Which Supercharger would you go with?

[rgeorge33]

To change the oil with the Sprintex unit, I removed the airbox tube from the throttle body. In the pictures I posted above, you'll see that the MAP sensor wire is in the way. You can either push it to the side or just unhook it. You still use the OEM filter and can easily get to it with the air hose out of the way.

[Timmy]

To change the oil with the Sprintex unit, I removed the airbox tube from the throttle body. In the pictures I posted above, you'll see that the MAP sensor wire is in the way. You can either push it to the side or just unhook it. You still use the OEM filter and can easily get to it with the air hose out of the way.

This is GREAT information guys, keep it coming. This is the type of stuff that you read little bits and pieces of and then forget about. When I get a chance, I'm going to edit my original posting and try to include this stuff. Maybe this can become sort of a living document of the differences between the SC's.

[Alucard rawg]

I have a few questions the bypass valves seem to be hurting the low end on the pd blowers. The dyno charts I have seen make it seem that the turbo may even be better for wheeling than the roots and that blows my mind. ( dyno charts and real world =2 different things) I get that vacuum controls the valve but how? I would want a roots because I want off idle torque but the bypass valve seems to be killing that. what kind of boost are you seeing while crawling at low rpms and little throttle? if you disconnect and plug the vacuum line does the valve say open or closed?

[2k13jk]

The bypass valve on my ripp which i changed for a tial blow off valve its main job its to let boost in when enough vacuum pulls it closed and lets off excess boost throttle body closes it dumps the boost to prevent compressor surge you need the valve or youll pretty much destroy something in the motor

[gbaumann]

I have a few questions the bypass valves seem to be hurting the low end on the pd blowers. The dyno charts I have seen make it seem that the turbo may even be better for wheeling than the roots and that blows my mind. ( dyno charts and real world =2 different things) I get that vacuum controls that the valve but how? I would want a roots because I want off idle torque but the bypass valve seems to be killing that. what kind of boost are you seeing while crawling at low rpms and little throttle? if you disconnect and plug the vacuum line does the valve say open or closed?

I can speak somewhat to Magnuson's bypass because that's what I have. According to Mag the bypass is not supposed to close until manifold pressure is at 0 bar. Think of that as wide open throttle. For guys with manual transmissions that works because you can pick a gear and step on the pedal which opens the throttle dropping the pressure and closing the bypass. For automatic transmissions guys it's an issue because you don't pick your gear and the computer's selection is most often not good. If you don't step on it all the way you're not closing the bypass all the way. That's how the system is designed. If your foot is light on the pedal then you're not on boost.

DO NOT DISCONNECT THE BYPASS VACUUM LINE! Yes, it will put you on boost all the time like a diesel or dragster. But you won't have software calibration for that condition and I genuinely believe you'll risk leaning out. Also, the effective compression and cylinder pressures will, in my opinion, wear the motor out. The block, heads and rotating assembly are not designed for it. The superchargers and turbos we are using are designed to give you the occasional boost of power you need and then sit on the sidelines to save fuel and save wear and tear. They are ideally designed for off-the-line acceleration at wide open throttle or when towing heavy loads that you need to build momentum to get going.

[UselessPickles]

The only supercharger experience I have is a quick drive in a 3.8 Sprintex Wrangler JKU with an automatic transmission. There were definitely times when I could feel bypass valve open/close as I adjusted the throttle and crossed that manifold pressure threshold, because there was a small sudden change in power delivery that could be reliably reproduced by modulating the throttle. I noticed this while cruising at freeway speeds in overdrive. I could imagine that the magnitude of the change in power delivery would be bigger if you were flirting with that threshold in 1st gear while trying to climb over something off road. Have any of you supercharger guys experienced anything like this?

One thing I like about the turbo is that boost is not an on/off thing. It's a continuum of boost that scales with engine load. Smoothly pressing the pedal gives you smoothly increasing boost. On the other hand, the roots and twin screw superchargers can actually give you near full boost at low rpms if you push the pedal down enough to close the bypass valve, but no matter how much you press the pedal, the turbo just can't give you much boost at low rpms.

[FLIPmeOVER]

My vote is RIPP.

Im close to the money, and RIPP will get it. Most widely used. The lift to shift thing sucks for autos, but i have a manual trans.

Also, with "lift to shift" being annoying, Id still get a RIPP if i had an auto. Ill tell you why, i rarely floor the pedal. pay attention to how often you actually floor it, and keep it floored.

[UselessPickles]

Ill tell you why, i rarely floor the pedal. pay attention to how often you actually floor it, and keep it floored.

That may change once you have forced induction

I floor it through 1st and into 2nd gear at least once per day when weather conditions permit. Stupid wet and/or snowy roads have been causing some epic battles between traction control and the turbo. The turbo usually wins before I even get to full throttle.

[Timmy]

...I could feel bypass valve open/close as I adjusted the throttle... [snip, snip] Have any of you supercharger guys experienced anything like this?

One thing I like about the turbo is that boost is not an on/off thing.

Well, for what it's worth, your experience is 100% opposite of mine. In a different application, I get tired of the turbo. I have driven turbo'd VW's and Audi's now for about 13 years, and every time I punch it across an intersection, I sit there and yell at the car "go you stupid fast car, go" and then when it hits 2500 RPM, it's like a kick in the butt. There is NOTHING linear about it. < 2500 RPM, no power, > 2500 RPM, full power. Granted, my Audi's are all chipped to higher boost, so the boost hitting is more dramatic then what Audi originally programmed in.

Now shift to my driving experience of Audi's with superchargers (the S4, A6, and A7.) There is NO on/off in the experience. The supercharger is dead quiet and fully smooth and linear in it's delivery. Happens to be the same SC that Magnuson is using.

Pickless, did you look through that PDF that I posted a link to in this thread? I think you would find the graphs at the bottom most interesting in the comparison of naturally aspirated vs. turbo vs. supercharger and why Eaton is showing an SC to be a better application for maximum MPG and maximum performance.

[UselessPickles]

We're talking about different things with on/off vs linear transition of power. You're talking about power delivery at full throttle, through the rpm range. Yes, in that situation, my turbo kicks in pretty quickly in the 2500-3500 rpm range. Not like an on/off switch, but a very quick ramp up in acceleration.

I'm talking about part-throttle throttle control under higher load at more stable engine speeds. If I'm at freeway speeds around 3000 rpm with my turbo, there's a very smooth relationship between pedal position and boost/acceleration. With the 3.8 Sprintex kit, I could feel a small harsh transition when the bypass valve opened/closed as I smoothly pressed/released the pedal through a certain position.

Yeah, I looked at that PDF. It was pretty cool, but I don't think it's really relevant to the decision of adding an aftermarket bolt-on FI kit onto an existing NA engine. That document was about using FI with a smaller engine to get similar power with better fuel economy compared to a larger NA engine. We're talking about adding FI to gain not-entirely-necessary additional power on an already completely engineered stand-alone OEM NA engine.

More importantly, that document is about a small engine with FI developed together as a complete OEM package fully integrated with the ECM. In OEM packages, the ECM has control over the bypass valve (for superchargers) or wastegate (for turbos) to have much better control over when boost comes in to play and how much of it. A bolt-on kit will never be as refined as an OEM system, because the ECM for an NA engine does not have the programming in it to electronically control a bypass valve or wastegate in relation to everything else going on with the engine. Bolt-on kits must rely on simple actuators controlled by manifold pressure, calibrated by choosing which strength spring to use in the actuator. This gives much less control and requires more compromises to ensure that significant boost does not come it at times that would be incompatible with the operation of the ECM programming that doesn't have the flexibility to be fully aware of boost transitions in its calculations. For example: closed-loop mode.