Contour Enthusiasts Group Archives Forums Modifications Zetec Performance svt zetec contour???

Originally posted by Kremithefrog:

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a s/c never really reaches true full boost,,,

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You have got to be kidding me...... A blower gives boost depending on how fast you have it set to turn, thats why different size pulleys are used. Smaller pully=SC turning faster=more boost.

Originally posted by Kremithefrog:

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and as I said, a turbo is also always spinning though not always boosting, but reaches full boost much sooner than a s/c ,,,

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Its all in the design.

I have 2 mechanics here right now laughing at this post, total experience in building performance V8s is about 30 years. Guess you know more than they do. I had to tell them to see this post cause I knew they would get a kick out of it. I guess my experience building 2 SC motors are a mute point here, too

Get this straignt- An engine can have equal output whether SCed or turbo charged..ITS ALL IN THE DESIGN.

All hail the boost god.............Kremit

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A home built turbo kit is going to be THE most cost effective way to make good power. But it's very easy to screw it up. Due to the stresses and heat invovled, not to mention the fact you have another independent heat engine operating (or two!) under the hood, there's just more to think about.


However, when you do it right, they work great. Just look at Porsche. They engineer them right, and the system is just as reliable as a NA engine.


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My other thought is for power adders on the track, the big teams (Audi, Porshe, etc)seem to have good results with them vs SC's (and other than the Steeda car, I haven't seen a centrifugal out there).
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SC's just can't compete, plain and simple. They are drawing power off the crank to power the compressor, and the turbo uses waste heat. Not to mention boost control.


I've often said, superchargers would be great if you could take a centrifical blower, gear it up to make boost early, but then have a CVT transmission to slow it down at higher revs, the idea being to tailor the compressor speed to provide the right amount of boost early, and hold that boost until redline.


The fact is, turbos do that already, with a much more simple system, and again, you can't ignore the fact that they are using waste exhaust heat instead of crankshaft power.


Roots blowers are horribly inefficient. Centrificals have peaky power delivery. Nothing down low, then too much up top.


A proper turbo should be able to supply full boost below the torque peak, and hold it steady all the way to redline. If you're really smart, you can have an intelligent controller that varies boost with rpm, and can give you an absolutely flat torque curve. Hit a healthy boost at max torque, and push harder as you move past the volumetric efficiency peak of the engine.


What's funny is, 90% of the supercharger fans I see on the Focus boards ONLY do it for the "golly gee whiz" factor of having "that cool blower whine", or because they saw it in Mad Max or some stupid [censored] like that.

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Originally posted by CRZYDRVR:

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Originally posted by Kremithefrog:

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a s/c never really reaches true full boost,,,

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You have got to be kidding me...... A blower gives boost depending on how fast you have it set to turn, thats why different size pulleys are used. Smaller pully=SC turning faster=more boost.

Originally posted by Kremithefrog:

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and as I said, a turbo is also always spinning though not always boosting, but reaches full boost much sooner than a s/c ,,,

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Its all in the design.

I have 2 mechanics here right now laughing at this post, total experience in building performance V8s is about 30 years. Guess you know more than they do. I had to tell them to see this post cause I knew they would get a kick out of it. I guess my experience building 2 SC motors are a mute point here, too

Get this straignt- An engine can have equal output whether SCed or turbo charged..ITS ALL IN THE DESIGN.

All hail the boost god.............Kremit

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Tell me about it.....it is all about design....S/C can compete with T/C....all depends on car/engine/etc....Zetec S/Cs just don't make more torque....I'd still take one....at least it wouldn't mess up my ATX.

Originally posted by Kremithefrog:

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Obviously many of ya'll don't understand s/c and turbos,,, thinkmoto and this thread starter included... As seawulf said a s/c never really reaches true full boost,,, and as I said, a turbo is also always spinning though not always boosting, but reaches full boost much sooner than a s/c ,,, but since ya'll can't do any research and can't get it through your heads what I'm saying, then go ahead use a supercharger and CLAIM how much better it is than a turbo....... afterall it's your money.


And thinkmoto turbo lag is not defined as the period of RPM where you don't have boost... but you probably can't understand that... we've already seen how smart you are.

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Originally posted by Thinkmoto:

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Well considering you like to quote people so much kramit. Here is a direct quote from how it works TURBOs

Turbo Lag
One of the main problems with turbochargers is that they do not provide an immediate power boost when you step on the gas. It takes a second for the turbine to get up to speed before boost is produced. This results in a feeling of lag when you step on the gas, and then the car lunges ahead when the turbo gets moving.

One way to decrease turbo lag is to reduce the inertia of the rotating parts, mainly by reducing their weight. This allows the turbine and compressor to accelerate quickly, and start providing boost earlier.

So my proir statement is still all so wrong according to you huh

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Thank you......Kremit, you have been schooled....don't make me go scan some books.

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Ok, as for the drivability of turbos...

It shouldn't be a problem if you pick the right turbos, and don't get stupid with the sizing and boost. Most turbo setups are developed with drag racing in mind, and that camp falls for the "bigger is better" [censored] all the time. They choose huge turbos, decrompress the motor, and use tons of boost. The turbos take a week to spool up, and kick you in the ass when they do.


My method of picking a turbo:



Choose your target horsepower.
Choose the smallest turbo that will get you there.



Most drag race guys complain that "you'll want more power later" "Boost is addictive, you'll want more", etc... They choose big [censored] turbos that could power a Kenworth, and then drive it with a tiny engine, with no response, and brag about how much power they COULD be making if they turned up the boost and ran rocket fuel.

Just set your goals, and pick the smallest turbo that will get you there. You'll have the best response and drivability that way.

With properly sized turbos, they work great on track. You should be well above the "boost threshold" in any corner. As such, boost comes on almost instantaneously, and linearly with the throttle. Where you get into trouble is with a massive turbo that doesn't spool until 5000rpm. You come out of a corner at 4000, get on it, then halfway down the straight the boost hits like a freight train. This is another thing that has led to false ideas about turbos. You often hear superchargers guys say they don't like turbolag... Again, this is caused by these guys who use turbos that are too big.

Another thing is throttle bdoies. Most of these drag race guys run these huge barn door throttles, that flow 1000hp with only 10* of opening angle. I've seen guys put these on stock engines, and then brag about how cool it is that they have a hard time not hitting the person in front of them in traffic because the throttle is so touchy. Then you combine that thing with a turbo.... the boost is like a light switch.

On mine, I can get full boost by 2400rpm. On track, I'm rarely below 4000rpm. At 4000, I've got enough exhaust gas that it can accelerate the turbo in 0.2 seconds. So, as you roll onto the throttle coming out of an apex, the boost is linear and instantaneous. Feels just like a naturally aspirated motor. Ok, almost. There is a *slight* "squishiness" to the throttle. But it's very easy to work with.

In my opinion, a good target is to double the power of the motor, with 10-15 psi. Beyond that, you're going to have to decompress the motor, and that's when you start getting into drivability problems. A low comperssion motor with no boost is a dog, and then the boost hits hard. A high compression motor will have more power when off boost, and the change in power output as boost comes isn't as abrupt.

I'm running the stock TB on mine, and refuse to change it. I'm sure I'm losing a couple peak horsepower, but I get much better throttle control. Since the air from a turbo is compressed, you don't need such a big throttle to flow the horsepower. Smaller throttles make it easier to control the power at lower rpms, and if you want a little more power up top, just blow on it a little harder... I'd bet half a psi would give you just as much top end power increase as going from a 55 to a 65mm TB.

Anyway, that's enough for now. Any questions?

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The Whipple Twin Screw Supercharger-
Incredibly high adiabatic and volumetric efficiencies
Positive displacement design
Very flat efficiency curve combined with positive displacement design gives the most achievable torque of any method
Instant boost
A true compressor
Direct drive from the crankshaft
Compact and lightweight design
Virtually silent operation
Low temperature increases during operation
Very little power consumption
Unique combination of low rpm torque and high rpm horsepower due to the screw compressor design
Have the ability to run from 1 to 60 lbs. of boost

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So much for SC being inefficient, or not having instant boost. Properly setup, one of these will have INSTANT boost OFF IDLE and low to mid RPM all the way to redline. Which is where most of our cars spend their time at in traffic and everyday driving. I dont think any of us keep our motors at redline all the time. I have not heard of any turbo system that make boost of idle, there is always some lag. If anyone has a link to one, I would love to see it, not just some guys opinion. Im always willing to learn something