bad440
everything,all the time..
so who's broken an sir rod?and why?i have seen the cast crank failures but not the rods....:dontknow:
eagle sir rods who's broke one?
- Thread starter bad440
- Start date
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Mad Dart
Nothing to see Here!
Prob another BS myth. A bad tune on a big shot of NOS is probably only reason and they blame the rod is my guess.
The 4340 scat I Beam is a better rod for close to the same $$ so people talk crap about the Eagle SIR.
The 4340 scat I Beam is a better rod for close to the same $$ so people talk crap about the Eagle SIR.
bad440
everything,all the time..
:read2::scratch::dontknow:
yeah so far......
forced 340
Well-Known Member
i broke one... but it was when i had the 340, 740gram trw pistons, and 10#s of boost making 640 rwhp. nasty break too... broke the cam, block, starter, oil filter relocater, and oil pump/pan! i knew it was a ticking time bomb, i beat the **** out of that engine for 8 years before the turbo kit was built then it took another 2 years of beating on to break it! i would use them again in my next n/a engine for sure!
Mad Dart
Nothing to see Here!
Think they say 500hp/6000rpm limit. You definitely were over their limit in both areas. haaaa prob piston speed and piston weight has something to do with the abuse the will live under.
On the boosted set up, did it go lean before the bomb went off, or did you squeeze it a Lil harder than you normally did in the RPM department? We're all the valves still in the head after the autopsy? Reason I ask is I over revved a 340 once and did the same thing with stock rods. After the autopsy I found out it actually dropped a valve which took out the piston, cyl wall cam and everything else in between. Sounded like a Glass jar of marbles when it happened.... So much crap went everywhere. When I put the new stroker in there were chunks of the old engine flying out the exhaust. Big pieces too!
moper
Well-Known Member
Years ago - like 4-5 at least I think - when they first came out there were issues with the metalurgy in the SIRs. At least that's what I heard it ended up being. The pin ends would pull off them and a couple guys had some analysis done on them. They seemed to address it because there haven't been any mention of them coming apart in years. They are a cheap rod - not a high performance rod. So they do have limits. If you wouldn;t use a stock rod in that application, don;t use an SIR. that being said - I've got them (SIRs and stock rods) reliably going 450+hp.
forced 340
Well-Known Member
she broke as soon as she hit boost... about 25-2700rpm... the piston didnt touch the head at all! the rod broke at the small end, swung around and just broke the hell out of everything! the engine was not built for boost at all! nothing was right for psi... it was what i had so i made it work. i knew i was going to build a boosted engine sooner or later.
Mad Dart
Nothing to see Here!
Wow, I guess you already ran them through the ringer on your previous set up....LOL!! Cool great information.
forced 340
Well-Known Member
yup! like i said... i beat on it for 8 years before the turbo went on it then it took another 2 years to break it! i have them im a w2 headed 416 that i built for a buddy of mine. the engine in his 71 dart. beats the hell out of it, drives it to the track runs low 11's (it would be in the high 10's with caltracs) and drives it home..
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