I am in no way interested in getting a turbo because i just don't have the time, money, or knowldege to get one, but I am interested in why a person would choose a single over a dual. I guess cost would be a factor, but I have seen people switch TT Supras to single. So what exactly are the pros and cons of each?

 

In regards to the Supra in a book I have on turbos there is a short story on a person/company building a twin turbo for a 4 or 6 banger, after all the time and money spent they came to realize that the eng could not spool the twin turbos up enough at low eng speed causing serious turbo lag.

 

fast spool, very efficient power...

 

Twin turbo's seemed to have been a very common solution to the lack of large efficient turbo's years ago. However there are currently extreamly efficient,large turbo's on the market that can support over 2,000hp by themselves.

Here's my opinions

Advantages of a single turbo: easier,less complicated plumbing - focusing all the exhaust energy at one turbine to get it going - less intercooler tubing to pressurise - to make 2000-2200hp it would be cheaper to buy one PT101 for $2495 than two PT76GTQ at $1540 each($3090 total)

Advantages of twins: plumbing looks cool - people are more impressed by twin turbo's even if the car is slower that a single

HTH,
Steve

 

dont they make a PT106 aswell thats good for something like 2300-2500? man i wish i was rich enough for an engine that could handle that

 

You know what bugs me too is I see people make posts, I want a twin turbo and they give no reasons. Obviously, they have not researched because its true what Steve says. Single turbos are efficient, cost effective and simpler in the end. And they do look cool.

 

You hit the nail on the head there Guido,they give no reason and obviously havent researched this.I know you've plumbed more than one custom turbo setup,imagine if you had to fit twice the plumbing

Steve

 

Well... it sure would be FUN! LOL

As long as it wasnt my money I was spending. LOL

 

Going single also gives you the chance to experiment with some of the huge diesel turbos like the ford guys are doing...

 

For me, the decision between building a single turbo system and a twin turbo system was the cost.

True, its cheaper to buy a single if you are buying brand new, but there are very few junkyard singles that would work on a 350. You'll find very little more cost-effective than a pair of turbocoupe t-3's.

If i had an unlimited budget, it may have been a different story, however . . .

 

dont tell that to the JYD 351W ford guys

 

It's not quite that simple.

Traditionally the problem has been finding turbos small enough to run twins on smaller engines. Large turbos have always existed.

The reason that twin and quad turbo setups exist is that it is easier to make them spool well. The inertia of the rotating assembly can be represented as a ring with a specific radius with the weight of the assembly, this is known as the radius of gyration. The inertia (resistance to moving) of the rotating assembly is proportionate to the ^2 of that radius and the mass of the wheels… is greater for the larger wheels. Typically, if you choose a pair of turbos with comparable airflow qualities to a single the single will take 2.5-3.5x the energy to spool, so to get it to spool at the same rate as the twins you have to run a significantly smaller turbine side which will become a restriction at the top end sooner. (there is also a much more arcane reason involving manifold design and trying to keep 3 or fewer cylinders connected to a turbine that almost everyone ignores).

The real advantage that large singles have over twins (besides the obvious packaging…) is that you can more easily build a larger compressor that is more efficient then a small one, so typically you will get 2-5% better adiabatic efficiency out of the large turbo so you can run a _slightly_ smaller intercooler (or a fraction more boost/airflow with the same intercooling).

In the long run, things tend to work out for either at the track since in most cases we're talking about way too much turbo on too small an engine and if the turbo spooled like a "street" setup you would go into compressor surge anyway, but for an ultimate, all out setup on a v8 you'd either have to go quad turbos or twins with divided housings, but since for the most part you can make more power with a single then you can use this is pretty much an academic argument.