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Chris G.
Dodge Dakota
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3/22/2006
00:48:36
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 Subject: RPM's in a 318 Magnum
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How hard can you push a stock Magnum 318 before shifting? Does the engine have an RPM rev-limiter? thanks.
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Xrated
Dodge Dakota
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3/22/2006
09:42:27
| RE: RPM's in a 318 Magnum
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You have one and you never tested it?? :P
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Xrated
Dodge Dakota
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3/22/2006
09:44:58
| RE: RPM's in a 318 Magnum
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The rpm rev limiter is around 5200 and i heard some guys making better 1/4mile times by shifting it when it was reaching the rev limiter. I got to plug in the G timer and test that theory.
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Chris G.
Dodge Dakota
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3/22/2006
09:56:06
| RE: RPM's in a 318 Magnum
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I have had mine all the way to 6,000 by accident. I'm scared to push it that far again.
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PB
Dodge Dakota
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3/22/2006
18:32:36
| RE: RPM's in a 318 Magnum
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my 93 went to 5700 one time I hate to do that though especially because of my very high miles. it went that high because my trans didn't shift. this was doing cookies on ice though
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gen1dak
Dodge Dakota
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3/22/2006
20:05:51
| RE: RPM's in a 318 Magnum
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The stock bottom-end on the LA/Magnum engines is safe through 6,000rpms. Remember, the hottest engine in the family was the 340 Magnum, and it was such a screamer, it was nicknamed "Baby Hemi" despite the fact that is was a wedge-head. The cranks and rods are very robust, but for hard running, it's wise to invest in some stronger hardware like ARP rod and crank bolts. My first LA was a '69 318. It was rebuilt with all stock hardware, fitted with hotter cam/induction/exhaust. I routinely ran it to 5,800rpm shift point, and it never broke, and that was with the light-duty rods. From the mid-70's on, they all had heavier rods.
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GraphiteDak
GenIII
3/22/2006
22:34:17
| RE: RPM's in a 318 Magnum
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I wouldn't worry about pushing a 318 to 6k. Only sucky thing is most rev limiters are just barely past 5k, WTF??? And the superchips only bumps it to 5500. The engine would scream with some help in the cams/heads/intake department.
The superchips moved my 4.7 from 6k to 6500. I run my 4.7 to 6500 every so often. And I don't even break a sweat either.
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.boB
Dodge Dakota
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3/22/2006
22:44:55
| RE: RPM's in a 318 Magnum
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As was said, the bottom end is pretty stout. It will safely run 5500-5800 for quite a while. Short bursts 6500 wouldn't scare me at all.
But the real limiting facter is the hydraulic roller valve train. If everything is set up just right, you can get them safely to 6,000. But in reality, the valves start to float at around 5,700.
As for the shift point, you should ideally bracket the torque curve with your shifts. For example, your torque peak is 4,500. When you shift, the rpm's drop by 1,000. You should set your shift point at about 5,000. Ideally.
Revving a stock magnum motor to 6,500 rpm's is pretty pointless. You're way past the power curve, and have stopped accelerating with any gusto.
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Chris G.
Dodge Dakota
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3/23/2006
09:58:02
| RE: RPM's in a 318 Magnum
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Yea, but pushing it to 6,000 in park would blow it up, right? HAHAHA. Is there a way to adjust the shiftpoints in an Auto tranny? It would be better if I could push it to 5,500 if I kick it into passing gear. Mine seems to achieve most get up and go after 4,000 and up.
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ewraven
Dodge Dakota
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3/23/2006
18:21:53
| RE: RPM's in a 318 Magnum
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I once saw 8000 RPM in my 93 5.2 Dakota. I floored it at roughly 20-25mph. To this day, I'm honestly not sure what that transmission did but that engine revved all the way up to 8000 RPM before I could let off the gas.
In the ten thousand miles I drove it after that happened; I never had any problems related to that over rev. Let me tell you though; I've been to a real Nascar race and that 5.2 at 8,000 RPM sounded identical to a Nascar V8 at those engine speeds. That was with the stock exhaust and everything too.
Of course, I do not recommend anyone go out and overrev there engines on purpose. That scared me to death when it happened. I had just bought the truck; I was in Air Force Tech school at the time and as such, I had little to no money.
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gen1dak
Dodge Dakota
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3/23/2006
21:16:11
| RE: RPM's in a 318 Magnum
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But you had enough money to buy an 8,000 rpm tach? Not buyin' that story.
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ewraven
Dodge Dakota
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3/23/2006
21:25:24
| RE: RPM's in a 318 Magnum
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That was via the factory tach. This was eight years ago; so bear with me please. I do remember that 8000 RPM number vividly.
I don't remember what the markings on the factory tachometer went up too though? The needle did swing WAY past the end of the scale on the Tachometer. And I've heard a V8 at 8000rpm before and my little 318 sounded identical to one.
I was shocked and scared when it happened. I was really really easy on it on the way back to the base and routinely checked the fluids after that. That truck never did burn any oil in the 10k miles I owned it.
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Chris G
Dodge Dakota
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3/24/2006
23:10:21
| RE: RPM's in a 318 Magnum
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What the crap? Mine tach only goes to 6,000RPM's.
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ewraven
Dodge Dakota
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3/25/2006
07:51:59
| RE: RPM's in a 318 Magnum
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What year truck do you have? The tach in my 99 only goes up to 6000 RPM too.
I don't remember how high the tach in my 93 went up too. I think I probably just estimated it to have gone up to 8000rpm by how far the needle went past the numbers on the guage.
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gen1dak
Dodge Dakota
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3/26/2006
01:37:04
| RE: RPM's in a 318 Magnum
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With a rev-limiter of around 5,200rpm, as soon as it hit that number the fuel would be shut off, so even if by some freak of physics it actually could hit 8 grand with sheer inertia gained before the cut-off (and that won't happen either), you wouldn't have heard it. No fuel, no NASCAR-style exhaust noise.
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ewraven
Dodge Dakota
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3/26/2006
11:19:20
| RE: RPM's in a 318 Magnum
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Actually, rev limiters cannot stop a mechanical over-rev from happening. Such as if you are going forty mph or something and the transmission downshifts into 1st gear instead of 2nd or 3rd. The rev limiter will not stop the engine from spinning to some super high RPM.
There is a video out there of a guy with Acura RSX driving down the freeway with a passenger who was doing the filming, the driver downshifts at highway speed into the wrong gear. He was doing like 75mph and downshifted into 2nd gear by accident when he was meaning to go into 4th gear. His engine buried the tach needle and was totally trashed. Pieces of the engine and a big oil slick were all over the road where it happened. A rev limiter will not stop something like that from happening.
I'm not lying about what happened though; I really have no reason to, I just think it's an interesting story and a testament to how well built the Magnum 5.2 is. I floored it, the transmission downshifted I believe; and the needle swung around like two inches past the end of the readout on the tachometer and that baby sounded just like a Nascar engine for that second or two until I guess it finally upshifted or the truck slowed down. It seemed like an eternity to me at the time though. And that wasn't the only time it happened in that truck. It happened a second time as well though it didn't bury the tach needle like it did that first time. That truck had some serious problems; like I said, it was on it's third transmission when I bought it with only 26,000 miles on it.
I still to this day have really no idea whatsoever what went wrong in that automatic transmission when that happened both of those times. Someone once told me that it is called a "flare up" and it was a problem area for those transmissions back then in those trucks. I've never heard anyone else complain about such a thing though. I will try to remember to ask a Dodge mechanic friend about this next time I see him. He's been working on Dodges at the same dealership for over twenty years, if anyone would have heard of this before, it'd be him for sure.
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GraphiteDak
GenIII
3/26/2006
17:41:58
| RE: RPM's in a 318 Magnum
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So you have a manual tranny in that truck? DOWNSHIFTING to the wrong gear would give 8,000 RPM's. The inertia would be incredible on a stock crank/rods, etc but the 318 is the toughest engine out of all the old school V8's made.
I guess it depends on what tranny you had because with my auto, and 4.56 gears, I'd have to probably do near 50+ to hit 8,000 RPM's.
Right now I just hit 40 MPH at 6500 RPM's.
I usually shift mine at 5800 to 6000. It DOES breath a little past 6000 though but yeah past it's peak but it pulls.
My stock tach goes to 7k. That's because of the 4.7 motor. The 318 ones I've seen all had 6k tachs.
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ewraven
Dodge Dakota
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3/26/2006
18:20:19
| RE: RPM's in a 318 Magnum
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It was a stock auto 1993 5.2 Dakota 2wd with 3.92 gears. I honestly don't know what that transmission did. The 8000 rpm number is just a guestimate after seeing how far around the dial the tachometer needle went. Maybe it was only 7000 rpm? It was definately way past 6000 rpm or whatever it was that tach read up to. lol That was a long time ago.
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Chris G.
Dodge Dakota
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3/27/2006
09:18:44
| RE: RPM's in a 318 Magnum
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LOL i'm scared to blow mine just pushing 5,500. It sounds like it's racing when it's at 5,000. I don't think the rods could take even 5,700 on a 318. Correct me if i'm wrong. I'm talking totally stock config here.
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toolfan
GenIII
3/27/2006
12:59:50
| RE: RPM's in a 318 Magnum
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Chris G. your wrong have you ever read junkyard jewel when they built up a 318 with 270,000 miles on it and just re-ring the motor and did some head work & a cam. 370hp and they were revving the 318 to 6,100rpm and make great power.
http://www.hotrod.com/howto/113_0304_junk/
there's the article enjoy!
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GraphiteDak
GenIII
3/27/2006
19:27:50
| RE: RPM's in a 318 Magnum
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YUP. The 318 has really beefy rod bearings compaired to say a Chevy 350.
ewraven, 20 to 25 MPH wouldn't be jack with a 3.92 auto.
I have 4.56's and can hit 40MPH at 6500 RPM's.
You would need to go over 50MPH in 1st gear to even THINK of getting close to 8k!!!
Maybe your tach wigged out or your tranny slipped out of gear? Although a auto is not known to slip, then be totally fine.
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