zman, my post is absolutely true. Read it again, and pay particular attention to the post that I quoted. It has the following little tidbit of information that you may have missed: "Originally Posted by oilslinger53 from a performance aspect wouldn't it be where the torque and horsepower curves intersect?"
Put it on a dyno, see where the numbers start to fall off. No reason to go past that, so there's your redline.
Probably this one, where he's driving over his crankshaft. I suspect it might have more to do with tune up than red line though. Larry T
Yep, like this. FWIW, a dyno measures torque and rpms. It uses the formula (^^^^^) to plot horsepower. Larry T
2 different meanings to "red line". The original was simply the color change on the tach scale indicating the shift point. On a truck, boat, industrial engine the red line is just the point where there's no more power - nothing to do with safety. On a race engine you stopped there to prevent driving over the crank. This has nothing to do with too much power, or what cam, CR, etc. - only about inertial (tensile) load, which varies as RPM^2. Raising the shift point from 5,000 to 7,000 is not +40% (7,000 ÷ 5,000), but +96% (7,000^2 ÷ 5,000^2). The valves may float, points bounce, etc. so you never reach the destruct point, but if you p*** this the rods break at the bolt or the pin comes out of the piston. Better rods and piston? Rods break at the beam, bearings spin, blah. To calculate maximum inertial stress, where: Z = acceleration in f/s/s N is RPM S is stroke n is rod ratio 2189 is a constant Z = (N^2 × S × (1 + (1 ÷ (2 × n))) ÷ 2,189 Results: 200,000 is death for anything but F1, 80,000 is safe for a lawnmower.
That's the pic I had in mind Larry. You're probably right about tuneup, but the same thing happens when you exede the red line. What are the odds against driving over your crank shaft?
On my Website under tech there is a whole section on the pros and cons of long stroke short stroke and the reasons why, If you would like take a peak. The website provider has a problem with the script migrating to the right which i cannot seem to resolve but it is still readable. It is the last tech at the bottom of that page. http://seniordragster.bravehost.com/POLYTEK.html 5252 ? That is 33000 (33000lbs X 1Ft = 1HP)divided by 2 Pi (6.28........) =5252. So torque in Ft LBS X RPM divided by 5252 = HP. because of this torque and Hp are always the same at 5252 RPM ie 400 Ft Lbs Torque X 5252RPM /5252=400 HP That s the significance of 5252 and has zip to do with redline. RPM as i said before is decided by Cam duration (all things being equal or up to surviving the Rpm the cam is capable of. ) Redline is how high it (The valve train) can go in RPM safely with out valve float basically speaking . Peak power is usually in general terms around 500 RPM less but that is only in general terms.
I agree the cam is a big deciding factor, as long as the other components can stand the pace. I built a 350 for my old T, solid cam, dart heads, victor Jr etc, pulled real hard to 6300-6500 then it dropped off. I played with cam timing by +/-8degrees and all sorts, peak power RPM moved up/down a lot but it never went any faster although it would rev to 8500+ without breaking! I ended up runing the cam 2 degree retarded, power peaked at 6700, shifted at 6000-6200 and ran it hard and reliably for a few years. (Only broke TH350s and 9" diffs)
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