Turbo vs NA warmup and driving habits

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2,789
Location
California, USA
I think it's safe to say it's agreed upon around here that it can be detrimental to beat on a car/engine before it's warmed up. Sometimes compromises must be made (e.g. when you're driving a car that just doesn't have much power) but when dealing with cars that have surplus power you've got more of a choice in terms of how to drive it while it's warming up. Suppose you have two cars with relatively equal power, but one has a larger NA engine (bigger displacement, more cylinders) and one has a smaller, turbocharged engine. In general, would you treat them the same, or would you be easier on the turbo one? For the sake of discussion, let's compare an NA V8 with a turbo I4, and to make the comparison even better let's say that the displacement of the V8 is exactly double that of the I4 (so the combustion chambers are the same size). So you've got the same displacement per cylinder, and the same number of main bearings and crankpins getting the combustion forces (although the 8 will have 2 cyls per crankpin). The only difference is that the 4 is burning "double" the fuel/air mix in each cylinder. Do you assume that the 4 is more highly stressed and thus should be treated more gently, or do you assume that both engines are built to withstand the same treatment? It seems to me that the bottom end shouldn't "care" since it's similar between the two, and each part of the crankshaft is getting exposed to basically the same magnitude of force, and that the cylinders and pistons had better be beefier in the 4 anyway since it's a F/I application. And that's just the engine side of the question.. what about the turbo itself? In a performance car it's easy to think of the turbo as an add-in that should be pampered as necessary, but more "pedestrian" cars are starting to come turbocharged too. I seriously doubt all the VW TDIs and Chevy Cruze 1.4t's being driven around are going to be babied before warm-up all the time -- no more than a VW 2.5 or a Chevy Cruze 1.8 would be anyway. And in a non performance application, you're going to need a higher percentage of peak power just driving around than you would in a performance application with more power, so it seems like the turbo would be worked harder anyway. I'd guess most of BITOG would err on the side of easy treatment, but what say you? Is "an engine an engine" when it comes to how you use its power output during warmup and while driving around, or does how the power is delivered have a large affect on the way you drive?
 

rationull

Thread starter
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2,789
Location
California, USA
Drat. I don't know how I accidentally posted this here. I was meant for Automotive General. If any mod sees this I'd appreciate a move over there smile
 
Messages
1,639
Location
L.I. NY USA
Many of the questions you pose explain why I would never consider a small turbo engine. I like my engine to have enough power to "get the car out of its own way" without having to go all turbo and high revs. I prefer an engine to make power the old fashioned way, big pistons. I would take something like the CTS V with the turbos because the v8 by itself won't need to spin like mad to move the car at an acceptable clip before it warms up. An engine that creates 140hp at 5600-6000 rpm with the aid of a turbo scares me. ESPECIALLY when its cold outside. I like my engines to push the car at a good clip in the 2000 rpm area. Of course this is all my opinion.
 

crw

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1,715
Location
Pocatello, ID
Living at elevation, I'm looking forward to our turbo'ed future. Turbos don't loose power at high elevation. As to the question... maybe that's where 5w-40 and 0w-40 oils come in?
 
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11,474
Location
Florida, Cape Coral
I like my 245 hp turbo engine. Enough power at 2500 rpm for a daily driver without getting into the turbo and the power is there when I want it. The big advantage is I get good fuel mileage. Big piston are always at a disadvantage when you discuss power and economy. I don't treat my turbo engine any different than my non-turbo engines unless I have been really pounding it on a long highway drive. I let the engine cool down for a minute or so before shut off. Ed
 
Messages
1,506
Location
Ruidoso, NM USA
I had a Twin Turbo Audi 2000 S4 and I certainly drove it "easy" until the oil was warm and by "easy" I don't mean I could not keep up with traffic. I just did not "WAIL" on it! It had PLENTY of torque @ 2000 to 2500 RPM to get out of the subdivision and onto the freeway without any real stress. My Current M Coupe has, like the Audi, a oil temp gauge and a warning to wait until the oil is warm to run full throttle. Good advice for a performance car and makes sense in any car. I am in the "start and drive away camp"...never a warm up at idle for me.
 
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Messages
10,008
Location
Upstate NY
I let it warm up as much as possible before beating on it. My driving routes for work help in this. It's about 4-5 minutes of low-speed steady-state operation before needing to really use the turbo. The gearing helps, since 1-3 are low enough to really launch the car without using the turbo much. Driving around, I've tended to rest my hand on the shifter and foot nearby the clutch to make a quick downshift when needing more power. I try to keep out of the turbo because it really knocks down the fuel economy. It's tough since it spools at 1800 RPM and provides full power by 2200 RPM. When I really beat on it, it's driven gently for a few minutes before shutdown to let it cool down. If it's not possible, I'll let it idle for a minute or so to cool it down. Having a car powered by a tiny engine with a big turbo (16 PSI factory tuned, up to 25 PSI aftermarket tune) is great for fuel economy most of the time, and power when needed.
 
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3,496
Location
VA
Well it boils down to the fact each cylinder in the turbo engine is producing twice as much HP so has far more pressure/side loading on the pistons as well as higher pressure on the bearings... More load will equal more wear in the long run, still there are '87-'88 Thunderbird Turbo Coupes running fine that have over 250K mi and the pistons have never been out of the block... Yes lots of those engines died a early death, but in almost every case it can be attributed to lack of maintenance... Unfortunately they couldn't survive the general public's apathy toward upkeep as well as a V8...
 
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36,521
Location
ME
My volvo 940 turbo has a water/oil cross-cooler and the water temp warms up fast, within a mile. PO put a turbo on at 200+k, now at 232 and hanging tough. This is an almost full size wagon with a 2.3 liter 4 cyl. Luckily (?) we only get an automatic without torque convertor clutch so the engine never really lugs. It makes boost in everyday driving, and more if you wail on it. But it has a touch at 2500-3000 RPM and mid throttle, then will upshift before getting into the revs where boost would be unnecessary.
 

JHZR2

Staff member
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46,291
Location
New Jersey
I certainly dont want to be pushing a lot of boost when the engine is very cold. But I dont want to be pushing an NA engine very hard either. But I always drive with a very light foot, so dont have to worry about it much.
 

gathermewool

Site Donor
Messages
8,938
Location
New England
I just drive my STI normally until it warms up. It has plenty of low-end torque, even if I'm only at the onset of boost. Turbo vehicles also usually have a lower compression ratio than NA vehicles, which could results in less stress during warmup.
 
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24,710
Location
Dallas,Tx USA
My friend has a 500+ hp 300ZX twin turbo,and if you have never felt tt boost,it`ll scare you to death!!!!! Makes a roller coaster feel like it`s standing still.
 

JAG

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5,320
Location
Fredericksburg, VA
Many modern turbo engines reach peak torque at much lower rpms than naturally aspirated one with equal peak horsepower. I don't think the proposed comparison has enough assumptions (ex. Torque curve data, surface area of bearings, rpm range used, etc.) to have a correct answer. Turbo engines are built to handle the extra loads so I don't think trying to find that answer is worthwhile. Regardless of turbo or not, high rpms are bad on a cold engine because it tends to starve the top end.
 
Messages
252
Location
Austin, TX
Most people get in their car, throw it into gear in under 30 seconds and go. Most cars that get regular oil changes and standard maintenance are fine for many years. That makes me wonder, does it really matter? If you are beating on a V8 or a turbo 4 banger will a little warmup time make much difference in the life of the engine if its properly maintained?
 
Messages
903
Location
wa state
my stock turbo 2.4l will hit full boost well before 3000 rpm's and hold peak torque from ~2200 rpms all the way to 4800 rpms, redline is around 6240rpms. There is no need to rev it out to get the car scootin along. I would think the smaller 4 cyl would be taking more stress than a v8 due to the fact it normally puts out more power per liter. I always drive normally until my coolant temps are high enough for the tstat to start opening, and idle oil pressure is 30-40psi. I drive 9 out of 10 trips without hitting the positive side of the boost gauge. The turbo isnt needed to accelerate, its just a bonus if you feel like using it.
 
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Messages
11,196
Location
NY Capital District
I want to note that the cruze hits max boost at 1800RPM. So I rarely have to go over 3k to accelerate, except when merging. So... It's a moot point. Turbo 4cyl =/= need to rev high to accelerate.
 
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8,576
Location
Ohio
To be a fair comparison it would have to be comparing a turbo 4 to a larger displacement 1.8-2.0 NA 4 of similar power output. The larger displacement 4 will likely have a longer stroke, higher compression ratio, and need to rev more and hold a lower gear to match the turbos low speed torque. I think cylinder friction wear is the real issue, and that's why the smaller turbo engine might not be at any real disadvantage in engine life.
 
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10,783
Location
Jupiter, Florida
One thing to keep in mind, cast iron cylinders exhibit decreasing wear as the temperatures increase. If I remember correctly, the magic number is 160 deg F, wear is excessive below that number, and decreases markedly above that number. A interesting curve on a graph. Anyway, I'd suspect at turbo engine, forced to make boost at low temps would exhibit excessive cylinder wear.
 
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11,196
Location
NY Capital District
Originally Posted By: Cujet
One thing to keep in mind, cast iron cylinders exhibit decreasing wear as the temperatures increase. If I remember correctly, the magic number is 160 deg F, wear is excessive below that number, and decreases markedly above that number. A interesting curve on a graph. Anyway, I'd suspect at turbo engine, forced to make boost at low temps would exhibit excessive cylinder wear.
You really think cylinder temperatures on a boosted engine are lower than a N/A engine at low RPMs? Your logic confuses me.
 
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