Rod bolt question? 8740 or 2000
I have 8740's in my LS3. It makes 650hp plus to the flywheel and I shift it at 7k all day long!! It may blow next time out but so for so good. Good luck with ur build. If not sure go with the 2000's.
RPM loads the bolts, not nitrous or boost.
The stock bolts do well, don't they?
The aftermarket rods have 7/16 bolts. The 8470 is better than stock.
The 2000 is only a little better than the 8470.
Ron
The stock bolts do well, don't they?
The aftermarket rods have 7/16 bolts. The 8470 is better than stock.
The 2000 is only a little better than the 8470.
Ron
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TECH Fanatic
Joined: Jun 2011
Posts: 1,343
Likes: 8
From: Katy, TX
and as others have said, its RPMs that drive the need for bolts with a higher preload. I recommend checking the dynamic forces on the rod bolts against what preload you can achieve, verified with a bolt stretch gauge. 8740 should be good to around 7000 or so, based on the last time I checked (assuming reasonable conservatism and contingencies).
TECH Apprentice
Joined: Oct 2007
Posts: 302
Likes: 20
I wouldn't bother with the 2000's, they're not much stronger, not enough to warrant spending more.
Lots of old BBC's were rebuilt with 3/8" stock thru-bolt rods and spun to 7K plus, swinging big ol' heavy pistons. Don't overthink it, but it's good to think everything through and determine where to spend your hard earned cash.
On The Tree
Joined: Jun 2010
Posts: 120
Likes: 2
as stated above , RPM will stress rod bolt not the power level. because on a power stroke the rod will push against the crank and the rod bolt will not be stressed. But on the finish of the exhaust stroke the piston will be pulled down so the rod bolt will take all the stress.
Anytime you change rod bolts you change the clamping force and bore distortion of the big end so its critical to check the roundness if you switch bolts. Even with hbeam rods there will be change and always better to be safe and do it right the first time!!
I agree with those saying rpm is the concern but would add piston weight factors in. Which is the reason why you might go heavier duty rodbolts for a nitrous or boost build as those pistons might be heavier.
TECH Fanatic
Joined: Jun 2011
Posts: 1,343
Likes: 8
From: Katy, TX
good point, I don't know for sure, but it seems that pistons for boost would actually be lighter because of the material removed from the top for the dish volume. maybe someone else can chime in on that.
Piston weight is always something to be considered as the extensive load increases with higher rpm. The piston crown and thickness can be altered but you also have to factor in ring placement as with any boosted application they will change in keeping the support above the top ring being enough to support the power adder.
For $40 bucks extra I would get the 2000's...
Same reason you get arp main studs, a lot of people don't need them for their 500-600 hp builds.. But they do it for peace of mind..
Same reason you get arp main studs, a lot of people don't need them for their 500-600 hp builds.. But they do it for peace of mind..
You think maybe they leave the crown thicker if a piston will see the extra load of boost or nitrous?