i dont really know much about either of them. All i was told is that a turbo will put off more horsepower just cause the supercharger steals some to spin. What is everyone elses thoughts on it?
a turbo uses the engine exhaust to spin it up, and therefore it needs to spin up to be effective.. a supercharger is there the instant you hit the gas.. no spin up, it is run off the pulleys.. a turbo can produce more power than a supercharger and takes up less room but it needs to be engine and vehicle specific a supercharger will fit more applications easier, and it requires less time to put one in and they are generally a bolt in application a turbo can gain more power by using an intercooler to cool the exhuast gases so you get denser air going in to the intake a supercharger can be tuned by getting smaller pullies to spin the supercharger faster quicker they are both great tools for more power and each one has its pros and cons.. it all depends on what you want to do with the engine and how much money you want to spend
Very well put! I would add that a supercharger adds stress to the engine as it is driven off the crank. It doesn't really take power away, being belt driven, it is just a loss of effiecency. The good thing is that the power is instant, constant, and adjustable. The turbo is probably more effiecient, but it has a lag about it. The engine must spin up pressure first before you get results, and the turbo also continues to spin beyond the point you need the boost. So on second thought, it loses a lot of effiencey that way. A turbo is always one step behind what you are doing with the engine, or the pedal, however you look at it. An intercooler is used to cool the air that is compressed by either an SC or turbo. They both create a lot of heat on the incoming air. To cool it makes more power. The thing is, if you use an intercooler, there is a loss of boost pressure that is seen at the intake manifold. Example: (simplified) If you boost your engine 10lbs at the SC, without an intercooler the engine 'sees' 10lbs of boost, or very close. Now install an intercooler. Your engine might only now see 8lbs of boost because the SC has to fill and maintain pressure in the intercooler system. Therefore, you will have to boost your system pressure to get back to 10lbs at the engine. Some of this loss is countered though. The cooler air probably makes up for it alone... just a guess. Dave
There are two classes. The Turbo is exhaust driven, needs plumbing with both intake and exhaust and takes up a lot of room. The second type is crank driven positive displacment, roots or centrifigal configurations. The positive displacment is the most responsive to throttle application from the lowest rpm. These types do consume power from the engine to turn but the net result is more power than they consume by quite a margin. What they all do is "force" air into the engine that results in more torque and HP. There is background supporting information to know about making such systems work but unless you are going to do one, I will stop here.
This thread might go on and on....Basically, speaking from experience here...I prefer a turbocharger on a PROPERLY tuned engine. Why? Cause I absolutely LOVE the fact that it is totally silent (if set up right) and when boost comes on, it's ON. When they aren't silent, the whistle is music to any hot rodder's ears. If you've never ridden in/driven a turbocharged V8 you haven't lived. The onset of boost and the torque and HP increase is simply mind-boggling. The word fun doesn't do it justice. Now, back to the blower vs. turbo debate. It's going to be hard to compare which is best. It boils down to what you're after. If you're after a hard-launching drag car, a roots style blower is the way to go. INSTANT throttle response especially if used with alcohol injection, which IMO, is the ONLY way to use a roots blower. Carbs suck...they're constantly having to be messed with, and it gets worse if you have more than one carb. EFI is coming around though. Centrifugal blowers, they work great, but they generally have a trade off. Either you will have very little low end boost and a strong top end charge or you will have a TON of low end boost and the top end charge will be the blower pushing a lot of heat. It takes RPM to build boost in most cases. The centrifugal also fits under a stock hood nicely. Turbos? Well, they're generally "cheaper" if you do your homework. By that I mean you can easily go down to a junkyard, pick up a pair of Holsets or a single Powerstroke turbo and rig it up on a 302. I've done it, for less than $1000 total investment. The rumor about a turbo being a high-strung (lots of RPM) power adder is false. I once had a 2.3 Ford 4 cylinder that made full boost (22 psi) by 2000 RPM. Yes, it's possible. Also had a 302 turbo in a maverick that had full 12 psi at 3000, which was the converter's stall speed so it worked GREAT! Or, depending on which turbocharger you're using, you can change the turbine housing to a larger one that will move your boost onset further up in the RPM band, and free up some horsepower. My stock 2.3 SVO motor made 22 psi at 2200 RPM. When I built the header and put a Holset off of a Dodge diesel on it, it made the same boost, but at 3800, but man did it pull like a freight train up top. I couldn't keep it off the limiter, literally. The clutch would not take the power. Comparing a roots blown car to a turbocharged car is like comparing a 2 stroke motorcross bike to a 4 stroke, the 2 stroke version needs RPM to make power (kind of like a turbo car) and the 4 stroke comes on instantly (like the roots car). Roots cars are great for drags because of the instant response and boost, but driving one on the street sucks because they eat up a LOT of HP which takes fuel mileage to an extreme. Passing everything but a gas station is a reality. A buddy had an 8-71 blower on a 482 Chevy in a '83 pickup...gets an honest 2 mpg at best. If he steps on the throttle to show off a little, he better hope there's a gas station nearby, literally. My old 302 turbo Maverick....got 22+ MPG and would run right with his Chevy, if not a little faster. Turbocharged engines can take advantage of smaller packaging and employ a intercooler, which makes the system more efficient. 80% compressor efficiency is not out of the question, where a roots blower is usually around 65% efficient, and that's considered excellent. Centrifugals are a little different. Kind of like a engine driven turbo. In fact, the compressor itself is exactly like a turbocharger's compressor, but it is belt driven instead of turbine-driven. They generally will fit under a stock hood, but they take RPM to build boost. 2 psi by 2000, 4 psi by 4000, etc...."generally". There is no "best" one. It boils down to personal preference. I prefer turbos (obviously). Yes, the lag is always there and there's nothing you can do about it. But, if you learn how to drive a turbo car, the lag becomes part of the fun and you can use it to your advantage (traction control). The 2.3 I had, I didn't keep it long enough to really play with it, but the times that I did get it running "right", I could floor it at 1200 RPM and it would take 2-3 seconds to get up to around 2500, which is where I would get 2 psi. Then 5 psi by 3000. Then 8-9 psi by 3500, then at 3800 the gauge would swing to oblivion and the speedometer would climb as fast as the tach. From a dead stop I could slip the clutch at full throttle until it heated up & would grab, which was right at about 3500 (I was already at full boost) and it was literally just as quick as my old built 5.0 Mustang was...easily. I actually think the svo was faster. As dumb as it was to do, I took it out on an old abandoned road and from a 2nd gear roll, it would be running over 120 mph before I could get it off the limiter and into 4th gear. Fun car, just never seemed to stay running long enough for it to be "fun". I wish I had the time, money, and place to "do up" another Maverick street car, this time with a turbo 460. Would be an easy build, but would require another M2 swap and the associated cubic dollars, both of which I simply do not have.
For a turbo you also need a block that can take the psi. I hear alot of guys slaping turbos on cars and plowing the block to pieces because their standard block will take 3-4psi, not 13-20.
I've been reading up on this alot lately as I plan on turbocharging my 250 I-6. The biggest problems I've read about are 1). setting up the carb for a blow through turbo or supercharger, 2). knowing when to stop cranking up the boost (saw 302 block split in half !! ). I've decided that I'm going to do a draw-thru turbo which draws air/fuel through the turbo and into the intake, will require minimal carb mods and less plumbing due to the fact that you cannot run an intercooler. I'll use either a Holley 600cfm or 2- 300cfm carbs. This set-up is similar to the first Buick turbos, and alot of VW, rail buggies. I'll use a water/alcohol mix to cool it down and lower the chance of detonation. If you are serious about this there are a couple of good books Maximum Boost and Supercharged written by Corky Bell.
The Chemical intercooler you are talking about can be used with Methanol which cools way better, and also gives more power that a standard intercooler. You should look at these superchargers that i saw in a mag. they looked just like a Turbo but were mounted in the front of the block up high.
Was this a Rotrex supercharger you are refering to? We just picked up a pair of the c38-81 Rotrex superchargers for a twin blown 347. Real efficient, small, easy to package and virtually silent. Integrated oil pump so no punching holes in your oil pan or tapping into engine oil for bearing cooling. http://www.wheeltowheelinc.com/pc-100-64-c38-81-head-unit.aspx Take a look at these and you may decide that you have to go with forced induction. :evilsmile Best part is that they are about the size of an alternator so packaging them is relatively easy.
Yes. I saw 2 mounted on a Denali XL. Provided tons of power. But they looked like a Turbo that sucked in Cold air. not exhaust.
That's an impressive unit but, belt or shaft drive, although response is immediate with no lag is a drain on overall power . Now consider the turbo set-up...40% to 60% efficient with some lag, not good but better over-all because it's basically "free" boost because it uses the exhaust to operate. Then you have to consider the cost. You could do a junkyard version of the turbo for about a 1/4 of the cost of the Rotrex !! Find a Holset or Garrett turbo, some muffler shop scraps, a carb bonnet and a few carb mods and you're all set. And as long as boost stays at 10 or lower, you don't need an inter/after cooler.
Yeah. I wonder what how hi a turbo will go before a 302 Maverick Engine will blow. Time to conduct an experiment
You don't have to waste anything to try it. A turbo will provide enough power to split the block right in half. And, even if it doesn't split the block, you may end up with other problems....Mine let go the first time at about 2200 RPM. Holed 2 cylinders (hole through the walls/no other damage) and I split a block just off idle at the onset of boost. That is where turbocharging can be hard on parts. Full boost can be had at a VERY low RPM if the turbo is matched to the engine. I know of a guy that used a 6.0 powerstroke VGT turbo on a 2.3 Ford 4 banger (SVO mustang) and bent the rods....made full boost (40+ psi....which is about the factory boost setting on the diesel) at 1200 RPM. Once the VGT controller was built, he had full boost at 1500, and it pulled all the way up to the 6250 fuel cut. Was expensive building the controller and rigging it all, but apparently it works well. And....if you find a turbo that is 40-60% efficient....sell it on Ebay and get a GOOD turbo. Holsets from a Cummins are close to 80% efficient, with about a 3:1 pressure ratio.
Mavman: How about an old 7.3 PSD turbo? How effiecient are they? I know they are Garrett, I have a few right now on my vans... They ought to be easy to come by. The big 444 turns up to just over 3k rpms, so on a gas burner the size of a 302, that should be equivalent to 5k, is my thinking correct? I read an article on turbo charging once that said something to the effect of: Any boost over 15 psi on an engine that didn't come with a turbo, might as well rig dynamite to the engine and get it over with, cuz it's gonna blow. Dave
