I didn't want to hyjack Mo's 1000hp thread so I thought I'd start another one about the pro's and con's of Turbo's vs Superchargers. I am certainly not an expert here and have only delt with a Kenne Bell supercharger on a 4.6lDOHC motor and Wieand supercharger on my Ford Flathead.................................so why don't more people use Superchargers to increase HP?, and why does everyone and their brother opt to put a Turbo on their car? I'm not trying to be a Smartxxs..............just asking the question.
I know for me I chose a turbo because if I want more boost all I have to do is adjust a manual boost controller. No pulleys that have to be bought and changed out. Also turbo setups are cheaper then superchargers. I had originally looked into superchargering my car but the blower itself was 2500 then I would still have to buy more parts to make it run. My entire setup running and driving cost about 2300. I would also say that less people turbo v8 cars, everyone puts a supercharger on a v8. Turbo cars also get better fuel economy do to being powered by engine waste, not by the engine itself. And most importantly the turbo (mine anyway) doesn't give it away at the stop light that its forced induction.
Both will make power..... I prefer the turbo's because it doesn't take power to make power, using waste exhaust to spin the turbine instead of being belt driven off the crankshaft.....
there are lots of factors that i consider before recommending which way to go. Intended use of the car. using mo's car, i suggested supercharger. his intended uses: be able to be driven daily, goto to a weekend racing event with out needing to be towed. reason for supercharger, they have a very linear power band. you will know how much power response the motor will have with any press on the gas pedal. this makes the car very safe, predictable, and fun. the down side is that it wont make as much power on the same amount of fuel as a turbo will and wont get as good as mpg as a turbo will. chances are he wont be able to get 1000 hp out of a supercharged motor that will fit in his car and meet all of his other desires. a turbo doesnt have linear power. when the turbo is not boosting you are driving on the power that the motor it self makes. then when the turbo spools you get a jump in power. there is no middle ground. you can be driving around on a 300 hp motor then get into boost and and instantly have 600hp. imagine trying to do an autocross with out having the power between the 300hp level and 450 hp level. all i can imagine is allot of killed cones. the good thing of turbo on a street car is that you could get better mpg out of a turbo. now not a big turbo that makes 1000 hp but some small ones that can generate boost at cruise speeds. turbos are great for full throttle power. they cant be beat with all other things being equal. its just they dont offer a linear power band that makes using the power a tricky thing.
In this discussion I'm not neccessarily talking about racing, but to take Mo's motor as an example, something that is raced and street driven.....on occassion. So, let me see if I've got it right here, you are saying that a Turbo has better efficiency than a supercharger, right? But doesn't a turbo create a lot of back pressure and exhaust flow............interruption.........for a lack of a better word? Also, what about the heat generated by the turbo. I understand the need for an Intercooler (had one on my 87 Turbo Coupe) which I would think is manditory, but what about the heat in the engine compartment and where ever it's exiting from the turbo housing. Also talking heat, wouldn't this make the turbo's life much, much shorter than a supercharger?
Superchargers are way cooler!! Turbos seem to be some weird thing that belongs on a Saab. To me anyways.
I had a Weiand 141 on my 289ci Flathead...........loved it and it really caught everyones attention.............and did produce 315hp which is about 75hp more than with carbs, but you are right they don't have the ability to play in the same league as even a 4-71 let alone a 6-71. I did price a Dyers setup for a 6-71 for a friend, and their polished unit for a SBF was about $3500 but that was less carbs or scoop which would easily run over $1500..............I know because I had 1/2 of a matched set of 650 Demon blower carb on my flathead.............I just love a Ford Flathead with a Roots type Blower.
and SOUNDS! You can't beat an honest answer! Same reason I want one. If I wanted fuel economy, I would be driving a 4-banger.
I know my turbo coupe was a factory car, but my 88 had an intercooler and was rated at 20hp more than the 87 non-intercool'd car, was this directly related to the intercooler? I would think that having the turbo interupt the exhaust flow would cause heat and back pressure.....................I'm just having a hard time grasping the concept I guess. I look at the N/A motor as an air pump..........the more you stuff in the more you have to get out...............and with the turbo in the way it would seem you are restricting the velocity and volumn trying to get out. Now I can see if you had twin turbo's, each bank of cylinders is feeding one turbo, but to have all 8 cylinders feeding 1 turbo..................not disbuting what you are saying, it's just not sinking into this thick skull fast enough.
Intercooling a turbocharged engine is pretty much standard fare. Air-Air intercoolers are highly efficient today and typically will bring inlet temperatures down to ambient or 10-ish degrees less than ambient. Given the amount of heat a turbo produces this is important. There are no backpressure problems with a turbo either. No exhaust flow interruption at all. Power is free since the turbo utilizes exhaust pressure to spin the impeller. No horsepower losses like you get trying to turn a blower. As far as radiant heat, yes, you will get some heat soak depending on where you mount the turbo(s). Heat blankets for the exhaust side help cut down on radiant heat considerably. The twins I have on my '07 are mounted on either side of the transmission bellhousing. Actually an ideal location if you think about it. Under the car has a perpetual airflow condition so the radiant heat gets carried away from the car and does not soak into the engine compartment. Also, the exhaust inlets are less than 12 inches from the exit of the exhaust manifolds so there is no energy losses. When properly sized for the application you cannot beat the horsepower increases a turbo (or twins) can supply. A belt driven supercharger has to deal with horsepower losses as rpm and boost increase. Turbos do not. Also, twins will ALWAYS produce more torque than a single in virtually every application. For ultra high horsepower street car applications you can't go wrong with a set of properly sized twins. Same with race cars. Typically, making horsepower isn't the problem......managing the power and being able to put it down is the problem. An electronic boost controller is a godsend for these applications while a simple manual controller is fine for simple street systems. Your worry with a single turbo was exhaust back pressure......not a problem when the exhaust is sized properly. You tie your two manifolds into a large single pipe feeding into the exhaust side of the turbo. On the outlet of the turbo you use a large exhaust pipe. Let's say you have a single 76mm.....you'd typically use a 4" downpipe and route it out the back. Some people will use a 4" and then split it off into a pair of 3" pipes.
consider this about the exhaust back pressure. when the motor is making enough exhaust to create a back pressure between the exhaust valve and turbo that is when the turbo starts spooling. when its spooling its moving air into the motor. so its taking the wasted energy of the motor that went out in the exhaust and putting it into the intake.
You know I looked into this and I have come too the conclusion... For the most part if you go with a supercharger or a turbo they both cost the same no matter what route you go... Most superchargers nowdays are a little bit more money then a turbo...(or alot more money depending on which one you get) but if you looked at something like a vortech V3 centerfugal kit for a fox body and put it on an efi engine like Mashori is planning those start about $1900, they are sealed self oiling units so they dont require anything special but relocating the battery to the trunk on our cars(you have too do this too a turbo setup 95% of the time too so I wont count that as a specific knock against the supercharger). And honestly since they are complete bolt on kits you could get one of those units put on and up and running in a weekend... Now too look at the turbo setup, yes you can buy fox body mustang twin turbo kit that uses a couple chinese turbos on ebay for around $1200.(a pair of nice turbos can run you $1200 alone) Then you have too make the exhaust manifolds work.. (throw them away and build your own, unless you no longer have shock towers) You have too pull the oil pan and install the oil return lines from the turbos because they are oiled by the engine, you have to run all the intake tube ect ect.. and then you have to run the exhaust, again the shock towers really create a pain, and the factory steering isnt that fun either on the drivers side. Now I cant install a turbo setup in a weekend, I know most people cant because they lack the fabrication equipment, the tools and the space. There are some talented individuals who have been doing setups like that for years that can probably do it but It would probably take me the better part of a month, fitting exhaust mainifolds, pulling the oil pan/possibly engine ect ect... So when you add the time into the equation you have to ask how much is your time worth and see if you have enough time to spend on installing a turbo setup, the other option is to pay someone to install your turbo depending on how soon you need/want it but that shoots the prices right out the window and you might as well just install a $3000 supercharger and get the looks too...
first of all, I'd just like to say that most should know well enough by now.. that nothing is free in this world... and that same rule also applies to turbos as well. Go look around at high-end turbo setups to see the swept headers and and purpose built heads/cam with added emphasis on exhaust flow(same applies to SC as well). Then compare those same types of builds to those with simpler and more easily fabbed log style manifolds. Are they making similar power per lb of boost? Obviously a rhetorical question and.. nuff said about that. Turbo consumes less power than a supercharger at similar boost levels.. but they are still leeches to some degree. It's just that pound for pound they consume less energy from the engine and everyone assumes since the engine has to get rid of the exhaust anyways?.. that it's all free energy. Which of course goes against the basic laws of physics in that it takes energy to make energy. Anywho.. you get the point by now I'm sure. As for inlet temps and the need for an intercooler?.. well.. we're right back to the basic rules of physics, thermodynamics, and metallurgy with less heat allowing either more boost.. or increased compression ratios to be used.. therefore giving additional headroom and or VE out of the deal if it's capitalized on. Also consider that controlling peak combustion temps(just as in an N/A motor) can be the difference between needing race gas and/or water/methanol injection.. or not. Intercoolers do just that(and is also why you'll never see a serious engine without one).. and can even reduce accelerated engine wear as a result of less heat transfer of metal to metal contact parts. RPM is not the only thing that increases wear(aside from dry starts) and turbos/superchargers can be tough on oils, rings, and valve seats too(even the self contained type units as well, although to a lessor degree in relation to oil related issues). As for the rest of what has been said.. superchargers are generally funner to drive on the street since you have faster power build off idle.. whereas we all know how laggy turbo's can be.. especially on a high HP application where the size must be larger to make big airflow/top end numbers. However, there are still many builds that use a smaller and larger turbo to widen the powerband and even the factories have used them for just that purpose. Porsche comes to mind right off the top but there are many others as well if you search for specs. Then there's the "all or nothing" comment in regards to turbos. While it is true that turbos can come on suddenly and create dangerous situations in the twisties.. they are also linear to some degree as well and just need to be tuned and modulated correctly with electronics, not to mention.. respected near their spool speeds in the corners. I've ridden in cars that are running partial boost at anything less than full throttle and they can hold those levels so long as the turbos rpm is kept constant. Gears can be more critical and even used to tune for specific tracks for turbo setups compared to the bigger low rpm torque of SC which can be much more forgiving(and sometimes preferable) for lap times if the gear is a bit too tall in certain sections of the track. I've ridden in bigger power SC, single and twin setups and the SC stuff will break traction off the line much quicker than a well tuned turbo setup which can be all the difference between winning or losing at times. Conversely.. a turbo setup that is not tuned or designed properly(go look at youtube for plenty of that stuff) can blow the tires off at higher speeds as the boost comes on.. whereas the SC has already dug into its linear power delivery/traction capability. As with anything at this power level though.. it's just a matter of tuning and driving the things the way that they run the fastest while still keeping you on the road or track. Either way you go though.. linear boost or surge boost.. the tail end can get away from you pretty fast with such a high powered car with too little tire.. which of course almost anything short of dedicated full race setup will surely have. Even then.. there are often physical or rule limitations that apply. When you're off boost on a turbo though, they are more predictable(much like an N/A in that respect) than an over zealously pullied SC. I see far more SC cars scrubbing time off a lap as they dance around for traction coming out of a corner.. than the turbo cars which are driven/tuned for power delivery once the car is straightened out and heading forward again. I've even watched dyno sessions where 3-4 guys sit on the trunk of a car to keep the SC from smoking the tires on the dyno on full throttle apply. Despite that tendency to unhook the tires at lower rpm.. SC will generally be faster on twisty road courses than a turbo setup because you maintain boost more consistently around the track if driven well enough. Turbo's can do that too.. but require more tuning for each specific tracks gear/rpm graph. Just my dirty penny on the subject from what I've seen so far.
