Balance Shaft Removal 2.5 QR25DE

[sexybeasty]

I have done some extensive reading and discovered that the balance shafts in the QR25DE engine are somewhat unnecssary, and result in a loss of HP due to parasitic drag, extra weight, oil frothing and subsequent starvation at high rpms, and limitations on engine rpms (the last two are due to the fact that they spin at twice the engine revolutions). In fact, the only benefit gained from them is a smoother engine. I would like to remove the balance shafts from my 2.5 engine and install a balance shaft removal kit from JWT. It's a cheap and relatively easy way to add 8-15 HP at only $80.00 (and save some weight, which is always good). By comparison, my Fujita WAI cost $160.00 and added only 6.659 BHP or 4.99 WHP, according to thier dyno results.

My questions are:

1) Has anyone tried this on thier 2.5 Altima yet?2) If so, did it increase engine vibration to a noticeable degree?3) Did it have any negative effects on engine performace or reliablility?4) Did it increase performance?

All the Se-r Sentra people do this; it is the gateway to building an engine with any amount of power. Without removing it, you really run into serious problems when adding go-fast parts to your engine. It is allegedly completely safe by all accounts, but I just wanted to hear some tesimonials and opinions.

[LongBeachCoupe]

some linkage to read available?

[sexybeasty]

I used google mostly, but here are a few links that I found helpful. Some might get edited or deleted b/c of where they came from

Got this from another post here; it's what got me started. The post didn't really get into balance shafts though:http://www.nittotire.com/blog_detail.asp?id=23... and this one:http://www.jimwolftechnology.c...D=432

Here's some academia:http://en.wikipedia.org/wiki/Balance_sh ... ni...2.htm

And some other forums please don't delete Jwt Balance Shaft Removal Kit - B15sentra.net - Nissan Sentra Forum

These things seem to be bad news for motors, and were actually the cause of early QR25 engine failures. They kill your engine at high RPMs through oil starvation due to frothing. They are just there to make regular folks who drive to and from work happy that thier "economical" 4cyl feels like a V6. John and Jane driver typicall don't rev thier motors high enough to realize the destructiveness of the balance shafts, so it never becomes an issue. Just to clarify, the shafts are not there to prevent harmonic vibration, or anything that would cause the motor to self-destruct. Besides, I don't think JWT would sell a product that deliberately harms engines, or gives you a lot of fun for 5K miles before your engine pops.

[sexybeasty]

Here are some more, relating to the Spec-V, but it's the same motor:

http://www.sportcompactcarweb.....htmlhttp://www.sportcompactcarweb.....htmlhttp://se-r.net/general/QR_balanceshaft.htm

You can do this without the kit, it's just that the kit includes the windage tray and scraper, which are great to have.

Oh, and it appears the crank at least is forged? That would be good news! All in all, the QR25DE is a very good block it seems.

[LongBeachCoupe]

so we would have to open the block for this it seems... (if im reading correctly)... if thats the case.. id wait till you can put all new components inside before i did this labor..

[cuzzbubba420]

Unless your doing the un-install/install yourself it may a bit pricey to have a mechanic do the mod.. I am interested in this for sure though as I have read the same information as you.

[Mr. Music]

so we would have to open the block for this it seems...

I think you just have to pop the oil pan off. Not like that would be easy though...

[sexybeasty]

Yeah, you just take the oil pan off. On a lift with the right tools (which I have), it's supposed to be a 2 hour job- tops. You can even read the instructions on JWT's site. Just wondering if anyone else did this yet.

For doing the pistons and rods, I'll find out if you can do that from underneath when I remove the balance shafts. I wonder if the crank is really forged in Altima 2.5 or is it just for the Spec engine? If it is, that's VERY encouraging news.

[nnguyen]

it seem that you can just cut the chain w/o removal of the balance shaft. seem like a little neat project to do. Expected to get at least 8 hp gain from it :O . not bad considering the kit is 89. plus the labor is not all that bad. you dont even have to remove the block. I think ima do it :O one question. is there any revision on our QR engine compare to the ones in spec or older altima 2.5?

:O ponderin

[LongBeachCoupe]

well we know the headers wont fit... idk if theres more differences...

[sexybeasty]

I don't think you will find the kind of differences like with the headers. The BS unit is self contained in the bottom of the block near the oil pan b/c of the design of the block- there's no place else to put them. Other manufacturers have put BS along side the crank and drove them off the accessory belt or some such means; in those cases getting to them was incredibly difficult as you would have to pull the motor then disassemble it.

With the QR25, there are no provisions for mounting the shafts anywhere else except the bottom of the motor, so I am nearly 100% certain there should be no surprises. I haven't checked to see if there is a crossmember or exhaust in the way that has to come out first, but that's not a big deal.

I'll contact JWT to find out more details- or I might just spend the 90 dollars. What's the worst that can happen- I'll take off my oil pan and have to put it back on

[nnguyen]

Just be careful. Since it do harm your engine in some way in the long run.! Try it out and let us know! =]

I think im doing CAMs pretty soon. and have it tuned by SGP or something :O

[Mr. Music]

it seem that you can just cut the chain w/o removal of the balance shaft.

Maybe... But if you remove the assembly, it will allow for more oil; on the order of another quart.

[sexybeasty]

Maybe... But if you remove the assembly, it will allow for more oil; on the order of another quart.

More oil is better, not to mention the weight savings...those things gotta weigh 40-50 lbs at least.

BTW, It shouldn't harm the engine in the long run; Yours truly might harm the engine doing it, but in theory (and practice according to other qr25de engine owners), it shouldn't harm the motor at all. If anything, removing them is a good thing.

I'm guessing to that I probably won't notice the additional vibration either due to the excellent mounts and vibration control in the altima.

[nnguyen]

has anyone try this yet? I think ima about to do it. Got a mechanic that ready to do it also. But not sure... kinda iffy. about ****ing up my 18,000 miles 08 altima engine lol. LET ME KNOW :O

[dldjros69]

Well nnguyen you should do it. Have your mechanic take pics along the way. I wonder how much hp this will really add.

[ReviT]

anyone done this yet? im so interested!

[nnguyen]

i would do it. but it seem like a 8-9 hours job since it took the other guy on sentra forum b16 to do his lol.

It more then just removing the oil pan omfg -.-

my mech can do it, but he said it himself he not even sure. plus no funds to get the bsr kit haha :O so broke after my rims.. i still want my fascia.

Anyone wanna fund the bsr kit? and ill try to do it? lol.

[ReviT]

i would do it. but it seem like a 8-9 hours job since it took the other guy on sentra forum b16 to do his lol.

It more then just removing the oil pan omfg -.-

my mech can do it, but he said it himself he not even sure. plus no funds to get the bsr kit haha :O so broke after my rims.. i still want my fascia.

Anyone wanna fund the bsr kit? and ill try to do it? lol.

on JWT it says it should only take about 2 hours. how the heck did u get 8?

[ReviT]

bump

is anyone going to try this?

[dldjros69]

Somebody try this already!!!!

[sexybeasty]

I'm totally doing this on my next oil change and will provide some feedback. I just got an oil change, so I'm going to wait, esp given the price per barrel I researched it and removing them is completely safe, so I'm expecting positive results.

[Mr. Music]

I'm totally doing this on my next oil change and will provide some feedback. I just got an oil change, so I'm going to wait, esp given the price per barrel I researched it and removing them is completely safe, so I'm expecting positive results.

Are you sure that JWT's kit works with our QR's? Pretty much every product made for the QR25DE does not work with the new ones in the Altimas since Nissan changed something... Make sure you take note of how it is installed just in case you need to put the assembly back on, lol.

[ReviT]

that was my worry. but it also says u dont need the kit to do this.

[sexybeasty]

def going to not cut the chain in case it has to go back in, or if I want to put it back in. I hope it can be disassembled like most chains, otherwise I'll have to order a new one from Nissan and go without my car for a few days. I'll check with JWT before buying as well to make sure the kit works on our qr25de.

[ReviT]

Ok has anyone talked to JWT about this? I emailed them but didnt get a response..

[D-Roll]

Good luck with gettin the chain off without cutting it LOL. There is a lot of engine vibration after doing this mod, bewre.

[sexybeasty]

D- how do you know there is a lot of engine vibration after you remove the shafts? Just curious b/c this is my first 4cyl car that has balance shafts; I've only noticed vibrations in those cars at very specific rpms (2200 in my OLD Camry). Also, the Sentra crowd says it's barely noticeable, but this could be b/c the Sentra doesn't have the same kind of ability to damp vibration and sound as the Alty- I dunno. Maybe we will feel it- it's tough to say...

Or have you done it and are holding out on us

[D-Roll]

D- how do you know there is a lot of engine vibration after you remove the shafts? Just curious b/c this is my first 4cyl car that has balance shafts; I've only noticed vibrations in those cars at very specific rpms (2200 in my OLD Camry). Also, the Sentra crowd says it's barely noticeable, but this could be b/c the Sentra doesn't have the same kind of ability to damp vibration and sound as the Alty- I dunno. Maybe we will feel it- it's tough to say...

Or have you done it and are holding out on us

I came close to doing in on my 02 SpecV, but never did it. I had friends of mine that did and regreted it. When you have MMI and an engine damper, your car will vibrate like crazy cruising on the hwy with the balance shafts removed. If you handle handle that, then go for it

[dldjros69]

So you are saying that it is an unbearable vibration?

How much power does this offer?