Quicksilver

iTrader: (1)

I'm slightly confused by your statement. If you could, please clarify some issues for me/us (I'll list my thoughts below)...


A turbo system can be setup to produce low and middle range power, middle to high end power, just high end power, or all three.

A S/C, depending on the type (roots or centrifugal type) provides different power bands as well (lower range for roots to mid and upper for centrifugal).

A turbo system would be more flexible overall, but is also more complex and expensive.

A S/C setup is easier to install and gives more gains for the money at lower boost levels, but is superceeded by the turbo for high HP applications (I'm talking about street driven vehicles here, not pure race vehicles).


Those are my thoughts. Please provide us some clarification on what you're thinking.

nismology

iTrader: (8)

I think what he meant was that if you compare PSI for PSI turbo vs. supercharger, the torque, at least with MEVI, will continue rise to redline or stay fairly constant with a SCer because the engine is getting more and more air. Turbo will have a big advantage in the mid-range but because it is only giving X amount of air no matter what RPM, the torque starts to drop off at higher RPM compared to mid-range.

twotone

iTrader: (1)

That is correct...
and since Craig said his roots setup because of these facts was superior to a turbo setup (by the gains at low-end being more then turbo) I want to know if I launch against turbo with more low-end and continue to rise to the redline wouldn't this be the better setup?
S/C is more reliable (especially or daily driven).. and if this setup can exceed low-end and continue to rise wouldn't this bypass any idea of a turbo setup

DA-MAX

iTrader: (10)

IMHO reliability goes as far as the means and methods used to tune the system. you can make a turbo set up on a Maximas as if not MORE efficient if you have the right methods and knowledge to do so. so flat out saying an SC is more reliable is relative.

twotone

iTrader: (1)

S/C is proven method..
Doesn't have as much problems as all the kits that have come out and the horror stories of blow turbo's (custommaxima's, PFI, etc)..
Its just been more reliable...
What do you hear more of blown SC or blown turbo?
Trust me if there is a kit out there that is tried and true I would love to go in that direction over the S/C.. but from all the facts a daily driver to be boosted the route is S/C.

Jeff92se

iTrader: (82)

Wha? "heard" that YOU have heard of? I have seen probably 3-5 SCs being rebuilt. I have only seen 2-3 turbo being rebuilt.

SC and turbo systems both have problems.
SC belts and pullies breaking/wearing out.
Turbos, mostly poor piping, exahust leaks and poor turbo drain. Mostly because of the grassroots nature of the builder.

ANY type of boost is taking a chance. If you want a bullet proof system, it doesn't exist.

Quicksilver

iTrader: (1)

That's not true either...like I said, you're basing your opinion on current kits for our cars. But you're not looking at the big picture. The fact is that the T/C "can be" made to do anything a S/C can do, only better since it's a much more flexible setup. It's all in the design. Can a S/C provide you with the same TQ from 1950 to 5500 RPM like the Jetta 1.8T engine? i sincerely doubt it. from most of the setups I've seen dynoed, the T/C system gives more area under the curve (when properly setup and tuned).

nismology

iTrader: (8)

Right but you're missing my point. The turbocharger will only be pumping X amount of air at full boost no matter what RPM. So it is only natural that the engine makes more torque at mid-range than close to redline while with the supercharger gets better and better or stays constant because it is getting more and more air as RPM's rise. It the same concept as a single stage nitrous system. There is X amount of nitrous being introduced to the cylinders at WOT independant of RPM. Naturally, as VE decreases, so will the torque output at higher RPM. It also decreases with the SCer, just not as much. The ideal setup would be a motor-assisted turbo to eliminate lag at lower RPMs plus variable boost that rises with RPM as VE drops, much like a supercharger. I'm not at all denying the mid-range advantage of turbos, which PSI for PSI, will be faster overall.

Jeff92se

iTrader: (82)

Wha? The VE of either a TC or SC is dependant on their respective designs. To say a SC won't lose it's VE as much as a TC(as the rpms rise) as a general statement isn't correct.

The ideal TC would be a VATN style TC

nismology

iTrader: (8)

I was referring to the engine's VE.

Jeff92se

iTrader: (82)

Still valid. Please explain in technical terms why a SC will be pumping more air as the rpms rise while a turbo will not?? Doesn't make sense as a general statement. Both will. But the question is will both pump more air in an efficent manner?? ie.. not heat up the charge air too much to negate the higher psi values??

nismology

iTrader: (8)

I have yet to see a turbocharging system for the street that allows for increased boost as RPM's rise unless you weld the wastegate shut. Given both the supercharger and turbo are within their respective efficiency ranges it's impossible. Perhaps you can enlighten me with a link or two.

Jeff92se

iTrader: (82)

Hmm you mean if you spin a SC with a certain pulley size it will keep rising the boost?? It might as well have a WG also. Because at a certain rpm it will only be boosting to a certain level. Again what's the difference??

What do you think is easier to change? A SC pulley or a **** on the boost controller?

Mishap

WTH? I cannot believe how incorrect your information is. A turbo does not create a constant airflow throughout RPM. It creates a constant pressure level by varying how much exhaust gas enters the turbine housing to spin the turbo. At higher RPM's the turbo is spinning much faster to provide more air to hold pressure inside the intake the same. That means on each stroke, the car is getting the same amount of air per stroke as at lower RPM's. In a centrifugal SC, it's impossible to build good low end boost w/o massive parasitic loss w/ tiny pulleys.

Reason why most SC setups continue to have torque rise throughout the rev range is b/c they don't make any in the low end. Sadler's turbo makes more torque at 3500 as a lot of SC's make at over 5500. The turbo has fully spooled by 3000 and accelerates throughout the rev band to hold boost constant. If he starts to push more boost the T04E may become a problem if it cannot provide enough flow to handle the engine's air needs but that's already to the point where the stock engine becomes a liability.

You don't need variable inlet turbos to get good power without any lag. If you want to make crazy power on an undersized engine, then you definitely need such technology but otherwise it's superfluous.

As it stands, the turbo already trumps the supercharger. The ideal supercharger however would be one that is geared to start boosting earlier while reducing drag and can increase the gear ratio to hold boost constant.

Another major part of the SC not heating intake temps as much is b/c they aren't capable of the same boost levels all the time. At redline, intake temps aren't all that different given they are taken before any intercooling. Compressing air creates heat...compress it the same and it creates the same heat. Heat from the turbine side is negligible at the speeds air is flowing through the system.

Neither system is at all like nitrous which is a constant flow of gas no matter what RPM so that comparison is invalid.

nismology

iTrader: (8)

If you refer to post 40, TwoTone said the SCer will have continuing TOP END while the turbo will not. While this is not entirely true, it makes sense to a certain extent. If you look at the torque curve of a blown 4th gen with MEVI, the torque will often times either increase to redline, or plateau. Since it is impossible for a turbo (with the current consumer technology available) to continue to increase boost with RPM, plus the fact that the engine's VE is naturally decreasing towards redline, the torque drops off. Either way, the turbo will be faster because of the HUGE mid-range advantage.

As for Mishap, point taken in your first paragraph. But the VE is decreasing for X amount of boost present in the intake manifold, so torque must decrease. It is almost impossible to get the same cylinder filling at 6500 RPM as 3000 RPM with a fixed boost level because VE is not a constant with relation to RPM.

Mishap

They have progressive boost controllers already. Just have to be able to spend enough money for them. Things like the Greddy Profec E01 can be used to tweak boost curves and provide overboost for those situations where extra power is desired. Things that would require pulling the SC to change boost levels. Even easier to see boost increase w/ RPM would be disconnect the wastegate and watch the engine reach 30psi as it lets go.

You can size a turbo to act almost exactly like a supercharger. Just size it so big that peak boost only hits at redline. Then you end up w/ peak torque at redline. Take a look at all those dyno charts, there isn't an instance where a SC makes more peak torque than a turbo at the same psi or even similar levels. Turbos just hit peak torque much earlier so the curve is nice and flat for the most part whereas on the SC it only reaches that kind of torque just before redline.

Forgot to mention...you don't have to weld a wastegate shut. Just disconnect the vacuum hose to it and it'll never open. Or not until long past the engine's breaking point

Quicksilver

iTrader: (1)

Judging by you last few posts, I can pretty much assume that you've never read Maximum Boost by Corky Bell. If you have, then you skipped some very important info...

JAIMECBR900

This is nice. We have a bunch of people that read books and articles and DON'T have turbo OR a S/C in their cars. Gimme a break. Stop arm chair quaterbacking already.

We can get super duper technical and really compare the differences between two distinctly different ways of FI. We can even bring in examples on how one system worked better on a certain day, in a certain car, under certain conditions. None of it, IMO, means a hill of beans. You know what does??? That you have FI at all!!! Instead of down playing the other systems possible weaknesess, we should all try to and point out the strengths too. Not a single person that actually has FI has ever made the leap to do the project while thinking about the BAD stuff. Everyone, if sane, always goes into the project with 8 sec fairies dancing in their heads. If someone had the skill, I'm sure we could sink the same $3-5k into a built 350 small block swap and gut the car and it would be faster than most S/C'd and T/C cars on the street. Is that what we want or can use? Probably not. What does that have to do with how a S/C or a T/C works? Nothing. Except that idiot who did the 350 transplant is now faster than you. Big deal! He's still an idiot.

Instead of you guys bickering back and forth you should agree that each system has it's stregths AND weaknesses and be done with it already. We have strayed so far off on tangents is not funny.

In a nutshell: A turbo can give you more HP period. A S/C is less expensive and easier to install. A big turbo gives big HP and big lag. A S/C will only give more boost when changing to a smaller pulley which depending on the setup (mine is a 15 min job) can be a PITA, so a turbo setup may be easier to boost up once installed and tuned. A turbo is expensive initially, but it has more flexibility to later up the boost levels using the same initial equipment. A backyard turbo will probably end up blowing either itself or the motor up. A properly installed and maintained turbo will last for as long as most would ever want or need. A S/C will also last as long as anyone needs as long as proper applications are used. There are inefficient turbos and S/C. The inefficient ones are usually single purpose types (i.e. race-only gargantuan sized turbos, screw type blowers, etc.).

Can't we all just get along???? Be nice people.

abradic

iTrader: (1)

There is one missing fact here. A supercharger keeps pulling in more and more air and the psi builds all the way to redline. It does this because the engine revs higher turning the SC compressor faster and faster. Everyone has that point right.

A TC is pulling in the same amount of air as a SC, but at a much earlier RPM. When both are at max boost, say 10 psi, both are moving the same amount of air. The difference is a TC achieves this at a much earlier RPM so the torque is reached earlier. A SC achieves this towards redline so full torque is reached later. A TC does this quicker because it only takes a certain amount of exhaust gas pressure turning the turbine to spool up the compressor to full speed. Most will see enough exhaust pressure at 3000 rpm to fully spool the TC. It can easily pull in more air if it wasn't bypassed through the wastegate, but that is the idea of controlling your boost.

A SC is not fully spooled until you are near redline, so you will build torque and pressure to that point. A SC only takes longer to spool all the way, but at 10 psi, both are pulling in the same amount of air. The difference is a TC gets to that volume quicker than a SC...at least a centrifugal one anyway.

twotone

iTrader: (1)

Ok.. now going with all of this in mind..
1. Which is a better application? TC? centrifugal? roots?
2. Which is more reliable for a daily driven car?
3. Which will give me up to 14psi on stock internals that can be driven without worry.

Problem here is I hear horror stories on both applications. I hear TC is really nice and better way to go but can I ask because TC spools up quicker is that worse for the engine? Is it worse that at low RPMs the torque is so high?(this would possibly be a problem with roots setup also). Is it safer for the engine to have gradually increasing boost by centrifugical setup?

I don't think one is better then the other.. and the about of stock turbo to stock s/c is more by far.. but these are specifically tuned applications. From what I have heard the applications of turbo setups seem to be having problems. Not quite done right yet... I think once an application setup is created after all the "bugs" that show up are fixed... This will probably be the ideal application for anyone with a max looking for boost.

Just looking for anyones opinions on these setups.. their pros and cons.. if spooling to early on roots or TC setups is potentially harmful...

My first reply was to Craig's post about roots which I was trying to learn about because it sounded like a really nice setup... but ever since I posted (and he didn't reply yet).. it just seems everyone is screaming at everyone else :P

I am just looking for help moving forward on this path.

Thanks

Quicksilver

iTrader: (1)

Well, my current car isn't T/C'ed, but I've custom built two systems for previous cars and purchased a car that had two turbos originally...

But I guess that doesn't count

abradic

iTrader: (1)

Well, I know I am not TC or SC right now, so take it for what it's worth...There is no better way. You have to look at what you want. It's like asking which car is better, Camry or Maxima. Neither one is bad. Neither TC or SC is bad, both are good and have their ADVANTAGES. I hate to use disadvantage. I personally love turbos and the feel they give you. They are also very reliable when setup properly. Look at factory turbo cars like the VR-4, 300ZX, and Supra. They didn't blow engines because it was set up properly. Setting up your Max properly will cost $$$.

A SC is no safe bet either if not set up properly. No matter which one you choose, there are plenty of people on this board to ask advice of. It's going to cost money to set up either a TC or SC. Stillen's kit is $3500, but it goes beyond that if you want a little more power run safely. You can easily boost 11 psi safely, but have the car tuned right. It's more than just slapping a unit to the engine.

As much as I love TC, my goal is to get enough money saved for a V2 SC in my max before summer time. It's a more proven kit because Stillen adapts it to a VQ application and has done the research on it...at least he claims it! People on here seem to have less demons with it than the TC guys. The TC kits are all "experimental" in a sense, and will probably cost more money to setup properly to have great reliability, but it can be done. Besides, the centrifugal SC is on the same principle and judging by some videos, sounds like a turbo. Hope that sound is accurate?

Lastly, I am just as concerned as everyone about reliability. I do understand that once I power up a a car from 190 hp to over 300 hp, anything can happen. Extra pressure and forces may lead to less reliability, but you have to pay to play. I don't think you'll be blowing engines, but maybe burnt clutches, trans issues, etc... It most likely won't happen if setup properly, but the odds are higher that it may.

Again, either way you go, it'll probably be fun and fast. Nobody on here seems to regret ever doing it, and people here seem glad to help you with your questions. I know I'll have a million of them if/when I get to the point of SC'ing.

JAIMECBR900

An armchair quarterback probably knows football....does that make him a REAL quarterback?????

I'm trying to difuse what has now boiled down to a ****ing contest between people who seem to be arguing about a moot point. If you can't give out positive info along with the negative, don't reply at all.

Quicksilver

iTrader: (1)

I gave my information...both positive and negative about both methods. What I don't like is people trying to pass off bad info and opinion as fact. Someone tried to state something as fact, and that was disputed with proven information. I know that you know your stuff, as do others here. But there are obviously people out there (and on this site) that don't. That's why it turned into a pi$$ing match. Myths need to be dispelled. All that I am trying to do (and others here as well) is stop the flow of dis-information. Also, I can respect your opinions, but don't lecture me on post etiquette when you're doing the very thing you just preached about...which if I may be so blunt, is posting non useful information which does not relate to the subject at hand.

Now, to get back on subject, ABK is asking us for our opinions on which system is better. Of course, with opinions being as they are, you're going to get a lot of responses. Not everyone has first hand experience with superchargers and turbochargers. Some of those people actually know the overall dynamics of the systems, but have never used them personally. Based on my personal experience and experimentations, I would suggest you ask a question that is less widespread in nature. What I mean is, ask specific questions about each system or part of your vehicle. I.E. ;

How much does a S/C (T/C) system for my car cost?

What kind of performance gains can I expect from this system?

What issues or problems does this specific system have?

What kind of effect will this system have on my existing engine?

What other systems on my vehicle will be effected by this version of forced induction?

What are the environmental impacts of my forced induction system of choice (OK, this isn't something most of us would ask. But I would, and so I listed it...) ?

What laws/rules/regulations (if applicable) am I going to be involved with when I alter my vehicle (emmisions...etc) ?


OK, you get the general idea ABK. Some of this information you can find on your own with help from you local law enforcement, department of transportation, and so on. Other info you can find here on this site, through further internet research, through reading published materials, and talking to performance shops in your area.


And Jaime, I wish the pi$$ing contest had never happened in the first place as well. I for one will at least attempt to lessen the fanning of flames on controversial issues from this point on...

Peace

Justin

Craig Mack

No problem. I doubt he would want to take the time to do all the dimensions and what not again. But if he can do it, theres no doubt in my mind that an Engineer (you) would have zero trouble whipping up some dimensions.