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Discussion Starter #1
I see the engine is using balance shafts similar to the 2.5 in my Daytona... And since they are actually pretty similar, I would imagine the first mod that should be done would be to remove the balance shafts, yes?
 

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I dont' know if that would be such a good idea straight out. I beleive the balance shafts are put in there to reduce the extra shaking caused by the increased stroke (increased over the 2.0 version). I know the mitsu 4g63(4) has balance shafts in both their 2.0 and 2.4 versions. if the motor is balanced really good, removing the balance shafts is a great Idea. 4 cyl cars tend to shake a little more than most bigger engines for some reason. that is why a lot of engine dyno shops won't put them on their machines. I know the local engine dyno around here wont' put a 4 cyl on his machine for that reason.
 
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Armond is the man when it comes to the 420a.. I've seen pictures of some of his "setup" for the avenger. I think he is probably putting down more power with that motor than anyone I've ever heard of.
 

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well, I am not putting down more power than some of the big boys like hahn racecraft.......yet ;). we'll see how this progressive nitrous controller works out, then it should be an entirely different story. :-D
 

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Discussion Starter #5
Well, the Dodge 2.2 and 2.5 that are on the G Bodies and many of the other K Based vehicles are indeed balanced pretty well, and its a recommended mod to make if the engine is so equipped (all 2.5s and the 2.2T3 had balance shafts; the other 2.2s didn't), but the engine in the SRT-4 may need them. I guess we'll find out how much of a difference it makes when someone buys one and takes off the balance shafts.
 

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Not that it matters too much, but the actual vibrations that the balance shafts are designed to combat have nothing to do with the balance of the rotating assembly. The balance shafts are designed to help combat second order vibrations that come from the basic firing order of the inline 4-cylinder configuration.

You can balance the rotating assembly absolutely perfectly, but you'll never get rid of second and third order vibrations in an inline 4.

With that said, the balance shafts while useful to extend bearing life, mostly are for keeping the additional engine harmonics from turning into noise in the cabin.

Should you remove them? I am not going to say... They are big, heavy and spin at 2x the speed of the crank (iirc). I guess it depends on what you are looking to do with your motor.
 

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they must go!! ill let you guys know what happens when i remove them. pray for me... :lol:
 

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I wouldn't worry too much about removing the shafts. Most people tear them out of the NA 2.4s (even a couple who have turbo-ed them) and the rotating assembly in this engine is basically the same.
 

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This seems like it will be a nasty project, dropping the motor down to get to them. Maybe I can get some guys at my brothers shop to do it for me, ill just bring in a case of beer and see what they say...
 

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iwntasrt-4 said:
This seems like it will be a nasty project, dropping the motor down to get to them. Maybe I can get some guys at my brothers shop to do it for me, ill just bring in a case of beer and see what they say...
Its really not that hard to do. In my 2.5 I took them out with the engine out, but I could have easily done it just by taking the oil pan off with the car in the air, and in fact thats how most people do this mod.
 

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Well, I haven't taken them out of my car. I was trying to keep the car as close to stock as I could but now I am putting on a 3" JRB exhaust and turning up the boost about 3 PSI via a grainger valve.
 

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balance shafts are not that necessary.
they are mostly there for everyday people.
to subdue the vibrations of having a long stroke 4 cylinder.
people have been removing them for years.
most people remove them from 2.4's when swapping them into neons.
sentra v-spec owners have also been removing them as of lately.
lots of dsm owners remove them.

i took them out of my 2.4, the motor is sitting on a stand right now awaiting a bunch of goodies for the cylinder head.
weak point on the naturally aspirated 2.4 are the rods.
keep the revs down and they are very reliable.

next year i'll spend the big bucks for longer rods and custom pistons with relocated wrist pins.

only reason i wouldn't remove them is to maintain warranty.
if i get an srt-4 i'd wait until 36k miles on it and then go crazy with it.
 

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you can use the rods from the 89+ 2.5 turbo motor in your 2.4 there even beefier then the ones used in the SRT-4 and PT turbo.
 

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I wonder if removing the balance shafts on th SRT will increase the lag being that your reducing the inertia.

For those who are new to the turbo seen, when you add a lighten flywheel , the engine spins easier being that there is less mass to turn. But that also means that the vehicle has less of a load which means it needs less fuel to maintain the power. Less fuel = less exhaust for the turbo to spool on the lower end.

If you remove teh balance shafts I think your lag will go up on the turbo?
 

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Exhaust Depot said:
For those who are new to the turbo seen, when you add a lighten flywheel , the engine spins easier being that there is less mass to turn. But that also means that the vehicle has less of a load which means it needs less fuel to maintain the power. Less fuel = less exhaust for the turbo to spool on the lower end.

If you remove teh balance shafts I think your lag will go up on the turbo?
No I would say it wont increase your turbo lag...in fact it probably wont affect it, but you will have more power all across your powerband (even before the turbo spools).

Balance shafts are just two counter roataing rods, spinning at witce the speed of the engine, sitting in your oil. Just imagine the power it takes to move these at twice the engine speed (say your at 6300rpms, they are at 12600 :shock: ). Now picture them sitting in your oil, frothing it up...
now consider that when you take them out, there wont really be more NVH, maybe a tad more vibration...but from all the people i've spoken with its almost unnoticable.
Now...take those suckers out!
 

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One of the guys up here toasted some bearings on the way to or from (can't remember) NG2K2 in his 2.4 swap. He removed the balance shafts and then compensated for the oil displacement by adding another 1/2 qt.

The theory is that the balance shafts in the N/A 2.4 also act as a windage tray. Consequently, he starved #4 on a hard turn and there goes that.

The new idea is to gut the balance shaft box (remove the shafts, chain, etc) but replace the box. One of the guys up here did that recently with his PT 2.4 swap. We'll see what happens :twisted:
 

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You guys need to go purchase that copy of Mopar Now (Winter 2003.) It shows the balance shafts and how to remove them. They said it will help with weight and reduce oil pan windage. I've got the entire article on the SRT-4 in pdf format if someone wants to host it.

It's big, 32MB. Host it if you want, but beware the mighty Mopar!

-Sam
 
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