chronopassion

. . . modification works. I do not mean in great detail, but what is the basic concept as far as being able to increase the hp? Also, is it only applicable for super/turbocharged cars?

CP

Spyke

Basic concept is, the larger pulley spins the blower faster, producing more boost.

Turbos arent driven by pulleys, so all you'd be doing on a turbo car is spinning the waterpump and alternator faster...

To complicate the issue, you may also see pulleys advertised for other types of cars (notably aircooled VWs) that are listed as "power pulleys". These are actually SMALLER than stock pulleys which spin the cooling fan (and alternator/generator) slower than stock, freeing up more power at the expense of less cooling airflow. Don't confuse these pulleys with the pulleys talked about here.

To go into a little more detail, a supercharger is basically an airpump that is mechanically driven by the engine, typically using a belt. The faster you spin the blower, the more boost you get. Up to a point anyway. A larger pulley on the crank will spin the blower faster at a given rpm, just like the larger sprocket on the front of your mountain bike will turn the rear wheel faster at the same crank rpm.

A turbocharger is an airpump that is driven by the exhaust gasses. Instead of a pulley on a shaft spinning the compressor (as on a supercharger), a turbine in the exhaust flow spins the compressor. No pulleys involved.

There is of course more to it, not the least of which is that technically, a turbocharger is one form of supercharging, i.e all turbos are superchargers but not all superchargers are turbos, but let's not get dragged down in that... I saw enough of that in the coupe vs hatchback thread!

Lynn

The supercharger is dirven by a belt from a pulley bolted to the front of the crankshaft. If the diameter of the crankshft pulley is increased, the speed of the belt is increased, which in turn increases the speed at which the supercharger operates. The incrased speed of the supercharger pumps more air into the engine. The pressure of the air is increased. Reducing the size of the pulley on the supercharger will also cause the supercharger impellers to spin faster.

This is not a linear process, however. There are limits imposed by the size of the supercharger and the efficiency of the intercooler.

Turbos, short for turbo-superchargers, do not uses a mechanical drive from the crankshaft to turn the impellers. Exhaust gas is used to spin an tubine. The turbine shares a shaft with the impeller, so the exhaust gas spins the turbine which then spins the impeller. Therefore, changing the crankshaft pulley on a turbo-supercharged engine will not effect the turbo.

Austin-c230k

I was wondering what were the bad side effects of having a faster spinning water pump and alternator?

SoCal240/6

But isn't the boost controlled by a wastegate or a computer or something?

For example, on a turbo car, you can speed up the turbo all you want, but you won't get any more power, unless you change the engine control unit (ECU) to allow it to use more boost. On a Turbo, the factory never uses all the boost that the stock turbo produces. That's why on Turbos, you easily get a lot more power by just changing the chip - it allows the engine to operate at the higher boost.

I don't know about the Hatchback, but it seems like it would be similar - i.e. that there would be some computer that controls the boost. If that is the case, changing the pulley without changing the chip would not do anything (do these pulleys come with a new chip?). Likewise, if the Hatchback is anything like a turbo car, you should be able to extract as much boost as you dare run by just changing the chip.

TimmyC230boy

DUDE!! the Coupe is Supercharged. Superchargers are BELT DRIVEN. you can't change the boost on a supercharged car unless you physically change a pulley. A new chip may allow the ECU to take advantage of the higher boost levels but there is no way to change a chip and make more boost from the blower. Just stick to your C240 performance and we will worry about the coupe's performance.

tommy

No, these kits do not come with chips.

I'd say something about why turbos are different than superchargers, that superchargers being belt-driven don't have the overboosting problem that turbos do, but I'd only show my ignorance, so I'll stick to the part of your question that I know of.

The chips for the supercharged engines basically advance the timing, and do not allow for more boost the way that GIAC chips do for the 1.8t VW engine, for example.

mdp c230k

Austin, the down side of spinning the water pump and alternator faster is that it wastes power that could be used to drive the wheels and they burn out the bearings faster.

SoCal, the wastegate only limits Maximum boost levels. Your explaination of how a chip increases HP on a turboed engine is not exactly correct. It uses timing and air/fuel ratios to get the extra power in most systems. The wastegate is usually set mechanically, not by electronic control.

In general the supercharger can provide a volume of air under pressure related to the speed at which it spins. The faster it spins the more pressure(number of air molicules increases in the same space). The more air you have the more fuel that can be burned to create power. If a stock engine at 2000rpm has the supercharger spinning at X rpm then a modified pulley might have the supercharger spinning at 1.2X forcing more air into the cylinders to allow more fuel to be burned at the same engine rpm. (all numbers totally hypothetical). This increase in pressure also appears like an increase in compression ratio(not really, just more air in the same space) for more torque.

vadim

Tough case....

trench

In the case of the C230K there are two belts driven off of the crank pulley. I think the aftermarket pulleys only increase the diameter pulley diameter for the side that drives the supercharger and alternator. The other accessories (water pump, AC) utilize the other belt (which still has the stock diameter). Some of the kits come with a underdriven alternator pulley to maintain the same level of alternator RPM vs. engine RPM.

Cheers, BT

Buellwinkle

I've been boosted with the alloy pulley and it feels good! It really moves now. I tried getting 1/4 mile times at the track but I have no idea what I'm doing and got 16.1. The first time I forgot to rev it up first and the second time I reved it too high and the wheel spun while the the guy in the next lane left there. Oh well, I tried.

I can tell you that it makes a huge difference and definitely woth $350. I hope to get a dyno in a while.

WyattEarp

Soon you will need more power.

TimmyC230boy

can you ever have enough Wyatt ?

Buellwinkle

The pulley is just the begining, the first step. Now to make the pulley really shine I'll need the intercooler and chip and I'll be at the cost effective max.

BTW: I tried getting ITG airfilters from multiple source in the U.S. and nobody has them (K&N doesn't make it for the coupe). Ben at Evosport said they may get them in a month. I found a very cooperative UK dealer (this is where ITG is) and they'll check to see if it's available. Full price is 25 pounds (about $37) but he'll cut us a deal for the forum. Don't know what the filter will buy but my WAG is 2hp.

So you don't think I made up my attempt to race a C230 (got some strange looks). Here I am making a fool of myself next to a Lightning that was very upset he was running 13.2. Said the track was slippery, that explains my numbers (LOL).

TimmyC230boy

the Lightning may be faster, but we (coupes) look better!

young

what's the deal w/ the ITG filter? that is, how does a filter help gain more HP?

Spyke

Aside from the power loss issue, a waterpump can cavititate if it's spun too fast. As for the alternator, I'm not sure if you're putting extra strain on the voltage regulator or not, but in any case there's no reason to spin it faster than you have too, from a wear standpoint.

Buellwinkle

What waterpump pulley? The only thing on the outside plane of the crankshaft pulley is a tensioner pulley, a idler pulley, a alternator pulley and the supercharger pulley. It turns out that if you spin the supercharger 20% faster the altenator spins 20% faster. Not a big deal as most tuners do not compensate for this. Kleemann's kit includes an alternator pulley that is about a 42% larger than stock and acts as an undedrive pulley. After the crank pulley increase of about 20% it underdrives the altenator about 22%. From what some experts I've mentioned this to said it's no big deal as there a lot of undrive pullies sold for many cars. People with Kleemann pullies I spoke to do not have any problems with the underdriven altenator pulley. Personally it's a hassle to install and the benefits are debatable. Here's a pic of the motor if that helps to see what's what. I labeled everything affected by the what the pulley kits upgrade.

Buellwinkle

ITG, like K&N are aftermarket filters that flow better than the thick paper element filters that car manufacturers use. K&N does not make a filter for the coupe yet. To compensate for these filters, car manufacturers have created air chambers like the large air filter box in the coupe. Once you increase boost by putting in a pulley, IMHO you need to increase airflow in and out of the system. Some believe that the 20% increase in boost does not require this and the current system was designed so over capacity that it's not necessary. I heard from both sides and one claims no increase at all on the dyno and one claims that he saw increases on the dyno. So what do I have to lose, besides money? So I expect about 2hp from what I've heard and seen. So if you subscribe to the formula that a $900 pulley can deliver 40hp than you are paying $22.50 per hp. So at $37 for 2hp you are getting a bargain! Of course that only addresses the input. The output requires a redesigned exhaust, headers to muffler and nobody has that available for our cars yet. You can get a muffler now but that's just part of the equation so I don't expect much power, maybe another 2hp and for $600 that's not a bargain.

BTW, the ITG air filters are supposedly what you get when you buy a Renntech pulley kit. At least Renntech believes it does something for you.

QC1

Buellwinkle, what pulley system do you have?

Buellwinkle

I have the alloy group buy pulley. It's $350 (U.S.) and should be available soon. Let me or Timmy know if you are interested. Once it's available the group buy list will be notified.

dswildfire

does anybody know if mercedes has a pulley upgrade or sells different diameter pulleys?

Lynn

MB only provides the one size.

young

the renntech kit comes w/ a tensioner pulley.

bajaiman

I got 5kw or 6.7hp at the wheels with catback exhaust system (I dynoed the car after exhaust installation), but it was just too loud for my taste so I put the original exhaust back on. I think adding an air filter would probably help.

I’m installing a Remus exhaust and BMC filter in the next two days so hopefully it won’t be as noisy as the straight thru exhaust system.