What to say about the past year? What has happened?
Everything and nothing has happened.
Sold the car, bought a new one, still have the engine and it's still in pieces.
We have recently started work on the engine after a looooong break. Give me six months and I'll have it up and running.
The waiting part is the worst, all the little things that keep popping up.

See, the thing I always seen overlooked in these articles has a lot to do with writer bias.

Turbo's are nice, and create a lot of power, but at different RPM ranges than what supers do. A lot of it has to do with application. A turbo works better on smaller engines than superchargers do. This is because of the initial powerloss in driving the supercharger. Also, turbo's are very "peaky", meaning that at lower RPM's they create much less power than they do at their "tuned" RPM setting, and have a decently large falloff after peak.

So, the choosing of super vs. turbo has more to do with driving style than what it has to do with the system. Yes, the turbo is a more fuel efficient method of creating boost. However, if you need more consistant power across all RPM ranges than you do at a specific RPM, superchargers are the way to go. Big CID engines benifit more from superchargers than from turbos because supers are "always boosting", even at the very low range were Big Block cars need the most help (Heavy cars, were most BB's are, need the extra help getting off the line). Super setups on large cars are designed with the intent of helping the engine get the car off the line quickly, then allowing the engines natural power carry it down the strip were displacement power is more than enough.

Because the power curve on them is more consistant, it helps in engine longevity because there is less wear from violent changes in pressure and heat that turbo's incur.

Turbo's on the other hand are best with smaller engines because these small engine setups need the help on the upper end. Small engines on small cars are easy to get off the line, but need help in the higher ranges were turbo's have their natural advantage. The higher the RPM's the more exaust is going through the turbine, the more it boosts. So these setups are designed to allow natural displacement and low weight launch it off the line, then the turbo's engage to carry it down the strip. It should be noted however that unlike popular belief, turbo power is not "free". Back pressure created by turbo systems rob your engine of power just like belt fed supers do. Once again though, supers have consistant drain were turbo's aren't. Higher RPM, higher backpressure, which is why in the top RPM's turbos experience power drop. Turbo size is also a consideration in aim. Bigger turbos create more power, but initialize later. Smaller turbo's create less power but engage earlier in the RPM range. This is why supers are more popular with drag racers, they need immediate power for the first 100ft were drags are usually determined.

Now, rarely seen, but very possible are turbo fed superchargers. This allows the low RPM power of the super to aid the engine in "off the line" and the turbo kicks in later for top end power. But that is a much more complex beast.

At the 1000-2500 RPM range superchargers beat out turbos because of the power characteristics mentioned above. At the 2500+ RPM range turbo's create more power than superchargers. So, it depends on what kind of racing you do, were you need the power gain, were you can accept the car to run "under it's own power", and what your driving style is. The caveat is that superchargers are a dumb idea on any small engine but turbos can suit large engines.

I think it's safe to say that each type of forced induction has its advantages and disadvantages, and max power power produced is usually dependent on

( drumroll please )

intended application and builder skill, i.e. not everybody wants/needs/can produce 1200 hp.

That being said, let's put this one to bed once and for all.

Monterey> Interesting reflections. I would like to make it a little more interesting though...
How about leaving on transbrake @ 5000rpm?
That should have a fairly large turbo spinning as well.

Don't get me wrong, I do love the superchargers. To have the consistent pull all the way is just plain awsome.

I know this is an old thread to everyone else but this is a new one to me being a new member. I am stuck in Afghanistan with nothing to do in my spare time but read up on old threads pertaining to my build when I return home. I can honestly say this was a LONG, but interesting and informative thread. For the 440 in my 68 Cuda I am going with the Dyer's 8-71 set-up. Not knocking any other type of forced induction, just for the look and drive I am going for, this best fits my application. A lot of good info from a lot of people, you can definitely tell when there is experience talking. For anyone wanting to know the full "in's and out's" of every type of supercharging I have to recommend the book "Supercharged-Design, Testing and Installation of Supercharged Systems" By: Corkey Bell. He touches more on Roots, Centrifugal and Twin Screw than Turbos, but he has another book strictly about turbos for those interested. I purchased mine off Bentley Publishers website and it got here quick, even being in Afghanistan. I can't even begin to describe all the content in this book, it's pretty much the bible of Supercharging in my eyes. (You'll have to excuse my bible comparison for any religious finatics out there, no disrespect intended at all) All I can say, is if this book doesn't teach you a thing or two or at least open your eyes to the best set-up for your application then there is no hope for you. I enjoyed reading this VERY LONG thread and will continue to look for others. Take care.

Kevin

There is no "BEST" solution. Both turbos and superchargers have their strengths and weaknesses. It all depends what you have, what you wish to use it for, and your budget.

But there are a few basic truths to consider. Turbos are not directly connected to the crank, so they always lag the engine during flat out acceleration. This is hardly a problem in a mildly turboed production road car, but as power to weight ratio increases, the lag problem becomes really significant. That is why there are no successful turbocharged production motorcycles. And why there are no four second turbo drag cars. Even though the existing Top Fuel rules do not allow turbos, if it where possible, someone would have built a three second turbo car. But in truth it would be completely undrivable, which is why nobody has ever bothered to even try to do it.

Likewise, try fitting a GM roots supercharger UNDER the hood of any vehicle is just about impossible on anything but a hot rod. Turbos are far more practical for most modern street cars, and because they are practical they are better.

I have had great success with both supercharging and turbocharging over the years, but by far the best results are from using both together. So called "twincharging". It combines the advantages of both, without the disadvantages of either. Excellent low end torque, lag free throttle response, and massive top end airflow only a turbo can provide.

There have been three mass produced production twincharged cars, the Lancia Delta S4, the Nissan March, and the current Vollkswagen Golf GTi. All used both a roots supercharger and a turbocharger together.

I find it curious that after seven pages of this thread, twincharging has never even been mentioned. I was probably one of the pioneers of twincharging, I have been building twincharge cars, and helping others to develop twincharge projects for over fifteen years. Google "Warpspeed twincharging" I have been involved in threads all over the internet on this topic. The best, (I am told) is now a "classic" thread on the Engineers Forum:

http://www.eng-tips.com/viewthread.cfm?qid=174690

I am the Warpspeed in that thread.

I'm of the belief that forced induction is in the eye of the beholder. I have spent many hours reading the pros and cons of supercharging versus turbocharging. Once its in the intake manifold, the rest is academic. I will agree that the turbocharger has its attributes with heat and engine compartment hogging being the primary issues. They are a plumbers dream. I presently run a Paxton Centrifugal Supercharger on my Dodge. About the only benefit I can see over my friends turbos is the lack of boost lag. Although this is a con of turbocharging, it is really insignificant to a degree. I am presently working on a mouse motor buildup utilizing a 6-71 roots supercharger and realize that the stresses on the front of the crank are of consideration but insignificant when using high performance forged parts. Remember, we are talking high performance here. The debate over forced induction systems will go on forever. Me personally? I like em' all. Turbo, Centrifugal Supercharged, and Roots Supercharged. It's mostly a matter of personal preference and aesthetics. Right? Cool is cool.

I pick Turbo's since they are much more effecient and make more power over a wider RPM range.
And it's priceless when a V8 owner finds out he just got his butt handed to him by a V6

10.32@133mph on 93oct. on drag radials.

So if turbos are more efficient and make more power, where are all the four second turbo cars ??

And don't tell me the Top Fuel rules don't allow turbos.
If supercharged Top Fuel cars can do fours fairly readily, you would think a turbo car should maybe be able to break into the three second class, huh ?

After all they are more powerful and more efficient right ???

Should be dead easy if you are right.

If you are wrong, that might be why NOBODY has been able to build even a four second turbo car. And the people that know, would not waste their time even trying.

You're missing one key word! NITRO! The only way they can go from 0-100 in .08 and do 270 in the 1/8 ,and make 7k HP is from the nitro. There is no way to make that kind of power,blower or turbo, without that fuel.

They did try large cubic inch big motor turbo cars.... they can't put all the power to the ground. Even back in the day!

Now that technology has caught up Someone might build one that'll be able to do just that. Only time will tell.

They can't put that kind of power to the ground now.. if you watch Top fuel cars from the back they lay rubber down the entire track. It's nuts.
~Scott

I will tell ya all about it oct 31,My plane lands in vegas at 9:30 and its off the the track for NHRA qualifing. Those car are detuned quite a bit also to able to get down the track.

Everyones moaning and groaning has me head in a spin...

LOL's. I'm thinking of going both routes. 6-71 for instant power....and twin turbos for the other end.... That way everyones happy.

Dave G

Everyones moaning and groaning has me head in a spin...

LOL's. I'm thinking of going both routes. 6-71 for instant power....and twin turbos for the other end.... That way everyones happy.

Not really. I think I'm going for the twin turbo's on the LS for the 36. I dont want a big huffer sticking through my hood. Personally want to be able to see the passenger side of my hood. And I'm concidering someone elses comments much earlier in the thread.....routing these towards the rear of the truck. Less heat....no space wasted.

Dave G

Well, I read all of the threads... I'm quite impressed with many, baffled by a couple (due to the interesting lack of education... No disrespect meant).

My take on this subject is pretty simple... I LOVE supers! Huffers are the eye candy of the car. While this is only an emotional response, it still has its place in making the decision between turbs and positive displacement stuffers. I love the look of the monster lurking above the hood of a tiny Vega. The tensioner, the cogged belt, the bug catcher, and all of the shiney stuff that makes your eyes pop. I know the advantages of the insta-torque when you tip the pedal. That makes other things get all tingly. The whine of the rotors and gears is music to my ears. I could go on...

Other side of the fence thoughts...

I have done a lot of reading. I have talked to other builder/racers. I have looked at installations. I have come to a conclusion... While stuffers are all of what I have already said, I have to give the nod to the turbo for most racing needs. As it has been repeatedly said "turbo lag" is virtually a thing of the past due to better combinations and adders. I think that someone also said that turbos impart more heat to the intake charge air due to the fact that they run hot exhaust through them to spin up the compressor side. No, there is no intermingling of the exhaust and compressor side (OK, maybe a little temperarure rise, but only due to proximity).

"Blowers" as they are called, have been around since the late 1800's. Yeah, I know that the internal combustion engine came around at the same time. But the Roots unit was initially used to pump air into mines for breathing air and tools. Hence the name "Blower". Man's erternal need to Tim Allen-ize stuff put that blower onto an engine to make more power. Thanks to them we get to have fun.

So, while I love the supercharger for its brutish looks and power adding capability, I also love the way that a turbo can make the car a sleeper until you tip the skinny pedal. I personally love the sound of a turbo, while others think that it sounds like a vacuum cleaner (never could get that one). Oh well, to each their own.

I haven't talked about the hybrid of the two (centrifugal). While I have seen some pretty impressive HP numbers for these, I' just not a fan (no pun intended).

Hopefully soon, I will have my 69 Stang loaded with a 341 SB with twins underhood. And then I can build the 70 Stang with a stuffer. Best of both worlds for a split personality. Now I have to win the lottery.

Oh, by the way... Diesels and drags. There has been an uprising of diesel draggers. These torque mosters can get into the 10's without much work. And I'm talking about a truck. Gale Banks makes some wicked aftermarket stuff for the slippery fuel boys.

And another note for the people that don't believe in the power capabilities of the turbo... Ever seen a tuner front wheel drive with a four and turbo that can kill a 341/two stage nitrous purpose built drag stang? I almost shat my pants the day I saw that. Granted the power to weight was an advantage. BUT IT WAS A FRONT WHEEL DRIVE P.O.S!!!

However it shakes out, enjoy the ride you have and build it the way you want. You can't go wrong if YOU like your ride.

Cheers to everybody!