[futureMACH1racer]

Originally Posted by prodrifterx lol unless they runnin alcohol fuel and meth injection with water ot air intercooling.

+1

[99redcobra]

found this info

Now, back to the compression issue. Anyone who has looked into supercharging has heard that you need a low (static) compression motor. This may have been true once upon a time, when roots type (positive displacement) superchargers and carburetors ruled the land, but it's not so necessary now. The problem with a low compression motor is that it relies heavily on the supercharger for its power. An 8:1 motor is definitely not going to be a power house. Sure, you can throw 18 lbs of boost on it and get some real power, but why? A higher compression motor of 9:1 or even 10:1 will have much more power without the blower. Then, with less boost you could easily have the same overall power - only it would be much more usable. Both of the motors (8:1 with 18 lbs boost and 9.5:1 with 12 lbs boost) will have almost the same effective compression and about the same peak power. The big difference will be where you see the power, and how much of a demand will be placed on the supercharger. Obviously, the 9.5:1 motor is going to have far greater torque and low end power as the boost is only starting to come in. It is also going to be much easier to find a blower to survive at only 12 lbs of boost -vs- one that would have to put out 18 lbs of boost. It is now very easy to see why a higher compression motor with lower boost is becoming so popular.

[futureMACH1racer]

I'm tired, and it's late so I'm not getting into a debate, goodluck with your high compression high boost engine.

[acmillr]

99, I'm just going to be straight about this.

1. You obviously wouldn't be here posting all this nonsense if you knew what you are doing. So, please take some of the advice that is being given to you.
2. Kenne Bell, Vortech, Sean Hyland, etc. are going to tell you exactly what you want to hear to get your money (period).
3. Technical information in magazines is usually about 50% bullshit and 50% advertising dollars at work. Keep that in mind as you read the MM&FF "Bible".
4. You can build a great boosted motor on areasonable budget if you use your head, but you in store for a big dose of fail if you are not going to listen to people that havbe already been down the road you are going. Sean Hyland hasthe money to run C16 in his daily driver year round- Do you??

[futureMACH1racer]

Originally Posted by acmillr 99, I'm just going to be straight about this. 1. You obviously wouldn't be here posting all this nonsense if you knew what you are doing. So, please take some of the advice that is being given to you. 2. Kenne Bell, Vortech, Sean Hyland, etc. are going to tell you exactly what you want to hear to get your money (period). 3. Technical information in magazines is usually about 50% bullshit and 50% advertising dollars at work. Keep that in mind as you read the MM&FF "Bible". 4. You can build a great boosted motor on areasonable budget if you use your head, but you in store for a big dose of fail if you are not going to listen to people that havbe already been down the road you are going. Sean Hyland hasthe money to run C16 in his daily driver year round- Do you??

+1 REP

[futureMACH1racer]

Well I would've repped ya, but this time it wouldn't let me. I owe ya one

[HBK_2007]

well i only have two things to say
1. i think 500 is possible N/A from a 4v but it is gonna be a PITA
2. with the newer tech avaible, i think it is possible to run more boost and c/r on an engine but 10.1 and 10+ psi

[prodrifterx]

Originally Posted by acmillr 99, I'm just going to be straight about this. 1. You obviously wouldn't be here posting all this nonsense if you knew what you are doing. So, please take some of the advice that is being given to you. 2. Kenne Bell, Vortech, Sean Hyland, etc. are going to tell you exactly what you want to hear to get your money (period). 3. Technical information in magazines is usually about 50% bullshit and 50% advertising dollars at work. Keep that in mind as you read the MM&FF "Bible". 4. You can build a great boosted motor on areasonable budget if you use your head, but you in store for a big dose of fail if you are not going to listen to people that havbe already been down the road you are going. Sean Hyland hasthe money to run C16 in his daily driver year round- Do you??

amen to that

[Goblin]

Originally Posted by 99redcobra found this info Now, back to the compression issue. Anyone who has looked into supercharging has heard that you need a low (static) compression motor. This may have been true once upon a time, when roots type (positive displacement) superchargers and carburetors ruled the land, but it's not so necessary now. The problem with a low compression motor is that it relies heavily on the supercharger for its power. An 8:1 motor is definitely not going to be a power house. Sure, you can throw 18 lbs of boost on it and get some real power, but why? A higher compression motor of 9:1 or even 10:1 will have much more power without the blower. Then, with less boost you could easily have the same overall power - only it would be much more usable. Both of the motors (8:1 with 18 lbs boost and 9.5:1 with 12 lbs boost) will have almost the same effective compression and about the same peak power. The big difference will be where you see the power, and how much of a demand will be placed on the supercharger. Obviously, the 9.5:1 motor is going to have far greater torque and low end power as the boost is only starting to come in. It is also going to be much easier to find a blower to survive at only 12 lbs of boost -vs- one that would have to put out 18 lbs of boost. It is now very easy to see why a higher compression motor with lower boost is becoming so popular.

Destroyed engines are also becoming more popular for the same reason. I see alot of people making the same mistake, all the time... everyday. First, you need to understand how forced induction actually works, and its real effect on power output. Assuming that a supercharger "puts out 18 psi of boost," or a turbocharger makes "25lbs of boost," is stupid, plain and simple. The PSIG you see on the gauge (commonly known as gauge pressure - PSIg), is a measurement of backpressure in the intake after the compressor, and before the valves at WOT. The engine is not recieving "18psi" of "compressed air," and making 300hp more than its static capability. It just doesnt work that way. The engine is creating enough of a restriction, to charge the intake system with air up to 18psi. We measure this, to gauge the improvements of the engine with a specific compressor, and its characteristics.

Look at forced air induction, as accelerated air flow... or basically, FORCED AIR! DUH! Anyways, the concept is simple, and most people get it bass ackwards because of magazines and stupid misread information, and false rumors. Theres a reason low compression is mainstream with forced air induction. If you understand how compressing air works, then you understand that when you do so, you produce heat. So, inside the cylinder, as the piston reaches top dead center, you are compressing air/oxygen and fuel particles. You are building heat as you do this. In most respective cases, you need this heat to help complete the burn once the combustion cycle occurs. From a performance stand point, too much heat can be a problem, if low octane (low flash point fuels) are being used. So, keeping the heat in the cylinders under control is critical. More compression (tighter squeeze) builds alot of heat in the cylinder. When you introduce MORE air, you build more heat once you compress it. The MORE air im talking about, comes in way from the supercharger, or turbo.

If your confused, look at it this way. Lets say your compression ratio is at 10:1, and the engine is an N/A 281ci. Lets say the engine is operating at 100% VE, meaning its moving 281 cubic inches of air per completed cycle (two revolutions). Lets say at this performance measurement, the cylinder temps are 1500 degrees. Thats just a number im throwing out there. Lets say we're using 93 octane gasoline, as our fuel. Once again, these are just numbers im throwing out here because i dont feel like getting the real ones. Lets say the flash point for 93 octane is 1800 degrees, under pressure. This means that our 10:1 281 is at the brink of detonation/pre-ignition just running in its N/A form.

Lets introduce forced air into the mix now. Put aside PSI, and LBS.. and all that bullshit, because thats just gauged measurements. The PSI inside the cylinder is what makes the horsepower, and its MUCH more than you can measure on a gauge. So lets say, with the compressor your using, you increase the VE to 150%. Thats just a tad over 140 cubic inches of air, EXTRA! So, total airflow is now 421 cubic inches per cycle. Remember when i said when you compress MORE air, you produce more heat? Well, heres the example. All that extra air, needs to be compressed inside the same cylinders. Because the engine is setup for 10:1 static at 281ci, the actual effective compression is going sky-rocket now because of the extra 140ci thats being pushed into the cylinders. This means that the cylinder tempurature is going to raise from 1500, to over 2000+ degrees. Well beyond the supporting flash point of our 93 octane. So now we'll have a detonating peice of junk, that melts pistons and destroys heads. If we're turbocharging, we can "turn the turbo down" with the wastegate, but you'd still be building more heat than your 93 octane pump gas can support. Same deal with superchargers and bigger pulleys.

Sure, you can run race fuel.. with higher octanes and flash points, but is that practical? Hell no. Most of us are poor, cant afford luxurys like that. Lower the compression ratio, boost it... and be happy. Or just run high compression, and no boost... Or, heres a great idea. Just shut up if you dont have a clue!

[ReverendDexter]

Originally Posted by Goblin If we're turbocharging, we can "turn the turbo down" with the wastegate, but you'd still be building more heat than your 93 octane pump gas can support.

For one, rep for the whole post.

I just wanted to chime in that I've seen a supercharger setup with a wastegate in one of the Mustang mags, thought it was a very cool, and I don't understand why it's not more common. Any idea? The only thing I could figure is that you'd have more parasitic drag spinning the larger supercharger, but it seems like a worthy trade-off for having full boost at a much lower rpm.

[HBK_2007]

awesome post. ive seen prochargers kits with waste gates