I've been searching though the forum trying to find info on the subject and have only found a bit here and there. There's a bit about it on the web but I'd like to hear it from people that own 4g63/64s.
So with that being said, what are the Pros and Cons of both.
It would be good to hear from you guys that own the Long Rod setups and why you built that particular setup over the Short Rod do you feel any notable difference or was your decision base on efficiency, longevity better Rod Ratio etc.

Thanks in Advance.

 

I can't think of any benefits on the long rod setup other than being able to rev higher and last longer due to the rod angles not being severe. If I started over, I'd built a long rod block.

 

LR2.4 to SR2.4 (for instance)-

Less vibration
Reduced sideload on cylinder walls
Increased rev capability with greater reliability vs a standard rod at the same RPM

NO DIFFERENCE IN POWER

 

How many engine failures have you seen in the 2.4 due to sideload?

Also how does a longrod rev higher, how is this different then a long stroke motor, i was under the impression a shorter stroke engine allows for higher RPM operation?

Or am i confused and does the shorter stroke involve a smaller crank and longer rods?

 

They can rev the same. The answer to your question lies in rod angularity. A long rod pushes less as the crank is at 90* and 270* rotation because its less angle at half stroke. The total angularity change is also less. Basically an engine with a smaller rod stroke ratio isnt going to last as long at a given RPM as something with a larger rod stroke ratio. Its related having a short stroke since the deck height only will allow some much. If you build a custom block with a deck height as high as it needs to be you could shove a HUGE connecting rod into a long stroke motor and get the best of both worlds.

Look at IHRA mountain motors for more direct application. They have added INCHES to the deck height of a big block Chevy, Ford, or Mopar in order to make their 815cid motors last as long as possible.

That I can think of, I have seen 4 SR2.4s fail after extended (and I mean LONG) time at high rpm. There are other factors that can cause the failure and when its catastrophic its not possible to point to one exact reason. However I look at F1 cars with a R/s of 4:1 running 18,000 for 2 hours at a time. Or even crazier, Volvo motors running almost a 2:1 ratio and running for 350k miles. They both do it for difference reasons but longevity is a key one.

2.3 or 2.4 with a R/s of 1.5:1 ratio- max angularity of 19.47*
2.4 with a R/s of 1.56:1 - max angularity of 18.75*
2.2 with a R/s of 1.659:1- max angularity of 17.58*
2.0 with a R/s of 1.7:1- max angularity of 17.06*

 

I think I just got smarter....

 

I have a collection of Aaron's quotes in a folder on my computer, and this is why.

 

The rod ratio has very little impact on RPM capability with regards to piston/rod forces, "all things being equal." We are talking 50-100 RPM difference at the 10,000 RPM level between the 150mm rod and 156mm rod, it's nothing.

Things aren't equal though and the long rod setup can have a lighter piston which reduces wrist pin forces. While the long rod ends up heavier compared to the short rod, the net effect CAN BE a lighter rotating assembly.

My opinion, but if it is an engine that's going to see actual competition, the best bet is simply using shelf-stock parts so that when you blow them up, you can replace them with little down time. If you start buying rods and pistons in non-standard sizes, you have the potential to waste an entire season waiting for new parts. If that's not a concern, then you might as well optimize if you are willing to spend the extra.

It does seem the longer dwell time at TDC can cause problems on low-octane fuels though...

 

My VIII will probably never see True competition as it is my DD, I only put 98 pump fuel in it, but will more the likely see racing fuel when it's finally built.

Thanks for the input guys, never such a thing as to much information so feel free to add. It'd be good to hear more opinions.

 

I thought Manley and Wiseco (And JE) was starting to stock these as off the shelf due to their popularity?

 

Smurf, I just ordered a set of LR 2.4 Wiseco pistons for a customer a few months ago... took 4 weeks to have the pistons made...

 

You guys certainly know your stuff at English, Thanks for the information

 

I stand corrected

 

We are working on getting the 1400HD (well have been for awhile) as a stocking item. I think it will finally start to happen here before too long. Some interesting changes coming to their piston line up

 

Would like to hear more about the changes as the 1400HD already seem to be the best on the market, Its what im using.