Aluminum Rods in a 2.3

[Blindsey]

I need to know if anyone has successfully run an aluminum rod with a stroker? There is some talk that they are too large and thus you can't clearance enough for them......

 

[Clutch GSX]

Why would you want to? Lighter pistons are meant for higher revs and strokers are meant for lower revs and more torque. Aluminum would be a bad idea even if it worked.

 

[SpeedAddict62]

Why would you want to? Lighter pistons are meant for higher revs and strokers are meant for lower revs and more torque. Aluminum would be a bad idea even if it worked.

This is completely untrue. First off, you should read this:http://www.kidzuku.com/StrokeOrNot.pdf

Remember physics from high school? Force = (mass)(acceleration). That is, if you want to accelerate a certain mass, it will require a certain force. Lower the mass and it will take less force to accelerate at the same rate and it will be less stressful on engine components. Besides this, lightening up the rotating assembly will reduce imbalance, which is even more important in a stroker, as you would see if you read that article.

Lighter IS better. The problem is keeping the part strong enough to handle the forces involved while being light as possible.

 

[Clutch GSX]

Lighter IS better. The problem is keeping the part strong enough to handle the forces involved while being light as possible.

Exactly. Pure aluminum is not strong enough to handle the extra stresses that a stroker engine puts out. Aluminum is one of the weakest metals. Purely aluminum pistons and rods simply don't belong in a stroker where the side stresses are exagerated and there is no need to have that light of a piston or rod due to the lower RPM that strokers will see. Your statement about balance is incorrect. A running engine in real life is never balanced. That guy's formulas dont take into account the amount of force behind the pistons during combustion and the extreme resisting force created in the pistons during compression. When the first two pistons are at top dead center the combustion process occurs at the same time the second two are on their compression stroke. There is the force of combustion behind 2 pistons and the force of comprssion resisting two. Then when that stroke is finished the second two pistons combust creating the force of combustion on two pistons and no force against the first two pistons which are on their exhaust stroke. After that stroke is finished niether have any forces directly acting upon them except for the inertia that was created by the previous two combustions. After that stroke (the intake stroke for the first two pistons and the exhaust stroke for the second two) the first two pistons are back in their compression stroke creating an extreme amount of resistance on two pistons while the other two are on their intake stroke then the process starts all over again. As you can see, there are always inconsistant forces acting against the pistons and rods at any given time and there is absolutely no balance. The link you provided is all theorhetical and fails to account for many real world factors. His equations and therefore his charts are simply wrong.

 

[SpeedAddict62]

This will be my last post here, because we haven't helped the OP at all, so if you want to continue this discussion, please PM me.

However, I've got to say...I can't imagine how rough our engines would run if both pairs of cylinders fired at the same time . Firing order on a 4G63 is 1-3-4-2. That means that if cylinder 1 is on the exhaust stroke, 3 is on power, 4 is on compression, and 2 is intake, and so on. You're right, theory doesn't account for real world factors, but it can be a very good model, and that paper is a great example. I suggest you grab a book and do some reading on engine theory.

Exactly. Pure aluminum is not strong enough to handle the extra stresses that a stroker engine puts out. Aluminum is one of the weakest metals. Purely aluminum pistons and rods simply don't belong in a stroker where the side stresses are exagerated and there is no need to have that light of a piston or rod due to the lower RPM that strokers will see. Your statement about balance is incorrect. A running engine in real life is never balanced. That guy's formulas dont take into account the amount of force behind the pistons during combustion and the extreme resisting force created in the pistons during compression. When the first two pistons are at top dead center the combustion process occurs at the same time the second two are on their compression stroke. There is the force of combustion behind 2 pistons and the force of comprssion resisting two. Then when that stroke is finished the second two pistons combust creating the force of combustion on two pistons and no force against the first two pistons which are on their exhaust stroke. After that stroke is finished niether have any forces directly acting upon them except for the inertia that was created by the previous two combustions. After that stroke (the intake stroke for the first two pistons and the exhaust stroke for the second two) the first two pistons are back in their compression stroke creating an extreme amount of resistance on two pistons while the other two are on their intake stroke then the process starts all over again. As you can see, there are always inconsistant forces acting against the pistons and rods at any given time and there is absolutely no balance. The link you provided is all theorhetical and fails to account for many real world factors. His equations and therefore his charts are simply wrong.

 

[1992awdlaser]

Just a few points:

1. Aluminum rods are plenty strong for a stroker. The reason they are bigger than steel rods is to make them stronger.

2. Lighter engine parts= safer to rev higher than normal. What I mean is, by using aluminum rods and lightweight pistons(Mahle), you are effectively making your engine have a higher safe rpm.

3. I suggest everybody reads the thread listed below, especially anybody that thinks because you can't rev a stroker as high as a 2.0L, that aluminum rods are bad.

http://www.dsmtuners.com/forums/cylinder-head-short-block/311352-contructive-info-aluminum-rods.html

 

[Clutch GSX]

Duh. Im retarded. But the facts behind my example are still relevant and the balance issue is still a non issue and Aluminum rods are still not necessary or safe for a stroker.

 

[1992awdlaser]

Read the entire thread with the link I posted. Aluminum rods ARE safe and PLENTY strong for a stroker. And they will enable the engine to rev higher safely as I mentioned before.


The only two things with aluminum rods are:

1. Clearancing. a 2.0L only needs to clearance the main cap braces. A stroker will need to clearance the block.

2. Rod bolts need to be checked for stretch and replaced as needed. All the aluminum rod motors I know of have over 10,000 miles on them without needing to change the rods once.

 

[Clutch GSX]

Well I think its safe to say that the newer forged quasi-aluminum rods are worthy of handling extremes without drastic effects. I was more refering to the conventional alumium which is why I said PURE aluminum. Todays aluminum is not pure aluminum. My main point was that Aluminum rods are used to rev higher more safely but strokers gain no advantage revving higher due to their lower powerband so there is no point. I never said that forged alumium hybrid rods are bad. Older pure aluminum rods are no good and aluminum rods in general aren't all that necessary if your max RPM is 7500.

I would also like to know how the rod bearing oil clearance is affected when the aluminum expands in these newer rods. Also does this affect oil supply to the rod journal?

 

[1992awdlaser]

Come on. Obviously we would be talking about today's generation of rods and not the 70's generation. Yes, aluminum rods back then did have problems. But all the aluminum rods made for our cars today are of new technology. A stroker doesn't have a set powerband, no engine does actually. You can rais the powerband with bigger cams, smim, or a bigger turbo.

Bearing clearances don't change much if at all. The bearings are touching each other when the cap is tightened down. The outer part of the big end expands, not the inner part.

 

[DSM_PWR]

.....but strokers gain no advantage revving higher due to their lower powerband so there is no point......

Are you kidding? the main reason people get strokers is to spool larger turbos, like the post above, you can easily raise the power band by adding bigger cams, SMIM, cam gears, larger TB, Bigger IC pipes, etc... and what do you have? a better lower and higher power engine

But you do have the main concept down

 

[Defiant]

Clutch, you need to subscribe to different comic books.

OP, if you'd like to try again, have at it.