remote mount turbo

[Marten]

Since my original post was off topic in another thread, i'll copy my post here so bam bam can "ignore it in a neater manner"

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how about remote mount turbo?
There are plenty of Specialist who can fabricate the custom piping and tune it. There's an US based company (http://www.ststurbo.com) which makes such bolt-on kits for US cars. I don't see why such setup wouldn't work on any car IF you can tune it.
I'm coming from bmw e46 so i still read and follow some of their forums. Here's a like to e46M3 with such setup. http://forum.e46fanatics.com/showthread.php?t=909391

discuss...

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My experience of long intake pipes with forced induction is that it really affects drive ability.

Sure raw power is there but fine mid corner control is compromised.

The 211 supercharger has an unusually long intake pipe that goes from the throttle body, down the side of the engine and round the back to the charge cooler and then back to the front of the engine to the supercharger.
The effect was that it's hard to control idle (stalls often) and you do get a bit of lag on quick throttle applications.

Id hate to have the same thing but so long down the length of the car.

[Marten]

I have no experiance in long intake pipes, but there plenty who seem to rock this type setup alot on cars which have litte or no room in engine bay. Those who have tried this setup seem to think it doesn't have such lag which is expected or spoken of. There's also plenty of vids on tube of different cars. I'm sure it doesn't perform as well as top or bottom mount turbos, but should out perform superchargers. I've followed few builds on BMW's and these seem to be working pretty well.

[adsgreen]

Here's a picture of the engine bay in a 211
Only one I could find - you can see the polished pipe running from the supercharger to the chargecooler.
Although out of shot, the same arrangement is on the other side to the intake manifold.
Conceptually, this is no different in that there is a long pipe to the intake manifold after the forced induction generator.
Just google the threads on problems with stalling and throttle response on part throttle. It is all down to the long pipe and really there's not alot you can do about it.
From the drivers seat it really feels like lag which on a supercharger is a very odd sensation - the engine really lost some of the immediate nature.

Also, this would be a huge amount of work and tricky with the v8 exhaust when compared to a straight 6 (only one exhaust manifold on the straight six).
The other problem would be fitting the intake feed. Again, with a straight 6 theres only one manifold and it's relatively easy to slot in after the throttle body (in the same way the supercharger is between the throttle body and manifold below). With the RS4 the only place you could do this is on the top intake manifold and it would mean fabricating a compeletly new unit from scratch.

[sakimano]

the only real benefit would be to say ' I have a turbo RS4'. I know lots of people love the concept of a turbocharged motor, but love can make you do silly things.

Unfortunately that's not really worth much in my view. The stock RS4 motor will handle 500+ wheel horsepower (600+ at the crank) and with a few good supercharger options easily able to eclipse that mark (TTS current, JHM and AMD in development) in a neat install with limited headaches and virtually no lag, there is really no place for a rear-mount turbo kit.

If you're going to make a turbo kit, do it right...twin turbos in the engine bay. A big single might work well for an inline 6, however on a V8 twins is more suitable. I'd guess that twins in the engine bay is possible (JHM did this on half a dozen B6/7 S4s already)...just makes you wonder, is it worth it and is it necessary? You'd need an engine build to make it really worthwhile...otherwise, stick with the superchargers.

[Marten]

I will look into the part throttle problem, but I can understand why would it occure.


I'm no doctor, but i've see one on TV


Lets say it's either singel or twin charger option. The piping would be different on the exhaust side depending on which route one would go. But the intake side should be very similar on both cases.
On singel charger one would need Y pipe after downpipes, which would direct both sides into one pipe. On twin charger the pipes from each side could run straight in one of the chargers.

Similar to this :


Basicly the exhaust manifold could stay the same if there's enough room to direct the pipes to the current location of the TB.

[Marten]

the only real benefit would be to say ' I have a turbo RS4'. I know lots of people love the concept of a turbocharged motor, but love can make you do silly things.

Unfortunately that's not really worth much in my view. The stock RS4 motor will handle 500+ wheel horsepower (600+ at the crank) and with a few good supercharger options easily able to eclipse that mark (TTS current, JHM and AMD in development) in a neat install with limited headaches and virtually no lag, there is really no place for a rear-mount turbo kit.

If you're going to make a turbo kit, do it right...twin turbos in the engine bay. A big single might work well for an inline 6, however on a V8 twins is more suitable. I'd guess that twins in the engine bay is possible (JHM did this on half a dozen B6/7 S4s already)...just makes you wonder, is it worth it and is it necessary? You'd need an engine build to make it really worthwhile...otherwise, stick with the superchargers.

Has the limits of the stock motor been tested or is that a general opinion? I mean has anybody pushed the engine to the point it lets go? As an example on the e46m3 platform it was belived that the stock engine wont handle more power than 400 rwhp (or so). But as the time went on and more tuners got into super- and turbocharging that engine it showed alot more potential. Now the HPF stg2 (stock motor) kits on "race mode" puts down 600+ rwhp.

The really not about what I am going to do or what would I do... I'm just wondering and trying to touch a subject which I belive hasn't been discussed for one or the other reason.

[Doug_S2]

the advantage of a turbo is lower down torque - which could also be the killer for rods as the supercharged cars are not silly high in torque and they are a gradual build up of torque, not a smack of torque in a turbo.

You also have the disadvantage of mapping a NA ecu for a turbo - which is not as nice a a supercharger on an ecu.

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The problem is that the engine is designed to be high revving and high compression (for large N/A power) - both of these cause issues with forced induction.
The strength required for a high performance N/A engine is different to that of a FI car esp turbo's. For example the valves on the RS4 are lightweight and hollow for quick movement but are technically weaker than solid ones.
This is before you get onto the subject of valve overlap which Doug's raised in the past - on the rs4 engine the overlap is massive (essential to get power up at 8k rpm) but the last thing you want with FI is the exhaust and intake valves open. In this respect the bog standard S4 v8 is likely to be higher power potential than the RS4 (lower reving and compression ratio too).

The massive advantage of the TTS is that the power addition low down is less so the internals are not stressed anywhere near like that you'd get with a turbo and the TTS power increases as the ability of the engine to draw in air decreases. I like them as they make the car feel almost N/A... just a much bigger engine.

The last thing you'd want on a V8 is a Y pipe.
The reason I say the v8 is more complex exhaust side is that you've got two standalone exhaust manifolds and piping. This takes up a lot of room under the car and you'd need to somehow squeeze enough room to run another lot of piping back to the intake manifold.

The V8 is a very snug fit in the RS4 - where as the I6 in the M3 is much more open esp on the sides so you do have room to play with.