Hey guys I've been running a turbo magnum engine for a couple of years now. I have a high and low boost setting on 420hp and 650hp at wheels. I've been running a standard magnum bottom end and the only thing that seems to let go are the pistons. So I'm putting a set of forged pistons in but not sure if I should upgrade the rods. I've had a look at some scat Hbeam rod and they don't look much stronger than a standard factory rods. Can anyone confirm what the magnum may be good for. Cheers
How much HP can magnum rods take happily
- Thread starter maca
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pishta
I know I'm right....
Magnum rods are 1.00 wide little end while the LA rods are 1.17 IIRC. Found that magnum stroker pistons would not fit LA rods without a little clearancing.
Locomotion
Well-Known Member
I believe you mean you had a look at "Scat I-beam" rods? The Scat I-beam look similar but are made from a better, stronger material (4340 steel) than OEM as well as better than Eagle I-beam (5140 steel). Piston weight and rpm have a lot to do with rod durability. But H-beams might be a better option considering the 650hp.
All my engines have been stock bottom ends so I don't spin them past 6000 to 6500rpm. The turbo engine is still making power at that RPM so it is very tempting to go higher but I never do. Magnum engines when ever released in Australia so if I damaged one I have to ship another one from the states. With the rods the car sees over 400hp on the street fairly regularly. However because of tyres the car only really sees 650 at the drags about 8 to 10 times a year and then it's only for about 10 seconds at a time.
No the ones I have here are H beam
rods.
I can’t put a finger on the ultimate hp the OE 4340 rods will take but I’ll bet that as sure as the sun rises, the rod bolts will fail first.
I noticed aftermarket rods by scat and eagle use different rod bolt and that’s the only thing I see different except the HP ratings going up with better bolts.
I noticed aftermarket rods by scat and eagle use different rod bolt and that’s the only thing I see different except the HP ratings going up with better bolts.
They'll take it till they break.
Isn't that the life of ANY connecting rod???????
Yup.
Locomotion
Well-Known Member
Sorry, I assumed incorrectly. H-beams typically are considered stronger. But there are exceptions. The Scat I-beam also have the bigger 7/16" bolts. But I'd feel better with the H-beam.
I would say that you have defined for us just what a stock magnum rod can take.......you have ventured into a zone few are willing to go, and have been successful, well done
fratzog lover
Well-Known Member
It's turbo HP as opposed to naturally aspirated HP. The rods, if prepped correctly and with a set of ARP bolts will handle more than you would think.
T56MaxTorq
Well-Known Member
I added arp rod studs to my stock rods on my turbo magnum. I run it up to 10 psi regularly.
When I built my 1st ever boosted engine I was told by the guy helping me that if you compare equal HP engines of NA and boosted that boosted is a little more friendly on parts as the power comes on a little more smoothly. How true that is I'm not sure but I have got very fortunate with all my parts over the years. The most suprising to me was the A518 trans I ran for a couple of years at around 450hp at the wheels. It held up fantastic.
I love the Aussie chargers. I'll post a pic of mine.
fratzog lover
Well-Known Member
Corky Bell has a good book called Maximum Boost. Grab a used copy off Amazon for cheap. It's a good one to have on the shelf if you are a turbo guy. Turbos don't have the same shock blowers, nitrous and high strung NA engines have.
nm9stheham
Well-Known Member
As I understand it, the rod bolts fail more due to high RPM operation and the resulting inertial loads, rather than from things like boosted power. 6000-6500 RPM is juuuust getting to the point where the bolts get stressed, IMHO.
Locomotion is right... it's the strength of the materials that is the basic improvement of the H-beam over the stock rod; yield strength of 4340 steel is almost 50% higher than 5140. It is also the H shape versus the stock rods I shape. The H is fundamentally stronger for straight bending forces like exerted on a rod. So you can't go just by appearances.
Locomotion is right... it's the strength of the materials that is the basic improvement of the H-beam over the stock rod; yield strength of 4340 steel is almost 50% higher than 5140. It is also the H shape versus the stock rods I shape. The H is fundamentally stronger for straight bending forces like exerted on a rod. So you can't go just by appearances.
nm9stheham
Well-Known Member
I had that impression too.....not sure what it means for strength if that is the case. The shape can be the same.
MopaR&D
Nerd Member
Powdered metal rods usually have a rough surface on the cap mating faces because the big end is fractured in half instead of machined... the connecting rods in my Magnum are definitely forged, the cap faces are flat from the traditional saw-cut method. I don't think Chrysler went with powdered rods in a V8 until the G3 5.7L Hemi, or maybe the 4.7L SOHC.
Ever considered a rod for a small block chevy, since you may be changing pistons anyway? They may be easier to come by over there, and i haven't checked all the specs but there must be a ton of possibilitys.
That's a very good idea. It was suggested to me that I use Chevy pistons and just resize my top rod.
I'll see if I can find an off the shelf Chevy piston with a dish of 20 cc.
I'm not sure what material I need to suit my horsepower
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