^ not that easy to be at full boost at 3k rpms.

 

with the SOT kit it is

in the end the motor's reliability comes down to tuning and driving habits. carefully tuning the fuel and timing and leaving a margin of safety will go a long way to extending the life of a boosted motor.

let's say the lifespan of the motor bone stock is 150,000 miles, I think it's unrealistic to expect that not to drop at least a little when it's boosted. also driving habits dictate the life expectancy. drive the piss out of a stock motor and you might not last as long as a 400whp motor that's only driven hard here and there.

couple of buddies of mine had the same exact year and model VR6 GTI for a while. get in one guy's car and the mileage on the dash would say 22mpg, the other guy's would be at 15mpg. same car, just one guy ragged the hell out of it. they take the cars to the track and one was trapping 6-7 mph faster than the other even with the same driver. abuse your car 24/7 and it's not going to last no matter what

 

[QUOTE=candymanjl,Mar 16 2009, 10:15 PM] with the SOT kit it is

in the end the motor's reliability comes down to tuning and driving habits.

 

the KW is less invasive for sure. like you said the extra low end means you're not revving out as much which has to help. even though I'm going with a turbo setup I'll still gain power down low and mid range. by about 4000rpm I'll have more whp than stock at redline. I wont have the same low end as a supercharger setup but I'll still be able to shift lower for normal driving and not have to rev out to pass someone on the highway.

 

Like others have said, its all about the driving. Also, the FI setups that have a better torque curve don'e seem to be dropping engines, so its a moot point. You would probably have to drive around fully boosted all day long, blasting off from every stoplight/freeway onramp etc. - which no one does.
The real weak link is the parts after the differential, after the torque multiplication.

 

Lets make a few destiguishments here. Making more torque at higher rpm or speed where inertia is assisting, is easier on the drive train. As far as the motor goes, asking the engine to make more trq artificially through boost at a lower rpm isn

 

[QUOTE=archtop,Mar 15 2009, 06:51 PM] I find with my KW setup I drive around between 2 and 5k most of the time. It seems to have plenty of torque to get the job done for me.I save the redline stuff for fun times but not on a constant basis. The kw kit makes around 150lb.ft at 3k and 200 at 5k.Boost at 3k is around 2psi and 5psi at 5k. So if your making full boost at 3k to up your torque and running a flat torque curve your probably pushing 5-8 psi between 2-5 k which is the working range of a boosted motor. You obviously have stronger pull but the price will be more wear and tear?There are trade offs for every mod.I'm just saying one of the strong points of a centrifugal supercharger is less wear and tear in everyday driving.The rotrex is an extremely efficient blower so it takes less hp to operate

 

Just my $.02.

I read somewhere a LONG time ago that it is REALLY bad for our transmissions to "bog" them at lower RPMs while cruising. Something to do with the gears oscillating possibly within the transmission.

It kind of makes sense, as centrifugal forces would balance any minor oscillations out as the RPMs got higher.

I think lower end torque would only make the problem worse, but as long as you are within the power band, and not "stressing" the transmission (like in a "bogged" situation), it should be fine. Torque is torque, IMO, regardless of RPM.

This is only from a transmission POV... And it may be WAY off. I just recall reading it somewhere that its REALLY bad on the tranny to bog it while attempting to hyper-mile.

John

 

[QUOTE=jwa4378,Mar 23 2009, 01:14 PM] Just my $.02.

 

When I said full boost at 3k rpms I was leaning more toward the 20+psi crowd. Sorry for the misinterpretation.