Twin Turbo vs. Single Turbo V6: A Dissertation

tower74

Has anyone who is saying that a twin is superior to a single ever actually seen the STS single setup? As I said early if I can keep my turbo temp down cooler but still produce 50hp less and if anyone has seen a how hot these turbos can get. That can't be good on them.

Nixlimited

Does it really matter? Different strokes for different folks. I think options and competition are good for everyone. Until these two different kits line-up at the track, it's all academic.

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blackonorange

What do you mean controlling heat? How are we gonna controll heat when we are beating On the car? Heat is gonna come no matter what having 2 turbos under the hood is not gonna help. I understand the combustion thing but our cars are already at the threshold NA why would we want to throw more heat at It?

Nixlimited

Notwithstanding that you continue to completely miss the point (i.e. that generally speaking, engines work because of heat production)--controlling heat, e.g. dissipating it with the cooling system. For example, the cooling system can be upgraded to dissipate more heat so that the car can take more "beating." Beyond that I really don't understand what your confusion is.

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Mike@GTM

Thanks for the compliments everyone! I tried to keep this as fact based as possible. One thing I did forget to mention is that this dissertation was mainly related to performance and engineering.

I must concede that cost was not as much a part of the discussion as it could have been. A single turbo system does have that one, distinct advantage. Despite the lower cost, however, a single turbo is not half as much money as a twin turbo system. As such, a person must still factor in the cost/benefit ratio between a single turbo system and a twin turbo system. In some cases, the cost is the deciding factor, and performance is secondary. For other cases, the performance benefits are worth the incremental investment.


I'm pretty sure that my original post gave all the technical details that would ultimately establish my stance on any single turbo kit. You may want to consider re-reading it?

Turbochargers are designed specifically to operate in high temperature environments. If you look at any factory turbocharged car, the turbos are always mounted as close to the engine as possible. No OEM has ever mounted a turbocharger more than 5ft away from the engine (I think Subaru has the record on the turbo mounted farthest away...and the lack of performance shows).

There are places you want heat, and places you don't want heat. I'll go into more detail in another post.

The advantages of a single turbo were mentioned in my original post. However, the advantages are significantly outweighed by the disadvantages (as described in my orignal post).

The single biggest advantage of a single turbo is cost...not performance.

Again, this is only related to V6 engines. If we were talking inline motors, we would be having a different discussion.

True, and definitely something to watch out for with single turbo designs as not all of them are designed that way.

I'm not aware of any.

So far, I have not seen anything to the contrary. Again, as the single turbo's only competitive edge is cost, anything other than the reuse of the stock exhaust manifold would work against that advantage.

Until I am proved wrong, I'll stand by it. But unless someone can invent a reverse entropy device and defy the laws of physics, I'll be standing for a long time yet.

On a V6? It would require a substantial amount of number crunching to find that crossover, but from some of the numbers that I have looked at, I suspect my original estimate of 1300+ may actually be conservative.

You know, just for giggles, I shot an e-mail to a contact I have at Garrett just to see if we can get the actual MOI numbers. In his estimation, a pair of GT2860RS turbos will have a very close total MOI when compared to a comparably sized single turbo (GT4094R). Remember that MOI is based on the square of the radius.

Furthermore, due to the loss of enthalpy from a longer exhaust pipe routing (required for a single turbo setup on a V6), the twins will be receiving more total enthalpy than the single and since their MOI's are so close already, the Twins will respond faster.


That's a good question. It's been awhile since I looked at it. Keep in mind that the stock exhaust manifold has two ply heat shields as well. I'll see if I can dig up those calcs at home.

I'm back at work now.

You know, I saw that dyno graph. No boost graph, no AFR. The thing that makes me wonder, is when Tower only made 438 at 8psi before he installed water/meth injection. Something just isn't adding up. The lack of information and dyno graphs is not helping your case.

Whether you are running a single turbo, twin turbo, or a supercharger, the 370Z needs additional cooling. Period.

If we, as human beings, were unable to control heat, you'd be riding a donkey, my friend...not a 330hp sports car.

I'll be making a more detailed post about heat, shortly.

tower74

So the guys throwing bags of ice on there engine blocks are wasting there time?(at drag strips that is).... I just noticed even on the dyno that we always received higher numbers when the car was cold and worse number the hotter the car got.
Don't get me wrong I under what you are saying but are referring a twin set-up close to the engine or a rear mounted turbo futher away from the engine? I know that the STS perfers to run cooler than front mounted....

Cell

I think you need to read the entire thing again.

Nixlimited

They are probably throwing bags of ice on their intercoolers or airboxes so that the intake air charge is temporarily cooled. If you through a bag of ice on an engine block it would immediately melt (assuming the engine had been run).

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tower74

Missed a part....and understand now on the enthaply part. Maybe should of read it closer, instead on saying " I think I can hear my brain melting from to much info".
It's just that for less money I can get a single set up for less and about 50hp less compared to a twin setup. I don't have to take the front end apart to maintaince anything, big plus. I not bashing GTM one bit, they were my second choice when I was looking at a turbo system. They only factor that made go to the STS was it was within my budget at the time. Trust me if I go to another system they WILL be the first I call. I have no "lag" from my current system, oil temps stay around 200 to 220(pushing it). Water temps almost never changes.

roplusbee

This discussion (that has taken place after Sam/Mike gave the onslaught of information) looks to be limited to specific platforms, since the Z and STi were the only examples discussed (in the origional post). I am not trying to derail this thread or start any mayhem either.

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Kingbaby

that's why that single setup that S&R did is very attractive...to ease the heat part for the 370Z guys you could cut vents in the hood over the turbo like the supra guys. Or a nostril like the 350Z guys.

525whp at 9psi has got me pricing out parts...

Where is the OP at?

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blackonorange

Well STs got there car to make 480 in 7 psi seems pretty good to me and the turbo is at the back of the car,

blackonorange

Yea I missed the general part .. My bad

Nismo370

11k twin turbo miles and I've never went into limp mode, and I don't baby her either.

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b1adesofcha0s

Great write up Mike! I enjoyed Thermo I/II and Heat Transfer as well, just hated the exams. You can throw Fluid Dynamics in there as well

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