spinn, do some more research. the average street driven supercharged v-8's are 400-500hp...street turbo setups range from 700-850hp on pump gas with better mileage...in race trim with high octane usually 1,000-1,400hp, without changing a pulley. and yes, initially when you compare a s/c kit to a turbo kit the turbo kits are more expensive but they normally come with a lot more of the necessary upgrades for the fuel and air system, oh, and they make more power too.
unfortunately in the communist state of california we try to get things done as inefficiently as possible and amongst other things we aren't allowed to install turbo systems on an emissions controlled on-highway vehicle that didn't come factory with a turbo or have an engine transplanted from a newer vehicle that came with a turbo...so legal street cars are limited to s/c setups.
Turbo's being more efficient than s/c's is an un-arguable fact that has been proven and documented hundreds of times.
look at race classes where turbos are allowed, they absolutely dominate...drag, autocross or road race.
There's a reason that hardly any production cars come with superchargers...they're either turbo'd or not forced induction.
I drive a Cummins Dodge and have it turned up to 30 psi, which is still mild and requires no engine work(not until 45psi, then I need a better head gasket) and it is absolutely amazing...I will not build a supercharged engine, turbo's are the way to go for so many reasons.

Yikes!! A lot of "opinions" stated. Some are correct and some are way off. First of all lots of cars come supercharged from the factory. All the "Kompressor" Mercedes Benz cars are supercharged along with the GTP Pontiac Grand Prix.

This issue is not even debate-able. For all out HP (horse power) the turbo is the winner. If you ever watch, or participate in races you will see turbo cars MPH real high for their ET, this is because of HP. Most will use nitrous to get off the line.

On the other hand superchargers (roots) make HUGE amounts of low end torque, the trade off is they are not efficient in the high end HP range. For a street car that is perfect.

As far as street cars with superchargers not making much power, that's because a lot of people run blowers (roots) for looks and they don't build the engine to make power. It's easy to bolt on a blower. Most people that go through the trouble of plumbing a turbo or two, usually do it to make power. Turbos are not "pretty" so that keeps the posers away. My blown engine makes power and was built to be street driven and on the ragged edge. It's rowdy, loud, and makes lots of torque.

The centrif. superchargers are very efficient and can make huge HP like a turbo. They are basically a belt driven turbo. Keep an eye out for them they will be hitting the scene pretty big in the near future. Some new innovations have them making big power and being dead reliable.

All forms of forced induction has it's pros and cons. You just have to pick the form that works best for what you are trying to do. One is not "better" than the other, some are just better at certain things.

THere are a lot of turbo cars/trucks being built these days. It is not black magic anymore and the HP is really inviting.

Make sure when you are comparing the two you are comparing apples to apples. A fuel injected computer controlled turbo engine will of course be more efficient than a carb'd roots blown engine. Also compare a non intercooled turbo with a card to a supercharged engine, you will see the difference is not that great. It's not only the turbo that makes that system "better", it's the fact that it's easy to intercool, computerize, and run injection. These things play a HUGE factor.

Royce

Royce,

very well put. I was going add my commentary, but you've said it all.
I got nothing to add to that. Other than that my 8-71 on a 541 dart makes 966 hp (no intercooler) and 876 torque with 13% OD. One streetable engine that is.

Fred

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I definately dont want to make the impression that a blower engine can not make huge power. They can. The question is which one is best in terms of power and efficiency. In those areas the turbo wins. If you only looked at easy of installation and tuning, the supercharger would win hands down.

Chris

happy easter!

there is not one 700-800 hp street turbo system that i know. as a matter of fact the kits avalible are prertty sad.

just remmember to make the playing feild even. to find out which one makes more power you would have to do a controlled expiriemnt. same engine,cam, fuel, and boost level. then one could tell. also a high money twin turbo system is not comparing apples to apples.

i mean comparing a 6 psi roots to a 30psi turbo isnt going to show you anything!

hey my buddies lightning runs 13.02 its supercharged, and its way faster than a freinds lebaron and that has a turbo...!? picking up what im putting down.?

yes i like the low boost remote mount turbo. i probably will end up trying a turbo setup some point in my life.

im not into the desiel scene. just not impressed with a 2,500rpm redline. they dont particularlly sound good either and dont run smooth. they have come a way, but can still tell they have the clackity-clack. the US market enjoys smooth well running engines, the diesel in a family application has always been a hard sell. albiet the better reliabilty,and possiblity for increased mileage.

i hate that word did i use it right?

Just call Banks and he will set you right up with whatever you need.

But they run for what, 5 minutes max...
Else you got a heater under the hood..

Here is my car , a 1000HP Supercharger, so you will have seen two
Here 1000hp Supercharger

I dare any turbo Street car to came on the track whit me

Also someone have the exact efficiency of Turbo ?
Centri. supercharger are in the 70% to 80%+ efficiency.

I dont agreed,...
First No coating will last on a supercharger Header du to the extreme Heat, so i think it will be the same on turbo unless i'm wrong... But turbo Use a "heat factory" under the hood no matter what you do, this not counting the extreme heat the turbo, bearing etc.. have to deal whit it..

As for changing the boost, you tell you can have a turbo that produce 10psi then change it to 20psi like that ???

----------------
Oh yeah, and turbo compressor effciency and boost curves will always make more power at the same boost level than any supercharger if both are properly designed.
---------------
Can You prove this ??? This is a non sence... 10psi produced by a turbo & 10 psi produced by a supercharger or whatever the way.. are the same... Except the turbo charge would be far more High temp compared to the supercharger..

well i agree. i want to see proof. the temps would be high with both. the turbo would have to be hotter.? got to go


im not spending 10k on engine, ever.

OK, here is some of the math off a thread awhile ago on another board. Here is the link. http://www.sr20forum.com/showthread.php?t=89383&page=2&pp=20 Mike (choaderboy2) is the one that wrote this up for those of you looking for the math behind all this. The math is all basic first semester mechanical engineering stuff.

Mike writes:
Here are some arguments for use of waste energy and parastic loss. So I used a Honda engine but I am too lazy to find my SR20 notes.

As stated before, turbos are driven by the wasted 30% of fuel energy dumping out of the exhaust stream without parasitic loses on the crankshaft. This use of waste energy is the main reason why turbochargers have a tremendous power advantages over superchargers.

To put this in perspective, even the low boost 6-8 psi street superchargers like the Jackson Racing and Vortech kits take about 10-20 hp from the crankshaft to spin them up. It takes over 800 hp to turn the big roots blower on a top fuel drag racer!

Here is the long and boring nerd way to add some validity to the power debate. Lets figure out how much power it takes to compress the air to make serious engine power. We will do this two ways; we will figure the differences in intake air temp for a turbo, a roots supercharger and a centrifugal supercharger. Then we will show how much power it takes to turn the supercharger. It should all make sense once it’s laid out.

First lets calculate Delta T for the various compressors. Delta T is the change in the intake air temp after it is compressed.

Delta T= Intake Absolute Temperature x (Pressure Ratio to the .238 power –1)/ Compressor Efficiency

Lets assume our engine is going to run 20 psi of boost or a pressure ratio of 2.36.
Pressure ratio= boost pressure+14.7/14.7

The temperature scale engineers use for absolute temperature is the Rankin Scale. On the Rankin Scale Zero degrees is absolute zero. So assuming our intake air temp is 85 degrees, lets call that 545 degrees Rankin.

Lets say our match car is a hot Acura GSR with a B18C motor. By using standard compressor matching equations , we figure that the B18C can flow about 45.3 lb/min going full tilt at 20 psi.

So here we go. Lets figure out Delta T for our good turbo first. Lets assume an efficiency of 78% as there are many turbos that can do that at the given flow and pressure ratio.

Delta T= 545 x (2.36 to the .238 power –1)/ 0.78
Delta T= 158 degrees

A 4-cylinder sized Centrifugal Supercharger is probably much less than 70% efficient at this point but lets be kind to it and assume that, Plugging and chugging gets us a temp of 177 degrees.

Now there are not any current roots blowers on the market that can support this sort of boost pressure on a small 4 cylinder car but lets suppose there is and lets be very kind, assuming it will get 60% compressor efficiency at 20 psi and 45.3 lb/min of flow. This is not likely but lets be nice to the poor roots. Plug and chug and we get a Delta T of 206 degrees.

Now Delta T is the difference in temp after being compressed. What would our intake charge temp be for the roots assuming an intake temp of 85 degrees? 85+206= an egg frying 291 degrees with no intercooler!

Now lets figure out the power required to make the boost from these three compressors.

The equation for compressor power needed is.

Power in BTU per minute= Mass Flow x Cp (a coefficient) x Delta T/ Compressor Efficiency

To convert BTU per minute to horsepower divide by 42.4

Power = 45.3 x .242 x 158/78 = 2220 BTU min/42.4 = 52 hp recovered from the exhaust.

So here is the Horsepower that won’t be taken from the crankshaft but recovered from the exhaust stream by the turbocharger on our vapor GSR.

If you check out the gas power cycle in a thermodynamics book, the PV diagram for you engineers, you need to correct the power equation a little for a supercharger. Since a supercharger adds pressure to one side of the motor and the turbo adds it to both, we need to do an estimation of the power recovered by the supercharger on the intake stroke.

The equation is:

((Boost Pressure x Engine Displacement in cubic inches x RPM)/2)/12 x 60 x 550

So for our B18C:

(20psi x 110 x 8500 rpm/2)/396000 = 24 hp

To figure out how much power the Centrifugal Supercharger takes from the crankshaft, lets plug and chug again, getting a 65 horsepower, subtract 24 hp and you get a crankshaft power loss of 41 hp

Repeating for the Roots Blower gets us a loss of 65 horsepower stolen from the crank.

So simply reducing our meager data, if you calculate the potential hp of our turbocharged B18C we will get about 453 hp. Thus well might be around 412 hp from our centrifugally supercharged version of the same motor and 388 hp from our roots equipped motor. Now this is vastly oversimplified and does not take into account differences in VE, air density differences for intercooler effectiveness or lack thereof, dynamic matching to compressor maps and engine tuning variable that have to be different between the types of compressors. Of these variables, all of them except for VE differences will be in favor of the turbo. This shows that all other things being equal, the turbocharge does have an advantage when it comes to sheer power output. The compressor efficiencies we used for the superchargers were very conservative. In real life the superchargers would probably be much worse at 20 psi. If we upped the boost higher, to higher pressure ratios where turbochargers really shine, the calculated differences would be even greater.
First lets calculate Delta T for the various compressors. Delta T is the change in the intake air temp after it is compressed.

Delta T= Intake Absolute Temperature x (Pressure Ratio to the .238 power –1)/ Compressor Efficiency

Lets assume our engine is going to run 20 psi of boost or a pressure ratio of 2.36.
Pressure ratio= boost pressure+14.7/14.7

The temperature scale engineers use for absolute temperature is the Rankin Scale. On the Rankin Scale Zero degrees is absolute zero. So assuming our intake air temp is 85 degrees, lets call that 545 degrees Rankin.

Lets say our match car is a hot Acura GSR with a B18C motor. By using the compressor matching equations used in our last story, we figure that the B18C can flow about 45.3 lb/min going full tilt at 20 psi.

So here we go. Lets figure out Delta T for our good turbo first. Lets assume an efficiency of 78% as there are many turbos that can do that at the given flow and pressure ratio.

Delta T= 545 x (2.36 to the .238 power –1)/ 0.78
Delta T= 158 degrees

A 4-cylinder sized Centrifugal Supercharger is probably much less than 70% efficient at this point but lets be kind to it and assume that, Plugging and chugging gets us a temp of 177 degrees or a hellish 262 degrees at the intake. Let me remind you that to my knowlege there are no centrifugal superchargers that can even reach 20 psi on a small engine on the market besides maybe Procharger and Procharger is a horrible design and I dispute that it can be much more efficent than 65% no matter what Procharger claims due to thick impeller blades, no diffuser and a raidial non-curved vane impeller blade, ie, 1950's technology.

Now there are not any current roots blowers on the market that can support anywhere close to 20 psi of boost pressure on a small 4 cylinder car, about 14 psi is the most I have seen, but lets suppose there is and lets be very kind, assuming it will get 60% compressor efficiency at 20 psi and 45.3 lb/min of flow. This is not likely but lets be nice to the poor roots. Plug and chug and we get a Delta T of 206 degrees. In reality the efficiency would be closer to 50% at 20 psi and the numbers much worse.

Now Delta T is the difference in temp after being compressed. What would our intake charge temp be for the roots assuming an intake temp of 85 degrees? 85+206= an egg frying 291 degrees with no intercooler!

Staying in the Compressors Sweet Spot
As we stared before a lot of how a turbocharger behaves is dependant upon how it is matched to the engine. Turbos come in many sizes and can be precisely tailored to the engines displacement and the owners desire in power characteristics. Since the turbo is not directly coupled to the engines crankshaft, there is some latency in the throttle response, described as turbo lag in the previous section of this article. As explained before this lag can be largely tuned out but it will always be there to some degree. Since the turbo is free floating from the crankshaft, creative sizing and wastegating enables the turbo to be kept in a more efficient range of operation over a wider band of the engines operating range.

Better Compressor Efficiency, More Flexibility
Another advantage that most turbochargers have is improved compressor efficiency over superchargers. Compressor efficiency is the thermodynamically calculated temperature rise of compressing intake air a given amount via the ideal gas law divided by the actual temperature rise of air compressed to the same pressure by the compressor in question. This is also known as the adiabatic efficiency. When talking about compressor efficiency, it is given as a percentage with the higher the percentage, the better. The higher efficiency means that the intake charge will be heated less while it is being compressed. A centrifugal compressor like the one found on a turbocharger is very efficient. Typically the efficiency is at least 70 percent over a broad range of engine operation for most turbochargers with state of the art examples having efficiencies around 80 percent. Typical good turbo compressors found in the aftermarket, like the Garrett TO4E have efficiencies ranging in the mid 70’s. Newer designs like Garrett’s GT series can have efficiencies of up to 80 percent. The more efficient the compressor, the cooler the intake charge air will be. In the case of an old school, less than 50% efficient, roots blower vs. a state of the art turbo, the difference in compressor discharge air temp can be over 100 degrees F at the same boost pressure!

Good turbocharger compressor efficiency is important for reducing engine backpressure on a turbocharged car as well. A more efficient compressor requires less power to compress the air, thus the turbine has to recover less energy from the exhaust stream. With less of a pressure drop required to recover the energy, the exhaust backpressure is reduced and the volumetric efficiency goes up. A more efficient compressor also has less turbo lag for this very reason.

The latest designs of turbos like the Garrett GT series and the latest offerings from IHI have highly efficient compressor and turbine wheels combined with low friction ball bearing center sections. The IHI compressor also features an abradeable lining to the compressor housing. This Teflon like coating is abraded away by the compressor wheel to allow the tightest possible housing to wheel fit. This significantly improves compressor efficiency. These high tech features reduce turbo lag to a large degree without sacrificing flow.

In contrast, some newer roots blowers like the Eaton, have improved designs and higher efficiencies in the low 60% range, a vast improvement from the old 50% efficient bus supercharger, but still much less than the typical turbocharger compressor. The roots design is less efficient because it has a lot of internal leakage and does not have internal compression, relying instead of external compression in the manifold. The Eaton’s improved efficiency over prior roots superchargers comes from its having some internal compression due to changes in its port timing and rotor geometry over old style roots blowers. Modern CNC machining techniques also allow the Eaton to have tighter tolerances and less internal leakage then the older designs had.

You might have heard of a Lysholm supercharger, which is very similar to a roots blower but has two rotating screws with a varying pitch to compress the air instead of 3 lobed impellers like the roots. Whipple makes a blower of this design. The Whipple should have superior adiabatic efficiency because of the designs internal compression. Whipple claims 75% although they do not publish compressor maps to validate this claim. The only Import Whipple application that we know of is the Comptech NSX kit, which produces 367 hp to the wheels.

Part 2 to post from Mike:

Centrifugal supercharger compressors like the Vortech are much more efficient. The V-5 supercharger used in their Civic Si kit can reach efficiencies of 73% over a fairly broad band. Unfortunately this efficiency is achieved at fairly low-pressure ratios, which would limit the engines swallowing capacity if you were to try to go to a full race high boost application. With small motor, the way to increase the swallowing capacity is to run more boost and higher pressure ratios. Higher boost means more air stuffed into the engine. With high flow and good efficiency at lower pressure ratios, centrifugal superchargers now on the market, seem better suited for large capacity V-8 engines.

Even with the Vortech superchargers broad (for a centrifugal blower) peak efficiency island, the turbo will still dwell in a higher efficiency zone of operation longer than the centrifugal supercharger will. This is due to the turbo’s wastegating allowing the turbocharger to operate in an efficient zone longer.

The inability to operate with good efficiency at high pressure ratios on small engines seems to be a major limiting factor for centrifugal superchargers when it comes to making race winning levels of power with 4-cylinders. Most centrifugal superchargers of the proper size for a 4-cylinder are out in the 65% or less Efficiency Island of the compressor map at a pressure ratio of over 2.4:1 or just a tick under 20 psi. The bigger centrifugal superchargers that can get into the higher-pressure ratios are in the surge zone with smaller 4-cylinder motors like ours. It takes more than 20 psi to win in the quick and outlaw classes these days.

At 2.4:1 the centrifugal supercharger is nearly off the map, close to the surge line on a small 4-cylinder motor and operating in an inefficient part of its operating range where it is heating the air and eating a lot of crank power. This is just not enough boost pressure to make serious quick sixteen winning power with a small displacement 4 cylinder. Many turbochargers are capable of efficiently (easily over 72%) operating at pressure ratios of 3:1 (30 psi) and higher on small engines without surge.

The final negative supercharger issue is the lack of tuning flexibility. On a turbo, you can drastically alter the boost levels by tweaking the wastegate pressure signal with a boost controller. Are you at 15 psi and dump in some race gas? You can crank her up to 20 psi and enjoy the power in a second. Are you racing, running 23 psi and the track starts to hook up better? No problem, turn her up to 27 psi to take advantage of it. With a supercharger, you have to change drive ratios, which is not very practical between rounds.

Vortech is the most efficient of the centrifugal superchargers on the market. Other brands struggle to get their efficiency into the mid 60’s.One of the reasons why some aftermarket centrifugal Supercharger compressors are not as efficient as turbochargers is that typically a small aftermarket company usually engineers them where as most turbochargers are designed by big OEM automotive supply companies and their product is highly engineered. OEM development sinks a lot of costs into optimization of the compressor design, especially in the long haul diesel and stationary engine market where every bit of efficiency is desired as every bit helps improve fuel consumption. Where Garrett has a whole building full of engineers and a multimillion-dollar test facility, an aftermarket company cannot muster anywhere near that level of engineering resources when it comes to design, testing and manufacturing. Buying a turbo from Garrett, Mitsubishi or IHI means that you are buying a unit with lots of engineering time and optimization, way more than what a typical aftermarket centrifugal supercharger will ever hope to have.

Better Matching to the Engine
Another reason why turbochargers are such kings of power is that turbochargers are used heavily in the long haul diesel and commercial stationary engine market. This market covers a wide variety of applications from small 4 cylinder Japanese panel trucks to huge Caterpillar earthmovers. As stated before, fuel economy is very critical to commercial operators as is precise engineering of the engines power characteristics. This diversity in application engine size and output plus the market demands for efficiency on a large commercial scale insures that much R&D money is spent on turbocharger optimization which means that there are literally hundreds of different sizes of turbochargers optimized for a great deal of different applications. This makes it easy to come up with some very nice turbo combination for most automotive performance users. The supercharger aftermarket tends to be of the one-size fits all variety with perhaps about 3 to 9 size applications to cover the performance car market.

So which is best for you? If a very broad powerband and very linear throttle response is paramount and you are happy with about a 40% power increase, then a roots blower is for you. If you don’t care about low-end power but want lots of peak power in the order of nearly a 50 to100% gain with a predictable throttle response then a centrifugal blower might float your boat. Do you want a CARB E.O.? Again a supercharger system has more choices.

A turbo system can be tuned anyway you want, from a responsive, lots of low-end system to a screaming insane, race only power monster. The only drawback is that disconnect from your throttle foot, which can be tuned to be either almost unnoticeable, to somewhat significant. There are less CARB approved options with a turbo.
How to calculate your potential HP output with a turbo
Once you have figured out your engines airflow at the boost you plan on running you can estimate your hp output pretty easily. To estimate your potential power output, you can do so easily with this formula:

HP= Airflow x 60/Air Fuel Ratio x BSFC

Airflow is in lb/min like we just calculated, 60 is to convert minutes units to hours, Air fuel ratio is self explanatory, BSFC is Brake Specific Fuel Consumption as measured in lb of fuel per hp per hour.

For guidelines, a highly boosted turbo engine running on street 92 octane unleaded pump gas might run an AF ratio of 10.5:1 to hold down detonation. Conversely, a highly massaged drag motor running a specialized high specific gravity turbo fuel might run an AF ratio as lean as 13:1. For estimations on BSFC, a rich tuned pump gas motor might run a BSFC of 0.60. A massaged, tuned to the edge drag race motor on specialized gas might run at 0.45.

So lets pick a crisp state of tune (conservative on race gas) for our hypothetical B18C.

Lets pick a conservative, on race gas air fuel ratio of 12:1 and a reasonable BSFC of 0.50, this is a very safe state of tune where you won’t be close to burning down any motors.

HP= 45.3 x 60/ 12 x 0.50
HP= 453

So our hypothetical B18C will put out around 453 hp @ 20 psi of boost. If you take the time to play around with the equations, the things the tuner has the most control over are the VE, through different size turbines, turbine housings, exhaust systems, headwork cam combos, etc and the tuning factors which include AF ratio and BSFC. The intake manifold temperature can be fiddled with different intercoolers or better yet, go and measure your cars post intercooler intake temp. You can play around with these numbers mathematically and see how they can affect your power and what you can do to extract more power.

All this are inacurate at the first point...

Today Centrif. Supercharger have efficiency around 80% not 70%
so all this is good for the trash... All the math here are done whit
a lower effeciency than REAL...

Then, In this text they tell they can use a 10psi turbo then push a 27psi on demand... If this can surrely possible whit and oversized turbo on a 4cyl engine you will not do that on a 8cyl.. Why, you will never have enough flow to sustain the 8cyl engine.. Then turbo like the supercharger, have and RPM limit, like in my F1 Procharger Turbine rated at 70,000RPM. If you exceed this you will run into problem..

a 4cyl is not the same as 8cyl engine... Pretty easy to put 20psi on a 4cyl since the flow is little, but try do the same on 8cyl whit 1200cfm+ Flow.. Thats another thing..

We are not talking about a little B20 honda that can run whit a hair drier....


As for the Crank part,

Stress on the crank ? Its a joke... The stress on the crank are exponensialy far more when a cyl. make explosion they put tremendous force on the crank.. The belt on the front have almost no impact on that at all... For sure driving the supercharger require some HP but
even if you use tell 50hp... Its a lot for a B20... But its a joke on a 8cyl...

Assume 20 psi of boost
You can guess 20 x 30HP = 600HP Gain From the Supercharger... I dont matter loosing 50HP....

Assume My current Engine ;
410SBC (+- 550HP+) + 600HP - 50HP = Still left 1100HP !!!!

All i have seen about turbo, when someone tell its better the only thing
they can tell is " my turbo dont require HP to drive it" Its true... But Its the ONLY advantage...

If turbo are popular on 4cyl the only reason is because they are cheap, widely available, and you can put almost anyting in a 4cyl since the flow is very little so almost any turbo will do the job.. and can boost a lot the power of a plain 4cyl engine.. I think i have never seen a supercharger on a 4cyl btw...

This is the way i see this at least..

There are ceramic coatings available at any company that will stand up to 2000 degree surface temps and over that in gas temps. That will work on any internal combustion engine since over that other things start melting.

80% effciency on a compressor is only a peak number. That is not where the compressor is spending most of its time. I will say that new cent. superchargers and turbo compressors are very similiar in efficiency. The advantage that turbos have is the ability to vary turbine speed independent of engine speed and a much wider operating range.

Even with the compressor efficiency taken out, the small parasitic pumping loss of the turbo is much less than the mechanical loss of the supercharger. It is just physics, guys. You cant change it. Of course this is assuming a properly built system with an adequately sized turbine.

As for boost control, yes, you can vary boost from 10psi to over 30 very easily with the same turbo. I actually have the ability to launch my truck at low boost and run it up after I get to the top of the track. Kindof like high nitrous in high gear after I get hooked. I am sorry this dissappoints you guys, but to deny it is idiotic. I have the ability to to this with my engine controller, but with a stock block and a tiny truck 800HP is plenty. I could actually only push around 20psi before compressor efficiency would start falling off due to the cid of my engine. On a small V8, it would work very well up to 30psi or so.

You guys need to study up and keep an open mind on this stuff. Just because you have a supercharger and have read a couple magazine articles about them, does not mean they are the best thing out there on all levels. But, like I said, they still make great power.

Chris

Chris,
I am not sure if your post was aimed toward me or not. I would like to think not.

If you read my post it covers it all in a nut shell. I personally never said either one was "better or best". Turbos have advantages and superchargers have advantages. It all depends on what you are trying to achieve. My engine and your engine make similar power, we get there two different ways. Which is better? Neither you are happy with yours and I am happy with mine. If we looked at our torque curves they would be VERY different. Mine makes gobs of torque off idle. Your will make more power in the higher RPM range. If we both dead hooked I would have the advantage off the line and you would start to catch me on the big end. If both cars weighed the same and all else was equal (HP), one car turbo and one SC, this would be the case. There really is no argument or debate, it's the facts.

On a slippery track the turbo has an advantage because the boost doesn't "hit" as hard. On a sticky track my blower would have an advantage because it would leave harder. Leaving harder is also harder on parts, this is another advantage a turbo has it is pretty easy on parts (unless you spool them up with a loose converter then they will hit hard too).

For torque it's hard to beat a SC, for HP you can't beat a turbo. HP and torque are two different things even though they are related.

The example of a top fuel car was used. There is no way the NHRA will let them run turbos, they already make over 7000HP with undersized over driven blowers. They can't hook all that power reliably as it is (much due to the amount of torque the engines make). Going to turbos would have the MPH through the roof (which the NHRA is trying to keep under control). This is also why they won't let them run more gear or better tires, they have to keep the sport "safe". I know the cars would be faster but, how much faster can they go? 330+ MPH in the 1/4 mile is plenty. If they went to turbos I still think the ET's would be the same they would just carry more MPH (assuming they restricted them like they do the blowers). Of course since none of this has been tested it is just my educated opinion.

The turbo systems that are rear mounted, seem to be both good and bad. Good because you can hide the things and bad because exhaust temp and flow will be lower back there. I haven't researched them much yet, so I don;t know all the details.

One other misconception it that a turbo is free power, this is not true. It is a restriction in the exhaust. While the amount of power it takes to run one is debate-able it is a fact that they use some power as well. There is no free pass when it comes to power no matter how you make it.

People tend to get closed minds and assume what they have is the best. I have an 8-71 roots blower, I knew when I built the engine I could "probably" make more power with a turbo or centrif. That didn't fit my plans or goals. It makes more power than I could possibly hook anyway. Now I am building a car to handle the power and hopefully stand a chance at hooking.

Hot rodding is about doing what "you" want with a car/truck. It's not about who is better or best.


Royce

Turbos sound like crap. Sorry, but I hate the way they sound.