is there anyone here with twin turbos? just wondering
thanks

 

Meccanoble, care to answer this?

 

Twin turbo's aren't necessarily any better than one well planned out single turbo system.

And I don't think anyone here has done it.

 

Chebosto................................... on his 350Z

Not on a max tho.

 

Why is it that everyone has this persona of wanting twin turbos? Even after countless # of threads. If twin turbos are so great, then why is it that all the Supra guys take out their twins to put in a single turbo?

Dixit

 

correct me if i'm wrong: i think single turbo has better velocity air flow if it's proper tuned, cuz it's straight in&out, rather than having extra pipes and lose its velocity travel... especially at higher rpm with turbo lag.

or it's jus my random riced theory again...

 

Wow. That is so far off, it's not even funny.

 

doesn't he have the greddy kit and isn't it single turbo

 

well I'll be...I looked at the pics closer and sure enough theres another air filter for the second turbo hidden over on the passenger side manifold.... definently

 

Twins are nice for engines that run lower compression. It's helps the spooling. But adding twins on an already relatively high CR, doens't make a lot of sense. You are talking about doubling/tripling the installation headach for maybe 20-30% better intial spool. No thanks.

 

Twin turboes are really only necessary on engines above 6 liters, as they actually have the exhaust to flow them.

 

Most of the BIG BIG power Skylines I've read about are running twins.

 

Mmmmm, skyline. But skylines are so much easier to install turbos on since thier engine faces the other way. The fwd maxima just doesnt have the room for them.

 

Yea, I know that much. I was just responding to these two comments.

Twin turbos only make sense in RWD cars because the engines are mounted inline with the body of the car so there is space on either side or on one iside n the case of the Skylines.

 

That's odd. Most of not all of the 700-800-900+hp Supras run a very large single.

 

No, he's got a good point if he's talking about twin turbos on a V6 or V8. Using two keeps the turbos right next to the exhuast headers instead of after three or four feet of pipe like what the turbo Maximas are having to do. The shorter the distance between the header and the turbo, the higher the exhaust gas velocity is going to be because the exhaust gas doesn't have time to lose heat. But twin turbos on an inline 6 like a Supra - wazzup widdat?

 

If you read Happyrice's post, he said single would be better but he stated the wrong reasons. The only Supras that I know of that run twins are track-only cars. Funny thing is most of the aftermarket Skylines I've "seen" runs twins, despite the inline configuration, and they're not sequential.

 

I was working on a system about a year and a half. It was with a shop called Westech in wisconsin. We looked at options like twin throtle bodies and all types of designs. It's really not worth it. Your looking at about 12,000 or more in parts and labor. Yeah it is possible, the ratio of value to power is not that efficient. Single turbo is a lot better and easier. Common now, Supras go to sigle turbo convertions. Us maxima owners just had the right state of mind to begin there.

 

supra owners change to a large single turbo setup because the way toyota designed the exhaust manifold on the supra. the design that they have works very well at the stock boost settings but as more power is desired by us power hungry aftermarket types the stock manifold becomes a problem. it is too restrictive at higher levels of boost and starts to cause backpressure and heat problems. after a certain point adding more boost will no increase power because of the increased heat and backpressure. the reason skyline owners keep their twin setup is because nissan designed a much better exhaust manifold for thier cars that does not have any of the problems that plague supra owners so instead of having a custom manifold made like the skyline's supra owners just go ahead with a large single with readily available manifolds from the likes of GReddy, HKS, Blitz, ect. also supra owners have 0.4 Liters more displacement to spool that large turbo. another reason is because the supra 2JZ motor is so stout from the factory that the internals can handle over 800hp from the factory while the skyline's cannot. so money can be spent elsewhere. also because of the lightweight internals of the skyline motor it revs much faster than the supra motor so it has no problem spooling 2 turbos which would come into boost much sooner in the rev range than a large single and the lower end is where skyline motors need all the help they can get because of of the small displacement. think of the skyline motor as a 6 cylinder honda b-series. because in essence if you slice off 2 of the skylines cylinders you have a stroked b16 at 1.7L. low torque but lots of high end. nissan and toyota put twins on because the smaller the turbo the faster the spool and you have to remember that not everyone is like us and will sacrifice some lag for lots of power with a big single. these cars have to be marketable so even your grandma can drive withtout waiting for boost to come on then losing control when it hits at 5000rpm and starts to spin the wheels uncontrolably. and big single turbo track cars are rare because one big turbo could have you waiting for boost to come on when exiting a turn when power is needed most or the boost could come on hard mid-turn and lead to uncontrolable oversteer. not good. well this is my debut post as i just bought a maxima so hello everyone.

 

Good, informative post, superdude. This answers some questions I've been wondering about.

One question. Even though a turbo in a twin turbo setup is smaller and therefore spools faster than a single larger turbo, it also is driven by only half as many cylinders, so it seems like it should be a wash. The only explanation I can think of is that there must be a nonlinear relationship between turbo size and spooling speed. Something like an inverse square relationship where if you halve the turbo size you quadruple the spooling speed, for instance.

 

it would be incredibly hard to come up with a correct formula for the spooling speed of turbochargers based off of their A/R ratio since every turbocharger will be spooled differently by different engines based on exhaust temperature, exhaust speed, engine dispacement, cam timing, compression ratio, how close the turbocharger is to the exhaust valves, efficiency of the exhaust manifold, stroke length, the list goes on....
in most twin turbo setups there is a control valve that spools up one turbo before the other like in a supra. there is a valve that spools the first turbo then opens a certain boost pressure and sends exhaust gasses toward the other turbo as well so this way at first 6 cylinders are spooling one CT26 turbo then when that turbo gets into significant amounts of boost the gate opens and starts to let the other CT26 spool up. until maximum boost is realized. this little gate that is in the exhaust path is also one of the major restrictions that causes the limit of using the stock exhaust manifold on the supra. this is of course entirely useless on a V-type engine as we have. and you would think that the effect of faster spooling would be lost on V-type engines since there would only be half as many cylinders driving each turbo but actually since these could be mounted on more efficient manifolds placed closer to the engine. in a single turbo setup you must combine the exhaust manifolds at some point that is further away from the exhaust valves and then send them thru the tubocharger. this extra length in piping cools the exhaust gasses and slows them down, effectively negating the belief of better spool up than the twin turbo setup. and for the same horse power lets say 500hp two turbochargers that can produce 250hp worth of boost will spool faster than one turbocharger capable of producing 500hp. and the power only gets higher from there. as most likely you will be able to find two turbochargers that can support 300-350hp each and still spool faster or just as fast as the 500hp turbocharger and will give you 600-700hp.