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Old 03-22-2014, 11:40 PM
PerilousActs PerilousActs is offline
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Default Aluminum Rods

Anyone here have experience with some of the newer alloy'd aluminum rods gaining popularity with the evo guys? I'm seeing reports of 10-15k miles on these without issues. And almost all of the places machining them will build you a custom set for roughly the set of what Carrillo rods run.
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Old 03-23-2014, 08:49 AM
Def Def is offline
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Aluminum as a rod material is pretty nice given that the low modulus softens the impact of combustion events to the big end rod. The fatigue life is the only gotcha, and in that case, it doesn't really matter too much what alloy you go with. Any of the structural alloys will fall down to the 9-12 ksi range at 1e6 to 1e7 cycle range on the S-n curve (look it up good info there on fatigue life/endurance limit - which Al technically does not have at infinite cycles).

I'm betting the fancy alloys are just a way to tout that they hold a ton of power when new, then upcharge a high premium. They'd be just fine being made out of 2024 or something like that that's not too outrageously priced.
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Old 03-23-2014, 12:25 PM
PerilousActs PerilousActs is offline
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I'm wondering if I can get 1-2 season of use out of them since people are getting 10-15k of mixed street and track use on evos. If so, I might be able to justify the maintenance of replacing them before failure due to the weight savings. I'm in the process of building my 2.2 bottom end and thinking of giving it a go.
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Old 03-23-2014, 04:35 PM
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How high are you planning to rev? Over 9k RPM it might be worth it, otherwise I'd just run aftermarket steel rods. Lots of SR20-Forum guys rev their NA cars out to over 9k with a VE head, some even do it turbo as well.
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Old 03-23-2014, 05:49 PM
PerilousActs PerilousActs is offline
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Well, that is going to depend on what turbo I end up going with I guess, but basically I'm planning a VE head similar to what mazworx is doing 11,000 rpm on (big valve, deshrouding valve, aftermarket springs with higher spring rates, etc). I'm building a long rod bottom end though using modified h22 rods (narrow the big end a bit ala Mike Kojima). Using them with a custom piston brings the rod stroke ratio up to 1.66:1 from 1.58:1 and hopefully helping with some of the loads at high rpm. That's why I'm thinking that the AL rods may be perfect to try with this setup.

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Old 03-23-2014, 05:59 PM
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Yea, they could be very useful over 9k RPM. Just stick to a reasonable replacement schedule and don't deviate just because things seem fine right then.
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Old 03-24-2014, 09:16 PM
Jason M Jason M is offline
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Not that this is entirely applicable to your question, but on the TF dragster, we run our aluminum rods until they they get pounded to short to run, or have fatigue cracks on the serated caps. We have a jig made up to monitor/log all of the connecting rod lengths that we have in service.
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Old 03-25-2014, 02:43 PM
PerilousActs PerilousActs is offline
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I went ahead and ordered a set. Cost me $689 with my specs. So still cheaper than I would pay for Carrillo's. Ordered them from http://rrconnectingrods.com/.
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Old 03-25-2014, 02:56 PM
Beejis60 Beejis60 is offline
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Quote:
Originally Posted by PerilousActs View Post
I went ahead and ordered a set. Cost me $689 with my specs. So still cheaper than I would pay for Carrillo's. Ordered them from http://rrconnectingrods.com/.
Doesn't Carillo make titanium rods?

or is that Cunningham? Or both?
What's the price difference between steel, aluminum, and titanium, if anyone knows? Just a little curious...
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Old 03-25-2014, 03:17 PM
PerilousActs PerilousActs is offline
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I believe Ti rods are in the $2kish range for a 4 cylinder from when I was looking the other day. Most places that do AL do titanium from what I've seen. There's a lot of info on both on evolutionm actually. I was pretty surprised, but there's a lot of big budget evo builds so I guess it makes perfect sense.
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