Greetings everyone. I hear many people say that one vital element of owning a turbo charged vehicle is to let the turbo cool down for a minute or so after a long drive. Since the LC250 shuts off the engine automatically when you stop, how are we supposed to allow the turbo to cool down? My understanding is that the engine allows the oil to flow through the turbo to cool it down. Does the air to water intercooler help after the engine shuts off. Your feedback is appreciated.
Letting turbo cool after parking
- Thread starter Pavman2473
- Start date
This isn't really an issue with modern turbos that are both oil and water cooled like in our LC250s. The air to water intercooler is specifically for cooling the intake air, as in it's separate from the engine cooling. The LC250 uses an air to air intercooler.
Edit: fixed some things
Edit: fixed some things
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The lc250, Tacoma and the 4Runner doesn’t use a water to air intercooler. These vehicles use an air to air intercooler. The unibody vehicles with the T24A use the water to air intercooler.
I think if the turbo is hot and you're still driving, the engine will stay on longer (not go into electric only mode) until it thinks the turbo has cooled.
If there's a time I'm ready to park and I think the turbo may still need a minute to cool down, I'll turn on Tow Haul mode to keep the engine on while I sit for a minute before turning the Cruiser off.
- Thread starter
- #5
My bad. I thought I read somewhere that it was. Oops.
This is not your normal turbo charged engine. if you have a chance, just look at the turbo gauge and you will see that the turbo barely kicks in. you have to be flooring that accelerator for that turbine to be active.
- Thread starter
- #8
I have noticed that. Once you’re up to speed it kicks in sparingly along with the hybrid battery. I’ve never owned a turbo and the keyboard warriors like to dump on them and the 4 cylinder. I don’t get it. I think it performs very well. Cheers.
I have not found this to be the case.
If I am accelerating at anything more than the lightest press on the pedal (anything more than 5-10%) or climbing a hill or driving faster than 70 mph or pulling a trailer then the turbo is showing some (>5 psi) pressure on the gauge.
At steady speed (<60) it often does not show any boost which seems like how it should work.
You don't have to worry about cooling the turbo in normal city or highway driving. It will be well within safe temperature range.
The only scenario you may want to consider let the turbo to cool down slightly is something like this:
- You drive up a long, steep climb on an highway while going 75 mph. By long and steep I mean something like you can find on I-40 in Colorado or US-93 in AZ climbing toward Hoover Dam - more than just a couple of miles, with steady 5-6% (or more) incline, on a hot day. Then you pull over into a rest area immediately without driving for a mile or two on a flat portion of the highway.
In such case you probably will make things better for your turbo if you slow down a mile or two prior to the stop and let the turbo cool down by driving 60 mph instead of 75-80, and then drive slowly through the parking area for another 20-30 seconds. This will allow fresh "cool" oil to flow into the turbo bearing and cool them down a bit.
The only scenario you may want to consider let the turbo to cool down slightly is something like this:
- You drive up a long, steep climb on an highway while going 75 mph. By long and steep I mean something like you can find on I-40 in Colorado or US-93 in AZ climbing toward Hoover Dam - more than just a couple of miles, with steady 5-6% (or more) incline, on a hot day. Then you pull over into a rest area immediately without driving for a mile or two on a flat portion of the highway.
In such case you probably will make things better for your turbo if you slow down a mile or two prior to the stop and let the turbo cool down by driving 60 mph instead of 75-80, and then drive slowly through the parking area for another 20-30 seconds. This will allow fresh "cool" oil to flow into the turbo bearing and cool them down a bit.
Turbos can be a bit polarizing... obviously, a turbo charger will increase an engine's performance...this can be a good thing if we're talking about adding some additional HP to an already adequate powertrain...but it's also become a trend to add turbos to under-sized engines to simply get "okay" performance from an otherwise under-powered engine to get better fuel economy numbers. Particularly in the case of the latter, it tends to mean that the engine is often over-worked, and could potentially cause operational and reliability issues down the road.
In the case of the current Land Cruiser (and Tacoma, and 4Runner, et al), I think this line is a bit blurry...obviously the new 4-cylinder engine is considerably smaller than it's outgoing V6 (or V8) counterparts, and would be a bit of a dog in these trucks and SUVs without the turbo...but I also haven't found the current powertrain to be all that taxed during normal driving conditions, with or without the turbo spooling up...and it does provide a nice boost of power and torque when needed.
(You can make a pretty similar argument about the need for the hybrid electric motor as well)
In the end, I think what folks really don't like is having to add a lot of complexity to an engine/powertrain that was once quite simple, powerful, and reliable...more components mean more parts that need to be maintained and more things that can break down... for better or worse, it really is just the how these things are going to continue to trend though...with today's standards and regulations, the gas-guzzling V8s and other inefficient high-displacement engines are going keep becoming more and more rare...
but I try to not be stuck in the past, and so far I've been nothing but impressed with what Toyota is getting out of the 2.4L 4-cylinder engine they're using now.
yeah, same here.
Does a turbo add significantly more complexity compared to two or four additional cylinders, injectors valves etc?
The turbo doesn't add much more complexity, but it has meaningful impact on other engine components.
It does create more stress on the engine itself - the only way you can get more power and torque from a smaller displacement engine is by significantly increasing combustion pressure and temperature, and consequently the load on bearings, cylinder walls, etc. Of course, these components can be designed to withstand these higher loads, but there is no free lunch, there will always be a trade off between how much power you can squeeze out of a certain displacement and engine longevity.
Turbos also introduce more stress on the oil. The oil is subject to higher temperatures when it is used to cool and lubricate the turbo, and the engine in general. It's a bit of a contradiction game, as you need very thin oil to lubricate a fast spinning turbo, and you want a thicker oil to lubricate the crankshaft bearing which are now subject higher loads / pressures.
Only time will tell how good of a balance between performance, longevity and cost did Toyota strike with these new engines. The Tundra engine debacle doesn't look good, but the T24A has been relatively trouble-free so far.
Personally, I don't expect the T24A engines to last as long as some of the best older large displacement Toyota engines. But it may prove itself to be sufficiently reliable and durable for most of people. I never keep cars beyond 100k miles (with one notable exception but that was when I was a poor college student), so I am not overly worried. But it may hit resale value or those owners who like to keep their cars "until the wheels fall off".
- Moderator
- #14
All a turbo is, is an air pump, driven by the exhaust gases. The more air/fuel you can jamb into the combustion chamber the bigger the explosion when the spark plug ignites which equates into more power . That being said ........ too much fuel (turbo not spinning up to speed, packing in too little air) equals poor combustion and the engine will run "rich" and not preform well. Too much air (fuel injectors dirty/fuel pump not suppling enough fuel, the engine will run lean and could melt the pistons. The waste gate system for the turbo (there are other similar systems) opens to allow excess air pressure to bleed into the atmosphere, preventing a lean condition. Because the hot side of the turbo is spun up by exhaust gasses, it gets extremely hot and the bearings would burn up in short order if not lubricated by engine oil. If the turbo was glowing red and you shut the engine off, stopping the flow of oil, the oil would boil in the turbo's oil passages, decompose, clog up the passage.......... etc. You're not going to get the turbo that hot with normal driving. But as mentioned above......... under heavy load situations, you should allow the turbo to cool down before shutting off the engine.
The air/fuel ratio, waste gate and timing are controlled by the ECM (fuel map) and uses sensors throughout the engine system to keep the ratio in the sweet spot according to the manufactures/owners preference. It's common practice in the high performance world, to tweak the fuel map to get the best out of an engine depending on application.
A supercharger does the same thing except it uses a pulley tied to the crankshaft and normally doesn't have a waste gate.
The air/fuel ratio, waste gate and timing are controlled by the ECM (fuel map) and uses sensors throughout the engine system to keep the ratio in the sweet spot according to the manufactures/owners preference. It's common practice in the high performance world, to tweak the fuel map to get the best out of an engine depending on application.
A supercharger does the same thing except it uses a pulley tied to the crankshaft and normally doesn't have a waste gate.
- Thread starter
- #15
I took the vehicle on a 200 mile trip Friday. You’re right. Outside of getting up to speed and inclines, the turbo was noticeably dormant.
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