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Discussion Starter #1
Not sure if anyone has done this or not. It's popular in both the Nissan Car world and the Mazda World. As reducing rotational mass even a few pounds can free up lots of power as well allowing the engine to rev faster.
 

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Side note... the RSX Type-S does not have the BS in their motors so it's obviously on there for cosmetic reasons. As the drive we all want a "smooth" feeling motor. The BS does nothing for the motor it's self but reduces the vibrations felt throughout in result of the motor...

just some food for thought
 

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Type S also has hydraulic power steering and we're electronic so their motors have to spin the PS pump. Removing the BS would help... IMO though, if you're that concerned about performance over comfort; save your money and do bigger things. ...like a K24 ;)
 

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kaizenspeed makes kits for the H22, thats what i did to my lude 3 years ago.. Gains are little noticable, vibration is vary noticable but not bad. Be interesting to see it done on the Si
 

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I remember this coming up a while back and the conclusion was that it was a MAJOR PITA. It would be worth doing if the motor was already out of the car and torn apart, but otherwise not worth the effort.
 

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Discussion Starter #9
not sure the motor has to be out. The BS is located directly below the motor easily accessible from dropping the oil pan. I know on the MZR motors it's 4 bolts and the thing drops out. Plug the oil feed oil and call it a day.

And yeah Vibration would be an issue but again this would be for the enthusiast not the everyday driver, and I would think the k20s are a little better build than the old H22 and such. No more Cast iron FTW.

Everyone talks about Pulleys and flywheels which only reduce weight 3-10 lbs. The Si has dual balance shafts and eliminating them would probably drop about 10 lbs off rotational mass.
 

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Dammit, for the life of me I can't find that article!!

I remember seeing a writeup, I believe at TOV, where someone took the time to remove the balance shafts from the Si. The results weren't all that great. He saw a 3 hp increase and said vibrations became very noticeable and annoying. The final conclusion was that unless you already have the engine out for some reason it's really not worth the time and effort to remove them.

Now where is that damn post.... grrr!
 

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Dammit, for the life of me I can't find that article!!

I remember seeing a writeup, I believe at TOV, where someone took the time to remove the balance shafts from the Si. The results weren't all that great. He saw a 3 hp increase and said vibrations became very noticeable and annoying. The final conclusion was that unless you already have the engine out for some reason it's really not worth the time and effort to remove them.

Now where is that damn post.... grrr!
Oh, yeah. Have fun over at the TOV trying to find old posts. Two years and they still haven't fixed the search.

Anyway, my car has gone past the point of daily driver. I love driving it, I just don't love driving in it. :surrender: Any additional NVH would rupture my soul.
 

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Discussion Starter #12
Yeah TOV has the most useless search tool in the world of forums!!!

Well 3 WHP is still pretty good for free power. Puts down the same amount as some pulleys would for the total cost of a few bucks for gasket sealant and such
 

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Discussion Starter #18
Nope the BS only eliminates second order vibration. Has nothing to do with the internal vibrations of the car. As far as wear things out faster, I'm not sure I've ever seen or heard of a race car with a BS... It's been done over and over again and time has proven that it doesn't affect the reliability of the car in any noticeable way.
 

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Discussion Starter #19
SPC even did it on their Rally Sentra...

Steps 4 and 5:

Balance shaft eliminator and early prototype camshafts Now, it seems like an exhaust would be a natural next step, but there was a rally coming up and eliminating the balance shafts offers some critical durability enhancements that we wanted to take advantage of. The purpose of the balance shafts is to cancel the natural imbalance of an inline four. This imbalance is minimal on a small-displacement engine, but as the pistons get bigger and heavier and the stroke increases, the imbalance gets obnoxious. This is purely a noise and vibration issue and has no effect on performance. In fact, it takes a significant amount of power to spin most balance shafts.

Most balance shafts are integrated into the block, but the QR25's are in a self-contained assembly in the oil pan. Where they're mounted, the counterweights on the shafts froth the oil like a pair of eggbeaters spinning at up to 12,400 rpm. It's unclear how detrimental this oil frothing is, but we didn't want to find out during a rally.

Jim Wolf Technology makes a kit that replaces the balance shafts with a pair of windage trays and some spacers carefully designed to cap off the oil galley that once fed the balance shaft bearings. The bolts holding the balance shafts in place also passed all the way through the lower half of the split crankcase into the engine block. In other words, they're major structural bolts, and the JWT spacers are critical to getting them back to their structural duty.

Unfortunately, there was a problem with the third-party dyno we tried to use between installation of the balance shaft kit and the first set of cams we tested, so we weren't able to produce a dyno chart of just the balance shaft gains. Jim Wolf tested the kit later on another Spec-V and found a constant 6 lb-ft gain in torque across the powerband, which equates to about 7 hp at redline.

Surprisingly, there's virtually no noticeable difference in engine vibration without the shafts. Apparently, the QR25's reciprocating bits are so light that even with the massive stroke, there isn't that much vibration. The QR25's engine mounts are also so soft, they absorb any additional vibration the shafts aren't canceling. Removing the balance shafts from the pan frees up an extra quart of space in the oil pan, bringing total capacity to 6 quarts.

We did have some unexpected problems in the two rallies following the balance shaft removal. Fuel injector wires started having fatigue failures about a quarter inch from the connectors, and one of the electronic throttle wires had a similar failure. Our best guess is that the unsupported sections of the harness were resonating, causing fatigue failures in the wires. It's not clear if this is from extra vibration from the missing balance shafts, or simply from the abuse of rallying. After replacing the harness, we zip-tied any free sections of wire either back on the connector, or to the nearest solid piece of engine. The problem has not come back.

The first in a long series of camshaft tests was next. The QR25 has no hydraulic lash adjusters, so changing cams involves an extra step of adjusting valve lash. Like any direct cam-on-bucket valvetrain, in which the cam lobe pushes directly on the valve bucket instead of using a rocker arm, this adjustment means swapping shims (or, in this case, buckets of different thickness) rather than something simple like turning an adjuster screw. Because there's only a limited range of bucket thicknesses, re-ground cams are impossible. Regrinds start with a stock cam and then grind down the base circle, which increases the bucket thickness needed to achieve the proper valve lash. Jim Wolf's cams are ground from a fresh cam billet, so the base circle is the same as stock.

All the prototype cams we tested, and whatever final cam gets produced, are designed to work with stock valve springs, at least up to the stock rev limit. Regardless, we used Jim Wolf's valve springs as insurance against valve float in the event of a red-misted over-rev during a bad downshift. Not that we ever do such things.

The QR25's variable intake cam timing eliminates valve overlap at idle, so even with cams, the car idles perfectly and is as civilized as the stock car. Most of the cams lost significant amounts of torque below 3000 rpm and didn't start making serious gains until 4000 rpm. The QR25 makes so much torque at that low engine speed, though, that the torque lost honestly wasn't missed. The engine is so torquey that in street driving (which rally cars do still have to do) we still frequently pull away from stops in second gear, even with the cams.
 

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I suppose the procedure must be the same as in k24, so you need a type s oil pump, you need to tap a hole in the block and don't remember what else. So it isn't a couple of $$.
 
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