Superchargers vs. Turbos, again, part 2

  • The old debate of superchargers vs. turbochargers has once again showed up, and unfortunately information was posted in another vendor section and we do not post in other vendors sections. So we figured it would be best to just get a common thread going on in a public place again, where anyone can post up what they feel.

    There is this comparison that was written awhile ago between turbos and superchargers - Dave @ DDM Works Supercharger and Turbo Info

    Even with that being said, some people seem to still think that one form of supercharging (yes a turbo is a form of supercharger) is better than another for everyone, this is simply not the case. The term "better" is a relative term and that being said, will mean different things to different people. All forms of supercharging have their pros and cons, anyone that will tell you otherwise is either highly misinformed or purposely misleading others.

    Here are some quotes from another thread -

    Quote -

    Turbocharging's extensively more adaptable and adjustable range of power levels offers the enthusiast many options, from upgrading to higher power levels later, to using the infinitely variable nature of turbocharging's boost levels to adapt power flow on the fly. With turbocharging, we can build a complete curve of power levels available on the same vehicle, whereas supercharging is limited to one fixed, pre-set power level which requires mechanical changes to alter.

    In a turbocharged machine, we can not only enjoy multiple boost/power levels at the flick of a dash switch, we can also automate them to automatically reduce power at lower speeds so as to enhance traction in the quite traction-limited environment of the Slingshot. We can therefore completely manage power to suit available traciton, whcih improves with vehicle speed. Our history of world records and championships in such disciplines has empowered us greatly to authoritatively manage this aspect on Slingshot. Supercharging offers no such capability.

    Further to the versatility of tubocharging, the Precision turbo we use is effective all the way out to 520 engine HP. Should one ever need to exceed that, numerous other Precision models exist that will bolt-in and go."

    Once of the cool things you can do with turbochargers is offer adjustable boost levels with the addition of a electronic boost controller. We have yet to see anyone really make use of this on the Slingshot effectively. In fact with a good electronic boost controller, we have setup different turbocharged engines to have 3 different boost levels that are instantly switchable, which is a neat option. The reason this can be done is that the air flow of the turbocharger is not directly linked to engine RPM, so therefore you can adjust boost levels by controlling the wastegate and create a setup like that. The belt driven supercharger is just hooked directly to the engine and boost is linked directly to engine RPM, so with a belt driven supercharger, you simply adjust the boost level on the fly with your accelerator pedal. As to which way is more "versatile" would depend on the driver and what they like.

    A gear depended boost controller is also a neat option and In the past, maybe having gear dependent boost settings could have been an advantage, but the Slingshot is not an old vehicle and like most modern cars has a very good traction control system. The traction control monitors rear tire slip and adjusts the throttle to maximize acceleration. With a turbocharger, anytime the factory traction control engages, it closes the throttle blades, which then slows the turbo charger and when the traction control dis-engages, the throttle opens back up and the turbocharger has to spool back up. This can create an issue in getting the turbocharger to maximize acceleration in the Slingshot with the factory traction control. The belt driven supercharger simply reacts just like a larger engine and the traction control on the Slingshot handles it much easier.

    Big turbos can make a ton of power, but having a turbo that is capable of making 520HP at the engine really does not mean the system can make that much or that it is really the best setup for a particular need. You could bolt on a turbocharger capable of 2000HP onto your engine, but to think there would be no compromises doing that would be foolish. Every choice has compromises that you make and going with a larger turbo than the power you are planning to use has compromises also. If your plan is to make 350HP at the engine, using a compressor that is capable of 520HP means the compressor is larger in diameter than needed, which means it weighs more, is more mass to accelerate, which increases the time it takes for the turbo to respond. Also, if you have that same turbo on a restrictive turbine A/R (like the Alpha kit did), you will never be able to achieve that peak flow of the 520HP by the compressor because the exhaust will not be able to flow that much air out of the engine. Other parts in the system like the intercooler, exhaust manifold and exhaust will also affect the peak potential power of the system, the 520HP compressor is just a small part in that system. We looked and could not find the actual compressor map for the precision turbo being used in these kits, the air flow of 520HP by the compressor is typically going to be at a very specific boost pressure and compressor speed range. It would be interesting to see that compressor map to see if the flow rate of 520HP is even in an area that is even achievable on the 2.4L and what the compressor efficiency is in that range.

  • The next quote -

    As opposed to a supercharger, which draws power from the crankshaft to drive the supercharger unit, turbocharging instead recovers otherwise-wasted exhaust heat energy. This is another reason it is preferred by today's OEM engineers, as it enables them to extract more from a gallon of gas. To this end, in order for a supercharger system to match a turbocharger's output, if both make the same power at the crank or wheels, the supercharged engine will actually be forced to create an additional 30HP just to drive the supercharger. Since that additional power required is consumed by the supercharger drive, it doesn't get to the wheels, but it is nonetheless still experienced by the engine.

    Today's racing scene is absolutely dominated by turbochargers, for all of the above reasons. In order for superchargers to remain competitive in classes where turbochargers are allowed, numerous concessions must be made by the turbocharged machines, specific limitations incurred so they don't just run away with it and obsoletize the superchargers overnight."

    There is no free power. In a normally aspirated or belt driven supercharged engine the "wasted exhaust heat energy" is used to help with cylinder scavenging, increasing the volumetric efficiency of the engine. A turbo charger uses this "wasted exhaust heat energy" differently, instead of allowing this heat to flow freely from the engine, the turbocharger introduces a restrictive turbine wheel into the exhaust flow. This restrictive turbine wheel backs up heat and pressure into the engine. When this heat and pressure builds, it spins the turbine and since the compressor is linked to the turbine by a shaft, the compressor creates "boost". The problem with this exhaust restriction all turbo's create is that heat and pressure used to power the turbo, is also the same reason for most of the failures we have seen on the Ecotecs by turbo kits so far. That heat and pressure on the Ecotec's relatively high compression engine (10.4:1) and pistons not designed for boosted applications is what is causing most of the engine failures we have seen. The heat builds up on the pistons, causing the upper rings to eventually touch and pop the top of the piston off and destroys that cylinder. A belt driven supercharger does not have this same heat and pressure problem, it has a wide open exhaust that allows the same heat and pressure to flow easily out of the exhaust system and not backup into the engine. A good thing about that same exhaust restriction by the turbo though is the reason that a turbocharged engine is quieter than a supercharged one. The turbocharger restriction acts similar to a muffler because of the restricion to flow it causes, the supercharger being wide open is louder because it allows all of the heat and sound to flow easily out of the engine. So for those that want a really quiet system, the turbo can usually be quieter.

    This restriction in the exhaust is actually the reason that OEM's are turning to turbochargers. Several years ago, OEM car manufacturers figured out that returning some of the exhaust into the engine helped with emissions. The system was called EGR or exhaust gas re-circulation. The rough idea is that instead of a 2.4L engine ingesting 2.4L of air every 2 revolutions, if you return some of the exhaust gas into the cylinders, that amount of fresh air ingested by the engine can be reduced, which means you have to put less fuel in, which increases MPG. When EGR was first introduced, there were complicated valves and pipes needed to make the EGR system work. The 2nd generation Ecotec's were able to do some EGR with the VVT system, but OEM car manufactures figured out that not only could the turbo charger allow a smaller engine to be used for the same power as a naturally aspirated engine, but the turbocharger creates a very good EGR affect naturally because of the exhaust restriction it causes. The superchargers do not naturally create this EGR affect because of the reasons stated earlier.

    I have no idea where this "30Hp" number is coming from for the power required to power the belt driven supercharer. A supercharger power need is based on how much work it is doing to compress the air and the efficiency of the supercharger to compress that air. Things like engine RPM, pressure ratio and belt ratio are minimums needed to remotely know the calculated power needed to drive the supercharger. A reference for this "30hp" number would be needed or how it is being calculated for further discussion here.

    Going back to the turbocharger, its inherent exhaust restriction will decrease the natural volumetric efficiency of the engine, which is why a turbo charger that is correctly sized and a supercharger that is correctly sized for the same power application will make very similar power at the wheels at similar pressure ratios. The turbocharger decreases the volumetric efficiency of the engine, but uses that exhaust restriction to power the compressor; the supercharger flows the exhaust out easier making the volumetric efficiency better than the turbo, but has to use that extra power to run the compressor, once again there is no perfect solution here.

    Really, we have no idea with racing what the rules are for superchargers vs. turbos, we honestly do not make our kits for just drag racing or any particular set of rules. The turbo is probably better suited for those that want what we call "lazy" power, just cruising along and want to pass, push the gas and there you go. The supercharger kit we feel is much more engaging to drive and we don't really care if OEM's are using turbochargers right now or if they switch to superchargers in the future. We simply make our supercharger kits for people that want that instant rush that only the belt driven supercharger provides. People that like to run in the twisty roads, people that want the experience that only a belt driven supercharger provides and can not be matched by a turbo, ever. Not to say we will never make a turbo kit, but as those that have our belt driven supercharger kit know, the feeling of the supercharger is something no turbo kit can ever match.

    Lastly, there was this dyno graph posted -

    There will have to be another thread sometime that talks about dyno's and how horsepower is calculated. There is a VERY obvious error on this graph that was made by the person who made it, whoever figures it out first, we will send something nice to. If no one figures it out in a couple days, I will post up the answer.

  • Lastly, there was this dyno graph posted -

    There will have to be another thread sometime that talks about dyno's and how horsepower is calculated. There is a VERY obvious error on this graph that was made by the person who made it, whoever figures it out first, we will send something nice to. If no one figures it out in a couple days, I will post up the answer.


    The error ......... its invisible ..... wadda I win ............ tongue-squared


    :REDSS: The ghost of SLingshot past ......

  • The overlays of the chart were manipulated. There is no way the torque and HP for the SC would continue at a plateau through 6500 RPM with the 110 mil pulley without them dropping off at the rev limiter. It seems as the SC chart is slid the right a couple hundred RPM because the onset of torque is steep with a SC which has been removed from the graph while the turbo seems to pulling power from a low RPM when there would not be enough exhaust flow to provide the power shown on the graph at that low of an RPM.
    Just a wild guest.

  • Wow... I just woke up from my nap and see the boost debate has heated up.

    I am going to just be the guy that kisses everyone's ass here... :-)

    The only reason I am even replying in this thread is because I'm asked quite often why I run a turbo. And the other question I get is.... Would I ever go to a supercharger....
    I think I can accomplish answering that by just describing my experience.

    I run a turbo because I like the "rush" of power it provides. It's like having an extra engine that just kicks on and pushes you...Because I have switched over to a user programble ECU I can actually dial my boost levels reliably. And I have a real failsafe style boost controller that will drop me down to the spring pressure (i have mine at 4psi) if it detects a lean condition. So i really dont have worry at all when i am holding the gas pedal on the floor and listening to the rev limmiter cut out. To me it is an absolutely blast to drive a turbo slingshot....With all that said.. it does has it's downsides. One way to describe it is that it's like petting an old pissed off tom cat. He will let you pet hm for a while. Then when you least expect it he will attack you and claw the shit out of you. That being said, You can definitely tune this explosive feeling out of a turbo but in my opinion it defeats having the turbo in the first place.

    Now I have driven nearly every variation of supercharged slingshot. And they all do one thing really really well. They all deliver consistent repeatable power at pretty much every rpm level. They are like having a farm tractor with the throttle lever with the rabbit and turtle on it. You know exactly what your going to get when you push that lever toward the rabbit. It's going to push you back in the seat at a consistent rate. And that can make the delivery of power deceiving. The power is so consistent that you don't notice the supercharger actually adding power.. Where I said the turbo is like adding a second engine with a flip of a switch, the supercharger is just like having one big engine just pulling you.

    One other question I do get sometimes.... What is more dangerous? Lets just skip the engine and tuning aspect.... So dangerous in this answer is going to be from a human health point of view. A supercharger is just as dangerous as a turbo in the wrong hands. However it seems to me that the supercharged engines have a much easier learning curve to keep them out of the ditch. As a turbo owner I can tell everyone that the more boost you allow the turbo to make the more your going to constantly be thinking about the turbo spooling up and breaking your tire loose. Sure....once you drive it for a few thousand miles you will learn what rpm ranges and engine loads will create what rate of spool up. So you can get good at being ready for the boost to kick in. But there is alway that tiny bit of unknown... I like that,...

    I'll leave the "Which one is best for the way I drive" or "What is easier on the drivetrain" or "Which one will not blow my engine up" to the vendors here... I absolutely love to see all the post from the vendors. This tells me they all care about making a great product that does what they say it will do. And the fact that they are posting here on this forum let's you all know your at the best place for information....

    See what I did there. Information....INFO... SLINGSHOTINFO.COM

  • @rabtech
    I would like to say you have built one hell of a beast that is the most powerful slingshot.
    With that said I think there needs to be one important question answered for those who would like to get boosted.
    Of the two systems, pound for pound, HP for HP, Torque for Torque......Which one, the Turbo or SC is the better bang for the buck?
    For me I would let those know what I have spent to achieve a reliable 320 ish HP on a un-forged motor if they PM me.
    It is not questionable that your white beast is awesome, but it might be good information for someone starting out to understand what it would take to produce 330 to 400 reliable HP.

  • @Slingrazor

    I think we have great base units in both SC and Turbo that will give someone looking for boost manageable, reliable and affordable systems.
    But then you have some of us who just can't get enough and want to keep pushing the envelope. Some of us will be successful and some of us will learn valuable lessons.
    For me it is all part of the excitement of owning a slingshot.

    The more people I meet

    The more I love my Dog!

  • @Slingrazor

    I think we have great base units in both SC and Turbo that will give someone looking for boost manageable, reliable and affordable systems.
    But then you have some of us who just can't get enough and want to keep pushing the envelope. Some of us will be successful and some of us will learn valuable lessons.
    For me it is all part of the excitement of owning a slingshot.

    You know that I have "tested the reliability of the DDM SC" and would never trade it.

  • Torque is what is measured by a dyno. Horsepower is calculated from that. Because of the constant used in the calculation's formula, both values will cross on the graph at 5,252 RPM. This can be manipulated by the dyno operator to make their tune appear to be better than it is.

    This graph appears to have two different runs using different metrics displayed together. It is definitely comparing apples to oranges. The DDM plot is shifted to the right to begin at around 2,500 RPM. This also pushes its display well past the rev limiter. Taking this into consideration, its curves would have originally crossed around 4,500 RPM. The graph shows the Hahn plot's curves crossing around 5,350 RPM. Both runs were charted using unconventional methods. If they were replotted using the conventional settings the displayed outcomes would be completely different. The Hahn would compress slightly while the DDM would expand noticeably.

  • You know that I have "tested the reliability of the DDM SC" and would never trade it.

    Yes sir. I wouldn't question that at all.

    Just sayin that some of us push the envelope for no other reason than we can!
    A lot of what we have done is not necessary.

    The more people I meet

    The more I love my Dog!

  • One last thing....

    And this is what I am asked the most often.... I actually forgot this question...

    How do you use 500hp? Well I don't. At least I don't all at one time. If you have been keeping up with my actually last dyno charts you will know I am set at 476hp. Not 500... Dave was stepping my boost up in 1 and 2 psi jumps and then tuning it and testing the stability of the tune. I finally stopped Dave at 16 PSI when we were on the dyno last time. We had already burned over 10 gallons of gas that day on the dyno. And It was getting dark and I still had a 5 1/2 hour drive home that night. So I have no issues with the 500hp stickers on my Slingshot... If I needed to bump it up another PSI to prove the point I would.

    Now getting back to the original question....

    You can use 500hp on a slingshot...You just have to use it with caution. Everything I am about to say is not special to my situation. It just seems that its really really important in my case to do the following things.

    I never take off wide open by dropping my clutch ... (Remember I still have my original belt, my original swingarm, and I have my original rear bearing). I always roll a foot or two before laying into the gas.

    I never speed shift my transmission. It just not able to handle 300hp and at the same time be shoved into gear. It just wrecks the synchronizers in the transmission. I can only imagine whet a sticky tire would do to the transmission with 500hp and someone bumping the clutch and yanking the gear shifter.

    I constantly watch the type of pavement I'm on. I look and see if its a deep black grippy asphalt. I look and see if it has a worn pebble finish. I look at old pavement that has been driven over for a long time and is kinda gray. Each texture tells me just how much power i can put down before the tire breaks loose.

    I have to watch the camber in the road when passing...Generally if I were to start mashing hard into the gas behind the car i am passing and i go to the oncoming lane to make the pass and that lane is cambered a lot. I will break loose and start to slide sideways at 80 or 90 mph beside the car I'm passing.

    When I go into a corner I am always ready to move to the brake pedal. Why.... Because when 16 PSI comes up you may not be able to stop the engine from continuing to pull even after you let off the gas. There is a slight delay before the engine decides to calm down after taking your foot off the gas. And it can pull you into a turn to hot. Or it can can kick your rear out and into the front of a car.

    With all this said...... When you finally get out in front or you have that clear stretch of highway to open it up. Its like nothing I have driven. From 40mph to 130mph it just warps the speedometer. And yes ,,, it is worth all that effort to keep it under control just for the opportunity to have that extra horsepower when you can safely use it. ....

  • Yes sir. I wouldn't question that at all.
    Just sayin that some of us push the envelope for no other reason than we can!
    A lot of what we have done is not necessary.

    You, @rabtech, @WingShot, @kenny_h represent what can be done to a TC system at different levels. If anyone has questions, they should contact one of you.

  • Thanks for the nice reply....

    I can absolutely say that unless you have a ton of cash or someone helping you with a portion of the expense (weather it be a sponsor paying for parts or a sponsor that is just supplying free labor) it will be a very expensive endeavor to break the 350 to 400hp level. And remember a 300hp slingshot will spin the rear tire just as much as a 500hp slingshot will.

    It's just not worth the time and money your going to outlay to get to that point. Your going to mess something up... Its just Murphy's Law.... And when you do mess an engine up it won't be just a "replace the engine" kinda fix... If you pop a stock engine with a turbo you can honestly run to the junkyard and grab a $350.00 engine and drop it in.

    When you pop a built forged engine you are seriously going to be sad... I am a grown 46 year old guy and I have been almost to tears in the past... And to a large degree it wasn't even the expense of the rebuild that made me sad. It was knowing that I was going to have to wait on a an core engine to be run through a machine shop and then assembled with all new high end forged components. Then you will have to make a trip to your choice of garage or vendor to have it installed. Everyone knows I use DDMWorks and it's nearly 6 hours each way to get it installed. And unless your going to sleep in the parking lot.... their is all the hotel stays... Don't forget them.... Over the past couple years I have stayed at the Best Western in Piedmont about 30 days.

    Now you may ask why I have spent so much time at hotels ... Someone that didn't know my slingshot's background could read into all this and think I have had problems...No, I haven't had problems. I am just continually trying to get the next 50hp..... Its like an addiction.

    Here is why I have so much time on the road....I have tried factory ECU tunes, Stock engines, Built engines, Haltech ECU's, Race exhaust, Quiet exhaust, Hahn turbo systems, Alpha turbo systems, 63lb injectors and now 85lb injectors, AEM Failsafe gauge controllers, Innovate boost controller gauges, oil pan turbo drains, oil pump turbo oil return systems. And I have tried several different cold air intakes for the turbo systems. I have even tried 3 different intercooler setups. I have had 2 different clutch setups. I have had full metallic clutch disk and lastly I ran a clutch disk with metallic on one side and fiber on the other. Both of the new disk were used with lite weight flywheels .

    Now I'm on a completely new and larger turbo and a custom hand fabbed exhaust that has boost operated bypasses.

    AND GUESS WHAT.... Im typing this from the hotel room at Piedmont right now!!!!! We just pulled the manual transmission and installed an automatic transmission with push button controls. And I have been at the Best Western for 4 nights...

    Overall I try to stay neutral on the forum. But I should be able to tell people my experience with DDMWorks. I love working with Dave and his whole crew at DDMWorks... They do a great job. I say that as a customer and as a friend.

    Remember,, everyone on the forum has the ability to post a story about your favorite vendor or a good experience you have had with a vendor.

    So I am not going to try to guess how much I have spent or how much DDMWorks has contributed to the white beast in their efforts to test and learn what each change has gained or lost. It has been fun and we both have learned so much over the last couple of years. I wouldn't do a single thing different....

  • @rabtech
    Thank you for the great reply!
    I am glad we can agree having a boosted sling is one of the best upgrades we have made to our slings.
    When I am asked TC or SC, after my bias wears off, I tell them to think about what they desire to drive 1 year from now and how much they want to spend to get it.
    What level of HP do they ultimately desire, and where are they going to be using it?
    Unlike the post from the other vendor, I can admit the SC and TC are just as good as each other in their given environment and use.
    (if you don't mind waiting for spool up) :POKESS:

  • cry-squared .... I just want a SC so I can be part of the smack talk.... cry-squared

    When the time comes it will be a DDM Works Super Charger for two equally important reasons. (1) I love the controlled nature of a SC. I love the twisty back roads and carving the corners. The SC let's me think more about the apex and my exit point than stressing about when the surge of power will come on during that process. Guess I'm not good at multitasking... smile-squared
    (2) I like to deal with above bar suppliers. This goes in my normal day job and with suppliers for MeanSling. Over the years you meet a lot of people and a lot of personalities and you can build a good picture of who they are and how they do business. Dave went out of his way early on to help me out with something totally unrelated to the SS. DDM Works are just good people. It is as simple as that. As a vendor I can only hope to be seen as an equal to the product and customer service going forward. Who knows where MeanSling will go in the coming years but if I'm a strong second to these guys than I'm doing damn good.

    Proud supporter of S.O.G.

    (Slingshot Owners Group)


    Owner/operator: MeanSling LLC :thumbsup: