Twin Turbo Configurations

[Guest]

Hey,

Back in the day there, a lot of Japanese vehicle manufacturers had a tendancy to fit their performance vehicles with a Twin Turbo configuration.

Nissan.

GTR Skyline

300ZX

Toyota.

Supra

Soarer (SC300)

Mitsubishi.

3000GT

In my opinion, after having owned a TT300ZX and driving a whole host of other vehicles from that era, the Twin Turbo design showed to reduce turbo lag and add a level of vehicle responsiveness that was unequalled to that of other single turbo vehicles.

My question is, what are the pros and cons of such a configuration? and to branch out even further, the benefits of the Toyota Supra adopting a sequential turbo setup (just in case I find a spare turbo lying around and decide to spend whole bunch of $$$ on the ute )

Darren

[cobrav8]

A lot of the Twin Turbos that you mentioned were on V motors - so have one turbo on each bank of cylinders. I assume this is for practical purposes, as opposed to sequential turnos which are for reduction in lag.

[driftpig01]

One of the best twin turbo jobbies was on the Mitys galant, 2.0l V6. It used a very small turbo upto 2500 then the large on kicked in. There was no lag at all. My mates put 350kw at all four wheels with minimal mods.

I think a twin setup would be to difficult on the T however a supercharged turbo might be the way to go

[bcl]

Main factors are cost, added complexity controlling both turbos, more exhaust plumbing, more space used, and an extra component that could fail.

In time we'll see some upgrades with 2 turbos on our Ford T; maybe something like 2 Garrett T25's or 30's.... someone will do it, and if my project was starting again I'd possibly go down that path. However, it would be very expensive, and unless you were chasing huge power I doubt it would be worth it.

It's obvious why the factory didn't do it ... COST ... for either twin or sequential variation.

At one stage in history twin turbos were seen as a holy grail, small one for early spool up, then the bigger one to take over from the smaller. Then I think most manufacturers thought it was too much extra effort for not enough gain.

Some people go the other way though ; say replacing the 2 turbos on a GTR with a big single, and I'd say because there are big turbos that now than handle huge power at very high revs.... this is really a drag situation not road use.

On the Ford, with much lower rev range, twin turbo would work well imho, but not really worth the extra effort and cost. The motor in stock form has far more torque at lower revs than most turbo cars on the market, largely because it has a 4 litre capacity and undersquare cylinder configuration..

Brian

[Lawsy]

A lot of the Twin Turbos that you mentioned were on V motors - so have one turbo on each bank of cylinders.  I assume this is for practical purposes, as opposed to sequential turnos which are for reduction in lag.

←

skyling = inline 6

Supra = inline 6

Soarer = inline 6

Just assume he never mentioned the rest.

[xlnt6]

Hey,

Back in the day there, a lot of Japanese vehicle manufacturers had a tendancy to fit their performance vehicles with a Twin Turbo configuration.

Nissan.

GTR Skyline

300ZX

Toyota.

Supra

Soarer (SC300)

Mitsubishi.

3000GT

In my opinion, after having owned a TT300ZX and driving a whole host of other vehicles from that era, the Twin Turbo design showed to reduce turbo lag and add a level of vehicle responsiveness that was unequalled to that of other single turbo vehicles.

My question is, what are the pros and cons of such a configuration? and to branch out even further, the benefits of the Toyota Supra adopting a sequential turbo setup (just in case I find a spare turbo lying around and decide to spend whole bunch of $$$ on the ute  )

Darren

Hey Darren,

You forgot one, and it's one of my favorites, the Series 6-8 Mazda RX7 !!!!

Now, here's a few points that you may not have considered. As you have rightly stated, in the early 90's a vast collection of Jap performance cars embraced the twin sequential turbo design, and they did this with the sole purpose of minimizing turbo lag associated with smaller capacity (3 litre or less) engines which had to have sufficient punch down low to "feel fast" off the mark and at the same time needed to have high enough HP rating to impress.

To provide this broad power feel, required a small turbo to provide boost at low RPM, but cause these turbos run out of flowrate at higher RPM, a sequential design is required to switch to a larger turbo which is effective at the higher flow rate required in the top end of the RPM range. So infact this design really acted like a single turbo (I know that in some designs both were operating and contributing to flow, but it is largely biased to the bigger turbo). OEMs did this cause, the majority of turbos of that era had plain bearings, and less efficient compressor designs with narrower efficiency lands vs shaft speed, ie they need to be operating within a small RPM range to be efficient. To alleviate some of the ineria required to get them to speed, the ceramic exhaust wheel was conceived.

Now in the last five years the costs associated with producing turbos that have ball bearing centres and much more efficient compressor wheel designs, due to improvement in modelling techniques and reductions in production costs, means that a modern turbo, a la Garett GT series, etc is able to cover the demands across a much broad range of operating conditions, effectively negating the requirement to use sequential turbos designs. This is doubly so, with modern engine management techniques which are able to handle higher CR engine designs which have inherently better low down characteristics then their earlier brothers, again alleviating the requirements for the turbo to be so effective at lower RPM.

As stated by Brian, the Ford 4 litre engine is naturally torquey engine and as such there is no need for a twin turbos in anything but the most extreme application. (Again, refer back to Brian, the king of extreme !! ). The only reason you'd want to twin turbo one was to achieve greater than the current HP achievable with GT35 or GT40 turbos, ie above 700-800HP. In that case you probably would use twin GT30 or GT35 turbos, and they would operate in parallel vs sequential. I'd hate to see (sic) what a twin sequential turbo on a I6 engine would be !!!, maybe the stocko GT3582 turbo then switching into some monster 1000HP + thingy !!!

So in summary I'd say the days of the twin sequential designs are dead, and I can't think of any new model cars being currently produced which still use this design.

Cheers

Robin.

[saleen]

I'm not sure which one it is, but one of the new Porsches has a variable vane turbo that changes depending on engine speed. Similar to reverse thrusting on a aeroplane I guess to some extent.

[saleen]

Oh here it is. http://www.autoblog.com/2005/11/27/next-91...rbine-geometry/

'The VTG turbo will allow Porsche's flat-six to mimic a twin-turbo setup with a much broader torque curve and more flexible powerband than a standard single turbo could provide on its own'

[Guest]

Hey guys,

Cheers for the feedback, I'm not of an technical or automotive background whatsoever,so just a few questions I was punting around.

I'm sure there were more twin turbo vehicles that heralded from the Japanese early 1990, twin turbo...banzai era, and yep the Series Vi(?) RX7 did slip my mind, and so did the Eunos Cosmos, oh and the Nissan Stagea....and so on.

Everyones replies thus far makes sense enough to me...so thanks

So in summary I'd say the days of the twin sequential designs are dead, and I can't think of any new model cars being currently produced which still use this design.

In repsonse to the above, isn't the Bugatti Veryon running a sequential quad turbo setup? I could be wrong....1.4million for such a vehicle is a bit of overkill....gimme an F6 and a qtr of the amount for mods and I'll send the bloddy thing to the moon!!!

Cheers Y'all

Darren

[ms700]

isn't the Bugatti Veryon running a sequential quad turbo setup? I could be wrong....1.4million for such a vehicle is a bit of overkill....gimme an F6 and a qtr of the amount for mods and I'll send the bloddy thing to the moon!!! 

Cheers Y'all

Darren

←

The Veyron does use 4 turbo's, and is also a V10 I think?

I read somewhere the fuel consumption when youre flat out in the big girl, something ridiculous, like 3 litres per 1 klm!