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con rods
https://www.slantsix.org/forum/viewtopic.php?t=16417		 Page 1 of 1
Author:  dusty7t4 [ Fri Mar 03, 2006 10:16 am ]
Post subject:  con rods
(I tried posting this in the engine section but didn't get any responses)

for those of you around 300 horse or at least alot more than stock, did you have anything special done to your rods besides the basic magnaflux, shot peen, check for straightness?

I have an engine rebuilder here that wants to grind off the ridge running from crank hole to cam hole along the length (side) of the rod, and round out all the 90 degree areas around the rod bolts. says that this is where they would fail at higher rpm and horsepower, etc and since I am going to be around 300 that I need it.

is he blowin smoke here or have any of you done this?

for those of you that have had a rod fail, what was the cause?

-dave
Author:  Dart270 [ Fri Mar 03, 2006 11:23 am ]
Post subject: 
That is a good prep technique for removing "stress risers" that can split into cracks under high load. The stock rods should be good to somewhere around 300-400 HP with good prep. More HP with lower RPM, btw (using boost for example). I have made about 270 HP @6000RPM with stock rods with no grinding, but balanced, crack checked, and new rod bolts.

Lou
Author:  slantvaliant [ Fri Mar 03, 2006 11:54 am ]
Post subject: 
The idea is to give remove or give a large radius to any inside corners. Removing metal to add strength - you have to love that.
It does need to be done carefully. Grinding can induce stresses in the workpiece, as can polishing. Done well, it's a good thing.
Author:  dusty7t4 [ Fri Mar 03, 2006 12:12 pm ]
Post subject: 
thanks lou and slantvaliant, that helps to know your experienced numbers

okay, so it IS a good thing, that is comforting.

how much do you normally pay for this treatment? If I remember right it was like 50 bucks a rod :shock: I could be wrong

I am wondering if the cost equals the benefit for a 300 horse slant. seems like since it is only 300 compared to other engines that are born with that hp, it might be overkill. I guess I am asking if you think 300 hp needs it

-dave
Author:  Dart270 [ Fri Mar 03, 2006 1:51 pm ]
Post subject: 
I don't think I would bother personally. You can buy a set of custom steel rods for about $800-1000, and you'll have $4-500 into yours by the time you're done.

BTW, an honest 300HP (~12sec 1/4 mile in a 2800lb car) is a big number for a naturally aspirated Slant. For boosted apps, you can turn lower RPM, make 300HP, and not worry about the rods without fancy treatment except good rod bolts and balancing/resizing.

I have a hard limit of 6000 RPM on my motors with stock-type internals. Of course, you can still blow your motor with any buildup...

Lou
Author:  Slant Cecil [ Fri Mar 03, 2006 2:59 pm ]
Post subject: 
You can debur and polish the side beams yourself with $75 worth of tools.
I'd first have the rods magnafluxed before putting any time in them.
Plus you can do the oil system mods with the same tools.
Author:  slantzilla [ Fri Mar 03, 2006 4:01 pm ]
Post subject: 
I have stock 198 rods in my moder. Mike polished them and put in ARP 340 rod bolts. (Sounds cool, but they are exactly the same bolt that goes in a Slant anyway) Mine are not shot peened.

I have 2 years on them with spray shifting at 6200, and at the end I was making just under 375 horse. Mike looked them over when he had them out this winter and they still looked good. :shock:

Slant rods are forged to start with, so they are a decent piece. Biggest mark against them is that they are long. :shock:
Author:  Ron Parker [ Fri Mar 03, 2006 7:10 pm ]
Post subject: 
Im with Bagel on this one i run stock 198 rods on my engine shift about 6100 been in there for three years. I doint know how much horsepower im making but the car goes on a good day 12.60 on engine in a 2400 pound car. Thanks Possum :D










Using A Tenessee Moonshiner To Burn A Bagel
Author:  james longhurst [ Sat Mar 04, 2006 4:50 am ]
Post subject: 
don't worry about it. i speak from experience when i say that a slant will still run with a broken rod! a little rough, but it made it across town! :shock:

-james
Author:  dusty7t4 [ Sat Mar 04, 2006 6:02 am ]
Post subject: 
I am going to be running around almost 11 to 1. plan to just magnaflux, straighten, peen and balance (new bolts too)

thanks guys

-dave
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