Balance shafts vs. lightweight flywheel

[Grant]

I have my block torn apart, and am wondering if i should remove the balance shafts and then balance the crank, or go with a lightweight flywheel
this is going to be my daily driver, not an all out race car, but i am going to aim for about 400 hp, and i am wondering whether driveablity will suffer

any advice would be appreciated, thanks

 

[squeak104]

I took my balance shafts out and had everything balanced. I haven't gone over 4000 rpms while I break the motor in but the only vibration I feel is when I'm at a stoplight. But I've got an auto so yours will probably be different since I don't have a clutch and all.

 

[JCMDSM]

I have both my balance shafts eliminated and a lightend flywheel. The reason I have both is for ease of installation (no need to have a new flywheel machined) and for saftey (balance shaft belt won't let go and ruin my timing belt). The vibration is only at idle really and you can cancel it out by finding a sweet spot in the idle where things don't vibrate so badly (for me its about 900 rpm). I would remove the balance shafts for sure so you don't ever have them ruin your head. If you want to get a lightend flywheel that wouldn't effect the vibration as much as the balance shafts but it isn't totally necessary for you goals. Good luck--Jon

 

[GVR4592]

If you put the block back together with the balance shafts you are asking for trouble.

 

[GTM]

I have my block torn apart, and am wondering if i should remove the balance shafts and then balance the crank, or go with a lightweight flywheel
this is going to be my daily driver, not an all out race car, but i am going to aim for about 400 hp, and i am wondering whether driveablity will suffer

any advice would be appreciated, thanks

A daily driver eh. Might I suggest you find someone who has lightened their flywheel and take a ride in traffic. The idle and low rpm may have more vibration than you would like. The 4 cylr inline engine has an inherant harmonic whip in the crankshaft which uses the flywheel and balance shafts to smooth this out. For decades 4 cylr engines managed without balance shafts and were still civilized because of the flywheel.

Now you are thinking of pulling more than 2Hp per cubic inch, what do you think you will need for an idle rpm... 1200, 1500. If you have another 4 cylr car practice holding the rpm at those speeds while waiting for a traffic light. I find just sitting next to something running that fast provokes anxiety. Nothing like showing up at school or work already stressed all because the beast has no idle. You may also find in your state that it won't pass smog, then what...

Cheers,
GTM

 

[Nanan]

I daily drive my baby about 260 miles a week and she has an aluminum flywheel and balanceshafts removed. As for vibration it does vibrate a bit at 800 rpm and 3200 but really I do not even notice it any more. The engine revs quick and I have great oil pressure with the balanceshaft front bearings blocked off.

Every engine is different as far as balance goes, some run rougher then others, really the only way to tell how it will feal is to yank the balanceshafts and find out.

 

[Grant]

Thanks for the advice

an aquaintace of my cousin owns a turbod civic, with a lightened flywheel, and he hated it, b/c it was impossible to shift smoothly b/c the revs dropped so quick, and i was wondering whether this would be a factor

Also, how much difference does taking off all that extra weight have

 

[fanatic26]

I have found that on an AWD daily driver, the lightened flywheel can be a bit of a pain. When putting around town you probably arent gonna be shifting quickly thru the gears and you will lose alot of rpms between shifts. I would do what GTM said and try to find someone with a similar setup and see if it is something you are gonna wanna deal with on a daily basis.

 

[BaddAssGst]

I have an 8lb flywheel and removed balance shafts and I drive the car every day. It is not hard to drive. I did have to change a habit of mine of going into neutral because sometimes the car would stall out. For the guy that said you wouldn't shift fast, you don't have to. I can shift fast and slower and the car doesn't jerk.

 

[Grant]

Is there some a flywheel that you can get that is maybe about halfway between a stocker and a super lightweight one?

Also, some said that the engine does rev quicker, does this make a major difference or perhaps a faster e.t.

does anyone know wether or not i need to get my crank balanced to do this?

 

[knighteclipse1]

I have a fidanza flywheel, its pretty streetable, but it did take alittle getting used to at first, but now its like second nature. I haven't had my balance shafts removed, but plan on it later. I believe they are both worthwhile mod's to do.

 

[GTM]

Is there some a flywheel that you can get that is maybe about halfway between a stocker and a super lightweight one?

Also, some said that the engine does rev quicker, does this make a major difference or perhaps a faster e.t.

does anyone know wether or not i need to get my crank balanced to do this?

Grant, Grant, Grant, do you expect to get the perfect answer...

Have you formulated a budgert

 

[DSMedEG]

My balance shafts are removed and even with a bent cam gear it still only seems to idle rough at warm up, im figuring that this might because of a dirty TB. as far as i have heard anyone shooting for over 300 hp need the BS removed, i could be wrong.

 

[Piranha451]

It is alright to remove the balance shaft and not get the crank balanced? (as in remove it while the engine is in the car)

 

[Nanan]

You do not NEED to balance the crank, the balance shaft does not actually do anything to effect the balance of the crank. The balanceshaft creates an inverse rotational mass to the crank that counters the vibration transmited to the body of the car.

It is a serious bi*** to pull the front BS with the engine in the car but it is possable, I did it.

As far as engine revs dropping quickly, yea the engine revs down much quicker then stock with the Al flywheel and BS removal. I have a stupid sick built double syncro all gear 5speed from TRE so I can junk the crap out of a shift and still not grind gears. On a stock trans you might miss the mesh point everyonce in a while and grind em.