safe to drive at 1500 RPM?
10-02-2005, 12:35 AM
#21
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Originally Posted by The Mike
1500rpm and you're worried its struggling? This is no joke but I drop mine to 6th and do 28-30mph at about 1,000 rpm. Has very slight throttle but can definately keep it constant or even speed up slowly from there. 1st 2nd normal rpm, drop way down then 6th and cruise very quietly. Neighborhood, park, ect..
10-02-2005, 09:14 AM
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My automatic i think puts me in 5th gear, no matter what, it rarely down shifts. so basicly im usely running at low RPM no matter what, SO nissan made a automatic that blows engine becuase it runs it self in low rpms.
I think you guys are wrong, i dont know much about cars BUT lower rpms means less spinning meaning less work on the engine? To me it sounds stupid to rev high when your going 30 miles per hour, alot of work for nothing.
I think you guys are wrong, i dont know much about cars BUT lower rpms means less spinning meaning less work on the engine? To me it sounds stupid to rev high when your going 30 miles per hour, alot of work for nothing.
10-02-2005, 09:44 AM
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I got a friend who drives her 300zxTT in 4th on the highway at all times. For some reason, 2000rpm in 5th at 55 freaks her out. I dont get it. I'm in 6th anytime I'm over 35mph. 30mp, 5th gear is usually where I'm at. The Z has plenty of torque at 1500-2000rpm - more than the RX8 or S2000 develop at redline! The VQ is simply a different engine. There is no lag, plenty of torque, and extremely advanced valve timing. These all contribute to a smarter, more powerful engine. It can surely handle low speeds in high gears, and is most likely better for it.
10-02-2005, 02:42 PM
#25
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Originally Posted by hhg35
if you drive 28 - 30 mph in 6th. How fast you go in 2nd, 3rd, 4th.
2nd ~ 3500 - 4k =30ish
wait for the drop in rpm
6th ~1000 and cruise.
10-02-2005, 06:01 PM
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Originally Posted by pargion
if i'm not mistaken, the owners manual says the recommended speed to shift into 6th gear is 33mph. that hits about 1200rpm. any thoughts?
Shown below are suggested vehicle speeds for shifting into a higher gear. These suggestions relate to fuel economy and vehicle performance. Actual up-shift speeds will vary according to road conditions, the weather and individual driving habits.
For normal acceleration in low altitude areas [less than 4,000 ft (1,219 m)]:
Gear change MPH (km/h)
1st to 2nd 8 (13)
2nd to 3rd 16 (26)
3rd to 4th 25 (40)
4th to 5th 28 (45)
5th to 6th 33 (53)
For quick acceleration in low altitude areas or in high altitude areas [over 4,000 ft (1,219 m)]:
Gear change MPH (km/h)
1st to 2nd 15 (24)
2nd to 3rd 25 (40)
3rd to 4th 40 (64)
4th to 5th 45 (72)
5th to 6th 50 (80)
this is from the manual... I personally I find it a little rediculous. I am unable to drive at such low speeds/RPM as is reccomended here. As a matter of fact... I don't think I have ever shifted in 6th gear bellow 60mph... I am always between 2500 - 4000 rpm cruising.
Last edited by Nano; 10-02-2005 at 06:04 PM.
10-02-2005, 07:46 PM
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Originally Posted by Kolia
the oil film on wich everything is running can then fail
This sounds absurd. If that happens, engine would seize not just have slight damage. I cannot emphasize enough the catatrophe or ill effect of metal to metal contact can be. Oil is like the blood of the engine, without it engine wouldnt move. I have many times had near WOT or WOT at 1500 - 2000 rpms without any bad effect. Engine seizure is a very rare occurance, happens most of the time because of oil pump failure or overheating of the engine. I am assuming when a torque curve is published, its at WOT. Since Nissan published a comparison of the VQ 300Hp and 287Hp engine, the torque curve started at ~700 rpm, that means they tested it at WOT at 700 rpm or idle speed. And the torque curve are usually published based on loaded test performed on a dynamometer. So the engine is fully loaded.
10-03-2005, 03:28 AM
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If you must keep the RPMs low, just shift at 3K every gear and you'll have NO problems with ANYTHING...
This even saves gas and you can WOT at anytime with NO problems.
This even saves gas and you can WOT at anytime with NO problems.
10-03-2005, 03:31 AM
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Originally Posted by spcemn_spiff
I am assuming when a torque curve is published, its at WOT. Since Nissan published a comparison of the VQ 300Hp and 287Hp engine
10-03-2005, 03:57 AM
#32
Originally Posted by spcemn_spiff
This sounds absurd. If that happens, engine would seize not just have slight damage. I cannot emphasize enough the catatrophe or ill effect of metal to metal contact can be. Oil is like the blood of the engine, without it engine wouldnt move. I have many times had near WOT or WOT at 1500 - 2000 rpms without any bad effect. Engine seizure is a very rare occurance, happens most of the time because of oil pump failure or overheating of the engine. I am assuming when a torque curve is published, its at WOT. Since Nissan published a comparison of the VQ 300Hp and 287Hp engine, the torque curve started at ~700 rpm, that means they tested it at WOT at 700 rpm or idle speed. And the torque curve are usually published based on loaded test performed on a dynamometer. So the engine is fully loaded.
I have friends who decided to blow a Toyota Corolla engine. Car on jack stand, brick on the gaz pedal and NO oil in the engine. The thing ran out of gaz, never sized... I didn't run very well afterward, but still did.
Engine testing is done at WOT, from max rpm down to stalling rpm, braking the engine with either an hydrolic or friction brake balance.
Frictions goes down with speed. So a slow moving piston is getting the most wear (It's actually the rings that wear). The rings uses the pressure in the combustion chamber to be pushed against the cylinder wall. Go WOT at 1000rpm, you get maximum wear (slow speed & high pressure) with less than optimal lubrication.
Low rpm at low load is alright. I know that if I do it, I'll probably not down shift each time I need to accelerate and load the engine.
10-03-2005, 03:57 AM
#33
Originally Posted by Tattude
Where can I find the results of this test?
10-03-2005, 05:03 AM
#34
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Originally Posted by Kolia
Engine faillure will not occure instantaniously when lubrication stops. Well, maybe on an american engine.
I have friends who decided to blow a Toyota Corolla engine. Car on jack stand, brick on the gaz pedal and NO oil in the engine. The thing ran out of gaz, never sized... I didn't run very well afterward, but still did.
I have friends who decided to blow a Toyota Corolla engine. Car on jack stand, brick on the gaz pedal and NO oil in the engine. The thing ran out of gaz, never sized... I didn't run very well afterward, but still did.
An engine designer will always try to prevent lubrication failure at ANY cost.
10-03-2005, 06:43 AM
#35
Originally Posted by spcemn_spiff
I was not talking about your personal experience.
An engine designer will always try to prevent lubrication failure at ANY cost.
An engine designer will always try to prevent lubrication failure at ANY cost.
He will design the engine so it will live an minimum time before failure, not to last forever.
10-03-2005, 09:40 AM
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Originally Posted by Kolia
An engine designer will design the lubrication system to run under average expected conditions, temperature, load, cold start endurance and such.
10-03-2005, 10:14 AM
#37
What I meant is that the engine is built for a purpose and according to certain specs. It is not built to last forever under the most extreme abuses.
What are these design specs anyways? Anybody here is or knows an engine designer and could tell us what they could be?
Are the specs for a VQ35 intended for a high revving Z the same as that of a low revving CVT equipped Murano? I doubt it…
Is the VQ35 tough enough to have a long life lugging itself a 1000rpm? Probably, it is a good engine. It probably won’t grenade itself just for doing that.
Is going on full load, WOT, at 1000rpm good for the engine? Is the engine seeing the same wear as WOT at 2000rpm? I’d need some seriously solid arguments to convince me of that.
The way you’re putting it, it would be impossible to blow an engine. Yet they do blow.
What are these design specs anyways? Anybody here is or knows an engine designer and could tell us what they could be?
Are the specs for a VQ35 intended for a high revving Z the same as that of a low revving CVT equipped Murano? I doubt it…
Is the VQ35 tough enough to have a long life lugging itself a 1000rpm? Probably, it is a good engine. It probably won’t grenade itself just for doing that.
Is going on full load, WOT, at 1000rpm good for the engine? Is the engine seeing the same wear as WOT at 2000rpm? I’d need some seriously solid arguments to convince me of that.
The way you’re putting it, it would be impossible to blow an engine. Yet they do blow.
10-03-2005, 11:10 AM
#38
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Originally Posted by Kolia
The way you’re putting it, it would be impossible to blow an engine. Yet they do blow.
10-03-2005, 12:08 PM
#40
Originally Posted by spcemn_spiff
My point was a reply to your post saying that lubrication fails at low rpms came out of thin air, I see no evidence of that at all or nothing to substantiate your claim. Thats what I wanted to address and I think the discussion is drifting from that.
All the guys I know who blew their main bearings where “babying” their engines on low rpm. So yeah, that’s my own personal experience and it’s worth what it’s worth.
I know that cylinder pressure will be pretty high if I try to accelerate from 1500rpm in sixth gear and it will last for a long while in engine time. Oil pressure might be high enough so as not to be chassed out of the bearings. I don’t know for sure.
I’ll try to contact one of the engine guys here to have their opinion.