NefMoto

talking about connecting rods.

pros/cons?

Drilled gets better oil lubrication to the small pins up top.

Literally something I was gonna question, but just assumed that rifling is a good idea.

Is it not supposed to be for prolonged revs?  I've just bought rods, but not sure if they're drilled or not.

Guy says they're not, but the little end has drilled holes, but that's all you can see from the picture.  I tend not to push much beyond 6k, so it should be reet.

1.8t, tops of 350 brake, it'll be reet. :)

rifle drilling is basically a hole bored from the big end to the small end through the center of the rod for what carsey said. It's supposed to make way for oil under pressure to the small end of the rod which normally is just sprayed by the oil jets.

I guess really I want to know the cons and when the cons out weigh the pros and vice versa.

I know this, but I'm saying the rods I've just bought I'm unsure about whether they are or not, the pictures suggest they are, but the guy I bought them off says they aren't.

Anyway, I think it'll be fine unless they're getting a hard beating for long periods of time?

personally id say they would be fine if you have good oil pressure through the squirters.

Non- drilled 1.8T rods have 2 holes under the small end of the rod.

you will be fine with non drilled rods since you have oil squirters,  i seriously doubt you will put enough miles on your car to have loose wrist pins . 300-400,000 miles.  but rifle drilling would prolong this from happening.  i usually get the rifle drilling option on all rods i order, just peace of mind for me knowing the pin is being force lubricated. as for cons i really dont see any cons to rifle drilling, it may reduce the strength of  the rod  slightly , but not enough for concern.

This was my thinking Chris, but not too sure now.

That said, I've just bought IE rods, I'll have the bushes checked for fitment at an engineering shop and hopefully all'll be reet.

Audi S3 2001.

I am after connecting rods too, and I am in the same boat concerning riffle drilled or not.

Integrated Engineering charges like 100$ if I want the set riffle drilled. The set is 399$.

Till now I am deciding that I wont get it riffle drilled. It should work just fine without it. Its fancy but it comes with a price.

I see no point of buying it riffle drilled, specially that I wont push more than 350 bhp and torques.

Rifle drilling is beneficial for vehicles with poor wrist pin lubrication.

IE, no piston squirters. It is completely unnecessary in this application.

I posted up a thread on a Facebook group we've got in the UK.

A massive argument started and the guy said exactly the same as DD.

I think this reply is a good one: 
"Because forced pin oiling is only a supply reservoir and is not in fact a pressurised bearing surface like a main or big end bearing....

The other downside is the oil can only pass from the rifle drilling when the rod is pulling the piston down the bore and there is space between the wrist pin and the bearing surface.....meaning 1 in 4 strokes!

Whereas a properly designed little end arrangement will supply a greater lubrication and cooling"

Long story short, I think it's just been another thing on the internet that says we should all have it, but, in fact, we'd be fine without.

So glad I started this thread guys! Thanks for the replies!


Adam, maybe you could ask your FB peeps about a machined ring around the wrist pin where the rifle hole would meet, allowing for oil to flow consistently. I'm talking maybe a .003-.005 deep ring, just enough for oil to flow under pressure but not enough to compromise wrist pin strength.

So far, rifle drilling seems like overkill.

I highly suggest people look into Rosten rods and other internal parts out of Norway.  Geir Rosten is the man.  They are simply the best of the mass produced rods.  Also, the oil port is pointless and weakens the rod.

www.rosten-performance.com

That's pretty far from the truth. Without the rifle drilling, on a 400-500 bhp 1.8t the bushings in a set of 19mm rods last 40-50k miles tops before they are way, way oversize. At that point you are pretty well hosed as re-bushing a tapered rod is a specialty job that very very few people are going to mess with for you. As for reducing strength- the oil hole is located at the centroid of the beam's cross section and contributes virtually nothing to increasing stress levels in the component. In fact, many of the very highest end applications are playing around with hollow beam connecting rods these days- usually diffusion bonded together assemblies to yield a hollow core. So, from that respect it's really a win win.

The factory didn't drill 4" long holes in a few million components just for fun....

On S4 V6 applications, I would say it is far more optional. You have way, way, way more pin bushing supporting the pins per specific amount of output. They will last a LONG time without.

There are plenty of options out there as good or better then Rostens. We hone all of our components right here in house on the same exact Sunnen machine that Carrillo uses (ML-2000). Scat also hones all of their parts in the US. Just stay away from anybody selling import stuff without even checking them or honing them to fix the big ends- which is most all of the ebay sellers and start ups.

Thanks for your input engine_nerd!

True about the oil passage thru the rod yes... but the "rifle" drilling get's it's name from the gun barrel drilling technique which is called barrel or "rifle" drilling, which creates a slight spiral down the length of inside the barrel. In a gun it's what make the bullet spin, which improves accuracy x a million... If I recall, rifling in oil passages was used in applications where oil drain back (if you will) was an issue, with rifling the oil would drain back slower (in between oil pump surges), hence helping "supply" oil to places that otherwise struggle to get or keep oil supplied.

Hope that makes sense.

Purpose of "rifling" is because in many applications the wrist pin does not even have oil supplied to it, meaning assembly lube is the last "oil" actually applied and supplied to the wrist pin... once assembled, on a motor with rods that have NO rifling, the wrist pin only gets oiled by "splash" which doesn't obviously supply much to the inside, meaning lubing the entire wrist pin and rod around it.

So anyways, the rifling of the hole or passage thru the rod helped the oil make it to the wrist pin. A straight thru hole as the motor turned and with the extreme lunges up n down as cylinders fired, along with rotation and enertia, the straight thru hole did not work as well as one rifled. The spiral allowed the oil to have a lil resistance to NOT just flow back down the passage, therefor making it to the desired location... the wrist pin.
*Some people believe the rifling also created better cooling, by way of more surface contact with the oil so it could withdraw more heat as the oil passed thru, but I do not believe this has ever been proven fact.

Are you sure you replied to the correct post in this thread?

Yeah I am dumba$$... Get over the other thread and read the answer to your question! Sheesh!
Rifle drilling was first used in Diesels I believe, then later used on motors with alot of wrist pin "slap" to help supply more oil to the bearing journal to eventually make its way out of the journal and fill the space to prevent or reduce "slap". This "hole" through the rod has a beveled entrance to assist with creating pressure to help the oil push thru the tiny hole, the hole is just the "A HOLE" with out rifle drilling they would likely just call the rods "drilled". When testing was done it was found that using "rifle drilling" that this assisted in the oil not being "slung" out by the rotation. So now there is such thing as "rifle drilled con rods"

Which our motors don't really require because our's have oil squiters (I just can't recall if they have rod or block squiters of the top of my head)

"you're welcome"

I edited and added more info to help describe it more completely.

CON: is the rod can be weaker. (typically this is the case when a rod NOT originally designed with the rifled hole). If you buy rods designed and tested with the rifled hole, you'll be totally fine.

PRO: is that oil will be "supplied" to the wrist pin, not simply lubed by splash/squirt.