Supercharger or Turbocharger for AutoX, and Track

[jwvand02]

Originally Posted by FRS Justin

Another thing to consider that a lot of people overlook is where the power comes from and the cost associated with it.


Since a turbo makes its power by using exhaust it's basically free power.


On a S/C it's made from tapping in on to the crank to cause the boosted condition. So your hp increase cost you hp to make hp. That will also cost you accelerated wear on the engine. ( front crank bearing will post links if needed) ( I should also add it was more common on the older S/C with big wide belts. In current days the crank wear has been minimized by belt tensioner designs and belt width in the more modern design of the S/C)


Definitely S/C have their place in the market or they would have been scrapped decades ago, but the age old debate of which is better boils down to your personal choice of what will work better in a given necessity.


A turbo will cost you more initially to setup (approx. a 1000 to 1500 in this case) but is easier to maintain. So if a easier install with you having to service the S/C with belts and oil changes works for you go that way. If you just want to shut the hood and go, run a turbo.


They both are going to make power, both are tunable, so it boils down to what you feel works best for you. good luck either way your going to be happy with the end result

The whole "where the power comes from" is a fallacious argument. The end result is you're still paying x dollars for y power gain, and it doesn't really matter how you get there from that perspective. The only part that's really salient in that argument is one that you didn't mention, which is impact on fuel economy, in which a really well tuned turbo will typically do better from an economy standpoint when you're not winding the motor out.

Turbos are also typically less fool-proof, they're not as easy to install for a DIYer and have more points of failure. They also typically have non-reversible steps, such as drilling and tapping the oil pan. The end result is that the cars take more work to sell and you have a better (if still minimal) chance of catastrophically damaging the car. Most of this is no big deal to someone who is experienced in working on FI cars and has the money and time to put into it, but for just a hobbyist a SC is often the better way to go for that reason alone.

I personally chose SC because I feel like it's the easiest and cheapest way to get to the sweet spot for the 86, but only because I have ready access to E85. If I didn't have easy access to E85, I probably would have gone turbo. I still miss my turbo car though, because even though I think they're less practical there's something I actually sort of enjoy about turbo lag

[bfrank1972]

Originally Posted by jwvand02

The whole "where the power comes from" is a fallacious argument. The end result is you're still paying x dollars for y power gain, and it doesn't really matter how you get there from that perspective.

Not completely true - take two cases, powering a sprintex 335 to get to 350rwhp at 6000 rpm and a turbo to get to 350rwhp at 6000 rpm. Spinning the sprintex at high rpms will take quite a bit of HP, let's say 40rwhp. So to get there, the sprintex & motor will have to flow enough to cpver that extra 40 at 6000 rpm. To Justin's point, the turbo will have some losses in the form of backpressure on the motor when pushing the turbine hard, but in the end there it won't have to flow as much air through the motor to make 350hp at the wheels. Does that make sense?

[mrk1]

Originally Posted by bfrank1972

Yes you can have really optimized turbo systems, like BMW's have, but most aftermarket kits always have at least a little bit of lag. Not necessarily terrible, but some prefer the razor sharp response of a well tuned supercharger.

There is no snake oil magic about BMW turbos, if you want razor sharp response from an aftermarket turbo it can be done. You will have to make compromises to gain that response but thats all in the setup. If you compare engine size to turbo size of an OEM setup the turbos are pretty small compared to aftermarket setups. Thats because aftermarket kits want more HP and made the compromise on response.

If someone came to me looking for a turbo kit and was ok with SC level HP output then response and low end power would be the focus and would be killer! This however is not a goal of most so your off the shelf turbo kits won't do this.

My problem with SC is that it can never spin up faster then the engine, sure there is gear reduction to whatever degree but at the end of the day its a fixed ratio resulting in X boost at X rpm. Turbo is free to go above and beyond.

[bfrank1972]

Well... snake oil no, but they do have some advantages - they have freedom of engineering the entire powerplant as a package. I get what you're saying, but they're able to optimize the entire system & packaging. For example, see below

[mrk1]

I can hear the "heat weines" complaining about that now haha

But yes I see what your saying and your right the aftermarket will never do it on a production scale.

[jwvand02]

Originally Posted by bfrank1972

Not completely true - take two cases, powering a sprintex 335 to get to 350rwhp at 6000 rpm and a turbo to get to 350rwhp at 6000 rpm. Spinning the sprintex at high rpms will take quite a bit of HP, let's say 40rwhp. So to get there, the sprintex & motor will have to flow enough to cpver that extra 40 at 6000 rpm. To Justin's point, the turbo will have some losses in the form of backpressure on the motor when pushing the turbine hard, but in the end there it won't have to flow as much air through the motor to make 350hp at the wheels. Does that make sense?

No, you're right, and I get it. What I'm saying is that doesn't really matter. At the end of the day, 350whp is 350whp no matter how you get there. The difference really comes in the delivery of the power and the fuel economy, so how the power is produced is really a 'why' not a 'what' when it comes to performance outcomes.

[FRS Justin]

Originally Posted by avishenoy1

Nice post, I think you did a good job of summing up the pros and cons of both options. That being said I think you failed to note the difference between Roots type SC's and Centrifugal blowers. The roots type will require far less maintenance than a centrifugal and probably even less than a turbo.

The Edelbrock kit has a self contained oiling system with a 100,000 mile recommended service interval.

Additionally, I'd like to add that any aftermarket turbo will most definitely cause more wear on the engine due to heat. OEM turbo's are usually placed in a location that minimizes the heat transfer to wear parts on the engine, but pretty much every aftermarket kit for our cars mounts the turbo right in front of the crank pulley.

So basically I would disagree with the argument that a turbo kit places significantly less wear on the engine internals. Turbos get hot, and heat causes problems.

Nice call on the types of S/C that will make a difference I should of elaborated I was just stuck on the comparison I posted earlier, your statement is a solid piece that should be considered.


I understand about Edelbrocks 100k service but I can't even think about waiting that long can you imagine the condition of the oil at 100k YUCK!!!



All your points are spot on. .......


EDIT

[FRS Justin]

Originally Posted by bfrank1972

Not really free power, a turbo is always an obstruction in the exhaust path, but superchargers will indeed add more load to a motor. Also not sure if mentioned specifically in this thread so far, but transient response is always better with a supercharger. Yes you can have really optimized turbo systems, like BMW's have, but most aftermarket kits always have at least a little bit of lag. Not necessarily terrible, but some prefer the razor sharp response of a well tuned supercharger.

Another excellent point, but it should be noted the only way to get that true instant response on a S/C is to run them in a overdrive ratio which heats up the unit and air charge and reduce the top end efficiency the S/C


Solid points you made

[xwd]

Originally Posted by FRS Justin

Nice call on the types of S/C that will make a difference I should of elaborated I was just stuck on the comparison I posted earlier, it is a solid piece that should be considered.


I understand about Edelbrocks 100k service but I can't even think about waiting that long can you imagine the condition of the oil at 100k YUCK!!!



All your points are spot on. .......

Even driven hard and spun faster it would be around 25-30K miles, which is likely several years for most 86 owners, so it's not really valid. Turbo systems are way more complex to initially install as well as maintain. I've had lots of turbo cars and seen quite a few engine failures attributed to turbo oiling issues, wastegate malfunction, boost control issues, or simply turning the boost up higher than you should since it's always an option.

I would edit your post since comparison a centrifugal S/C to a turbo is really comparing a belt driven turbo to an exhaust driven turbo. Even then the transient response of the S/C at 5000 RPM is going to be better than the turbo since the boost it creates is instant, dyno plots don't really tell that story at all.

[xwd]

Originally Posted by FRS Justin

Another excellent point, but it should be noted the only way to get that true instant response on a S/C is to run them in a overdrive ratio which heats up the unit and air charge and reduce the top end efficiency the S/C


Solid points you made

That's not entirely true.

[FRS Justin]

Originally Posted by jwvand02

The whole "where the power comes from" is a fallacious argument. The end result is you're still paying x dollars for y power gain, and it doesn't really matter how you get there from that perspective. The only part that's really salient in that argument is one that you didn't mention, which is impact on fuel economy, in which a really well tuned turbo will typically do better from an economy standpoint when you're not winding the motor out.

Turbos are also typically less fool-proof, they're not as easy to install for a DIYer and have more points of failure. They also typically have non-reversible steps, such as drilling and tapping the oil pan. The end result is that the cars take more work to sell and you have a better (if still minimal) chance of catastrophically damaging the car. Most of this is no big deal to someone who is experienced in working on FI cars and has the money and time to put into it, but for just a hobbyist a SC is often the better way to go for that reason alone.

I personally chose SC because I feel like it's the easiest and cheapest way to get to the sweet spot for the 86, but only because I have ready access to E85. If I didn't have easy access to E85, I probably would have gone turbo. I still miss my turbo car though, because even though I think they're less practical there's something I actually sort of enjoy about turbo lag

You make a excellent point in the first paragraph from a consumers point of view, which I did not consider. I was more into the efficiency of the F/I method point of view. So in my opinion it wasn't really a "fallacious" statement, but I can see your point of view, In all 3 paragraphs from a consumers point.

[FRS Justin]

Originally Posted by xwd

That's not entirely true.

please explain

[FRS Justin]

Originally Posted by xwd

Even driven hard and spun faster it would be around 25-30K miles, which is likely several years for most 86 owners, so it's not really valid. Turbo systems are way more complex to initially install as well as maintain. I've had lots of turbo cars and seen quite a few engine failures attributed to turbo oiling issues, wastegate malfunction, boost control issues, or simply turning the boost up higher than you should since it's always an option.

I would edit your post since comparison a centrifugal S/C to a turbo is really comparing a belt driven turbo to an exhaust driven turbo. Even then the transient response of the S/C at 5000 RPM is going to be better than the turbo since the boost it creates is instant, dyno plots don't really tell that story at all.

I'm trying to see this thru your eyes and I'm not understanding your post 100%. I have seen some of the points listed for failure on both Turbo and S/C so I consider them both to be able to fail equally in given examples. As far as level of difficulty for install that entirely is on the person doing it, Example I know techs that are fuel injection wizards but put a carb in front of them and they are lost. It's all in what your familiar with.
As far as response of a F/I setup, that is entirely based on tuning of the F/I product while the big name S/C companies have done a fairly good job on this a turbo can be tuned to respond the same based on design. Pipe sizing and Exhaust housing sizing Impeller sizing all go into making a system work well or not at all.


I do appreciate your input, it help me come to a conclusion that I never thought about. As far as how others perceive there choice in F/I systems and why.

[bfrank1972]

Originally Posted by jwvand02

No, you're right, and I get it. What I'm saying is that doesn't really matter. At the end of the day, 350whp is 350whp no matter how you get there. The difference really comes in the delivery of the power and the fuel economy, so how the power is produced is really a 'why' not a 'what' when it comes to performance outcomes.

Hah I do get your viewpoint - but I guess what I was getting to is stress on the motor - it has to work harder to put down 350rwhp than the turbo car. I was completely oblivious to this point until I joined in a thread with Moto Mike a while back. He sort of illustrated it to me - the motor has to work to produce 350hp at the rear wheels AND take on turning those rotors on top of the motor. Just for example, let's say mechanical failure rate for rods and/or pistons increases dramatically around 425 ft-lbs at the crank. The turbo car putting down 350rwhp will have a lot more headroom than the supercharged car.