Can you guys tell me the advantages and disadvantages on getting either a greddy twin turbo kit versus a supercharger kit? please help. thanks

 

s/c less money, easier install, no spool time, safer for engine and all of the race shops I talked to recomended the super charger.

 

https://my350z.com/forum/showthread....threadid=72808

It's along thread but worth the read...
Everyone will have their own opinions

 

With turbo, you can turn the boost up with a ****.
With S/C, you have to get out and change a belt.

 

Just curious, but do you have to "cool down" the engine before shutting off after driving hard with a supercharger as you would do on a turbo?

 

I think you mean pulley

 

Yup, pulley. Don't the belts have "teeth" though?

 

<-------look at avatar for answer.

Turbos offer higher torque and hp way earlier in the powerband than s/c.

this topic has been flogged to death a few times allready do a forum search on the topic there is tons of info out there on this subject.

 

People are going to be biased towards what they have. Ive got the vortech and think the same. For me it was the $$$$ i had to spend. Forced induction is good in both forms it really up to the individual, and most importantly the avaliability of a GOOD installer and tuner.

 

"HP costs money" How much HP do you want?

-I don't remember the quoter

 

Head to Head Comparison

Now it's time to evaluate the turbocharger versus the supercharger according to several important factors.

Cost
The cost of supercharger and a turbocharger systems for the same engine are approximately the same, so cost is generally not a factor.

Lag
This is perhaps the biggest advantage that the supercharger enjoys over the tubo. Because a turbocharger is driven by exhaust gasses, the turbocharger's turbine must first spool up before it even begins to turn the compressor's impeller. This results in lag time which is the time needed for the turbine to reach its full throttle from an intermediate rotational speed state. During this lag time, the turbocharger is creating little to no boost, which means little to no power gains during this time. Smaller turbos spool up quicker, which eliminates some of this lag. Turbochargers thus utilize a wastegate, which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses boost pressure, and if it gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down..
A Supercharger, on the other hand, is connected directly to the crank, so there is no "lag". Superchargers are able to produce boost at a very low rpm, especially screw-type and roots type blowers.

Efficiency
This is the turbo's biggest advantage. The turbocharger is generally more economical to operate as it as it is driven primarily by potential energy in the exhaust gasses that would otherwise be lost out the exhaust, whereas a supercharger draws power from the crank, which can be used to turn the wheels. The turbocharger's impeller is also powered only under boost conditions, so there is less parasitic drag while the impeller is not spinning. The turbocharger, however, is not free of inefficiency as it does create additional exhaust backpressure and exhaust flow interruption.

Heat
Because the turbocharger is mounted to the exhaust manifold (which is very hot), turbocharger boost is subject to additional heating via the turbo's hot casing. Because hot air expands (the opposite goal of a turbo or supercharger), an intercooler becomes necessary on almost all turbocharged applications to cool the air charge before it is released into the engine. This increases the complexity of the installation. A centrifugal supercharger on the other hand creates a cooler air discharge, so an intercooler is often not necessary at boost levels below 10psi. That said, some superchargers (especially roots-type superchargers) create hotter discharge temperatures, which also make an intecooler necessary even on fairly low-boost applications.

Surge
Because a turbocharger first spools up before the boost is delivered to the engine, there is a surge of power that is delivered immediately when the wastegate opens (around 3000 rpm). This surge can be damaging to the engine and drivetrain, and can make the vehicle difficult to drive or lose traction.

Back Pressure
Because the supercharger eliminates the need to deal with the exhaust gas interruption created by inserting a turbocharger turbine into the exhaust flow, the supercharger creates no additional exhaust backpressure. The amount of power that is lost by a turbo's turbine reduces it's overall efficiency.

Noise
The turbocharger is generally quiter than the supercharger. Because the turbo's turbine is in the exhaust, the turbo can substantially reduce exhaust noise, making the engine run quieter. Some centrifugal superchargers are known to be noisy and whistley which, annoys some drivers (we, however, love it!)

Reliability
In general, superchargers enjoy a substantial reliability advantage over the turbocharger. When a a turbo is shut off (i.e. when the engine is turned off), residual oil inside the turbo's bearings can be baked by stored engine heat. This, combined with the turbo's extremely high rpms (up to 150,000rpm) can cause problems with the turbo's internal bearings and can shorten the life of the turbocharger. In addition, many turbos require aftermarket exhaust manifolds, which are often far less reliable than stock manifolds.

Ease of Installation
Superchargers are substantially easier to install than a turbos because they have far fewer components and simpler devices. Turbos are complex and require manifold and exhaust modifications, intercoolers, extra oil lines, etc. - most of which is not needed with most superchargers. A novice home mechanic can easily install most supercharger systems, while a turbo installation should be left to a turbo expert.

Maximum Power Output
Turbos are known for their unique ability to spin to incredibly high rpms and make outrages peak boost figures (25psi+). While operating a turbocharger at very high levels of boost requires major modifications to the rest of the engine, the turbo is capable of producing more peak power than superchargers.

Tunability
Turbochargers, because they are so complex and rely on exhaust pressure, are notoriously difficult to tune. Superchargers, on the other hand, require few fuel and ignition upgrades and normally require little or no engine tuning.

Conclusion

While the supercharger is generally considered to be a better method of forced induction for most street and race vehicles, the turbo will always have its place in a more specialized market. Superchargers generally provide a much broader powerband that most drivers are looking for with no "turbo lag". In addition, they are much easier to install and tune, making them more practical for a home or novice mechanic.

 

only wanted to correct you on the cost issue. a turbo is much more expensive at least 25%. a vortech kit with ic is like 4500. the cheapest turbo available is greddy and turbo and ic is ~5600. plus the cost of installing a turbo is greater.

 

Not to be contradictory, but I have to mention a few points here. Before a turbo spools up completely, not only is it not making any horsepower, but it is actually robbing the engine of power by inhibiting the exhaust flow.

On another note, it is possible to rig a wastegate to a supercharger also. Rather than venting exhaust around the turbo in this situation it will vent over boosted air out into the atmosphere. Which can accomplish two things. It can allow the use of a pulley with maximum capabilities beyond that of what you actually need. Then you have the wastegate open at say 9psi. What this would actually do is let the supercharger acheive your desired boost level a lot earlier in the rpm range and maintain that boost until redline rather than just getting up to it at redline.

I have a slight issue with this statement. I've noticed a lot of people mentioning this and I'm not sure that this is entirely correct. A turbo is not more economical to operate. Turbo's don't run because the exhaust is hot, they run because the exhaust flow turns the impellar. The presence of a turbo robs the free-flowingness (not really a word...i made that one up) of the exhaust. This in turn reduces the output of the motor just like the presence of a supercharger reduces the output of the motor because the crank has to turn the pulley. The difference is that a turbo robs more of the engines power in lower rpms and when it spools up and compensates by delivering power it creates a surge, while a supercharger is more linear because the boost it creates is linearly proportional to the engine speed. A turbo's boost is exponentially proportional to engine speed.

 

Here is a chart showing dynos of three different FI setups. Which you rather drive? As far as cost if you take the kit out the the box and bolt it on and never touch it again the supercharger is cheaper by about 1500.00. But how many people are really going to do that? take a close look at the 8psi Greddy and 8psi Vortech. They are a great example of what 80% of the FI crowd will end up with. It's a FI with high flow exhaust and tuning. About the limit for daily driven without gettng serious.

You guys with the "lag" kill me. the only thing that makes instant low down power is the roots but it can only flow so much on the top end. The other superchargers (centrifcal) have terrible low end look at the charts, below 4k they are not spinning fast enough to make real boost (ie more that 3psi) thus no low compared to the turbos.

 

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