How many turbo V engines have you dealt with? Not 4 cyl, V engines. I've dealt with dozen and low mounted turbos always are far harder to get to, coke oil more often, and generally just suck. Even 4 cyl engines with higher mounted turbos are better than low mounted versions for the same reason.

BMW never made a good V8, but their turbo versions are better than the older NA ones and the TU3 update really solved a lot of the issues.

Curious how you avoid mentioning the stellar Audi 4.0 or Mercedes 4.0 engines.....those are insanely easy to work on. The Audi version is downright unfairly simple, I pulled my turbos off and uprated them in my garage in less than 6 hours with no special tools. For 90% of twin turbo engines you would need to drop the subframe off to get to the turbos just like what you see here.

I would ALWAYS take a hot V engine over any other configuration for serviceably and spool speed/overall efficiency. It's just so damn easy to work on them.

 

Yep, point one forward and the other backward, or stager them, but most use only one if they are a V6. Or alter the head design/spread the banks a little like Aston

https://www.enginelabs.com/news/first-look-aston-martin-new-twin-turbocharged-hot-v-3-0-liter-v6/

http://youwheel.com/home/2016/06/08/technical-analysis-audis-new-3-0l-turbo-v6/

Audi does it as well and there is no comparison vs their older side mounted setups, this is just better in every way. The ease that you can get to everything with is massively improved, the only reason this took so lo my to catch on is once upon a time cars were carbed and it's much easier to center mount those and only race cars had cross ram intakes that could possibly be run this way. However fuel pooling and carb freezing would still be an issue.

 

Why do low mount turbos coke more often? If anything, the Hot V approach is usually associated with heat management challenges.

Anyways, glad that some manufacturers are (edit: have been) reintroducing I6's.

 

I do not know anything about Audi, I've never even driven one. Mercedes hot V is too new, time will tell. I've had one NA BMW V8 and three of their hot V8s, they are not easy to work on at all. Point being, turbo engines in general are more delicate and more prone to issues compared to NA, we had a Landcruiser thread recently where I predicted the turbo engine would be more problematic compared to the old NA V8, and look, it is.

 

The interesting part, as stated previously, is that the LS500 has (mostly) been trouble-free, engine-wise.

 

Have you worked on a same year low mount turbo V8 of the same type of car? Like a paramera or even a V6 car? It's way worse than an N63 to get to them.

They tend to coke more down low based on frequency of having to replace them from damage or blown seals. There are simply less failures and parts bought for high mount systems

 

Oil lines are longer, have to travel further to return to pan and they trap heat under the heads in some configurations. When the car shuts down there is no air path for the rad fan to after run and blow air out of that are unlike a top mount.

The newer designs are just better, I didn't consider owning a turbo car until they changed to that so when the turbos inevitably fail I wouldn't have to go through that same process on one of my cars. Now it's easier to swap turbos than it would be to install headers on most cars

 

I'm not a mechanic, I like wrenching, but I don't have the time for it. I wrech on my motorcycles, but last time I wrenched on a car was over 10 years ago when I had my Lexus with the 3UZ, which in my opinion was the pinnacle of ICE engineering. That being said, I don't see how turbo placement would lead to engine to coke more, that's a product of direct injection and PVC/EGR systems. I know VW DI engines are notorious for carbon build up, and so are BMW engines. Toyota avoids it on engines with both port and direct injection systems, which is a compromise in itself.

Talking about seals, valve seals on BMW engines are a huge meme, as you probably already know.

 

BMW hot V8s are notorious for leaking turbo oil and coolant lines, I had all of them replaced when they were doing the valve seals on my E70. Regardless of design, turbo engines will always require more maintenance and be harder to work on vs NA, especially with all the emissions nonsense.

 

Oh they are. It's so bad that sometimes as soon as they say "using oil" I sometimes say "I recommend new car" since the shock of repair costs usually leads to that anyway.

The oil coking issue is not at the valves, it's inside the turbo oil feed lines and bearing. The longer lines are usually tight to the heads and get cooked when you shutdown for side mounted turbos. If you after run for 5-10 min it doesn't have an issue but with top mounts they usually include a nice air path for the main engine fan go run air over everything after you shut the car off. My A8 does so depending on how hard it's been run and it doesn't exhibit the issues side mount cars do.

 

I don't disagree with that, but if you are going to have them you should put them up top so it's no different than doing an intake on a NA V8. The revisions to the later BMW V8s specifically avoid the issues you had and there are upgrade kits for the older ones. As usual for that brand it SHOULD have been okay from the start, but it ended up taking 3 revisions.

I'm very disappointed Lexus/Toyota chose to slot the turbos where they did, adds unneeded, annoying service hassle and ultimately also increases package size and limits the cars this engine can show up in.

 

Well, don't forget with a 60 degree V6, there isn't as much space inside the V as a 90 degree V8, so a hot V design might not have been been an option. Either way, these components are going to "cook" as you put it, so high maintenance should be expected. Replacing turbo oil and coolant lines is not cheap, but not the end of the world, it's basically becoming a part "regular maintenance" in the modern reality. One thing I would consider with any modern engine if I was in it for the long run, is installing a set of oil catch cans.

 

people have to be on point changing their oil on a turbo engine, if anyone was lazy on their NA engine thats bad news for a turbocharged engine

 

That's kinda my entire point of why the hot V is so much better......modern turbo cars come with insanely good separators/catch vans already.

 

Good to know. How are factory installed catch cans drained? Retrofitted catch cans need to be manually emptied.