Tyre Sizing Question And Abs On R34 Gtt

[GTSBoy]

There are pretty much no series type twin turbo setups on petrol engines. If by "series" you mean compound, where one turbo blows THROUGH the other. If by "series" you mean "parallel but set up so that one comes on before the other", then yes there were a few. The Toyota twins were like that and the Mazda rotary twins were, but these all suck badly. This style is more correctly called "sequential twin" and they almost all suffer from nasty torque holes from not getting the sizing of the two turbos absolutely correct and not getting the switch over point right. And even if you do get those right it's still bloody hard to both spooling at the right speeds at the crossover in order to get a smooth transition from one to the other. They just suck.

Nissan's twin setup on RB26s was intended to try to get the same flow capacity as a larger single but with lower rotational inertia and therefore less lag. In some respects this was achieved (given the day - it WAS 1989), but in reality even this was a failure as only slightly more modern compressor and turbine aerodynamics than the evil 80s tech used in the GTR turbos will give you better performance than what the GTRs were born with. And to make matters worse, 2 smaller turbos are thermodynamically LESS efficient than a single turbo of equivalent capacity. And that is before you factor in all the duplication of crap. The only part of a 6 cylinder twin turbo setup that is easier to deal with is the exhaust manifold. Everything else becomes a massive effort to try to fit it all in and make it serviceable.

So, with respect to your car, once you get to silly big turbos like a T78, you are better off with a single than equivalent twins.

Now, I shouldn't have had to tell you all that, because it has all been written before, some of it by me, on this and other fora. ie, it is searchable and required no further work from anyone who had already put said work down at some earlier time.