2013~2016: CX-5 Balance Shaft Delete

[4G63T]

Lets talk about how we can delete the Balance Shaft on the SkyActiv-G 2.5 .

The Balancer Unit weighs around 17 lbs and adds resistance to the motor. Removing so would free the motor from wasting energy rotating it twice the speed of the crank from idle to all throughout the RPM range.

Previous Experience with BS delete:

Back in 2003-2004 I removed the BS from my 2003 Nissan Sentra SE-R Spec V . I gained 5-6 MPG’s on the QR25DE motor (2.5L 4 cylinder). There was a little Power gain about 8-10 hp. In addition, it took about a qt more oil due to the extra space created when deleting the BS. There was ver so slight vibration around 3.5k RPM’s . And between 0-10 scale, I would say the vibration was around a 1-2 depending if you are very sensitive person.​

Difference between the Mazda 2.3 Balance Shaft and Skyactiv-g 2.5:

From my observation, the 2.3 Balancer Unit can be removed simply by unbolting and dropping it. The Skyactiv-g 2.5 motor can not be deleted the same way. Unfortunately for us 2.5’ers , the Balance Shaft is Spun with a chain that is shared with the Oil Pump. See image below.​

Compared to the SkyActiv-G 2.0 without Balance Shaft:

The 2.0 does not have Balancer Unit. It simply has a chain from the crank that spins the oil pump and chain tensioner. Image Below .​

The Possible How:

I’m assuming both blocks (2.0 and 2.5) are very similar and maybe the oil pump parts are interchangeable on both motors. To delete the BS, we can probably do so by installing the 2.0 oil pump chain and tensioner after removing the Balancer Unit? Then obviously we would need to plug the deleted BS oil feed on the block. What will be a headache added is if the chain is not able to be disassembled to install/remove and needing to remove the crank/utility pulley etc..

Another option is if someone/vendor made a idle sprocket we can install in place of the balance shaft. Maybe something else to which we can take apart the BS case remove the balancers, put in the idler sprocket and install the unit/case back.

What you guys think ?

 

[KimGT]

seems legit, I don't think a little extra vibration ever hurt anything long term (rolleyes)

 

[4G63T]

seems legit, I don't think a little extra vibration ever hurt anything long term (rolleyes)

The Engine is internally balanced. The purpose of balance shafts are only luxury related. They are to reduce or eliminate vibrations felt that would be “unfavorable" to the consumer.

I dont want this thread to turn into a debate about whether it should be deleted, unless you have proof that the skyactiv-g 2.5 is not internally balanced (highly unlikely) and the BS is an absolute necessity.

Only bolts that ever came loose on the Sentra were the Secondary Valves in the intake manifold. That was not BS related and was a manufacturing flaw that happened to people that still had the BS. Long story short as a preventative measure they had to use Locktite to prevent them from possibly loosening.

 

[ColtX-5]

Removing the balancer is commonly done to fit the 2.5 engine to a Miata. Most say the increase in vibration is noticeable, but not objectionable.

I wouldn't do it. Too much cost and effort for zero rewards and some negatives.

The balancer adds rotational inertia to the crankshaft, but it is so unlikely that it is virtually impossible for the balancer to cause so much friction that removing it will free up "8 to 10 HP". I would believe 0.08 to 0.10 HP. Less rotational inertia will allow the engine to rev more quickly, but that is not horsepower.

 

[4G63T]

Removing the balancer is commonly done to fit the 2.5 engine to a Miata. Most say the increase in vibration is noticeable, but not objectionable.

I wouldn't do it. Too much cost and effort for zero rewards and some negatives.

The balancer adds rotational inertia to the crankshaft, but it is so unlikely that it is virtually impossible for the balancer to cause so much friction that removing it will free up "8 to 10 HP". I would believe 0.08 to 0.10 HP. Less rotational inertia will allow the engine to rev more quickly, but that is not horsepower.

From the above statement, I’m pretty sure you never held a balance shaft unit in your hand and tried to spin the gears.

On the Evo, from what I recall there was very minimal gains but I’m pretty sure its because the balance shafts were designed differently and required a lot less energy to spin. It was recommended to remove on high HP cars and the JDM Evo’s didnt even have it. There was a “factory” oem delete kit. Same exact motor between USDM and JDM only difference is JDM had balance shaft and “anti-lag” EGR. From reading the Mazda 2.3 motor, there is a gain of 3 whp, minimal but a gain where needed up top. The QR25DE Sentra Balance Shaft I held in my hand and just trying to spin it quickly with my figner’s, there was quite a bit of resistance. I cant remember exactly but similar to a 2-3 pound dumbbell.

Now imagine putting 2-3lbs at only 20 rpms on your fingers but the motor actually starts rotating at idle of 750 rpms to 6000+rpms. The resistance possibly increasing as rpms rise and Balance shaft spinning twice the speed of the crank. Thats extra energy being taken away to spin the BS.

If you put lighter wheels on your car do you not "free more power” and accelerate a little quicker? You even gain MPH in traps speeds at the 1/4 mile .

Different cars have different balance shafts. The skyactiv-5 2.5 seems to be a lot bigger than the Sentra’s was. Not necessarily would bigger unit mean more resistance but from eyeball view of its construction it seems to be.

Also, your not just reducing resistance on the motor when accelerating or cruising, but just idling as well!

 

[inlinev]

I don't understand, what the point of this is?

 

[4G63T]

Evo balance shaft. Its not an actual cartridge or unit/box, but rather a rod that slides into the block. Top to bottom, OEM balance shaft, AMS BS “delete” and last is JDM Factory OEM Balance Shaft Delete.

Mazda 2.3 Balance Shaft

[/URL][/IMG]

Nissan Sentra QR25DE Balance Shaft

And the Gigantor Sykactiv-g 2.5 Balance Shaft

 

[MikeM.]

The balancer adds rotational inertia to the crankshaft, but it is so unlikely that it is virtually impossible for the balancer to cause so much friction that removing it will free up "8 to 10 HP". I would believe 0.08 to 0.10 HP. Less rotational inertia will allow the engine to rev more quickly, but that is not horsepower.

This is correct. It might consume up to 1/2 hp at high rpm's. It must be remembered, it's floating on plain bearings filled with 0W-20 oil. The power consumed would be much less than 8-10 hp. However, removing the shafts would show up on a Dynojet style dyno as a significant gain, the Dynojet doesn't measure hp, it only attempts to derive hp from acceleration. In fact, the amount of hp gain from removing the balance shafts (when measured on a Dynojet style dyno) would vary widely depending upon which gear was chosen for the dyno run (lower gears would report larger hp gains). But, as you pointed out, that's not HP.

 

[erhayes]

Possibly overlooked is the fact that the balancer cage is part of the crankcase stiffener strength. If you must, then remove the balance shafts and reinstall the cage. Make a shorter chain for the oil pump drive. Ed

 

[4G63T]

I don't understand, what the point of this is?

From my experience better MPG’s and depending on how much rotational mass/resistance it has, some free’d hp.

Notice how I am saying “free’d” hp and not hp. The motor still makes the same HP just less resistance put on it. This is similar to adding light weight pulley or light weight flywheel/clutch. Also, maybe even similar to lighter weight driveshaft but driveshafts spin only when the car is moving but balance shafts always spin when the motor is running.

Heck people claim they notice differences running different oils or weights of oil on their motor and something like the BS that adds more resistance to the motor you think your not going to notice or experience changes that I described?

Whether you guys like it or not, my MPG’s increased by 5-6 MPG's when I removed the BS on the Sentra. Driving style and climate was the same. Why did my MPG’s increase?

 

[Rarebit]

I doubt you would get a 5 to 6 mpg bump on the CX 5. The 2 L has no balance shaft, and is not five or 6 miles per gallon better than the 2.5.

 

[erhayes]

A smooth engine is a happy engine. 4 cyl inline engines are inherently poorly balanced and the longer the piston stroke the worse it is. That is why smaller engines can get away without balance shafts. Subaru and small aircraft engine designed fixed it by using a 180 degree V.

 

[russiankid]

I think the gains are so minimal that it is not worth getting dirty and removing the BS. We don't even know how exactly the BS is setup on the 2.5, and what other issues would be encountered during the process. In addition, if you car is still under warranty during this, and something happens to the motor, kiss the warranty goodbye. Even if you try to replace the BS, you can tell the oil pan has been removed...

 

[MikeM.]

Whether you guys like it or not, my MPG’s increased by 5-6 MPG's when I removed the BS on the Sentra. Driving style and climate was the same.

Lot's of BS talk in this thread!

Yeah, the BS free 2.0L gets better mpg but most of the difference is not from the lack of BS but due to it's smaller displacement and lighter weight.

 

[yrwei52]

I doubt you would get a 5 to 6 mpg bump on the CX 5. The 2 L has no balance shaft, and is not five or 6 miles per gallon better than the 2.5.

Well said. The result is already in based on SA 2.0L and there is no way to gain that much MPGs as expected by OP with removal of the balance shaft from SA 2.5L.

 

[Chris_Top_Her]

That being said a lot of drivers are reporting 4 -5 mpg below sticker on the 2.5.. can 2.p0op owners say the same?

 

[4G63T]

Possibly overlooked is the fact that the balancer cage is part of the crankcase stiffener strength. If you must, then remove the balance shafts and reinstall the cage. Make a shorter chain for the oil pump drive. Ed

I highly doubt the motor is designed with he balance shaft cage in mind to stiffen the crankcase. Now what I do think is that the bs cage in place will help almost act as a windage tray to reduce oil splashing around and away from the pickup tube in hard cornering.

I doubt you would get a 5 to 6 mpg bump on the CX 5. The 2 L has no balance shaft, and is not five or 6 miles per gallon better than the 2.5.

I cant say for sure about the CX-5 I can only comment for a fact that it was the result on my Sentra. If I’m not mistaken the CX-5 makes more power per rpm vs the 2.0 . So less throttle to achieve same acceleration and hold cruise. Maybe there is some to gain with removing the BS?

A smooth engine is a happy engine. 4 cyl inline engines are inherently poorly balanced and the longer the piston stroke the worse it is. That is why smaller engines can get away without balance shafts. Subaru and small aircraft engine designed fixed it by using a 180 degree V.

That is true but engines today are made internally balanced without the balance shaft. The Balance shafts in general do not smooth out the motor all throughout the rpms but are made for target area of rpms.

Oh and I think you meant to say 180 degree H not V. FYI Porsche uses the H style aka boxer motor as well.

I think the gains are so minimal that it is not worth getting dirty and removing the BS. We don't even know how exactly the BS is setup on the 2.5, and what other issues would be encountered during the process. In addition, if you car is still under warranty during this, and something happens to the motor, kiss the warranty goodbye. Even if you try to replace the BS, you can tell the oil pan has been removed...

We wont know until we try. I saw gains in a different car. You are correct warranty will be out for the motor. I currently have 2200 miles on the cx-5 now. I dont believe removing the BS will cause issues as the Sentra did not have issues, I dont know of any issues with the mazda 2.3 and the whole Evo community does not have issues for those that removed the BS. I think cx-5 will also not have issues.

Lot's of BS talk in this thread!

Yeah, the BS free 2.0L gets better mpg but most of the difference is not from the lack of BS but due to it's smaller displacement and lighter weight.

Not sure what info your calling BS talk on in the thread?

I never said the 2.0 and 2.5 difference in MPG’s are due to the balance shaft unit. You are correct it is due to the displacement.

Correct me if I’m wrong arent Mazda and other auto companies using Electric power steering to help increase MPG’s over ps pump that is belt driven?

Well said. The result is already in based on SA 2.0L and there is no way to gain that much MPGs as expected by OP with removal of the balance shaft from SA 2.5L.

Maybe not as much but I think something that may still be worth it.

That being said a lot of drivers are reporting 4 -5 mpg below sticker on the 2.5.. can 2.p0op owners say the same?

Thats an interesting thought.

I get 25 MPG’s in warm weather and now in winter cold weather season I’ve been getting 21-22 mpg’s. But I only have 2200 miles so far on the cx-5.

 

[russiankid]

Even if you do see gains, it is still a CUV, not a performance car. That is just my opinion.

 

[erhayes]

I think I understand why people remove the balancing shafts for racing. With the shafts removed you are eliminating some of the rotating mass. By reducing the rotating mass, are in effect requiring less HP at the same RPM. You are therefor moving the HP plot with respect to the engine speed. You are not gaining HP (tiny bit) but, achieving it earlier. Now if you take ALL the rotating engine mass (crankshaft, flywheel, pulleys, alternator etc), and compare it to the mass of the balanced shafts removed, you have saved very little. Now, this may be significant to a race engine where 0.01 is important to a drag racer or 0.2 seconds per lap on a sport car circuit but, for a daily driver, I think not. Just my first thoughts about removing a balance shaft system. Ed Hayes

 

[mriber]

In my opinion, let's praise the man for being innovative. Let's see where this could go instead of being negative from the beginning.

Looking forward to see if you're getting any noticeable difference on your car!