Project Thread Twin or Single

[Lextreme II]

This thread was created specifically for Jibbby. Jibbby asked is twin superior then single. The answer is "DEPENDS"

 

[JustenGT8]

Depends is right....horses for courses and hardly worth debating as either will work well particularly for a street car.

If you consider the race track the ulitimate in performance just look to what a factory race team will use if the regs allow...twins every time on a V config engine!!

 

[XR8tt]

It realy doesn't matter if turbo / turbo's are correct size etc...
Generally twins come on sooner than single and a single can have power up top rpm.. BUT again that depends on sizing etc...
It sort of ballances itself out.. With single you get all the exhaust flow from both banks...

 

[JBrady]

For a true comparison you would need a single that is equal to the twins. By this I mean the total compressor capacity of the twins would equal the single and the total turbine capacity of the twins would equal the single.

This brings up the consideration that turbos are in fact two systems... a high speed gas turbine powered by engine exhaust. This turbine powers a high speed centrifugal compressor.

Therefore BOTH systems must be matched for a FAIR comparison.

In real life, on the street, a well designed single will perform nearly as well as a well designed twin with less cost and less moving parts. A well designed system of either configuration will outperform an average design of either.

This is kind of like arguing which is better; the blond or the brunette? Of course the answer is which one is better looking! (cooks, cleans and doesn't b@tch or F around!) Then again, how often is the blond really a brunette in disquise? But I digress...

 

[jibbby]

Funny John, I'll take the brunette and blond together at the same time.... Sounds like a good time...

First off I feel honored and flattered, to have a thread dedicated to me...I feel truly blessed...I may tell it on the mountain..

OK enough joking.....When comparing equal turbo flow between twins and a single I can honestly see a big single turbo when it reaches peak boost may deliver more of a power spike as apposed to a well setup twin... So if you going for big power and don't want those rears breaking loose under full boost a twin setup maybe the better choice for even power... Is that statement accurate to some degree?..

It's always really nice to get an even and long drawn out power band as apposed to a fast peaking power band... Do you see what I am getting at with the two?

 

[Fasteddie]

Guys,

this is exactly my dillema aswell for the 3UZ....
Here is what I "learned" so far:

V block > twin turbo most logical....but twice the hassle, more problems etc..obvious header design...mostly found in all V turbo production cars...so it "must" be good.

V block > single turbo...less problems, but the "optimal" header design can still be argued...so:
option 1: "twin turbo headers" with single turbo.....where to locate the "heavy" single turbo ?...turbo can't rest on the headers, headers might be torn...
option 2: connected headers (lextreme single turbo), mounting the turbo to the chassis....solid position for the turbo but have to keep the total length of the header within boundaries.

My engine/car builder says that a single turbo with connected headers (option 2) will work for what we have in mind: 3UZ single turbo (GT42r) with 800 rwhp...

I guess we will find out in the comming months....

 

[XR8tt]

Mounting turbo is easy single or twins.. Just mount on header, If there's any doubts of strength ? Then just weld a support bracket between motor and header nr turbo..The price of single is about the same or more as you would require an external wastegate.. With twins you can get away with two integrated gates.. In some drag race rules... Running twins can be classed as two multipliers.. But a bigger single is just as quick with limits to turbine size....The traditional drag racers don't like turbo's....

 

[jibbby]

My last question for you turbo guys....

When fitting the engine for twin turbo's can they be made to come on at different times during the rpm band?...Like one turbo will spool early on and the other later so you experience a pure even power band?

If so how would that work? Wouldn't the motor be unbalanced if both turbo's were runnning independantly on each side of the motor and boosting at slightly different times... Half the motor would get more boost then the other so I am sure that would not work out.....

The logical solution would be to run the twins like a single turbo setup where both would run off a the single exhaust pipe and fits to both sides of the motor...One turbo spools and then the other right after...Is that possible and is that correct.. I really just don't have any clue with setting up twins to spool at different times....

I would think if you could setup the twin turbo's to work in that fashion then they would work more effecient then single turbo setup by far..


Or can you use different sized twin turbo's one larger and one smaller in size mounted on the one single turbo exhaust pipe to create that same effect?

 

[jibbby]

As I see it if you have balanced twins working on a V8 motor that will allow to go with smaller turbo's that spool up a little bit faster.. More even and balance turbo exhaust flow since both are working off each independant header..

So if that is the only way to setup twin turbo's on a V8 I see no real big diffence between singles or twins...Both turbos will spool at the same time just like a singe... What's the point then????

As you can see I've been racking this over in my head for a few days now...

 

[Lextreme II]

Please refer to the first two pages of this thread http://lextreme.com/forums/showthread.php?t=2711

 

[JustenGT8]

You have provided your own answer Jibbby.....for the same max air flow, twins will spool faster than a bigger single. You are also optimising exhaust energy as you're not losing it as heat shedding off long header pipes needed to plumb the single.

You could stage with a bigger turbo on one side and there's no 'unbalancing' of the motor One bank will run with different exhaust back pressure but while not ideal will work OK. There's a local kit for a V6 that only runs the turbo off one bank, works well for what it is but again, obviously not ideal.

Rest assured that any half decent turboed UZ will be an awesome performer. While twins provide the best result in an ideal world you don't often get that so in many cases a single will perform just as good.

As Jbrady said so neatly, a well designed system will out perform an average system whether single or twin.

So if twins are blonde and brunette is the single, then SC's must be Redheads eh?

 

[jibbby]

THANKS GUYS FOR THE REPLIES AND LINKS!!!!


I am learning................It all makes clear sense to me now...:smokin: