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#1
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RPMs
Thanks for the replies regarding carbs and manis...I think Ill get headers first. The question now is how do I know what my red line is on a 69 340 Swinger with a mild cam, 8 3/4 rear with 3.55s?? Thanks.......Gary
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#2
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Redline is mostly, if not alllmost solely determined by the cam's profile with springs used.
Supply cam specs for a redline limit. |
#3
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When the nose starts to come down...SHIFT!
Little Campbell...as in the river? Caught a few steelhead in that river... Chilli-whack eh! Nice town,,,spent a couple of days at your airport....fogged in with a Cessna 185, trying to get to a fishing lake up in the mountains. We'll be in Mission for the Oldies Race August 10th, gonna be there? We'll get thet old Swinger swingin' for ya. |
#4
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I would say if you have a chevy or a ford just hold the petal to the floor untill you hear a loud bang then you know it's time to shift.
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#5
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My understanding of redline is the "Never Exceed Speed" for an engine (or aircraft). If you operate the engine in that zone, catastrophic destruction takes place. I have also thought that the redline was usually determined by the failure of the bottom end of the engine - thrown rod, spun bearing, etc
I think that redline was originally from Formula One engine builders who would paint a thick red line on the tach, to warn the driver when to quit revving I am open to having my shirveled old mind changed, though! |
#6
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I agree with you, Doug. "Redline" of an engine is the RPM limit which it is not save to exceed. But it is not necessarily determined by the point at which the lower end fails. A valve floating into a piston could be described as a catastrophy as well.
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#7
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Purrrrfect! I see a line isnt all that important. Just jack it before the valves start floatin! Hey Cuda are you talkin bout the "littlecambell" out in White Rock? Thats where I got my first steelie....So your right about the handle! Theres like a million ironheads in the Chilliwack River(Vedder), thats why I moved out here. Zoo area now. Best steelheadin on the planet is at Gold River on the island, all catch and release. Ill do my damndest to show at Mission in august...usually working out of town then Right now am workin at Mission now and hear the track every weekend.
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#8
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Right... any engine destoying even should be considered passing the "red line"!!!
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#9
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That should read "event". Sorry!
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#10
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Just to expand on this a little more, keep in mind that if you use the definition of "redline is where it breaks if you go past it", that redline will change as a motor wears. Valve spring weaken, rods and bolts stretch, etc. Production engines, which needed to have warranties, also needed to have a little breathing room in the published redline numbers. So actually, you can wind a fresh engine higher than published redline with little fear of damage. In fact, the factory tuning is such that power starts to fall off before you really got into the danger zone. If you are using optimum shift points for your power band, you have little to worry about.
The problem comes when you modify the engine. Bigger cams move the power range up the RPM band - now where is it safe? Traditional rules of thumb about maximum piston speed are only guidelines. All else equal, a lighter piston can sustain a higher redline than a heavier one. At what level do you start risking your rods? This is complicated. A lower power engine can safely spin the same rod and piston combo to a higher speed than a higher powered one. So things that you wouldn't normally consider as affecting redline such as induction systems and head porting actually do have an effect, when stretched out to the ragged edge of reliablity. I guess the only way you really know where your redline is, is in that moment immediately after you've exceeded it. |
#11
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Run the engine/car on a dyno. Find peak power. Theres your shift point. A few hundered RPM's more is redline.
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#12
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Right on, about the wear!
rumblefish, I don't think redline would have anything to do with power curve. Actually, with a bad cam selection, I think you could have the power peak(s) at an RPM higher than the engine's destruction point, couldn't you?? To calculate red line, without destroying the engine, you would calculate the lowest failure RPM of each component, when stressed by the other components, I think. For instance, maybe an Eagle rod would have an 8,500 RPM failure point with a 700 gram piston, but a 9,500 RPM failure point with a 550 gram piston. After doing those calculations for each component, your red line would be the failure RPM of the lowest rated component?? No?? |
#13
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Just tryin to give another angle to the original question.
I now see it as a question of running the street/strip as to make best times. So, in the power curve, there is a redline for best times. Just another angle. Otherwise, yes. |
#14
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Actually, I think this is the very first time I've ever had to disagree with Rumblefish. But only slightly. Sorry my friend.
It has to do with optimal shift point. I believe it's actually a little past peak horsepower. This is because if you shift at peak, your RPMs drop further, and usually put you further down the power curve, than if you go a couple hundred RPM past peak. It's like the best cam, you want the most area under the curve. Where exactly you shift depends on how fast you build up power as you approach peak compared to how fast it drops off past peak. As with anything, only real-world testing can give you the best answer. |
#15
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As with a lot of things, there meaning change. I believe I have read something about the formula 1 red line being painted on the tach by the engine builder, that was a long time ago. But as time went on the meaning changed for different fields of motor sports. for instance, in drag racing, doesn't red line mean the point at which you shift to remain in the optimum power curve? If you rev past peak power to the point at which when you shift you are at the same power at the bottom side of the curve. Of course that will change from engine to engine, tranny to tranny, car to car, etc. Of course, like mentioned earlier, you could have an engine that is poorly designed that exceeds the breaking point before reaching the far side of the curve, then I guess we fall back to rule #1. I think in formula 1 it still means the point of no return, don't those engines just keep on making power until BOOM??
But then again, I could be wrong. |
#16
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72Challenger, you are more accurrate.
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#17
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I guess I'm just too old to adapt to this new lingo you youngsters use. I used to be pretty hep to the jive!!
To me, red line will always be the engine destuct point, but thanks for the engaging discussion - see what a nice loser I am?? |
#18
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accurate has only one "r".
gotcha, 'fish |
#19
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LOL
Thanks Doug
Good thing I have a duaghter in 2nd grade. Were learning to spell. |
#20
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littlecampbell:
Yup, know all those rivers.....you ever run into a Steelhead fanatic by the name of Rob Baker? Hope you can make it down to Mission on the 10th weekend, it's a fun race. What's a Redline....I think in your application it would be the optimum shift point for the quickest ET. or MPH whichever you want to run. When determining your "Redline" or shift points there are a few things consider: 1. The rule of 5200 where the HP and tork curves cross. 2. The strength and quality of the components. 3. Trans gear ratios 4. Longevity 5. Convertor technology. 6. The size of your checkbook. So to expand a little more: 1. 5200 rule, if you look at any dyno sheet you will see that the HP and tork curves cross at 5200. So now your working on a trade out more HP or more tork? 2. Components: Pretty obvious but the recommended power band on the cam should be considered as well as the head flow and general quality of parts. You can build a motor that can pull 700 HP at 7200 but with stock rod bolts it would catastrophic to attempt it. 3. Trans gears: You need to calculate how far your RPM will drop at each shift point and be sure that you don't drop below the power band or the engine may bog. 4. Longevity: This is pretty obvious also; a motor shifted at 6200 will probably last 5 years before any major internal maintenance is required, whereas a motor spun to 7200-7800 on every pass may need to be freshened annually or weekly. 5. Convertor: You need to know the flash point on the convertor, if you drop below the lock up point on the convertor it will slip and build tremendous heat, which can lead to tranny failure. Of course there's more to determining the Redline but your time slips are going to tell you even more. You may go quicker at say 7000 RPM shifts but it may be inconsistent and susceptible to weather conditions and make the car inconsistent, whereas a shift point of say 6200 on the same car will make it run within a few thousandths on every pass. My own experienceÂ…Â… If I shift at 6200 the car runs dead nuts, if the weather doesn't change too much it will run 3 passes easily within .005, if the tires slip a little on the launch it'll drop .02 but, if I move the shift point to 6400 it'll make it up and run the number. My Formula one redline is probably 7000, my head flow redline is probably 6500-6600, the cam is good from 3500 - 6800, convertor stalls at 4000 and my wallet stalls at 6200. I lose 1500 RPM on each shift (727 with 2.45-1.45), so I wind it to 6200 and it drops to 4700, well within the power band, convertor lock up and within the tork strength of my wallet. This is close to the max HP at the top end of the power curve and the shift drops it to very close to the peak of the tork curve..and of course the 5200 point. Here's a good exampleÂ…. Driver "A"- 340/727 shift point 7400, ET 11.80 @ 114, 10 races into the seasonÂ….BOOOM!Â….a year laterÂ…still not backÂ….he exceeded the speed of his wallet. Driver "B"- 318/727 shift point 6200, ET 12.33 @108, 2 years and still going strongÂ…we know the speed of our wallet. I think that's enough, you've got my point by nowÂ…Â… I think that Rumble fish was saying the same thing Â….in a lot |
#21
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yep.
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#22
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LOL
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#23
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In Arkansas that means pie are squared I think.
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#24
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Do they even have pie is Ark.????
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#25
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Hey Doug, I'm right there with ya. Redline normaly indicates that if you push it much further, it's going to come apart. Shift point is something different.
A good tach has a green light for a programed shift point and a red light for when pass the programed red line. |
#26
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I think Littlecampbell...a fellow Canadian Hockey Puck type brother from the great white north was actually looking for a shift point.
In Canadian the redline refers to the shift point...well at least it did back in the 60's and 70's when he and I were growing up around "Them Thar Parts" which is Canadian for auto parts, not a place as they would say in Ark., Spokane or Texas. Littlecampbell: I'd quit that job if they wouldn't let me off to go to that race Aug. 10th. You can always get on that high payin' tax free Canadian unemployment enjoyment.....besides you were lookin' for a job when you found that one.... |
#27
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SURREY?
Hello Cuda!....SURREY you say ..cats out of the bag now. Ill spend an extra 20 bucks to take the long way to avoid that place!! Actually the Flamingo Hotel had some good peelers. Cant afford to go on UI anymore,would have to ground the Swinger ...94 octane or any octane for that matter is about 3.20 a gallon....Hey would luv to see that 440Dart ...I guess Ill just set the tach to about 5700 to 6000....Off to work now to pay for fuel.
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#28
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....and now the Surrey Girl jokes start....
I guy just can't keep a secret around here.. |
#29
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Canadian tachometer lights
Let me see if I got this.
A flashing green light means you are in gear, but below the lower limit of the engine's power curve. A green light means you are in gear reving within the power curve of the engine. A flashing yellow means you are aproaching the optimal shift point. A yellow means "get ready to shift." A red light means it is time to shift. A flashing red light means you have exceeded the optimal shift point. When all the lights go out, it broke. Billy |
#30
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No.... I think the solid red means your at the Surrey House of Illrepute.
A flashing red means they have a sale on all girls with less than 3 teeth. |
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