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It wouldnt fit on a valver. On a 172 cup it probably would. Blowers tend to run out of puff at high revs, whereas turbos are the other way round -in general. Im not saying that this is what all blowers and turbos are like, but just the nature of how they work gives them these characteristics - hence the old Lancia engines with a supercharger for instant boost at low revs and then a turbo to take over at higher revs once it had spun up.
Superchargers have no lag to speak of but their flow rate is optimised for one particular part of the rev range. They also rob some power from the engine to drive them.
Turbos use power that is otherwise wasted out the exhaust pipe, but do need to spool up before they get going so not much good really low down in the revs. Lots of low lag small turbos out there or hybrids with the low lag capabilities of a small turbo and the boost capacity of a larger turbo. In a valver its a lot more practical to try and get a turbo in than a blower.
I LOOKED INTO HAVING ONE ON MY WILLY. ONE PROBLEM IS SPACE !! tHERE IS NO WHERE IN THE ENGINE BAY TO FIT IT,
WITHOUT REMOVING THE POWER STEERING GUBBINS. tHE COST WAS NOT THAT BAD BUT, LIVING WITHOUT POWERSTEERING !! I DONT THINK SO !!
sO THAT IDEA WENT IN THE BIN !! NOW AFTER HAVING STAGE 2 WORK DONE. i THINK MAYBE ITS TIME TO LOOK AT T/B.
I remember reading somewhere a couple of years back about a company that was producing electric turbos... they were really compact units too.The idea obviously didnt take off though because I havent heard about them since...
"Turbos use power that is otherwise wasted out the exhaust pipe"
Arrrggghhhh... I really hate it when people say that when they are comparing them to superchargers!!!
Its a load of crap...
Putting a turbo on an engine robs a fair bit of power, its like having an extremely restrictive exhaust. It causes a lot of back pressure between the engine and the turbine which makes it harder for the exhaust gases to leave via the exhaust port and so a greater volume remain in the cylinder after the exhaust valve has closed. This means that the combustion process is less efficient, because this gas takes up the volume that should be filled with fresh air/fuel mixture. However the Turbo is forcing in additional air and so that outweighs the losses due to the added backpressure.
It doesnt however mean you are getting something for nothing! I think the fact that a lot of companies that are fitting aftermarket turbo conversions seem to think this is the case shows their knowledge is prehaps somewhat limited!
While Im on the subject... a Rotrex supercharger, which is basically the compressor side of a turbo mounted to an extremely efficient planetry gearbox that runs off the crank pulley, will sap less power than the average conventional turbo and it wont generate anywhere near as much heat which means that average intake temps will be lower which again means more power.
If you look at the turbod and supercharged Saxos as things stand at the moment the supercharged ones are getting better power figures even though they are running the same levels of boost.
Another thing with turbo is they spin up at a set rpm and only produce max torque for a very limited time before it starts to fall away. For most smaller road going Turbos every time you change up a gear you are actually using less and less of your peak torque and as a result you arent accelerating as quickly...
The only way to get round this as they do in motorsport is to use a large turbo that spins up at high revs and so you get the full effect of the torque in every gear... only problem with that is massive lag, which realistically isnt great for a road car, especially one not designed for the stress a turbo will put on it.
You only have to look at a power graph for a Turbo car to see that there is a very large change in power over a very short space of time and thats what puts a strain on pretty much every component in the engine and transmission. think about the easiest way to break a piece of string, you can apply a big force over a long period of time and it wont break, but yank it quickly and itll snap. Plus turbos generate a lot of heat because the spin upto such high speeds and again that will put extra strain on the engine.
Superchargers have their downsides as well, its just I cant think of any right now... Well apart from the fact that ultimatly they wont generate as much boost as a turbo, but in most cases that wont be the limiting factor itll be the strength of the engine and gearbox that dictates how far you can go.
What you need are 2 small turbos.........like I have
Sax, you raise some valid points...particualry about big turbos generating lots of lag...thing you get with s/c is a much more progressive torque curve...I would say a supercharger is a refined turbo charger...altho lets face it, in todays technological world, turbochargers and their control systems have become so good (Saabs low pressure turbo being a good example) that its barely noticeable a turbo is fitted.
My Saab 900 turbo had APS, think it stood for auto pressure system, Didnt suffer from lag. It was damn quick for a relatively heavy car. I bought it because Id had a N/A diesel as a company car for too many years. I just couldnt stop caining it. I would never have another turbo, I blew 2 engines and two gear boxes in 18 months. Top Gear had described it as bomb proof! Guess theyd never heard of me. Rather expensive to fix.
When you are stressing your bits, ask yourself if you can afford a new engine /Gbox. I see there is another valver with broken box on the forum with less than 70k clocked, the valver box was allegedly designed for only 120bhp, dont think youd want to mod one too much.
Im talking about the standard box that comes in the clio 16v, I two people that have had a valver box go (no third gear + grinding in other gears) below 80k miles. Neither of them thrash their cars. The Willy has an uprated box according to the sales brochure.
I thought Id read about the valver box not being strong enough on this site about 3 or 4 years back. Think it was this site, looked a lot different if it was.
Shows some clear pics of an s/c conversion on a VTR, as you can see you need plenty of room, from what Ive seen itd be a struggle to fit in either a 172 or a williams/valver... thats not say it wouldnt be impossible youd just have to be a bit creative...
As far as cost goes it depends how far you want to go, but a basic kit costs around £3250
i aint ever heard a supercharger that aint sounded good, used to be one on a mk3 golf at guildford cruise, that thing screamed! my mums merc is supercharged aswell, that dont sound like a hoover what so ever, although u can only really hear the exhaust on it, but sometimes the supercharger if u really floor it and it dont sound like a hoover, more of a whistle
lol mercedes engines, hardly stir the soul. Had a 230 SLK last summer, was pants. Maybe its because ive been spoiled by the noises of so many good cars.
evo on a cooper s:
"Straight after the Clio, you wonder where the get up and go has gone, the supercharged engine droning its way through the rev range with what sounds like mechanical boredom. Its as if Marvin the paranoid android from The Hitch-hikers Guide to the Galaxy has been recycled as the Cooper Ss engine. "
Going back to the supercharged vs turbocharged topic - Id like to point out a few facts:
1) A supercharger is not better than a turbocharger.
2) A turbocharger is not better than a supercharger.
They both exist because 1 will suit a given application better than another. If I was to modify my Cup down the forced induction route, I would turbo charge it. It’s all about how you want your power delivery – progressive and linear or sudden and explosive.
Turbochargers do not cause backpressure to the point you loose as much power as running a supercharger.
Take a 172 turbo for example: The torque curve may well peak for a short period in some cases, but this peak is way, way above the peak of the standard 172, and once it does start to fall off, it will always stay significantly above the standard curve right up to the limiter.
The stresses on the engine will be the same (without taking induction temperatures into account) regardless of how the boost is made. 1 bar is 1 bar. Doesn’t matter if it comes from a supercharger of a turbocharger.
Its not about how much boost they produce its the dynamic loads on the engine that cause the damage...
Take a piece of paper hold one end in one hand and the other end in the other hand... now slowly pull your hands apart, you can apply a massive force to the paper and it wont rip... now do the same but yank your hands apart as quickly as possible... Its far easier to rip the paper by pulling it quickly even if youre not applying such a large force. Same goes for engines gearboxs etc its often not the size of the force you apply its how quickly you apply it...
Look at the new Hartage Mini Cooper S (supercharged)... It produces around 215bhp and its reviewed in this months EVO it doesnt have an LSD an yet they said it is an extremely well mannered road car with surprisingly very little torque steer... Focus RS (Turbo) on the other hand similar power and performance plus its even got Quaifes latest ATB LSD and yet in all the magazines have said it sufferes badly from torque steer and that its a bit of a handful... Im fairly sure thatll be because of the way they deliver their torque, RS has bags of torque at low revs, Mini has a very progressive torque curve and delivers most of its punch at higher revs.