+- Madison Motorsports (https://forum.mmsports.org)
+-- Forum: Technical (https://forum.mmsports.org/forumdisplay.php?fid=4)
+--- Forum: Technical Discussion (https://forum.mmsports.org/forumdisplay.php?fid=11)
+--- Thread: Is low rpms + high load bad for an engine? (/showthread.php?tid=2004)
Is low rpms + high load bad for an engine? - JackoliciousLegs - 04-04-2005
Yes or No?
Just debating on cold startup whether I should allow a couple extra RPMs to get the car moving... or I should push the gas pedal harder at lower RPMs....
- mpg9999 - 04-04-2005
With absolutly nothing to back this up, I wouldnt do either. I'd keep the revs low and stay under light load. If I had to pick between red lining a cold engine and going full throttle, I'd go full throttle.
- ScottyB - 04-04-2005
mpg9999 Wrote:With absolutly nothing to back this up, I wouldnt do either. I'd keep the revs low and stay under light load. If I had to pick between red lining a cold engine and going full throttle, I'd go full throttle.
i've always kinda adhered to the same rule. i figure high revs and cold oil combined with initial lack of oil circulation (to a high degree) is asking for engine damage.
but i also figure that the pistons/rotors have to expand, right? so giving a cold engine large throttle imputs is asking for blow-by until they expand.
i dunno though, never really researched it.
- mpg9999 - 04-04-2005
Holy crap I didnt think anyone else was up at this hour.
- Ryan T - 04-04-2005
I'm inclined to agree with both of the above statements. I wouldn't do either unless I had too. If I was forced to do one or the other, I'd probably go with more load at low rpm's.
- CaptainHenreh - 04-04-2005
Well, internal comubstion engines run most efficiently at WOT.
The Metro (and other fuel efficient cars) is designed for you to be WOT @ ~2000 RPM's running around non-interstate highways.
I don't really see the problem with large load at low RPM's but I definitely see the problem with oil starvation to remote engine parts at high RPM's when the oil is thick. Having said this, the best option is clearly a remote start.
- Rex4life - 04-04-2005
low rpms? wtf? if i hadn't seen your engine on saturday i would never thought you had a rotary with that comment
- mpg9999 - 04-04-2005
CaptainHenreh Wrote:Well, internal comubstion engines run most efficiently at WOT.
Do you know why that is (without looking it up)?
- Mike - 04-04-2005
i agree with rex... high load and low rpms while the oil is thick and not lubricating.
- ViPER1313 - 04-04-2005
Your rod bearings will not appreciate your high load at low RPM theory.
- lillitnn92 - 04-04-2005
i abide by the same rule myself, i give it at least a decent warming before any WOTs.
don't always follow it though :oops:
- .RJ - 04-04-2005
I will take low load/high rpm over slugging the engine any day.
- ScottyB - 04-04-2005
.RJ Wrote:I will take low load/high rpm over slugging the engine any day.
even if it's a situation where you just jump in your car in the morning, crank it up, and head out?
- .RJ - 04-04-2005
Given those two choices - yes. Oiling will be better at higher rpm anyways.
- ScottyB - 04-04-2005
.RJ Wrote:Given those two choices - yes. Oiling will be better at higher rpm anyways.
that makes sense.
i don't usually lug the engine hardcore but i don't take it above about 2500 rpm until the temp needle is registering anything on the gauge. and even then, i don't take it above about 3000 until the water temp has been steady for a good 5 minutes (i don't have an oil temp guage).
- .RJ - 04-04-2005
Of course - low load, low RPM is preferrable to both right after cold start.
- CaptainHenreh - 04-04-2005
ViPER1313 Wrote:Your rod bearings will not appreciate your high load at low RPM theory.
I don't think Jack needs to worry about rod bearings.
But for me, I was always taught that if you cannot wait for the car to reach operating temperature, to short shift it.
- Rex4life - 04-04-2005
if i'm right jack pre-mixes. so oiling the engine isn't really a factor, is it?
- WRXtranceformed - 04-04-2005
I always let my oil warm up before I go WOT. My car knocks like a motherfucker if I don't and it's cold out.
Apparently when fuel injected cars are warming up, they're running in a very rich state. As the car warms up, the fuel maps drop back down to normal calibration, or in my case, the stage 2 93 octane guidelines.
I've also heard that since oil is thicker when it's cold it can't reach all the vital parts of your engine as quickly, which can lead to fucked up bearings if you push it really hard.
This might only be true in the winter time, and maybe only for my particular car, but after one uber knocking session I always wait until my car has warmed up before I get into heavy boost.
- Andy - 04-04-2005
WRXtranceformed Wrote:I always let my oil warm up before I go WOT. My car knocks like a motherfucker if I don't and it's cold out.my gf's subie makes that knocking noise too (I hope it's not knock.) crazy boxer engines.
Click and Clack says low rpm, low load is ideal for the first couple of minutes. But extended warmups aren't necessary and can be bad for the car because an idling car won't build up oil pressure nor warm up as quickly. Because the car doesn't warm up quick enough, it runs rich for longer, consumes more gas that can also end up mixing with your oil .. . blah blah blah