LT1-LT4 Modifications - used rods
07-21-2007, 05:54 PM
So I guess the engine I have sitting in my garage has I beam style rods, I'm gonna need something a little better I guess. Unless Eagle underrates their parts. They say the I beam rods can only hack 500hp, on the bottle I'm shooting for 575 rwhp. So I guess I need some H beam rods.
Would I be ok with used rods? New H beam rods cost $430 for what I need, well this is another expense I wasn't expecting for this motor.
07-21-2007, 06:21 PM
Nothing wrong with a used set of rods. Just have them checked out to be straight and true and make sure they don't need reconditioned or anything.
07-22-2007, 09:40 AM
Before metalurgy and machining were as good as they are today a lot of builders prefered used rods to start with because if there had been a flaw it would have shown up.
07-22-2007, 06:43 PM
Thanks guys, guess my search for a good set of used h beam rods and a forged crank are on.
Guess I'll save the eagle I-beams for when I put the other lt1 in my truck.
07-22-2007, 08:39 PM
Here is an alternative rod for you, they are rated to handle 700 HP @ 7500 rpm. http://store.summitracing.com/partdetail.asp?part=SCA%2D25700716&autoview=sku
One other thing that you can factor into your decision is that most connecting rod manufacture's rate their product at 50-70% of their strength ability. That is done for longevity mearsures at a certain HP measure. You can also get a upgraded capscrew/rod bolt fastener to give you better clamping pressures and longevity of your connecting rods. ARP has these ugrades available with their ARP2000 material. Just for instance, Eagle rates their H-beam SBC rods to handle 750 HP. With the ARP2000 upgrade they are re-rated to handle 1,100 HP. With the L-19 ARP upgrade they re-rate them to 1,400 HP.
07-22-2007, 09:06 PM
Thanks for the info, I will have to look into that. The current rods that are in it are eagle I-beam rods, rated for 500hp, and 6k rpm, so I was concerned. So perhaps I could use the arp fasteners as insurance on what I have and be safe? I might still try to get some h-beams, I know in the nitrous section they don't think the stock crank is a good idea for the 200 shot, even with the 4 bolt mains.
07-22-2007, 09:45 PM
I think that your stock crank could handle it with a few steps of preperation.
1) Have a machine shop that has the ability to put as large of radius on crank as possible, even if this means turning it down 30 thousants (0.30"). Try to get a 1/8" radius(this is what your aftermarket 4340 forged cranks have). This will cost around $175 give or take.
2) Cryo treat the crankshaft after having the crank turned down. It is best if you can find a place that practices a 24-32 hr soak time. The company that I use recommends having the crank turned down, cryo'd, and then polished. This will cost you around $80. FYI the cryo process increases the durability of graphite cast iron by 97%.
Here is the web site of the company I use for cryo treatment( www.cryogenictechnologies.com ). There is alot of info on here so that you can inform yourself to see if you want to have this added cost factored into your build. Then you can look around close to where you live and find a cryo treatment close to you and have things taken care of. One other thing that you might look at is how much rpm you plan on spinning your motor to. There is a differance between 500 HP @ 6,000 rpm & 500 HP @ 7,500 rpm due to centrifugal forces.
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