Jump to content
SAU Community

Recommended Posts

each has their place in the car performance world

there is no such thing as " no lag " and " 0 rpm lag" its a load of rubbish

each has lag and takes time before the compressor is efficient

Thats untrue - positive displacement supercharges have zero lag they run a bypass vavle so that there is little/no flow throught the charger. As soon as the bypass vavle is closed you have boost. Also it is possilbe to control boost on most posivite displacement chargers as manufactures generally run a double sided vacuum actuator - so all you need to do is remove or apply pressure to vary the amount of air that is bypass from the compressor. We often do this on the VS-VT V6 superchargers.

The biggest compliment to the FSI engine is that it is direct injection so that higher compression ratio's can be used as chamber quenching is optimised. Another neat idea is the clutched supercharger as this will reduced the forces required to drive the charger once the turbo is brought into action.

To me the best thing nissan could do would be to introduce direct injection, crank the compression ratio up to 10:1 and add varaible cam timing.

...did anyone catch the episode of Top Gear where some mensa woman was doing the "Star in a reasonably priced car" bit and she asked Jeremy what the difference was between a turbo and a supercharger, and he had no idea?

For a guy who gets to drive some beautiful cars, and has done so for decades, he really is clueless.

Useless twat, bring back the TIFF!!!

To me the best thing nissan could do would be to introduce direct injection, crank the compression ratio up to 10:1 and add varaible cam timing.

I believe that is exactly the technology they introduced with the VQ25 engine series. Naturally aspirated compression is somewhere up around 11:1 and it's reputedly a pretty good bit of gear - for the power it is producing.

I believe that is exactly the technology they introduced with the VQ25 engine series. Naturally aspirated compression is somewhere up around 11:1 and it's reputedly a pretty good bit of gear - for the power it is producing.

I would then add 15Psi of boost pressure on top of that. That way you can produce lots of drivable toque plus top end - you also gains lots of response.

Also has anybody seen nissan's new variable vavle control - what a bucket of shite. You cant help but think it was designed by the law department in order to get around current patents!!!!

Just as an aside, the GM diesel trucks [dirty GM's they are called], run a supercharger and turbocharger together. They are a V6 and make as much power with this setup as much bigger motors. Oh and they are two stroke deisels as well. Downside is they do like a drink!!!!!

PS They have been around for a long time, +30 years, I'll do a search and confirm when they first came out to confirm that, but I drove one at least 30 years ago [there goes my age now].

Some of you guys have a lot to learn. Others are getting there, very few actually know what they're talking about.

Go build a twincharged engine - ask lots of questions and learn as much as you can along the way. That's what I did, and the result is quite simply spectacular. It really is the best of all worlds. Snappy transient boost response at ANY RPM (even at 1000rpm you can have positive manifold pressure), good fuel consumption (for a 400hp car), giant midrange torque with NO compromise to top-end power (235rwkw from a stock-cammed RB25/30 on 9psi) and a much safer engine compared to a turbocharged-only setup because it runs so far from the detonation threshold. During valve overlap, if you have more pressure in the inlet tract than in the exhaust manifold, you get positive pressure sweeping the chamber clean of incredibly hot exhaust gas residuals - hence a cleaner, significantly colder charge. More power, less chance of detonation, more efficient engine.

Comparing superchargers to turbochargers and asking which is better is a bit like asking whether an apple is better than an orange. At what? When? On which engine? For what purpose? Which supercharger type? Which turbocharger? The list goes on.

If I had to choose between a street 500hp RB26 running an Opcon twin screw blower and a 500hp RB25 running turbochargers, I'd choose the supercharged one. If the car's purpose was drag racing, i'd go the turbo and run a giant stall convertor because top-end power is all that really matters for a drag car.

Essentially the "debate" boils down to three simple words;

Horse For Courses.

each has their place in the car performance world

there is no such thing as " no lag " and " 0 rpm lag" its a load of rubbish

each has lag and takes time before the compressor is efficient

Although, some manufacturers, eg Porche, are finding ways to minimise it a lot. I have recently driven a new Hyundai Santa Fe turbo diesel and you can hear the turbo spooling up even when you only just holding your foot on the throttle at 900rpm constant. It's bloody amazing, honest you can hear the whistle it makes at 900RPM!!!

This is due to their new VGT's(Variable Geometry Turbo). Works something along the lines of changing the diameter of the exhaust turbine using a vacuum actuator, so that at low engine speeds it is the right size to boost and at high engine speeds it changes to stay efficient and increase flow.

I don't think it is that new though, Porche have been using it for some time.

Although, some manufacturers, eg Porche, are finding ways to minimise it a lot. I have recently driven a new Hyundai Santa Fe turbo diesel and you can hear the turbo spooling up even when you only just holding your foot on the throttle at 900rpm constant. It's bloody amazing, honest you can hear the whistle it makes at 900RPM!!!

This is due to their new VGT's(Variable Geometry Turbo). Works something along the lines of changing the diameter of the exhaust turbine using a vacuum actuator, so that at low engine speeds it is the right size to boost and at high engine speeds it changes to stay efficient and increase flow.

I don't think it is that new though, Porche have been using it for some time.

Most diesels dont run a throttle's that's why you can hear the turbo spool at idle as there is either boost or atmoshpeheric pressure. And yes I am aware that some modern diesels run electronic throttles. The new triton even has stepper motor control varaible vane turbo.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • From the pictures I have when doing the job the flywheel is the same diameter, I don't think they're playing weird tricks like putting weights at the outer diameter to increase flywheel inertia or anything like that. The OEM flywheel is definitely heavier, but it's not a huge difference. Quoted weight savings of the clutch is 2 kg so I can't imagine the flywheel being lighter than ~7 kg. Kind of regret not weighing it before the clutch went into the car but as far as driveability goes I have no complaints.
    • HKS trigger kit should be very easy to integrate with a Link. It's a 36-2 crank trigger. Hard part is finding the motivation to take off the timing belt and everything on the front of the engine to install it. You also need to cut out a hole in the oil pump housing so the sensor can read the trigger wheel. Changing out the cam sensor for a 24 tooth setup is probably good enough but as others have mentioned depending on what underlying assumptions are changed it becomes more of a problem. Reading the crank state off of the cam is an abstraction that works in the general case, but if you have an edge case it makes less and less sense. There is a GTX2860 gen 2 that can take a compact 5 bolt housing so it's direct bolt on but I'm not 100% sure of what's involved. Peak compressor efficiency drops off a bit on these turbos vs -5s, 77% vs 73% but you get way, way wider region of operation. The -5s have a really strange surge line in their compressor map that is all over the place. If you think the hot side on the -5s aren't open enough you can try the Tomei T550B turbos which a local tuner seems to be happy with:
    • i need a complete tail light for my R33 GTR if you have please let me know.
    • I need a great maintenance workshop around Idaho, if you know one please let me know..
    • Hello friends, i have a good friend in Canada that looking for a good condition 1993 GTR around him please if one or know someone around you that is willing to let it go please let me know so that i can inform him.....Thanks
×
×
  • Create New...