GReddy twin turbo kit or vortech supercharger?

[Bobby23]

I am torn between the two and can’t make up my mind. I want to keep the mods I have already, ( MREV2, Spacer, Greddy cat back NA, Crawford HFC, popcharger/z-tube). I know if I get the greddy kit, I am going to have to get a new exhaust (larger diameter piping for excess exhaust heat), test pipes instead of my HFCs, and doesn’t the greddy kit come with a new lower intake manifold as well? Therefore, I would have to try to sell some of my old mods and buy new ones if I want to gain the best performance.

Would I have to make all of those changes with the vortech? What would you guys recommend? From what I have been, reading it would be less expensive for me to get the vortech. The prices of the two are very similar but I do not think I would have to make as many changes to my current mods. I’ve heard that supercharges work better on G’s as well. I'm looking for the most realiable too.

[joe603]

OK...here's the thing. A turbo doesn't like to have backpressure, so exhaust mods are a must. A supercharger needs some backpressure to be more efficient. The only mod you'll need to sell is the popcharger. You don't need test pipes with the turbo, but it will increase the efficiency of the system.

Now to answer your question on which one to get...that's your choice. The twins will have more power and torque, but as you've mentioned, it will cost about 30-40% more. Personally, I'm going with a vortech when the time comes. I plan on doing the install myself...a task that I wouldn't attempt with a turbo.

[G_whizz]

OK...here's the thing. A turbo doesn't like to have backpressure, so exhaust mods are a must. A supercharger needs some backpressure to be more efficient. The only mod you'll need to sell is the popcharger. You don't need test pipes with the turbo, but it will increase the efficiency of the system.

Now to answer your question on which one to get...that's your choice. The twins will have more power and torque, but as you've mentioned, it will cost about 30-40% more. Personally, I'm going with a vortech when the time comes. I plan on doing the install myself...a task that I wouldn't attempt with a turbo.

Not that Joe is stupid by any means... there's just no ..."I agree" icon..

[zozoka1212]

Now we are talking.

$$$$$$

nice

I would go with Vortech.

Are we getting some pics of the install?

zozo

[Bobby23]

Joe: Yeah that’s why I was leaning toward the vortech. I know the vortech comes with fuel management mods, but what else would you recommend to help insure better reliability? ( Intercooler, new radiator, new pulleys, oil cover ex.)

I dont want to go cheap and end up messing up my engine. How many hours does it usually take a shop to put on the charger ( I know its less time then the turbos). What kind of $$$ are we talking? I know its usually $49 an hour. I live in Orlando and I was planning on having Titian motor sports put in on for me. They are not known for G’s but have a good rep with Supras and I know a few of the guys there.

[JeromeS13]

Personally, I'd go with the Greddy kit. I've seen numerous people START out with a Vortech or a Stillen SC. Then, they just aren't satisfied and want more. So, they eventually sell the SC kit and buy a TT kit.

If it were my, I'd go with the Greddy TT kit w/ UTEC or get the STS kit

Just my $0.02.

-Jerome

[joe603]

Joe: Yeah that’s why I was leaning toward the vortech. I know the vortech comes with fuel management mods, but what else would you recommend to help insure better reliability? ( Intercooler, new radiator, new pulleys, oil cover ex.)

I dont want to go cheap and end up messing up my engine. How many hours does it usually take a shop to put on the charger ( I know its less time then the turbos). What kind of $$$ are we talking? I know its usually $49 an hour. I live in Orlando and I was planning on having Titian motor sports put in on for me. They are not known for G’s but have a good rep with Supras and I know a few of the guys there.

Reliability comes from a good tune. The Vortech has a decent intercooler...the only thing I would add would be an oil pan spacer. It will have a fitting for the oil line for the charger too.

I've been quoted 7k for a complete install, including tuning at forged performance. (10k for the Greddy/JWT twin kits) Really it depends on the shop.

A twin setup will have about 50 more TQ and 20 more HP than a vortech with the normal pulley. If you go with more boost, then the numbers are close. However, the major difference between the kits is that with a twin turbo, full boost comes much sooner in the RPM band. This will put you back in your seat more than the 'charger and seem faster. Both will be a huge improvement over stock.

Let us know which way you decide to go! Ohh... and pics or

[Bobby23]

I would have to spend alot more $$$$ on the turbo kits and the chargers are safer on your engine

[Bobby23]

Yeah if i go through with it i will post up pics...Im either going to get a bike or the kit for my car. thank you for all your suggestions

[tollboothwilley]

I have a friend who bought his 350Z from FIDANZA and was at the SEMA show. He's been running the vortech supercharger with almost everything else that you can switch out already swapped. Its not enough for him so he wants to get the TT now.

For longevity of your engine, Superchargers are going to be much better.

I was reading an article in MotorTrend, i think it was, and the new Corvette ZR1 they opted to go with a SC over TT because of a new blower that has efficiency very near TT.

Either way you go, good luck and show us lots of pictures

[gwoods]

Superchargers use hp to make hp, basically your motor is turning an air pump.

Turbochargers use wasted energy (exhaust pressure) to turn a pump.

You might consider a wet nitrous kit? 75 hp shot should be safe forever on a stock motor. You's be around $1200 for a SAFE complete Nitrous kit. If it wasn't enough you could sell it for what you paid on ebay.

Jeff

[Tampa G35 Sedan 6MT]

I would love to go with the TT Kit becasue of the TQ.....

That is what our G's are missing! I wish i had about 100 tq more.. But a turbo should give you numbers like 400 TQ.

I whish our G's had a Tq band like the 335i's But that is the only thing i would like from a BMW



DJ

[Bobby23]

I know the twin turbo will make more power but (you guys are going to hang me for this next quote) I dont need a pro-street race car. lol If i had the money for an everyday car (that I wouldnt have to worry about breaking down or putting miles on it) then yeah sure why not, i'd go all out.

I'm just looking for the next step in mods that will give me a good amount of power and still be safe on my engine. I think the charger is perfect for that. $7k for a vortech instailed, $10k for a greddy kit, thats $3 in difference. I dont feel that the extra power for a twin turbo (which is harder on your engine) is really worth it. I have an 06 and plan on keeping it for 4 years maybe 5 and then selling it. I dont feel like paying through the roof for blowing a rod or something to that effect by going "all out" on a twin turbo. I know how I drive and id be hard on the engine =)

Would I want the extra HP yeah who doesnt but i just feel that the vortech would be the best way to go.

[gwoods]

Nitrous Oxide

[joe603]

NO2 can be more volatile than boost...boost will not explode in your intake! Besides, I want an "always-on" power adder. NO2 would be perfect for the dragstrip though...

[krytiuk]

I dont understand how people are saying that a supercharger is less stress on the engine. With a charger or TT you are still puting boost into the motor. 7psi TT is the same as 7 psi charger. and the turbos will not rob any power, as they are run off the exhaust while the charger is run off the crank pully. The supercharger will take 20 hp for every 100 hp you add. The turbos dont take anything away.

I was also looking and trying to decide which way to go on my G35 coupe. I decided if I go with the kit, it will be better to go big or go home. So if im spending 7 k what is another 3K.

[joe603]

A turbo is harder on the engine because it makes full boost much earlier in the RPM band. Because it's more efficient than a supercharger, more torque/stress is applied to the engine drivetrain. So your in full boost for a longer duration than a supercharger typical is. Because the supercharger uses engine power to build boost, it's output is directly proportional to engine speed. The parasitic loss makes less total added power and thus easier on the engine/drivetrain when compared to a TWIN turbo.

Think of it this way. You have a 100HP shot of NO2. It's better to spray in the mid-to-high RPM band, instead of low. You wouldn't have it on from the line, you'd wait until after the 60' mark at least. (Of course this is all variable...depending on your application, budget, and bullet-proof~ness of your car.)

Because of the nature of a Turbo, an intercooler is required. The hot exhaust gas heats up the turbine and transfer's the heat through the shaft, and into your engine. A supercharger doesn't work that way, and you can get away without an intercooler. So the heat is another concern, as excess heat can cause detonation. A turbo acts like a giant plug in the exhaust, decreasing efficiency...so the argument of "free" power is deceiving; you lose some power from the exhaust flow (this is why a low-to-zero restriction exhaust is needed with turbo apps.)

In the end which system you get depends on what you want out of the car. The money factor is substantial. The additional 3k for the twin turbo is over 40% of the superchargers' 7k bill...which because it's a much easier install, can actually be 5k if you do it yourself. Now we're talking 50% of the cost. A twin turbo install is MUCH more involved, and should not be attempted unless you really know what your doing.

Hope this helps!

[Bobby23]

well said joe

[C-Kwik]

OK...here's the thing. A turbo doesn't like to have backpressure, so exhaust mods are a must. A supercharger needs some backpressure to be more efficient. The only mod you'll need to sell is the popcharger. You don't need test pipes with the turbo, but it will increase the efficiency of the system.

Actually, no motor likes to have backpressure. While observably, reducing backpressure too much on a NA motor will cause a loss of low-end power, it's not backressure (or a lack thereof) that accounts for this. It's a lack of scavenging.

Consider first off, that all matter has mass. Air, while light, still has mass. Therefore, air that is moving has momentum. Where this becomes relevant here is that small diameter exhaust pipes will move a given amount of aitflow at a certain speed. A larger diameter pipe will move the same airflow at a slower speed. In a smaller diameter set-up, the high speed air will have much more momentum. This column of air has a significant amount of momentum which causes a negative pressure area behind the exhaust valves of the motor as it's direction of travel (away from the motor) creates a relative vacuum. When the exhaust valve opens air is then sucked out of the cylinder. Or at the very least, impeded less by backpressure.

With large diameter pipes, the exhaust gas speed is slower and this scavenging effect becomes lessened. This becomes apparent first at low RPM's where airflow is low. AS RPM's rise, so does airflow and sufficient exhaust gas velocity can exist coupled with good flow, which is why many large pipe exhausts can open up good top end power sacrificing some low-end torque.

The catch here is that in order to get good exhaust velocity, the pipe size needs to remain reasonably small. The side effect is indeed increased backpressure.

[C-Kwik]

A turbo is harder on the engine because it makes full boost much earlier in the RPM band.

While peak cylinder pressures are certainly higher at respective RPM's that have more boost (ignoring compressor efficiencies), it is not necessarily anymore stressful to the motor than it would be at higher RPM's.

Because it's more efficient than a supercharger, more torque/stress is applied to the engine drivetrain. So your in full boost for a longer duration than a supercharger typical is.

A turbo or supercharger's efficiency is actually inversely proportionate to the stress on a motor given the same amount of mass air flow. To understand this, you need to consider what the efficiency is derived from and what it's effects are. They are universal to both types of chargers. I'll touch on compressor efficiency as it's the easiest to understand, most widely used and relevant to turbos and superchargers. Keep in mind that positive displacement superchargers in many cases provide boost even at idle.

First, compressor efficiency is simply a measure of how efficiently it compresses air. All gasses heat up when compressed (PV=nRT). But mechanical methods of compressing air are not 100% efficient and heat the air more than the theoretical amount that could be calculated. Compressor efficiency has a very direct connection to the aerodymanic efficiency within a compressor. That is, the more smoothly air can flow through the compressor, the less, the air gets unnecessarily heated. This varies with air flow through the compressor, the pressure increase and the speed of the compressor mechanism(compressor wheel, screws/lobes, etc).

The effects of increased efficiency is that for a given mass of air, it will consume less power and result in a cooler charge. Higher efficiencies consume less power because it is operating in a more aerodynamic range. This translates to less input torque needed (regardless of being a supercharger or turbo) to spin the compressor wheel of a turbo or centrifugal supercharger or screws or lobes of a positive displacement blower. Quite obviousely then, this means less power consumed from the crank of a supercharged motor. For a turbocharged motor, it means it can run at less backpressure to compress the same mass of air. The cooler charge translates into a denser charge of air. For a given mass of air, it translates to a need for less boost pressure and/or a smaller requirement for intercooler size. Both ease stress on a motor however, for a given mass of air. A cooler denser charge lowers the boost needed which can reduce the likelihood of detonation. Less backpressure or less power consumed by the crank translates directly to more power. So at a given power level, the higher efficiency compressor will be less taxing.

Because the supercharger uses engine power to build boost, it's output is directly proportional to engine speed. The parasitic loss makes less total added power and thus easier on the engine/drivetrain when compared to a TWIN turbo.

While the drivetrain might see less stress it is a result of less torque at the crank. Less torque there means less at the wheels. As a result, you get a slower car. But the stress induced on the motor is exactly the amount of power that is sapped by the supercharger.

Think of it this way. You have a 100HP shot of NO2. It's better to spray in the mid-to-high RPM band, instead of low. You wouldn't have it on from the line, you'd wait until after the 60' mark at least. (Of course this is all variable...depending on your application, budget, and bullet-proof~ness of your car.)

NO2 is a very different beast. While I don't think there is a big reason from a motor reliability standpoint not to squeeze at lower RPM's, conceivably, it would be hard to keep traction in line putting 100 more HP off the line than usual.

Because of the nature of a Turbo, an intercooler is required. The hot exhaust gas heats up the turbine and transfer's the heat through the shaft, and into your engine. A supercharger doesn't work that way, and you can get away without an intercooler. So the heat is another concern, as excess heat can cause detonation.

Turbos and superchargers both have the same requirements for intercooling. As I stated before, compressing the air is what drives the temperature up so much. High temperature air is less dense and more prone to detonation so there is no difference here. In fact, with the average turbo being more efficienct than the average supercharger, supercharging would likely need an intercooler more than a turbo.

Most supercharging applications that don't use intercooling run low boost so that the charge temperature isn't so high as to be a big issue. However, some more power could be realized with the use of some intercooling as a denser cooler mixture under the same pressure would have more oxygen.

A turbo's turbine runs quite hot, but is isolted well from the compressor. the shaft can transfer some heat, but it is minimal as the bearing section which is oil cooled and in come cases water cooled as well, will carry much of the heat away that would otherwise be transferred to the compressed air.

It should be noted that the upcoming ZR-1 Corvette will be intercooled. The intercooler is located on top of the compressor with the compressor flowing air up into it, through a core on either side and then back down into the motor. It's a liquid-to-air design. Stillen also has a liquid-to-air intercooler available for it's RWD VQ supercharger kits.

A turbo acts like a giant plug in the exhaust, decreasing efficiency...so the argument of "free" power is deceiving; you lose some power from the exhaust flow (this is why a low-to-zero restriction exhaust is needed with turbo apps.)

While a turbo is a restriction, it is not necessarily as bad as you might think. They can become huge restrictions to flow, but typically, when such a situation exists, it is because it is being operated outside it's ideal range and application. A properly sized turbo will put the most efficient areas of the compressor at or near the area you need the power to be on a motor. As I stated before, the high efficiency areas will yield the least power consumption for the amount of air and do so without heating the air as much.

A much less discussed topic is turbine efficiency. It's sort of a black art as there is not much info out there on this, but there are similar concepts to compressor efficiencies. Turbines have high efficiency ranges like compressors. When matched well to the motor and compressor, it will convert available energy more efficiently into compressor wheel torque. Turbines run primarily based on a pressure differential. The more efficient the compressor and turbine are running, the less pressure it will need in the turbo manifold. This means more air can be diverted via the wastegate reducing backpressure and increasing flow. The reason turbos favor large exhaust systems is because it generally helps increase the pressure differential across the turbine. Or more accurately, it allows one to run lower backpressure (by diverting air through the wastegate) to achieve the same pressure differential.

A good turbo set-up can achieve back pressure levels that are a fraction of the boost pressure. This is where you get a lot of the talk of the free power you get from a turbo system.

As for reliability, there is no difference for any motor in regards to the boost. The motr does not know where the boost comes from. A certain mass of air at a certain pressure at a certain temperature is the same to the motor regardless of the source. However, the biggest problem for a turbo comes in the fact that boost is controlled independently of the motor. A supercharger, is directly connected to the motor. So it's boost level is essentially controlled by the motor. By contrast, a turbo is generally controlled by a wastegate. A good wastegate handles it's task quite well, but if it fails or even the simple and relatively easy to break wastegate signal hose breaks or comes loose, it can easily go into an overboost situation. In most reasonable applications, a turbo can easily outflow the limits of a motor or it's fuel system.

Another potential problem for turbos is that the boost can be less predictable. Temperature and load are two factors that any turbo car owner can very easily see inconsistencies. Some turbo cars will see a couple extra psi in cold weather. And some will see quicker spool-up in higher gears as there is more load. These are not a make or break tye of thin as a good tuner can easily compensate, but it does add some more complexity to the tuning vs a supercharger, whose boost curve will always remain static in relation to ambient pressures.

In the end which system you get depends on what you want out of the car. The money factor is substantial. The additional 3k for the twin turbo is over 40% of the superchargers' 7k bill...which because it's a much easier install, can actually be 5k if you do it yourself. Now we're talking 50% of the cost. A twin turbo install is MUCH more involved, and should not be attempted unless you really know what your doing.

The only real difference between a turbo install and a supercharger install is that you are required to remove and install exhasut components. It is not necessarily more difficult in that of itself, but given the G35's engine configuration and lack of room around the exhaust manifolds, there is some inherent difficulty. But the actual mechanical difficulty is not much different.

Another potential option is the Turbonetics kit.It's a single turbo design and simpler to install (allegedly) and priced competetively to the supercharger kits. I saw the kit in person when they launched the G35 version and it appears to be of good quality. I haven't seen any negative results of using this kit yet.

[joe603]

After a header install on my late model V8 Firebird, I vowed to never mess with exhaust components again! To much to go wrong...and with Twins, you have double the potential for leaks. -no thanks.

A supercharger install is much easier and is one of the main benefits to the application. And trust me, any turbo system will add heat to the engine bay (except STS systems), that's why an intercooler is required. For a supercharger, you don't have to have one...but it will give you more HP.

[C-Kwik]

After a header install on my late model V8 Firebird, I vowed to never mess with exhaust components again! To much to go wrong...and with Twins, you have double the potential for leaks. -no thanks.

Surely, any turbo system that requires that the OE header to be removed introduces some possibility of an exhaust leak developing. As does an intake manifold replacement to install a positive displacement charger. But much of it actually boils down to choices of hardware and quality of parts. Some kits provide nuts and bolts that should never be used for the exhaust side of a turbo system. The OE manifold uses mechanical locknuts to prevent them from backing out. Many turbo kits provide regular nuts. Some provide spring washers, which will not hold for very long at all. Where bolts are required, some kits fail to provide any means of locking them into place. It's probably a matter of cost, and surely can be a headache for those who buy their kits and don't know what hardware should be used. I've seen some fairly poor gaskets provided for use with many kits as well. Having dealt with these very issues, provided the manifold is made decently, leaks are not going to be inherent of a turbo system, but a lack of properly engineering a kit and its components. Well conceived kits do not have these types of issues. Notice factory turbo systems don't inherently have exhaust leak problems. It's truly a matter of engineering the kit correctly.

A supercharger install is much easier and is one of the main benefits to the application. And trust me, any turbo system will add heat to the engine bay (except STS systems), that's why an intercooler is required. For a supercharger, you don't have to have one...but it will give you more HP.

Way wrong. Turbos do tend to heat up the engine compartment (if mounted in the engine compartment), but that's because the turbine is there to radiate up to some 1400F of heat. However, this is not the reason an intercooler is needed. The heat from the turbine is fairly well isolated in most set-ups from the compressor and the piping to and from the compressor. The heat generated during compression of air is what accounts for almost all of the heat in the intake of a turbo motor.

Consider P1 / T1 = P2 / T2

where P1 is the initial pressure and P2 the final pressure and T1 is initial Temperature and T2 is the final temperature. Lets say ambient air entering the turbo is 80 degrees F. Converted to Kelvin, it's about 300K. Lets assume we make 1 bar of boost (14.7 psi). At sea level, we already have 1 bar of pressure, so the boosted absolute pressure in the intake would be 2 bar. Solve the equation for T2 and you get:

T2 = (P2 x T1) / P1 = (2 Bar x 300K) / 1 Bar = 600K

600K - 273 = 327 degrees Celsius or 620.33 degrees Fahrenheit.

That's about 540 degrees F more than you started with just from compressing the air. Now keep in mind that this is an ideal increase in pressure. The reality is that there will be adiabatic inefficiencies occuring during compression. That is, if a compressor is operating at 75% efficiency, there will be 25% more heat created than necessary under theoretical calculations using the ideal gas law.

There is no way the air is heating up that much from convection or radiation. There is a lot or air being moved, and the dwell time of the air in the pipes is going to be quite small. Couple that with a boundary layer of air in the pipes that won't be moving and there is little heat transfer actually occuring. And while the car is moving, much of the air in the engine compartment is being cycled out. The air in the engine compartment while the car is moving will not be hot enough to cause a transfer of heat into the hot pipes. In fact, heat would likely make its way out of the hot pipes into the air in the engine compartment as heat always transfers from hot to cold.

Once you do the calculation, it becomes easy to see why an intercooler is necessary with any compressor that is running anything but mild boost. And arguably, most superchargers are not as efficient as turbochargers in application which may further compound the need. To make matters worse, most supercharger companies make a rather limited amount of compressor sizes. Turbo companies by comparison, tend to have a huge variety of compressors and turbines to choose from allowing one to match the compressor to the application much more ideally.

[MUNNNJEE]

what do you have? manual or auto?

it also all depends on what your looking for in terms of gains in HP or TQ?

what your going to use the FI for?

twin turbo or single turbo?

fact is turbo is going to cost more then a supercharger

both have their own risk but i wouldnt want to worry about my belt slipping on a supercharger...usually happens when ppl decide to go for a smaller pulley (generally something smaller then a 3.12)

turbo has more potential then supercharger