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What do you prefer, Turbo or Supercharger?

What do you prefer, turbo or supercharger?

19K views 75 replies 25 participants last post by  TravAZ 
#1 ·
I have a new 2017 SS base, which I am starting to customize. With all the kits out there now, I thought there would be more talk in this area here. I could not find any threads on this discussion so figured I'd start a poll and get your opinions on what you think is better.
 
#4 ·
I voted for SC, but bought a TC because that's all I could afford.
SCs have a very predictable relationship with rpm. Always same boost at same rpm.
Turbos lack this consistent relationship.
Any forced induction system can result in engine problems, but most people feel the SCs are less likely to do so.
Instrumentation (boost gauge and preferably AFR gauge) are needed for TC systems to track how the system is doing. Since the SCs are consistent with how much boost they produce at any given rpm, gauges are not as necessary. Some folks may not agree with this last statement, but I believe it is the consensus of most SC vendors.
 
#5 ·
Great info! So SCs don't need as much babysitting. I was reading that SCs produced boost at higher RPM and turbo at lower. But you say they are consistent.

Only thing I wasn't crazy about SC's were the sound, they sounded more high pitched and ramped up with RPM and sound clips seemed annoying to me. I liked clips of turbo sounds much better.
 
#6 · (Edited)
I guess I need to clarify my statements.

SCs will indeed produce more boost at higher rpms than at lower rpms as the SC is directly linked to engine rpm by the belt(s) powering the SC. The direct relationship between rpm and boost means the SC produces a more consistent boost. This means, all other things being equal, a SC setup for the Slingshot should always produce the same outputs under the same conditions in every Slingshot the system is installed in. Because of this consistency, gauges are not considered as important for SC operation. It's probably still a good idea to at least monitor AFR, if not also boost pressure.

Turbos can produce more boost at lower rpm, but this can be a problem on the Slingshot, since the Slingshot can already spin the rear tire w/o any forced induction. Since turbos are driven by exhaust gases it is possible for them to produce varying levels of boost under the same conditions. This isn't usually a problem, but can be under certain conditions. Since boost can vary somewhat, most turbo owners run boost and AFR gauges.

Some gauges are built to monitor both and even provide feedback to shutdown boost if your system is setup for that, but do not seem to work well with existing TCs, SCs and ECU reflashes. Reportedly, some boosted owners are trying to get the issues sorted out. I bought an Innovate SCG-1 for my Hahn turbo system, but will probably only use it to monitor boost pressure and Air-Fuel ratio until someone hopefully figures things out. AEM also makes a unit that can control boost, IIRC.

Some people like turbos and others prefer SCs. Some for consistency of boost. Some for the sound.

I hope this clarifies what I tried to state above.
 
#7 ·
A supercharger is a belt-driven centrifugal compressor. At low speed the compressor is turning "quite fast" because of the belt running off the engine, and it creates boost. As the engine spins faster the belt turns the compressor faster and more airflow is created, continuing to add power to the engine. This relationship continues until at some point the compressor fan loses efficiency and spinning it "faster" creates "a little more boost," and the supercharger suffers "boost falloff." Think of a little battery-powered hand fan with a 3" blade--it cools your face, and the faster the fan blades spin the more it cools you off--up to a certain point--past that point you can spin the blades as fast as you want and they won't do anything noticeable (beyond cooling your face). You can upgrade to a box fan to cool your whole body, but the bigger fan is going to move more air at lower speeds and cool more than just your face, so there are tradeoffs, including using more energy at low speeds (called "parasitic drain" of the supercharger).

Turbochargers are superchargers, but instead of being driven by a pulley and belt off the engine, the pulley is replaced with a radial-inflow exhaust gas driven turbine (turbo). It's really a turbine driven supercharger, or turbo-supercharger, or just turbocharger. Low exhaust gas speeds don't spin the exhaust-driven fan very fast, so the compressor fan which is on the same shaft also doesn't spin very fast, and doesn't do any compressing. Now you floor it and dump all this exhaust gas into the exhaust fan and start to spin it up, which also spins up the compressor fan and starts to create boost, and that process repeats and repeats and you're waiting on it...this is "turbo lag." Turbochargers don't have power at low RPM (not true any more, but hold that thought for now). However, at higher RPM there's plenty of exhaust gas to spin the exhaust turbine, so there's no lack of compression from the compressor fan at high RPM--meaning turbos don't produce power at low RPM and produce lots of power at high RPM.

From the factory, the Slingshot has "too much" power at low speed, and not enough at high speed (where wind drag slows it down). A turbocharger is the perfect fit, power where you want it. About that lag: Modern turbos are much lighter than the older turbos, so they don't have lots of mass, meaning the lightweight fans spin up quickly. Also, If the turbo is sized correctly, the exhaust gasses at low RPM can be used to spin up the exhaust fan "early" and create boost at low RPM, eliminating lag--the down side is you can floor it at low RPM and create more boost than the engine can handle, blowing it up.

In summary, the turbocharger is perfect for the Slingshot, except you have to be careful not to blow your engine up at low RPM, and since the exhaust and therefore compressor fan doesn't match engine speed a bunch of stuff is needed to get rid of extra boost created in certain situations so your engine doesn't blow up (it's a common theme).

To make things a little more fun, the supercharger guys didn't sit around idle, they worked on compressor fan design, belt ratios, flow characteristics, and got less boost at low RPM and more boost at high RPM, without blowing up engines! Win to the SC guys! Mostly. They still have "boost falloff" up top, but it's not much. For the normal person, the supercharger is the way to go--easy to install, maintain, and won't blow up your engine. For the "I must have all the power I can wring out of this engine at all costs" group, there's still the turbocharger, and all its complexity, which will wring the power out of the top end without remorse. (And blow your engine up if you want--there's that too.)

I have a turbocharger, it's incredible fun, and makes way too much power if you want. It also failed and is under repair. (Things happen.) Squirrel loves the power, but for her we'll eventually put in a supercharger, they give almost as much fun but without all the risk, and they're much easier to maintain with no gauges to keep an eye on, just have fun!
 
#8 ·
Thanks so much for the information both of you, very helpful and informative. I think I now have a good understanding of how each of the systems work.

I like the idea better of less risk to engine of the SC. I don't spend all the money on a fun toy for it to break, just to spend more...by the off chance I missed monitoring some gauges. At the same breath, if the turbos have been tooled that minimize risk for this engine, that sounds like the way to go for most performance bang for my buck. I wouldn't mind some gauges that started yelling at me if I pushed it too hard, to get my attention back to them though. lol
 
#9 ·
You have to understand how they differ to understand why you might feel one is better than the other for your needs.

A supercharger runs off the motor so it is parasitic drag. You are using horsepower to make horsepower.

A turbocharger runs off the exhaust so it's free horsepower.

That right there is why I am such a proponent of turbos. Nothing beats free power.

With a smaller turbo like the Alpha Precision turbo, turbo lag is almost non-existent. The bigger the turbo, the greater the lag on building boost.

Obviously my turbo bias is apparent by the above but it depends on what you want. A supercharger is unquestionably easier to install if you are not mechanically inclined. Here in Colorado turbo's rule because of our thin air - at 13K feet in the mountains you don't want anything adding drag on your motor. You'd be amazed at how much the thin air taxes a motor.

The bottom line is neither is safer for a stock motor if you over-boost (either by changing pulleys on the SC or increasing the spring rate on a TC).

Take into account what you can afford and how your mechanical skills are and go from there. A good, complete turbo outfit like the Alpha includes everything including the intercooler. It also has the CAI put in the optimal area for cold air flow. Some of the lesser kits do not include an intercooler and the air intake sits right off the turbo. Nice and hot air there (something I do not like about the Hahn).
 
#10 ·
Without getting into the technical side of the issue, since that is not my area of expertise, I thought I would provide my observation of the economic and mass production side. Last year I bought a new car, a 2017 Ford Mustang. It has a smaller engine than my Slingshot - 2.3 liters.
It is turbocharged from the factory and provides 310 hp, using premium gas. For what it is worth, Ford engineers decided that this was the way to go for their small engine to get lots of power and still provide some fuel economy.
I find that the car goes pretty good with the 6 speed automatic transmission and can keep up with most others on the road. Passing is no problem and one time, I saw 100 mph on the speedometer with it not feeling that fast and not trying.
Why did they choose to use a turbo instead of a SC? Who knows, except those at Ford, but they made a good choice for a mass produced vehicle that would surprise many that have been passed if they knew they have been passed by a 4 banger.
 
#11 ·
....Without getting into the technical side of the issue, since that is not my area of expertise, I thought I would provide my observation of the economic and mass production side. Last year I bought a new car, a 2017 Ford Mustang. It has a smaller engine than my Slingshot - 2.3 liters.
It is turbocharged from the factory and provides 310 hp, using premium gas....
My GF has a 2015 Ford Edge Sport with the 2.7L twin turbo Eco-Boost V-6 and I can tell you that thing flat shits and gets. 315 HP and 350 lbs ft torque. I have smoked more than one wanna boy racer/ricer and love to see the shame in their eyes when they realize they got smoked by an all wheel drive small SUV type vehicle. It's funny.
 
#12 ·
Superchargers are for those people that dip their chicken nuggets in lame sauce. ;)

A turbo may be more work, but the power potential and sounds are worth it!
 
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#14 ·
Superchargers are for those people that dip their chicken nuggets in lame sauce. ;)
Wow Trav, tell us what you think! o_O

@Nozzledog brings up a really good point, let me add that engines tend to do a somewhat "fixed amount of work" over their lifetime--go easy on them and they last a long time, or give 'em hell and burn up all that power quickly, up to you. A supercharger runs more fuel/air into the same engine all the time, meaning higher compression all the time, meaning more power all the time, meaning it will break sooner. Same with a turbofan driven supercharger (turbocharger)-Alpha is into boost just off RPM-no lag and insane power everywhere has a price.
 
#13 ·
A supercharger is like putting a larger engine into your vehicle and running the a/c all the time (power drain). You could almost think of a 2.4L SC with 7lb boost is just like having a 3.6L engine... ALL THE TIME (including the gas mileage of a 3.6L).
A turbo will act more like a small engine at low rpms and a big engine at higher rpms.
It's power is not completely free. The turbo a little power robbing back pressure and exhaust heat buildup, which some may find annoying.
You will find car manufactured tend toward turbos because they can advertise the MPGs of a small engine and the HP of a big one. They forget to tell you that if you drive it for the HP, you get just as bad gas mileage.
 
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#15 ·
I personally went for the Turbo for 2 big factors...cost and drivability...The SS already has traction issues, with the minimal turbo lag, you actually get a decent take off with out having to feather the acceleration. I have driven one with the DDM supercharger and yes, the power is awesome right from the get go, but if it weren't got a 305 rear tire, it would just spin the rear forever. I also feel like the turbo seems to pull harder on the top end of all the gears vs the SC.
 
#20 ·
I went with the Supercharger due to its simplicity and, as the video explains, I need the power at the top.
 
#21 ·
That is a good video for helping people understand some of the differences. A couple things to note that may or not make a difference to most people...

They sound very different and superchargers are in most cases much louder. They make more sound/noise at idle at the blower and usually the exhaust sound is also louder. This is because in a turbo system, the turbo acts as another small muffler on the exhaust side.


When driving conservatively, gas milage will most likely be better on a turbo setup. A supercharger is always taking energy from the motor to spin.

The power delivery is different as noted. The most noticeable differences is full throttle pulls starting around 3000 rpms. A turbo builds boost very quickly down low so roll on power feels much more impressive. A supercharger needs belt speed to produce boost, so be prepared to be downshifting to get into higher RPMs to build boost.

Both are great! I've installed and driven both and wouldn't own anything but a turbo kit. I'd rather install a SC kit, but you just can't beat the performance and sound of a turbo kit.
 
#22 ·
My experience has been apples to oranges but I have driven both. I have driven a factory supercharger setup and factory turbo setup and the supercharger was much more responsive overall. However, the supercharger was on a gaser and the turbos have been on Superduty trucks so as I said, apples to oranges.

From those on the forum with the superchargers they report great things about them so I am looking forward to when mine arrives. I spent a lot of time speaking with the suppliers and DDM seemed to be the best fit for me. As far as parasitic loss, well I drive mine for pleasure so it is a waste of fuel any time I drive it.
 
#23 ·
A supercharger will have better immediate response when you are at higher RPMs where it can make a good amount of "instant" boost. There is a big difference in immediate response at 4000 RPMs and 6000 RPMs on a supercharged Slingshot.

A turbo is feels much more responsive at lower RPMs. This is especially noticeable when driving through twisty roads and/or at track days when you are in 3rd / 4th and don't want to down shift. On a few tracks I run, if I ran a SC, I would need to do a lot more shifting from 3rd to 2nd to stay in higher boost and the power band. On a turbo it will build considerable boost even at lower RPMs, so there isn't really a need to keep on going back down into 2nd and then up to 3rd.

Points like above are why I tell everyone to try to meet up with locals to look at and ride in their boosted machine before making a purchase.
 
#24 ·
Using the gears when I am running the twisties is part of the fun! lol.
 
#26 ·
My guess is that they don't install gauges to monitor how they are running. They aren't required but always a good thing to know if you are running rich or lean. I also think that since it's so easy to change boost levels, that some people make changes with out having the supporting mods to go with it.
 
#27 ·
From what I have read and been told, supercharges have less to get out of wack than a turbo charger. When I purchased my Supercharger from DDM I asked if I should get gauges too and I was no, not needed with a supercharger.
 
#28 ·
The biggest reason is because there are A LOT more turbo chargers running around out in the wild. Many of these were self installed and some had install issues. Some early kits weren't tested out completely and blew motors for other more technical reasons that have been fixed.

Also, some people like myself (blown motor club) avoided all advice and ran more boost than recommended. My motor broke a chunk off of #1 piston at over 12psi in 4th gear.

A supercharger is safer in some regards. Fixed boost, no wastegate, and it won't let you "lug" the motor.

If your primary goal is safety and ease of install, pick a SC. If you want a lower price, more customization, and better sounds, pick a TC.

The biggest mistake is waiting forever to make a decision. Either one totally changes the fun factor of the machine. :)
 
#29 ·
Here's what I get from everything I'm learning. A turbo relies on exhaust volume to rev up and create boost. The issue is that, at a given rpm, the exhaust volume changes base on the load the engine is under causing an equal change in intake boost, whereas a supercharger is only affected by rpms and load doesn't matter. The intake air is a more of a constant with a SC and easier for an ECU to manage. A TC needs many more components to manage that flux of exhaust/boost volume. The more components and variables, the less stability and reliability.
The question is if the added stability/reliability of the SC evens out the added constant load that the blower puts on the engine.
It is evident that a TC produces a better net to gross power ratio than a SC, meaning the engine does not have to work as hard for the same useable power, but requires a lot more monitoring and complexity to do so.
 
#38 · (Edited)
Here's what I get from everything I'm learning. A turbo relies on exhaust volume to rev up and create boost. The issue is that, at a given rpm, the exhaust volume changes base on the load the engine is under causing an equal change in intake boost, whereas a supercharger is only affected by rpms and load doesn't matter. The intake air is a more of a constant with a SC and easier for an ECU to manage. A TC needs many more components to manage that flux of exhaust/boost volume. The more components and variables, the less stability and reliability.
The question is if the added stability/reliability of the SC evens out the added constant load that the blower puts on the engine.
It is evident that a TC produces a better net to gross power ratio than a SC, meaning the engine does not have to work as hard for the same useable power, but requires a lot more monitoring and complexity to do so.
There have been a lot of reasons that the turbo guys have blown a lot of engines. Some of the early kits out had some design issues that caused boost creep and caused engine failures. From what we have seen here and also heard from talking to people that have blown their engines with turbo kits, there are still some problems out there that most likely will continue to cause failures of engines on turbo kits being sold. Like @Nozzledog mentions above the turbo is relying on the exhaust gas energy to spool and then uses that power from the exhaust to compress the air going into the engine. The problem we are seeing in a lot of the failures, is these engines stock are not created for boost and have a relatively high compression ratio (10.4:1) and the pistons are not designed for boost, the upper ringlands in particular. Since the turbo acts like an exhaust restriction (turbine blade is in the path of the exhaust), the exhaust heat and pressure backs up into the cylinder head and the turbo kits cause the engine to be much hotter than a naturally aspirated or supercharged engine. If a person does short spurts with the turbos, or at 5-6psi this extra heat does not create too much of an issue. However, if you raise the boost pressure in the intake manifold, you also raise the pressure on the exhaust side of the engine on these turbo kits. This higher pressure and temperature causes more heat to back up into the engine. This heat will start to soak into the pistons and get down to the upper compression ring. As the heat gets into the upper ring, the upper ring starts to expand and eventually if there is enough heat put into the system, the ends of the ring touch. Once the ends of the ring touch it can expand no further in that direction, so it starts to put stress onto the upper ringland on the piston and eventually it puts enough force to pop a piece of the piston off. Once the piece pops off, it rattles around in the cylinder and destroys the rest of the pistons and cylinder. That has been by far the most common failure we are seeing with the turbo kits that we know of that have blown an engine. Typically it is also cylinder #2 or #3 about 75% of the time and cylinder #1 or #4 the other 25% of the time.

The fueling of the engine is another issue that we are seeing, although not because of the more variable flow rates of the turbo based on throttle position. It is true that a supercharger is more linear than a turbo in the air flow rates, but the tune mainly uses RPM and MAP pressure to determine fueling and reacts plenty fast enough for changes in airflow. Also, with a supercharger those changes in airflow happen actually much faster than a turbo kit because of the much quicker response with the supercharger. Something related to fueling that we have just started to see and test for now is the fuel injector flow rates on the injectors that are shipping with some of these kits. @TravAZ was one of the first ones that brought this to our attention. As far as I know right now, we are the only company shipping out forced induction kits with flow matched injectors that are within 1% flow rate. If we have a customer with a turbo kit call us up for help, either with a machine that is not running right or has blown up an engine, we also recommend that they flow test their injectors now. We are seeing a pretty good amount of variance with some of these sets ranging from just a couple percent off to over 20% off in flow.

The supercharger kits though do require power to be taken from the engine crank in order to drive them. The power required though is not much most of the time while cruising. There are 2 reasons actually that we have a blow off valve on our supercharger kit. The first reason is that when you let off the gas while under boost, that pressure does have to go somewhere and the blow off valve allows that pressure to release. The other reason, is that while at idle and cruise, the blow off valve is open and prevents pressure from building. This means that basically the supercharger is moving air, but no compressing it. There is power required to move the air, but since the pressure delta between supercharger inlet and outlet is basically the same, not much work is being done and the power requirements are relatively low. I do not have power figures on Rotrex supercharger that we use on this kit, but the larger heavier Magnusson supercharger we use on the Solstice used less than 1hp cruising down the road with the bypass open. The Rotrex should be just a little higher than that because it is constantly also pumping oil to lubricate and cool itself, but should still be far off from a 20-30hp drag on the engine all of the time. Also, remember that an engine is basically an air pump and with the supercharger or naturally aspirated you have a relatively low exhaust pressure, but with the 2 turbo kits that are common at this point on the Slingshot, you have a very high exhaust pressure between the turbo and the engine. That means that the air pump is not as effecient and the volumetric efficiency of the air pump is decreased. This decrease in volumetric efficiency with turbo's though is also one of the reasons that OEM's like turbos, they provide great EGR (exhaust gas recirculation). With higher EGR under cruise conditions, the exhaust gas takes up the place of fresh air coming into the engine, which means you do not have to put as much fuel in, and increases fuel economy. The bad side of that is the pressure and heat build under full throttle and can cause the failures that I listed above and the reason that OEM's use much different pistons in the engine than what is found in the LE9 in the Slingshot.

Hope that helps,
Dave
 
#31 ·
Having had both a turbo and now supercharger I have to say a SC is way more fun. To keep it simple they just spool up differently. If you like blastin down the road with your hair on fire as fast as you can go - get a turbo. If you like that immediate power and are running the twisties- go with a SC. IMHO!!
 
#33 ·
Didn't a Turbo win the hill climb at SSITR? I honestly can't remember cause I didn't go to the event. I think the SC was second? I might have them flipped around. If the turbo won the Hill Climb...I'd say the Turbo does just fine in twisties ;)
 
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#35 ·
A lot of us higher elevation folks prefer the Turbo over the SC just for that reason.
 
#39 · (Edited)
Good information. I agree that the piston are the weak point and ring gap variances from motor to motor are why some people survive at certain boost levels and others don't.

Alpha is now sending out flow matched injectors. Not sure if Hahn is. From all the testing, the biggest issue was at very low pulse width idle variances. At 50% throttle and 100% throttle variances tended to be very small. If your machine is running weird or showing odd AFRs, its not a bad thing to flow test.

These are different systems that behave differently. Try to meet up with some owners to see what your prefer. The best advice is to choose one of the main vendors that you like and trust. If your not comfortable with install, have that shop assist or a knowledgeable forum member.

A big issue with this thread is people like myself are trying to help people compare TC to SC, but a lot of the kits are different. For example - someone with a Hahn kit at 8psi isn't going to have the same opinion as someone with an Alpha kit at 12psi. Same goes for someone with a KMS at 6 psi to a JonVi at 10psi.
 
#40 ·
I definitely need to check my injectors. I don't think they are running as good as they should be. I am also only running the 6lb set up from Hahn and have some sputtering on the top of 3rd gear. But I don't really get on it a lot. I cruise around, unless I get trapped in to running faster than I should be. lol
 
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