel ‘buzzy’. This is what can cause long term issues – fasteners that back off and metal fatigue in brackets and other items.

Will the parts fail? Not necessarily, some will last just fine, but some won’t. I don’t see the advantage for a street engine.

tommo951

^^^^^^^ He knows what he is talking about!

Premier Motorsp

Like Chris White already said--

You can balance everything that rotates down to the microgram, and you still need the balance shafts to have a smooth running engine.

Here is why:

Check how much the piston has moved down in the bore at 45 degrees past TDC. Now check how much the piston has moved up in the bore at 45 degrees past BDC.

You will notice that the numbers are NOT the same.

A casual examination of the piston motion would lead you to believe that piston #1's motion would be counter balanced by piston #2's motion. This is not true, however, as the example above clearly demonstrates.

In my experience, engines without balance shafts constantly have parts falling off.

M758

Chris what kind of hp gains did you see when playing around with Paul Bloomberg's 944 NA spec car motor on the dyno? I think it was something like 3 hp when not using the balnace belt.