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cruising RPM. speed


Nissanland
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Came across a few topics in here, but none that really said anything to my likeness.

 

When I'm at 65mph the tac is reading at 1550 rpm. In my Titan at same speed I'm at 1250/1300 rpm. Just curious if y'all are in the same rpm range, I don't have any problems with power in my opinion. The high mileage engine really surprising at power, smooth running, and fuel economy. Around 15/23 for the pathfinder and compared to the titan at 14/24. I really can't complain.

 

G

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ah NO....32's and the speed at 62= 65mph per GPS. I know the rpm is on low side, it's been this way ever since I did the tune up. At first it ran a bit ruff, but I wiggle the wire's like precise1 said and walla, smooth idle and low rpm's. I idle at around 550rpm. Ngk plugs, the best possible wire's, royal purple synthetic oil/ transmission and castrol oil for the axles, and transfer case. Fram air filter

Edited by Nissanland
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Well..the 1550 rpm at highway speed would explain your phenom highway mileage..must be nice, sheesh..way to include the rest of us there bud. 1550 at 65 sounds remarkably low, you said you're using Royal purple in the engine and auto trans? Castor oil in the transfer and diffs huh...I'm thinking the secret lies more with the castor oil than the purple stuff.

 

I've used Royal purple before and I'd be wary of running such a thin molecule oil in a worn engine, I hope you check your oil level atleast twice a month for consumption. I blew an engine in my honda Prelude once cause I didn't know how much Royal Purple my engine had been burning while doing 115 mph down one of our toll ways on a regular basis. That was it for me and you know, it's only really sweet the first couple of weeks after a fresh oil change, then the magic fades. What kind of spark plug wires? What type of 32" tires?

 

Now I wanna run out and clock mine at 65. I wanna say I'm pulling like..2450 at 70 mph...which I thought was fairly decent, I've got 31" tires Castrol Syn Blend 10w30 in the engine, God knows what in the transfer/diff and no clue what's in the trans. And that's with the hot MSD coil and NGK V-power plugs. Ahh you didn't mention any exhaust work, you stock or upgrade?

Edited by gv280z
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My VG30E with 265-75r15 and whatever happens to be in the transfer cases / transmission turns over about 2200 rpm at 62mph..... How did you get that thing to run at 1550??

 

sent from under Ernest the Pathfinder

 

 

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I don't know how the diesels run but that sounds a little high, is that with overdrive on? I think Nissanland's truck has different gearing, say like..for instance if we are trying to compare offroad versions vs base versions that maybe weren't setup with low gearing, which is our case I'm thinking now.

 

I've got an lsd 4x4 with auto trans and stock 31" tires, what about you guys. It has to be in the gearing.

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I've got the LSD in the back on a 4x4 auto so that gives me a 4.625:1 on the 265-75-R-15 buuuuuut that is full stock other than the _slightly_ larger tires for the gas engine..... the math would dictate that he's running about 2.80:1 final or so ....... I wonder how that gets out of its own way when I find that the 4.625 to be a bit slow off of the line.

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When I'm at 65mph the tac is reading at 1550 rpm. In my Titan at same speed I'm at 1250/1300 rpm. Just curious if y'all are in the same rpm range, I don't have any problems with power in my opinion. The high mileage engine really surprising at power, smooth running, and fuel economy. Around 15/23 for the pathfinder and compared to the titan at 14/24. I really can't complain.

 

G

I'm willing it bet... no.

I can't recall if you have the manual or auto tranny, or what gearing (HG43 or HG46 on the passener fender plaque), but my 1995 with auto tranny, 4.63 gears and 31" tires runs about 2600 RPM @ 68 mph (indicated) IIRC.

 

ah NO....32's and the speed at 62= 65mph per GPS. I know the rpm is on low side, it's been this way ever since I did the tune up. At first it ran a bit ruff, but I wiggle the wire's like precise1 said and walla, smooth idle and low rpm's. I idle at around 550rpm. Ngk plugs, the best possible wire's, royal purple synthetic oil/ transmission and castrol oil for the axles, and transfer case. Fram air filter

Normal idle is 750-800 rpm, I believe your tach is not displaying the correct RPM. See if you can have it hooked up just to test it.

I've never heard of a remotely stock WD21 anywhere near 2000rpm at 65 mph, much less lower. I don't think it would even generate enough power to push the brick shape that fast at that rpm... :shrug:

 

B

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I don't know what gears I run, but will look into that in morning. Okay the tachometer is off by about 200rpm. I took a mobile tachometer hooked up and then retest truck at speed, @ 65= 1850/1900 rpm and idle is closer to 725. I don't know how or why but it has been driving excellent. Power/pull/economy. I changed the oil in engine to castrol synthetic blend, 10w30 & still same rpm. The purple was/is clean as if it was poured out of a bottle. Left the automatic transmission fluid alone, it's still purple. If I put truck in power mode rpm jumps up apx 150rpm, and overdrive is another 250rpm. Other than the lift/tires, everything is stock configuration. No special exhaust system,air intake or fuel system.

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Another thing, I have to replace the oxygen sensor, the stock unit is giving me a check engine light. I don't know how much that affects the rpm, power. But as I said before, I can't complain about it.

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I doubt that too... :tongue:

 

I don't know what gears I run, but will look into that in morning. Okay the tachometer is off by about 200rpm. I took a mobile tachometer hooked up and then retest truck at speed, @ 65= 1850/1900 rpm and idle is closer to 725. I don't know how or why but it has been driving excellent. Power/pull/economy. I changed the oil in engine to castrol synthetic blend, 10w30 & still same rpm. The purple was/is clean as if it was poured out of a bottle. Left the automatic transmission fluid alone, it's still purple. If I put truck in power mode rpm jumps up apx 150rpm, and overdrive is another 250rpm. Other than the lift/tires, everything is stock configuration. No special exhaust system,air intake or fuel system.

That idle sounds better, but the 1900rpm is still quite low @65. You must have the HG43 (4.36 IIRC) gearing, and paired with the auto and the 32" tires gives you that. Well, if it ain't broke... :shrug:

 

B

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Why do people on here think changing the oil will affect the rpms it runs at, at speed? The gearing is the only thing that affects this...

Well I think that because the engine can now make the same power and maintain speed for less rpm because the engine is spinning over more easily, so more / same amount of power for less rpm, and more complete combustion.

 

Sent from my SGH-T989 using Tapatalk

 

 

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As adamzan said the only thing that determines rpm to speed is final gearing. The oil and wait might make very slight difference in hp and mpg if your lucky. All other things be the same.

 

 

Sent from my iPhone using Tapatalk

Edited by sailone32003
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Well I think that because the engine can now make the same power and maintain speed for less rpm because the engine is spinning over more easily, so more / same amount of power for less rpm, and more complete combustion.

 

Sent from my SGH-T989 using Tapatalk

MAYBE if you have an auto, and your torque converter won't lock...But then if that's the case you have other issues.

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Actually I think was off in my thinking, I was actually thinking of less fuel consumption to make the same power...so, unrelated. Anyway I'm just an armchair engineer spouting my own personal fancies :-)

 

Sent from my SGH-T989 using Tapatalk

 

 

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My auto on 33's cruises 60mph @ 1,961rpm. The RPM's stated for the four cylinder diesel motors are most likely correct. four cylinders will almost always rev higher than a six cyclinder at whatever matching speeds. four cylinders have to spin faster to "keep up" with a slower turning six.

 

65mph, 4.625 gears, 32" tires, factory transmission, you should be spinning 2,191rpm. Factory auto gearing

 

65mph, 4.375 gears, 32" tires, factory transmission, you should be spinning 2,072rpm. This is only if both your front and rear diffs were swapped though

 

But if your tach is showing 200rpm off, it's hard to say, other than that your engine is spinning where it should be, even though it's indicated incorrectly.

Edited by silverton
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I only changed the oil to show a earlier comment concern about the purple oil and that it wasn't the reason for the good rpms,I didn't do it thinking it would. I am sorry I had one of my bad pain day's so I didn't get a chance to get out bed, (M.E. Cronin pain disease)besides the fact that the wife took the pathfinder to her daughter's home for Easter. I will check the gearing in am. I don't think it's anything to worry about, I think it's just a good engine and I'm lucky enough to have been blessed with it. Has good power and descent mpg. I am glad we're able to get a good read of rpm rates across the board from members trucks. We can open this up to what y'all are getting with your setup for others to see. Gears/tire size, and the rpm/mpg that coming out. It might help those still building up or making changes to they're own rigs. I'm hoping to get a permanent mounted diagnosis reader of some sort to get a more accurate reading of all the engine readings, rpm/speed/fluids temperature as I really don't think I'm gonna trust the almost 20 year old gauges. Any thoughts on something there would be awesome. I know I can't get a bulldog but something like it. :) thanks for sharing

Edited by Nissanland
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Well I checked my speedometer and it was off by 5 km/h so I was doing 95 instead of 100 km/h. I since fixed it so it shows correct speed now. I'm certain my tacho is bang on the money because at idle it's at 750 and that's what it says it should be per guide book.

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