russde Reader
5/12/22 7:44 p.m.

In my (still ongoing) search for a sporty'ish wagon (or sedan) that gets good to great gas mileage and is kinda quick and handles better than my GX470, I'm finding a TON of cars are now 2 liter turbos (the most frustrating ones are the BMW's, come on guys the 320, the 328 and the 330 are ALL 2.0t's?)

Why? Is that the sweet spot for efficiency vs power vs packaging? Is it because of regulations (furrin' as well as 'murican)?

I'm impressed with the level of performance these things are able to acheive...but the cro-magnon in me just keeps saying that if 2.0 is good 2.6 would be better, and 3.99 would be awesome.

How about longevity? Are these little things lasting 200k? Do the turbos last that long?

So many questions....

Error404 HalfDork
5/12/22 7:48 p.m.

Mine is at 120k/15yrs and burns a fair amount of oil but it's a VW so if it ain't burning oil then it's probably broke. Pretty sure VW EVs have an oil resevoir to burn to keep up appearances. 

I feel the same about the tiny turbo engines, if 1.x is good then what about 4.8? 5.0? 

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
5/12/22 7:55 p.m.

I imagine it has a lot to do with taxes in other countries like Europe and Japan, which (IIRC) have different tax "brackets" for displacements. I would guess 2.0L is the largest that falls into the lower-tax bracket? IDK

Incidentally my GTI is a 2.0T at 45k or so, no issues so far. My warranty goes to 72k so I'll decide then how long I'll keep this thing lol. 

tb Dork
5/12/22 8:05 p.m.

In reply to irish44j (Forum Supporter) :

This is my understanding of it. For a long time now, anything in Europe or Japan larger than 2.0 liters gets a hefty tax charge and is practically priced into another category entirely. In order to get serious performance out of tiny little engines turbos have basically become standard equipment to circumvent the displacement penalty.

Even 2.3-2.6 liters are considered the bigger, torque monster options in some instances if you have a fat wallet and want to check all the boxes to guzzle gas across the EU...

cyow5 Reader
5/12/22 9:05 p.m.

For what it's worth, BMW's naming convention went out the window long before 2.0 turbos. My '07 328 has the same engine as the 325 and 330 aside from the intake manifold and tune. 

Even then though, BMW fervently stuck with 1/2L per cylinder. The I6 is a 3L so the I4 became a 2L. Once you commit to such a scheme, engineering becomes easier because the engine topography becomes kinda modular. I think others then jumped on board. At least in the US, I don't think there's any tax implications 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
5/12/22 9:17 p.m.

Slightly undersquare cylinders of about 500cc have turned out to be the sweet spot for efficiency, yes.   I forget the precise details why.  Smaller cylinders have more surface to volume so more heat is lost to the cooling system and it is hard to get compression up without compromising the combustion chamber shape, larger cylinders are more detonation prone because the edge of the chamber is further from the spark plug.  I think that was a lot of it...

It does amuse me that the corner that VW painted themselves into with an 88mm bore center architecture turned out to actually be prime real estate.

The engine in my 282k mile Volvo has its original turbo.  Mind you, the engine had 166k (allegedly) when it went in at 230k so the engine itself has about 210k...  but it is an OLD, robust design.  It is directly related to the turbo on, say, a 1981 Audi 5000.  Last weekend I clicked off 32.2mpg trip average.  81mm bores, stroke in the 92-95mm range (I forget),  absolutely no short side radius in the intake ports to speak of, when the valves open the air goes to the back of the chamber.  Not the best for VE but there is about 18psi of forced induction available when go is needed.


parker HalfDork
5/12/22 9:43 p.m.

The turbo went on my Cobalt SS at about 200k.  Replaced it and the timing chains.  Everything was still going strong and didn't use any oil between changes when I sold it at 255k miles.


alfadriver MegaDork
5/12/22 9:50 p.m.

In reply to Pete. (l33t FS) :

As I'm aware, Volvo has been using turbos for fuel economy for a VERY long time- longer than most others.  While 80's turbos were supposed to be power of the big engines with the economy of the small- they were more tilted toward power.  Somewhere in there, Volvo really looked at engine design for efficiency more than the power.

I really don't know the details of that, but when I was visiting there for a "turbo conference" in 2002, their efforts were clearly shown to me.  But I was also clearly instructed at the time that Ford only looked at turbos at performance enhancements.  Thankfully, we've all moved onto the efficiency work.  But, as you have experienced, Volvo has been doing it for a very long time, and really well.

In terms of the optimum size, one would think that an OEM would spend a LOT of time and effort to design one total system that could be used across a lot of engines of different displacements- like 1.5, 2.0, 3.0, and 4.0.  But it's pretty shocking to learn how that doesn't actually happen.  And instead even the common single cyl displacement engines have no parts shared at all....  sigh..

Rigante Reader
5/13/22 4:28 a.m.

UK road tax is all emissions based, so for a post 2005 car that isn't up to the Euro 6 emissions standards you pay around £680 in yearly road tax. An old 3L like an e39 is £300 road tax, but a modern 2.0t BMW may only be £30 a year as there's only unicorn farts coming out of the exhaust.  BMW 2.0s have puny cam chains and self destruct often. I'm not sure if the newer ones are better but the 2010 ish ones are shocking. the chain is like the technical lego ones 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
5/13/22 6:13 a.m.

In reply to alfadriver :

And this is in a "high pressure turbo" vehicle geared to performance.

My S40 had a "1.9l" (2 liter) four with much higher compression (10:1?) and a much smaller, twin scroll turbo.  (TD03 12T) I had seen over 40mpg on a regular basis.  Driving at higher speeds while towing a trailer to Iowa, I saw 34mpg.

Oldboy Speedwell
Oldboy Speedwell Reader
5/13/22 7:48 a.m.

Scattershot post here, please forgive my ramblings.

2.0T does indeed seem to have taken over the world.

My car has a rather antiquarian SOHC 1.6 liter, but bags of character because BMW decided to use an Eaton blower to amp it up.

It seems to me that many late model or contemporary 2.0T's lack character, or am I completely misreading?

How did the old Saab B202 achieve such a distinct exhaust burble that other 2.0T's don't have? Was it the design of the cast iron manifold? But now I'm really divergent because exhaust tuning is a totally different topic.

Never an Alfa owner but a longtime admirer - I've often read that many Alfa-fans prefer the 1750 over the 2000, are their characteristics really that different?

alfadriver MegaDork
5/13/22 8:40 a.m.

In reply to Oldboy Speedwell :

No, they are not that different.  People claim that the 1750 revs faster, but in reality, the two engines share a stroke, and are only separated by bore.  IMHO, it's based on the general sound of the 1750 with Webers vs. so many of the 2.0l's with SPICA and emissions tuning.

The truly different engines are the short stroke engines in the GTA jr.  Those things spin to the  moon for a production 60's motor.

Aaron_King PowerDork
5/13/22 9:56 a.m.

I don't know about "modern" 2.0T but I gave my brother a 99 SAAB 9-3, with the Triumph derived  motor, with 245K miles on it.  Original turbo, timing chain and clutch.  He drive it to over 300K before he got rid of it.

MotorsportsGordon Dork
5/13/22 10:24 a.m.

I think also it gives extra strength to the block to handle more boost etc going down to 2 litres. Most of the normally aspirated 4 cylinder engines will be in the 2.2 to 2.5 litre range so running at 2 litre gives more cylinder wall etc to handle higher boost etc.

trucke SuperDork
5/13/22 10:32 a.m.

Check out the Honda Accord 2.0t with the 10 sp auto!  That thing is quick!  

russde Reader
5/13/22 1:02 p.m.

Thanks for the insight...


<off to research BMW 2.0's self destructing...>

pointofdeparture UltimaDork
5/13/22 1:04 p.m.

In reply to russde :

The N20 was the really bad one subject to multiple class action lawsuits, I have heard that the newer B48 which replaced the N20 is a significantly better engine.

Our Preferred Partners