Scat rods/crank limitations

soupbean wrote:So with the aluminum rod "life span".... How do we determine when the life of the rod is gone? Other than when it spits out of the pan...

You measure their center-to-center to check them for stretch.*  And you also buy a lot of them, not just a set of 8.  The more often you are servicing your engine, the more likely you know when you swap out a rod.  In the case of low hp/low rpm builds, aluminum rods of today can last a lot longer than most people think they will. Of course, a steel rod will last a lot longer in such an engine; choice in rod matieral depends on a lot of things.

Paul

* In schmitty's answer above, stretch is one possibility of what is being indicated when the bolts don't screw into the rods effortlessly anymore. Overall rod dimension should be check as well.

As it seems the topic has scattered like a pack of rats at the dump firing range! I can provide you with the information you seek, just click the link!

Dave.

http://scatcrankshafts.com/

Walter Grose has been mid 7s with his turbocharged a headed 533. Maybe he will chime in.

Here is my delima, my strong desires of staying n/a were short lived as I know many of you have been in the same boat. I sprayed the car with a small plate and it liked it, and I did too  . The decision was made to send my intake to Steve for some "room to grow" but in alignment were Blake is with his current set up, I was told not to spray more than a 200 shot and not to turn it harder than 7200 with the Scat forged crank and the h-beam rods with arp 2000 bolts that I currently have. Something tells me I will "lay the dick" to it as Jon said next year. Trust me, I know anything can happen but I want to be confident that i have the right parts in place to be able to let it eat consistently, not just a one time thing just to say it HAS done it.

I was also told if I go to a different rod and keep my crank, I can get away with more. But at the same time, I see some of you guys prefer the Bryant cranks and I'm sure there is a reason for that.

soupbean wrote:Here is my delima, my strong desires of staying n/a were short lived as I know many of you have been in the same boat. I sprayed the car with a small plate and it liked it, and I did too  . The decision was made to send my intake to Steve for some "room to grow" but in alignment were Blake is with his current set up, I was told not to spray more than a 200 shot and not to turn it harder than 7200 with the Scat forged crank and the h-beam rods with arp 2000 bolts that I currently have. Something tells me I will "lay the dick" to it as Jon said next year. Trust me, I know anything can happen but I want to be confident that i have the right parts in place to be able to let it eat consistently, not just a one time thing just to say it HAS done it.

I was also told if I go to a different rod and keep my crank, I can get away with more. But at the same time, I see some of you guys prefer the Bryant cranks and I'm sure there is a reason for that.

 
 
With your parts and a GOOD tune up the odds are good for a reasonable engine life @ 250 spray.
 
A poor tune up at 250 will kill something grave yard dead.

go big or go home........... 

soupbean wrote:Here is my delima, my strong desires of staying n/a were short lived as I know many of you have been in the same boat. I sprayed the car with a small plate and it liked it, and I did too  . The decision was made to send my intake to Steve for some "room to grow" but in alignment were Blake is with his current set up, I was told not to spray more than a 200 shot and not to turn it harder than 7200 with the Scat forged crank and the h-beam rods with arp 2000 bolts that I currently have. Something tells me I will "lay the dick" to it as Jon said next year. Trust me, I know anything can happen but I want to be confident that i have the right parts in place to be able to let it eat consistently, not just a one time thing just to say it HAS done it.

I was also told if I go to a different rod and keep my crank, I can get away with more. But at the same time, I see some of you guys prefer the Bryant cranks and I'm sure there is a reason for that.

well if you are going to lay the "dick" to it check the piston casting numbers to see if they are for heavy nos use,other wise the 250 shot will be your limit.as john said my scat crank and rods have lived through a 48 jet this year.i currently have the motor down to hopefully fix the head gasket problems I have been plagued with this year.the crank and rods check out good the bearings look good enough to use again.crazy thing is the king main bearings are 3 years old and the thrust bearing was hardly any ware.

That IS direct port..... the tune will be good.

If I may, offer an explanation that could assist you in reaching a responsible decision.

The task before you is to hammer an eight penny nail into a oak board that has not been drilled. You have a choice of two hammers. One hammer is a carpenter's hammer and the other is a ten pound sledge hammer. Oh did I mention you will be holding the nail with the fingers on one hand and swinging the hammer of choice with the other. Which hammer do you prefer?

What the f**k is my point you ask! The lighter load of the carpenter's hammer versus the heavy load of the sledge hammer may make a difference to your fingers if you miss the nail!

That that that's all folks!

Dave.

LivermoreDave wrote:If I may, offer an explanation that could assist you in reaching a responsible decision.

The task before you is to hammer an eight penny nail into a oak board that has not been drilled. You have a choice of two hammers. One hammer is a carpenter's hammer and the other is a ten pound sledge hammer. Oh did I mention you will be holding the nail with the fingers on one hand and swinging the hammer of choice with the other. Which hammer do you prefer?

What the f**k is my point you ask! The lighter load of the carpenter's hammer versus the heavy load of the sledge hammer may make a difference to your fingers if you miss the nail!

That that that's all folks!

Dave.

I'm still asking this very question  

the point is you are playing roulette if your tune is off so pick your hammer

My concern is with the nail

When I was a kid, I had hundreds, maybe thousands, of hours behind an aluminum rodded engine - it never broke. And it has the worlds crappiest oiling system, splash oiling. And subjected to violent stops from rocks and stumps. Yep, the lowly Brigs & Stratton flat head lawn mower engine.

But then I know a guy who broke a Scat rod right in the beam below the piston on firing up a new BBC. And another guy who lost two SBF's in a row with Scat rods breaking.

XEngr wrote:When I was a kid, I had hundreds, maybe thousands, of hours behind an aluminum rodded engine - it never broke.  And it has the worlds crappiest oiling system, splash oiling.  And subjected to violent stops from rocks and stumps.  Yep, the lowly Brigs & Stratton flat head lawn mower engine.

Those applications are tough sons of bitches! Every time I service my mowers I wonder how do they survive as they do in such harsh environments! Dust, summer heat and used for many things other than the original intent. I too have seen mowers, especially push mowers that appear to have never been serviced and nine times out of ten the engine will outlast the mower deck or rider! Yes sir, tough sons of bitches they are!

Dave.

LivermoreDave wrote:

XEngr wrote:When I was a kid, I had hundreds, maybe thousands, of hours behind an aluminum rodded engine - it never broke.  And it has the worlds crappiest oiling system, splash oiling.  And subjected to violent stops from rocks and stumps.  Yep, the lowly Brigs & Stratton flat head lawn mower engine.

Those applications are tough sons of bitches! Every time I service my mowers I wonder how do they survive as they do in such harsh environments! Dust, summer heat and used for many things other than the original intent. I too have seen mowers, especially push mowers that appear to have never been serviced and nine times out of ten the engine will outlast the mower deck or rider! Yes sir, tough sons of bitches they are!

Dave.

Pump them to 100+ per cylinder and see how they do then.

put a billet alum rod in it and then try it again.......:-)

dfree383 wrote:Pump them to 100+ per cylinder and see how they do then.

I would assume as good as any internal combustion engine that's power has been increased 20 times it's original intent!

Dave.

XEngr wrote:When I was a kid, I had hundreds, maybe thousands, of hours behind an aluminum rodded engine - it never broke.  And it has the worlds crappiest oiling system, splash oiling.  And subjected to violent stops from rocks and stumps.  Yep, the lowly Brigs & Stratton flat head lawn mower engine.

I have seen several Tecumseh engines on "Eager 1" lawn mowers at the SEARS repair facility which all had broken aluminum connecting rods.
They EXPECTED it to happen, sooner or later.

Thanks for the input fellas!