You can't compare turbo engines developed in the 90s to Toyota's modern output. And what made things like the old I6 reliable wasn't the turbo itself, it was the cast iron block for the engine which allowed it take tremendous abuse.
Turbo V8 is vaporware.

 

Toyota does have a turbo V8.. Been in production since 2008, it is still in production

I am gonna do a shameful plug, no turbo means no turbo to eventually go wrong.

 

Diesel engines =/= gas engines. I was referring to the TTV8.

 

Toyota had the 4.5L turbo diesel V8 on the LX450d. It might have ended production though 2007-2021. New J300 offers a 3.3L TTV6 diesel now on LX500d

 

The diesel is still used in the Land Cruiser pick up truck

 

That's terrible, hopefully very isolated.

V8 is gone we all know that, inefficient as it was it would never have any problem like this "reduced power". Complexity sucks. 5.7 was simple.

 

if you go back and see am sure the V8 also had some teething issues, all engines do. What Toyota does better than most manufacturers is that they keep fine tuning and ironing out issues over time. There where similar concerns when Lexus went with a 2.0 T in the NX instead of v6. Fast forward few years NX has turned out as reliable as anything else in their line up so hopefully Tundra will be the same.

 

It took Toyota this long to get the new Tundra to market and it still has bonehead design issues, such as not being able to replace the turbo without a major dismantling? Turbos require maintenance and replacement, so, need to be accessible. Based on my mechanic friends and co-workers experience, Toyota and the other Japanese manufacturers used to be excellent in making their products serviceable when compared to the Germans or Americans. Perhaps with the added complexity of today's mechanicals, not even the Japanese can surmount this challenge? They threw in the towel and are leaving owners to deal with it. It's a disturbing trend.

In the future, will owning and maintaining a vehicle be equivalent to owning and maintaining an aircraft or a yacht? If you have to ask the cost of maintenance...you can't afford it!

 

From what I've been reading the shape of the hood and be extension engine bay makes it almost impossible access the back of the engine. Forced to pull the entire cab instead.

 

Toyota has made some bonehead moves in the past. Nothing new. LS460 is a PITA to change a O2 sensor in some applications. My 4.7 the cats are built right into the headers as one big piece, but the 4.7 in Land Cruiser use a two part unit. But go figure. The 4.7 is an interference engine Whereas my new 4R is a chain I am sure there will be no long issues and Toyota will figure it out. Just crazy to see that cab off the frame.

 

To be clear...An engine with a timing chain can be either (a non-interference or interference engine). Too, an engine with a timing belt can be either. I believe your 4R is an interference engine.

Agreed on most points in your post, but, a timing belt vs a timing chain is a separate issue from interference vs non-interference. Generally, modern chains are now preferable because they are as smooth and quiet as belt, yet have no replacement interval. At the same time, engine design is trending toward "interference" as higher compression ratios are achievable, which leads to higher efficiency. In the past compression ratios were kept low as it was difficult to prevent detonation. Now, engine controls are so advanced, detonation is less of an issue.

 

You make some very valid points. Both my 4Rs are interference engines (didn’t know the V6 was). It’s just the belt is a concern and a PITA whereas the chain gives a lot more reassurance.

 

Agreed, not sure why engine designers couldn't have come up with a good chain design prior to abandoning it and moving toward belts. With the trend of moving back toward chains now, it's clear a quiet chain was possible all along. The pessimist in me wants to believe belts were favored in part because they are a cash cow for the dealers and parts sales for the manufacturer.

 

Toyota has flipped flopped all over the place through the years, I don’t follow other manufacturers of their belts. They used to chains or belts all through the 1980s, 90s and 2000s. 1990-2000 4Rs used chains for the 4 cylinder, and belts form6 cylinder…then in 2003 they went chains for the V6 but belts in the V8. Toyota at some point used a dual row timing chain engine in the 1980s, not sure what applications …then cost cut it to reduce it to just one chain when it was revised. I don’t know all the details.

I think they just used belts as it was cheaper to make. The new engines are more powerful, belts probably can’t handle the power, but I truly don’t think they are as well built or as long lasting as the older stuff. I like both my SUVs, the 4.7 just seems like a better engine and still feels brand new after 18 years on the road…never a hiccup. Not one (knock on wood). Will see if the V6 feels brand new in 2039

VW still uses timing belts if you can believe that. VW had a lot of engines with belts

 

That's one of my criteria for buying a vehicle. Must use a chain rather than a belt.