Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
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if you wanna go i beam i would go with the scat pro comps over the eagle. There rated to 750hp. Or if you are stuck on eagle then upgrade to the h beams. just my 2 cents.
__________________ 1986 Camaro. 383 SBC. Scat forged bottom end, Diamond Pistons, Bullet solid roller, Crower HIPPO Roller lifters, Motown heads that flow 320cfm, Comp Pro Magnum Rockers, Ported Hurricane Intake, TRC 950 Carb.
TH350, RMVB. ATI 8" converter.
Strange S60 With 4:11's and Detroit Locker. Strange Adj Shocks
All Spohn Suspension.
275/60/15 MT ET streets. Sportsman up front.
if you wanna go i beam i would go with the scat pro comps over the eagle. There rated to 750hp. Or if you are stuck on eagle then upgrade to the h beams. just my 2 cents.
I have the short block assembled and balanced.. I was just wondering what other folks thoughts are. I can go 500hp naturally aspirated, or toss a blower on it and run in the mid 600s. But I don't want a rod to go through my nice new 400 block.
I agree, I'd do H-beams had my original target been 600+ hp.. It wasn't until I realized how much the car weighed that I came to the conclusion that I need more power to make the same trap speeds as a thirdgen fbody..
Really unless someone has a lot of experience with breaking those rods, its guesswork. Usually parts have some sort of factor of safety but less so with stuff like connecting rods. I'd imagine 50-100HP over the rated power wont kill it but likely beyond that you're venturing into risk territory especially if they're not totally perfect.
Have you tried contacting Eagle? Just ask them what their factor of safety is, if any.
Have you tried contacting Eagle? Just ask them what their factor of safety is, if any.
I spoke to them once. I spoke to a guy who is more paranoid than my machinest. Asked about their cast cranks for a build, told me not to even think about using it in a manual car unless the car weighed 2000lbs and I was slipping the clutch.
I asked about the rods, he said I had the "old SIR rods" (with the bolts not cap screws). He didn't really give me any indication of guarantee one way or the other, and like you guys said, he said it's a factor of RPM more than anything. But again mentioned that with a manual trans things shock.
Now, I have a TH350, so I'm sure it will be mooshy but I went with the forged crank because I may put a TKO in the car eventually.
Ken:
Cam is XR288HR. In a 400 I think it's safe to assume it will flatline around 6,000.. Figure 6200 max.
The combo should be pretty stout. Figure, 525 or so hp naturally aspirated if I go with 10.9:1 compression. If I went like 9:1 and ran 10+psi of boost it could potentially be in the mid 600s.. Though durability starts to be questioned.. (1976 400 block, bored .060 over, I beam rods, 2 bolt mains)..
My machinest told me to keep it in the low 500s. If I do this again, I'll buy a dart block I think.. The '70s 400 might have been a poor choice on my part.
NO WAY would I put boost of ANY kind on that block.Run this one N/A,and enjoy the HP.At .060 over,what started as a ticking time bomb (the stock 400 block) turned into an A-bomb.I'd bet you any amount of money you want that if you boost it,it will split a cylinder within 20 full passes.
The SIR rods,however,are safe way beyond their rated HP level.Never had a single failure due to one in any engine,Ford,Chevy,Mopar,SB or BB.
__________________ Some people are like slinkies, they aren't good for anything, but you can't help but smile when you see one tumble down the stairs.
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