Best suited turbocharger

Ive just read some of that link, there are great big holes in it, and it sounds like something written by John Lane...

Firstly, he says a turbo doesnt increase exhaust back pressure, which of course it does, hence the reason we get more horsepower if we use a larger turbine housing - We use larger turbine housings to get more power at peak revs, why?, as backpressure is reduced, volumetric efficiency goes up, so the 20psi at the inlet, is now 20psi with more flow through the engine. and as he hasn't talked about turbine housing size at all in relation to power production and VE in the whole article, which backs up him not getting the idea.. An engine is nothing more than an air pump, with some fuel and spark thrown into the mix, but with any pump, if we restrict the output, it will get up to pressure really quick, but there will be a limit to how much output it can flow at its peak...

This is further backed up by him saying that lag is a function of turbine wheel, shaft and compressor rotational inertia - If he understood turbine housing a/r's and turbine trims, he would know this is not the case..

Yesterday, I fitted a HKSG30 turbo from a 1993 Skyline GTS to a friends 200sx, which was fitted with the standard turbo. The Skyline turbocharger has a ceramic turbine wheel, and a plastic compressor wheel, far, far lighter than the steel shaft, turbine and ally comp wheel on the standard turbo - but it was laggier, because the turbine housing was larger, and the compressor wheel had a different trim, which meant it was in surge earlier than the standard turbo - It had less 'rotational inertia'....but slower to spool...

Whatever happened to superchargers? Did they die a complete death after VW used them in the 80s?

Seems like they'd have massive benefits here: No lag - just constant boost right through the range, no heating up the intake charge by passing it through roasting metal. Plenty of pulleys to choose from at the back of the engine to drive it. You could plumb the exhausts straight down and out the back taking the heat all away from the top of the engine and reduce the backpressure and - the clutch slave cylinder would be more reliable and a doddle to change without the turbo getting in the way and boiling it up.

Or is that not in the spirit of Renault and its turbocharged history? I guess the good old supercharger suffers from reliability problems, less efficiency than a turbo or some other issue or everyone would be using them.

Superchargers sap power because they need driven, they are also heavy and need mounted and plumbed in at the back of the engine. Obviously there are advantages and Mercedes and Jaguar both still use them on their cars.....it has been proposed before...think Stephen is still planning one for his car.

The Jag V8 supercharger is said to sap over 50bhp, of course it more than makes up for it with the boost it provides.

Again though no such thing as a free lunch.

Oh and you are heating up the intake charge - by compressing it (Boyles Law and all that) Not as much since the exhaust gases aren't cooking things but you still can't avoid it.

The main benefit of supercharging is the lack of exhaust restriction which you normally encounter with turbocharging. The engines original volumetric efficiency is unchanged (as you havent restricted the exhaust) so its free to make more power at the same boost as a turbo setup, abeit the power lost to actually drive the unit...

Downside is they can keep up with high boost, high revs and high airflow requirements.

Steve has a centrifugal type (like half a a turbo) which is very efficient, but doesnt make the very low end torque boost like a screw type, but they sap loads of power and more difficult to fit...

On the subject of manifold flanges ,just stripped the turbo off and found a dorty great crack highlighted here
Anyone got a decent one or does it matter that much

4 "other" weddings.

How many wives do you need, normally 1 is more than enough for regular stress.

4 "other" weddings.

How many wives do you need, normally 1 is more than enough for regular stress.

Norman the Mormon

On the subject of manifold flanges ,just stripped the turbo off and found a dorty great crack highlighted here
Anyone got a decent one or does it matter that much

Yes, I have one somewhere, but it really doesnt matter unless its cracked so much that it can fall off...

Least with your pic youve highlighted the division in the manifold flange to Simon, between the two banks..

I take it with twin scroll the seperation continues to the wheel, two spirals to the turbine then they join at exit .The blades must be totally diff to a std turbo then

I take it with twin scroll the seperation continues to the wheel, two spirals to the turbine then they join at exit .The blades must be totally diff to a std turbo then

Yep, but the turbine wheel is no different. The GT series of turbos have the option of normal housings, wastegated or not, and twin scroll option, again with or without internal wastegate...

It is exactly a normal scroll, divided into two, and both scrolls meet at the turbine wheel exducer (largest diameter part of the turbine wheel)