This is probably a real newb question, but here goes anyway.
I have been reading about how the rotrex and whipple superchargers are much quieter than the roots blowers, I know turboes are silent (more or less), I've had a couple turbocharged cars.
I want to go with forced induction on my '01, I love the drivability of the stock torque curve so I'm leaning towards an MP62 based setup. However, I hate noise! That probably sounds contradictory from someone that owns a convertible, I actually find my stock car rather pleasant to drive, I don't like loud or harsh exhaust noise for example, just how loud are the roots type compressors?
Superchargers whine because of their gears. Turbos are quieter because they have no gears. Engines were developed to run timing belts instead of chains to reduce friction and weight efficiency losses and to reduce noise. Superchargers have tremendous friction and rotating mass losses compared to turbos. Supercharged cars always get worse mileage than stock, even when being driven normally. Superchargers are parasitic drag devices. Many here get far greater mileage than stock with their turbo cars.
A turbocharger sized properly for your desired powerband will make more power more quietly with less fuel than whatever supercharger you might be considering. You can make boost at 800rpm or 8,000rpm depending on what turbo you choose. Not demonstrating this understanding in your initial premise leads me to believe you don't fully grasp just how readily turbos are tailored to every need.
Thanks six shooter, i do understand turbo sizing and spool up time etc. I guess I should have added that I am interested in the supercharger route as much for the simplicity of installation as the power curve. I'm not to keen on running oil and coolant lines if I would be happy with the noise level of a supercharger. I haven't even heard a supercharged engine run, so it is a total unknown for me. I keep looking at the rotrex kits and wondering if it would be possible to fatten up the lower rpm range a little.
To be honest, i don't even know why i hesitate in going with a turbo, I loved the power output of my Volvo 740 turbo (intercooled and running 9psi boost and bigger exhaust). The power was seamless and it pulled hard from down low all the way to redline. I do notice the turbo lag in my truck (LBZ 6.6 Duramax), if you mash the throttle from a stand still it seems a little weak, then all of a sudden the turbo spools up and it takes off.
I think I have been getting to caught up in looking at the dyno sheets posted by the kit makers, it seems the turbo kits are lacking bottom end (but then again, they are probably using a midsize turbo for more top end ?) I like the the advertised torque curve of the JR MP62 kit. I also like the cold air box available for the JR kits. Although I am capable of doing some basic fabrication work to build one if I had to, I am getting lazy and like the idea of a true bolt on. I am only looking for around 200rwhp.
Is there a particular compressor you would suggest for quick spool up and a similar to the stock torque curve? According to dyno runs I had done on my car, I am getting 90 ft-lbs@3000, peaking at 98ft-lbs@4800 and dropping off to 80 ft-lbs@ 7000 (bone stock @ 3500 ft altitude). Obviously I am not going to get an identical torque curve, i don't expect that, but I would like close. I love the way my car pulls from about 3k to 7k in any gear for day to day driving.
Speaking as a supercharged Miata owner, I think you should get a turbo. Anyone who tells you that installing a pre-fabbed supercharger is easier than a pre-fabbed turbo has never done one or the other.
9psi from a MP62 will be too loud for you and that's just the belt noise.
I selected a supercharger over turbo for one reason - AutoX performance.
You'll notice that there is no miatasupercharger.net. Ever wondered why?
Oh, and to answer your previous question. Some are born great, some have greatness thrust upon them - I think Hustler got both.
Why would the drive belt be any louder than say the ribbed and ridiculously long serpentine drive belt on ford V-8s?
Because superchargers suck a lot of power just to spin. To transmit that power requires a bunch of belt tension = noise. The nose pulley on the supercharger is very small causing a tight wrap radius = noise. The belt itself is a multi-vee = noise.
Personally I love the sound of a supercharger, and it's belt, at full chat.
For your expressed desires regarding torque curve I would say to look at a gt2554 size turbo. Compare dyno sheets from our dyno sheet posting thread with what you are making now. They have early spool characteristics. For these in a kit form, check out the BEGi-S kits. If you are moderately budget conscious I would look at the BEGi Shanghai kits. If you are willing to do a bit more studying, you can save more still and source more parts used, piece by piece, from our for sale threads.
If you decide you want more kick in exchange for a slightly higher powerband, the gt2560 is the next size up from the gt2554. You can also make adjustments to spool characteristics on a given turbo by swapping to different A/R housings. A turbo can be tailored like an Armani suit.
And yes, the folks at GM chose a laggy turbo for the Duramax engine. They didn't have to, but I'm sure they had their specific reasons/goals.
[QUOTE= and yes, the folks at GM chose a laggy turbo for the Duramax engine. They didn't have to, but I'm sure they had their specific reasons/goals.[/QUOTE]
I don't know if it has anything to do with the variable vane geometry, or if it's something else. Adding an AFE stage 2 intake and Bullydog programmer smoothed the transition, but it is still quite noticable.