Is balance shaft delete worth it?

[TheFlashDSM]

Yes balance shaft delete is beneficial, due to the fact that there’s less rotating mass on the crank, if you’re going to delete the balance shafts, make sure you get the GSC race balance shaft delete kit, as you want the ground down style balance shaft to help support the oil pump gear

 

[bastarddsm]

In all my years all I've noticed from the bs delete is a slight bit of buzzyness at like 3600rpm exactly. Urethane motor mounts on a stock engine are more detrimental than the BSE.

Also for those considering the dummy shaft. I've seen about 10:1 engine failures from a spun rear bearing than broken bs belt or a dead oil pump. Oil pumps die from a bad oil supply not some imaginary helical gear non supported death ray bullshit.

 

[Thecarfixerguy]

1) Either port the relief valve in the OFH, or use the oil relief valve spring from a Mirage/4G61 that comes without BS' from the factory. Oil pressure is perfect in all the engines I've PERSONALLY done this to, and all of them lasted longer than their setups, owners, cars, and none of them failed due to anything but a bunch of knock/tune failure or just too high horsepower for the piston/rod setup.

How is the OFH porting done? Just drill a larger bore? Some instructions or a tutorial link would be awesome. I tried searching and came up with a lot of references recommending porting, but no instructions. Also a good link on where to get the 4G61 spring would be great.

 

[enriquez2000]

Basically yes a larger bore like this.... i used a carbide bit and dremel. You may find replacing your spring would be enough. They sell them at extremepsi

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[Spleen8urLSX]

Not to contradict anyone knowledgeable but it seems as many are putting entirely too much thought into this. Deleting your balance shafts with helical cut oil pump gears is NOT going to cause failure, this has been done for years by do it yourself guys and some of the most reputable shops in the business. Does it mean you HAVE to delete your balance shafts? Of course not, no harm in keeping them if you keep up on maintenance and things are proper. On the upside deleting them you eliminate an extra belt and bearings that can cause catastrophic failure along with eliminating rotational weight. As far as vibration goes that’s 100% irrelevant if you’re using polyurethane motor mount bushings or inserts, once you go that route the cars going to vibrate far more noticeably than what a balance shaft elimination will do and if you have poly mounts you’d never know the difference if you have balance shafts or not. To add to that, I can say from experience in a FWD poly mounts are pretty much a must in anything other than a stock car (unless you like torque steer that much or wheel hop blowing apart driveline parts), so don’t know if we’re talking a fwd or awd but at that point the vibration factor is thrown out the window anyway.

In short, it’s all personal preference, won’t hurt either way if done right. Every situation is different but just to give an idea, ostars long standing stock block record was broken by a 230k original mile 6 bolt bottom end that had been in 5 different dsm’s over 12 years making pass after pass, with balance shafts eliminated and helical cut oil pump gears, when that one finally got hurt the replacement proceeded to go 8.90 at 151, also with no balance shafts and helical cut oil pump gears, take that as you will. Again, all preference, if you want to keep them it won’t hurt a thing.

 

[Thecarfixerguy]

Basically yes a larger bore like this....

Thanks! That’s exactly what I needed. Looks pretty basic. I guess the idea is to allow the pump to bypass a higher volume of oil when needed.

. To add to that, I can say from experience in a FWD poly mounts are pretty much a must in anything other than a stock car

Thanks for that insight. The car is FWD. I plan to do AWD conversion in the future if I can find the parts, but I’m trying to get the engine built and dialed in to drive this summer. AWD will have to wait for another year or so.

 

[DSMPT]

Either deleting or keeping, do it right with right parts. Then you wouldn't have most of common issues.
Since many people have already mentioned about how to delete, I skip it. I should mention in case if you keep it. Use a high quality balance shaft belt such as HKS, Gates blue, Tomei, Genuine Mitsubishi, etc. And set the belt tension properly (This is important. If the balance shaft belt is too tight/loose, it would give you more vibration and the belt life span gets shorter). I have seen many people using a good aftermarket high quality timing belt A, BUT with a cheap local store balance shaft belt. This does not make sense much.

As for the oil pump helical gear without balance shaft, '92 + cars that have a smaller displacement 4g6 engine came with the same helical gears and front case as DSM but without balance shaft from factory. If the helical gear + the stub shaft combo would cause some issue, Mitsubishi wouldn't have done it.

 

[Spleen8urLSX]

As for the oil pump helical gear without balance shaft, '92 + cars that have a smaller displacement 4g6 engine came with the same helical gears and front case as DSM but without balance shaft from factory. If the helical gear + the stub shaft combo would cause some issue, Mitsubishi wouldn't have done it.

I was going to make mention of this as well when I chimed in, my thoughts as well. My only worry with mentioning that was someone would argue that extra .4 liters of displacement would somehow make the balance shafts necessary which I don’t feel would be the case. If I had to guess the balance shafts were in the engineering equation purely as a way to make the engines smoother in the “classier” models, as the smaller displacement Sirius engines were typically found in more economy oriented models, but I could be entirely wrong there about Mitsubishi’s reasoning behind it.

 

[bastarddsm]

The shorter stroke of the 4g61 makes the balance shafts less needed. The secondary imbalance forces go up with the square of the stroke, 75mm vs 88mm vs 100mm is a big deal when you are selling premium sports cars (TEL) or kinda luxury cars (galant) vs cheap econo shitboxes (csm).

 

[slugsgomoo]

I'm running the GSC race shaft in my 2.4 because of the difficulty in finding straight gears anymore.

The biggest problem with 100mm crank cars is not running a girdle and having the mains walk around IMO.

Even Mitsu's documentation refers to the balance shafts as being there for comfort, and anyone who has deleted them knows the impact. If you've never gotten to drive a car where it still has them, but someone put the timing belt on with the oil pump 360* out of phase, it's pretty humorous (other than the fact that it causes PK at an insane level). It was fun diagnosing that one.