Twin Turbo VS Single Turbo

[WydRyd]

OK, lets get some debate happening here.

What's better? Twin turbo or single turbo?

Pro's of Twin Turbos

- prestige
- greater low end torque
- more linear power band
- quicker spool-up

Cons of Twin Turbos

- more expensive
- more complicated plumbing
- more variables/components to cause problems

Pro's of Single Turbos

- cheaper
- simpler plumbing
- greater top end HP

Cons of Single Turbos

- more lag (depends on match to engine)
- more aggressive power band when boost kicks in


Opinions please?

[sammygon1]

Neither, go for a variable vane turbo and get the best of both worlds.
It's only time and money.
-Sam

[WydRyd]

Sam, I'm talking about those of us who can't afford to spring for a new 997tt, or afford the ECU technology to control the VVT's

You can probably get very close spool-up using a pair of small snails to provide almost lag-free spool up, without the big top end HP of two slightly larger snails. The 993tt and 996tt developed peak torque fairly early on in the RPM band by using a pair of small K16 turbo's and developed ~410BHP peak

[RarlyL8]

I posed this same question some time ago.
The power brokers all vote for 1 big turbo.
The street guys vote twins.

You forgot one very important (to me) issue with twins - weight.

[tsuter]

Or is this better??????




Muhahahaha!

[PhatRedHead]

very nice counter, i always liked a superchargers whistle

[Kroggers]

This is one of those options that I keep wondering about. If you have an older 3.0 then you will probably need to rebuild it before stuffing the turbo on to it. Is it not therefore a better $ to HP to just replace the 3.0 with a 3.6? Or am I missing something here???

[JeremyD]

Follow the factory - twin turbo 959 - twin turbo 993 twin turbo 996 twin turbo 997. They did it for a reason - not because they got a two for one at their local jegs...

[Don Cothard]

I must vote for the single turbo in my car with the K27HF the pull is so liner its almost like NA but much faster. There isn't the sudden kick in the pants that I had before but it pulls from start (low end) all the way up I don't run out of air at the top end.
Don

[hobieboy]

You can't beat twin turbo for the ultimate throttle response (compared to single); even if you are using the car on track only.

More I look at it, if you can fabricate, plumbing is all not that much worst than single turbo?

[qlander]

Guys, tt is the way to go. I have one and have also driven the 993 tt extensively.

The only time I noticed any turbo lag on my 996 turbo S was two months ago having some fun with a 575 marranello. Those 12 cylinders do provide a lot of torque and I did have to anticipate my throttle blips just a little.

I still love my 930 though. The sudden Oomph is unbeatable as a rush.

Q.

[beepbeep]

After certain size, twins are as good as single one. But if you believe your boost treshold will come sooner with two small ones you're in for a surprize. Most big ones are aerodynamically more efficient than small ones.

You see, It's quite complicated. What Joe Sixpack calls "lag" is amalgam of different things and parameters.

You have at least four things to think about:

1. Turbine inertia
2. Aerodynamical efficiency.
3. Sizing
4. Plumbing

With other words, two small turbos will spool upp quicker once "on cam" but might come "on cam" later than big efficient one. Note the difference between "boost treshold" and "spoolup intertia".

It's not turbine weight that prevents turbo from providing boost at lower revs but intricate interplay of it's sizing, shape and volumetric flow trough engine. Once over the treshold, it's inertia starts being more and more important.

What's best? For power: two big ones with ball bearings and short plumbing!

For response: two small ones, undersized and maxed out.

For cheap and reliable power: good single.

Personaly, I don't think it's worth bothering with twins under 3.0L, unless packaging is a issue.

[RarlyL8]

tsuter - what engine is pictured? Looks like a 930 intake manifold and a 3.6L fan.

How about this: All other things being equal, would a twin turbo configuration with short run headers result in better driveability and a broader power curve than a K27 on a stock Euro exhaust (3.0L-3.3L)?

[tsuter]

Originally posted by RarlyL8
tsuter - what engine is pictured? Looks like a 930 intake manifold and a 3.6L fan.

That's right. Its a 993 with a supercharger kit and custom cast manifold from Turbo Performance Center. I guess it could have the 3.8 motor kit but it would still have the same fan.

[Frank@AMS]

GT Series turbo, spool up and top end

[WydRyd]

Originally posted by Frank@AMS
GT Series turbo, spool up and top end

Hmmm.. that's what I'm considering as a future upgrade path. Either a nice GT35/40R ball bearing unit, or a pair of small Garrett's

[Frank@AMS]

what type of power are you looking to make?
where are you looking to spool up at?

[WydRyd]

I'd sacrifice top end HP for quick spool-up anytime. It's a street driven car, so I don't want BIG HP and I don't want boost to come in max at around 4000+ rpm's. I want max boost in the low 3K rpm's.

[Frank@AMS]

I would recomend a GT35 non-ball bearing with a t4 hot side, you would see full boost just around 2900 to 3000rpms.

We just finished a set up on my brothers car, a custom GT37/40 non-ball bearing set up. full boost came on at 3600rpm and only wanted to keep going. I can most likley get another one of those made up if you want.

[WydRyd]

If a GT35 NON-ballbearing can get full boost just under 3k, how much quicker would a GT35R ball-bearing unit spool, in comparison?

What's the GT35R with 0.82 A/R rated at? 600-650?