Balancing Rotating Assembly

[00Joeindastarbo]

Currently building an engine and would like to know how many people have balanced the whole rotating assembly Pulley, Crank, Rods, Pistons, Flywheel and Clutch when forging there engine.
Is it really necessary unless you are uprating the valvetrain and increasing the limiter.
It obviously has its advantages but how many people are running 250bhp+ on a bottom end which isnt fully balanced.
Would just like an idea as I really want to progress with the project and dont have the £300+ for an uprated clutch being the time of year it is.
I know I shouldn't really skimp on things but i have read about just getting the bottom end internally balanced meaning Crank, Rods, Pistons.
Thanks and you will be repped for your input.

 

[sx_turbo]

becuase i'm using the stock flywheel and stock crank pulley, only my internals were balanced,

if i were to do it all again though, i would go for a lighter crank pully and light flywheel and get the lot balanced.

any way just the internals will be fine, they should all be atleast within 1 gram of each other, although the guy that built my engine got them all within 0.5g of each other.

 

[dac69er]

i spoke to a local engine tuner about this yesterday and he said that on a road car that is a relatively new design engine it is pretty much a waste of time unless you are changing any of the internals or raising the rev limit above stock. even then the tolerances are so close that its often not worth it anyway.

due to this, i didnt bother going ahead with it myself.

 

[Tim@TBDevelopments]

i ballance everything when doing my engine builds, and i'm yet to find a factory crank, flywheel, dampner that has a good quality ballance.

they do feel alot smoother after i'm done even with almost stock engines. get it done i say

Tim

 

[spuddy]

My 440hp was unbalanced.

The new engine is balanced though cause I wanna rev the nuts of it.

 

[Tim@TBDevelopments]

yeah but ballancing everything, CC ports, working out Compression ratios etc etc is the difference between doing a proper race engine build and something put together in a garage.

no offence intended

Tim

 

[dac69er]

yeah but ballancing everything, CC ports, working out Compression ratios etc etc is the difference between doing a proper race engine build and something put together in a garage.

no offence intended

Tim

but as you will know, going to to those specs on a road engine is often a waste of time and money as the improvements will be minimal.

for most people a garage rebuild is plenty good enough, as long as it is done properly.

 

[Tim@TBDevelopments]

not really, those things just effect reliability and doing a job properly. things which i change for road and race applications of lightness is rotating parts, cam, compression ratios etc etc

but for any engine regardless of use all my engines get rotationally ballanced, static ballanced, Compression ratios ballanced. its the diffenece of just sticking forges into an engine and prepairing an engine designed for 130bhp for alot more power.

as for cost i do this as standard on all my builds and my costs are still on part with everyone else in the industy

Tim

 

[dac69er]

i agree on a full build yes, but for the avarage person wanting a rebuild, or even a basic forged rebuild the average cost of the extra work outweighs the benefits.

if you can keep the costs down but still provide all that work then thats good, but alot of places will charge extra.

 

[Tim@TBDevelopments]

i don't give it even as an option. in my opinion it gets done properly or not at all. i won't put my name to an engine that isn't done properly

probably why at the moment i have a 100% engine build reliability record. Not had a single one fail yet because of workmanship or quality. and being doing this quite a few years now.

Tim

 

[dac69er]

that is fair enough mate. too many cowboys about slapping stuff together and not caring.
just building up my first engine at the moment. will see how long it lasts

 

[Tim@TBDevelopments]

on main tip is to make sure you use a torque plate when having the cylinders bored and honed.

now these are uniquie to each type of engine so not the kind of thing a normal engine builder will carry unless they do alot of 4E engines. this will similate the head being fitted and distort the block. so when you remove the torque plate the block will be ovalled but then return to perfect round when the head is bolted down.

alternatively you bore it in a natural state and when you bolt the head down it will oval the block out meaning the piston rings don't seal as well leading to increased blowby and loss of performance in comparison.

Tim

 

[dac69er]

surely the distortion on the block is pretty minimal though?

surely you can get a universal torque plate? as long as it has one side that is flat and holes that allow you to bolt it to the block then it would have the same effect???

 

[Tim@TBDevelopments]

it is measurable and in engine building if its measurable then its definitly worth noting. its more than you think.

well ever engine has a different head bolt spacing. you also want it the same thickness as the head so when you use the head bolts there not pulling from threads futher down in the block casing. Also you have to have the 4 big cylinder holes in the middle so that you can get the borer/honing tool in there

Tim

 

[spuddy]

yeah but ballancing everything, CC ports, working out Compression ratios etc etc is the difference between doing a proper race engine build and something put together in a garage.

no offence intended

Tim

None taken, your absolutly correct. My last engine was built in a garage and was never up to spec, it lasted and that was enough. This time I'm having it built professionally and properly cause I know what I want from it now.

Some good info, still very very tempted to get the MR2 built, sold most of the stuff in favour of doing more to the starlet. Don't suppose you have a 5S-FE engine laying around do ya?

 

[00Joeindastarbo]

it is measurable and in engine building if its measurable then its definitly worth noting. its more than you think.

well ever engine has a different head bolt spacing. you also want it the same thickness as the head so when you use the head bolts there not pulling from threads futher down in the block casing. Also you have to have the 4 big cylinder holes in the middle so that you can get the borer/honing tool in there

Tim

Who in the Uk holds such a tool surely its quite specialist going by what you are saying

 

[spuddy]

Who in the Uk holds such a tool surely its quite specialist going by what you are saying

I wouldn't have thought a cast block would bend or distort much, would have expected it from Aluminium blocks.

I'd like to see a pic of one, just out of pure curiosity cause no idea what it's like.

 

[John@ECC]

I wouldn't have thought a cast block would bend or distort much, would have expected it from Aluminium blocks.

I'd like to see a pic of one, just out of pure curiosity cause no idea what it's like.

We have them in work, i will show you next time your in.

 

[spuddy]

We have them in work, i will show you next time your in.

Aye I'd be interested to see it. Barrys going to drop my second nitrous tank in when his cars in, just chuck it in my car. Also wanna talk to you about removing my roof.

Sorry for the hijack!

 

[Tim@TBDevelopments]

None taken, your absolutly correct. My last engine was built in a garage and was never up to spec, it lasted and that was enough. This time I'm having it built professionally and properly cause I know what I want from it now.

Some good info, still very very tempted to get the MR2 built, sold most of the stuff in favour of doing more to the starlet. Don't suppose you have a 5S-FE engine laying around do ya?

i don't i'm afraid mate. the 5s is good but there are little things which has to be bodged on them to work, like the oil cooler etc and oil squirters

Tim