Are two tuebos realy better than one?

I was reading through the sticky thread in the forced induction forum when I saw something that made me wonder why our cars (any cars) are designed to use two turbos, why two? What makes our engines special enough to need that extra turbo in there?

the use of two smaller turbos means less turbo lag. If they are sequential then they are also different sizes, one being slightly smaller than the other. The smaller one spools first and then the larger one. This is also done to reduce turbo lag.

Ahhh is that why VR4s get all their torque at 2500rpm?

You could always do a single turbo conversion which is generally reffered to as a "oversized turbo" conversion. I had a friend with a Supra who did a single turbo conversion and the power was amazing but it was not streetable, in other words, you had to launch at like 4000rpms or it would stall out. single turbos also work over time and produce way more heat, enough heat in fact that his heatshield stuff on the hood partially melted. oversized turbos are good for power but only if its a stricktly track car. the RX-7 is one of the cars with different sized turbo, one spools up before the other.

What about the turbos on 4 bangers like the GSX, STI, EVO?

Launch at 4Krpm even when you're not racing? Wow....isn't that bad on your engine if you do it ever time like that? ;o/

twin turbos are usually used to reduce the lag time.....the smaller turbo spools up fast but lacks the power at the higher rpms....and then the big turbo kicks in....its beautiful....there's nothing "special" about the 3000gt engine that allows it to have 2 turbos instead of one....they just decided to do it that way. really you could twin turbo any car if u wanted to cram them in there......its pointless to put 2 turbos on 4cyls because they dont really have the power to use both turbos efficiently.

i want to clarify a few things about this discussion

there really is no advantage to running either one, except for effeciency. For example, i am going to compare inline engines with V engines.

It is generally more efficient to run a larger single turbo on an inline engine and smaller twin turbos on a twin turbo engine. Lets say that the result of the turbo/turbos are the same CFM (airflow). I will use 1,000 CFM for example.

On the inline engine, you will have one big turbo that flows 1000 CFM, and in terms of lag, it all depends on how much energy you can push through the turbine housing. Lets just say you have an Inline-6 engine such as a supra, you have 6 cylinders and 3.0 Liters pushing into one turbo.

On the V engines, you will have two turbos, each one flowing 500 CFM each. Each turbo is being driven by a bank of cylinders, since V engines have 2 banks of cylinders. In the 3/S, you have 1.5 Liters and 3 cylinders pushing each turbo so not nearly as much energy going through each turbo.

As a result, the lag will be the same on both set ups, and the potential top end horsepower will be the same on both set ups. Basically, both set ups will produce the same results if you acquire setups that are equal in magnitude. The main reason for the twin turbo set up is to make things easier so you dont have to reroute the exhaust manifolds to move all the way around the block and into the turbo, which will create even more lag because the exhaust gases have even futher to travel.

As for our turbos spooling up soo quickly out of the factory is that the stock 9b turbos are soo pathetic and soo small that it spools that fast. If you put a single turbo on a supra that flows the same as both of our stock 9b's, the lag will be exactly the same.

If you want a huge single break boost is always an option :)

you can only brake boost on an automatic, all vr-4s came in manuals. Your only option on that is to get a stutter box.

Launch at 4Krpm even when you're not racing? Wow....isn't that bad on your engine if you do it ever time like that? ;o/

Yeah his supra was stricktly for the track. all it ever did was race so it was typical to have to pull the engine out and swap or fix stuff often , but thats how it is with real race cars, the more power you drop in them the more often you'll have to fix em.