Single bank turbos on V engines

[r988]

I was idly thinking about some of these single bank fed turbo V configuration engines that pop up every now and again. Normally they seem to be found in some cheaper kits for V6 or V8 engines and even the odd OE vehicle and I wanted to confirm some suspicions I have about them.

I can think of some kits available for the GM LS1 V8 and Nissan 350Z/350GT V6 off the top of my head. I'm also fairly certain that Saab had a single bank of the V6 feeding a single turbo on one of it's older V6 900 models. Though I checked and the current Saab 2.8L V8 Turbo, while also a single turbo V6, is fed by both exhaust banks, presumably with some elaborate pipework.

So I've established that it's relatively uncommon and seems to be mainly on rather low boost/cheap applications. I presume this is something to do with problems with unequal backpressure/exhaust pulsing and perhaps even discrepancies in temperature on one side of the engine relative to the other when only one bank is used to feed the turbocharger? I guess they can get away with it for very low boost applications for a cheap and easy way to give a small torque boost but it becomes problematic when higher boost/power is run?

Is this the case or am I on completely the wrong track and there is some other reason why they are uncommon?

Surely a single supercharger would be cheaper/easier in such situations for an easy/cheap torque boost on a V engine, ala GM/Buick 3.8L supercharged V6?

Are they completely fine on low boost applications or are there still long term complications, which is perhaps why Saab abandoned them fairly quickly?

Are there any other production cars that have used a single bank turbo?

Note that I have no intention of instigating any project along these lines, just have a need to feed my curiosity.

[Deltafox]

Seen these before and have to admit it aint the best or the right way to go about it, although it will work to some degree.
The other bad idea is putting a turbo at the tailpipe like some idiots do in the US.
The system volume must be freaking horrendous with monster lag.
What a waste of time, do it right in the first place.

[trackcar]

turbo technics did a lot (for an afetrmarket conversion that is) of Ford V6 conversions on a single turbo off one manifold.

[eliot]

Comes down to packaging, twins on a V8 suits the layout. I considered a single, but couldn't work out an easy route for the cross over pipe. Singles on V8's are pretty popular in the states.

[F.M]

I`ve a Rover 3.5 single turbo(rotomaster) Janspeed engine in the garage.....fine upto about 6-7psi...
although the crossover pipe is not a masterpiece of engineering..

Why waste the nice balance by one bank driving one blower..common sense dictates use the 2 banks...but engine bay space is sometimes a problem..as well as cooking the engine bay with heat..

[old64er]

the renault V6 turbo used one, as demonstrated in my friends metro

Edited by old64er on Monday 10th July 21:14

[chuntington101]

there are loads of single turbo V8s in the states! its can be easier to package a single turbo rather than 2! also a single setup is normaly cheaper and simpler, only needing 1 turbo and weastgate. thus making it cheaper!

take a look on LS1tech.com for plenty of pics of single turbo LSx engines

thanks Chris.

[Boosted LS1]

But that appears to be feeding both engine banks. This is about a single turbo feeding 1 engine bank and leaving the other bank atmo fed. I'd never do it, smacks of bodgeness to the highest degree

Boosted.

[GreenV8S]

Would it be possible to balance the engine by throttling the 'open' side of the exhaust to produce the same back pressure as the turbo'ed side? It's a nasty solution, but probably not as nasty as running the two banks with completely different exhaust characteristics.

[old64er]

sorry, i misunderstood the post.

I have never seen that type of installation, where only 50% of the cylinders are force fed.

It seems strange to load an engine in this way??

[annodomini2]

old64er said:

the renault V6 turbo used one, as demonstrated in my friends metro

Edited by old64er on Monday 10th July 21:14

But its fed by both sides of the engine, this guys talking about only one side.

[900T-R]

old64er said:

sorry, i misunderstood the post.

I have never seen that type of installation, where only 50% of the cylinders are force fed.

It seems strange to load an engine in this way??

In an 'asymmetric' turbo installation, all cylinders are force fed through a single intake/plenum - but the 'hot' side of the turbo is driven by the exhaust gases of only one cylinder bank. This was used in the Saab 9-5 3.0t to provide a modest, but useful performance boost in the low/midrange rpm band with as simple a configuration as possible. Not only you can simply hang the turbo on the end of one exhaust manifold as per an in-line engine (in fact, in the Saab's case the exhaust turbine housing was integrated into the manifold) but as you're only using the exhaust gases of three cylinders to pump more air into six, the resulting boost pressure was low enough to remain unregulated - there's no wastegate on this one.

[GreenV8S]

I thought this thread was about having the exhaust side of the turbo connected up to one bank, and the intake side connected up to both banks? So the exhaust is asymetrical, but the intake is symetrical.

[900T-R]

GreenV8S said:

I thought this thread was about having the exhaust side of the turbo connected up to one bank, and the intake side connected up to both banks? So the exhaust is asymetrical, but the intake is symetrical.

That's basically what I was saying - only, Saab did call this arrangement 'asymmetrical' without further qualification.

[GavinPearson]

The only real reasons for this are packaging and cost. In terms of a car sold to the public, it will have been signed off by the manufacturer as adequately durable, but I wouldn't think of extracting more horsepower without expecting some complications.

[madmechanic360]

Deltafox said:

Seen these before and have to admit it aint the best or the right way to go about it, although it will work to some degree.
The other bad idea is putting a turbo at the tailpipe like some idiots do in the US.
The system volume must be freaking horrendous with monster lag.
What a waste of time, do it right in the first place.

funny thing is that i've seen somebody do it cos he just didn't wanna burn his hands on the manifold or other hot parts