Superchargers and rev happiness

I have never driven a non-clutch supercharged car. Is having a blower attached anything like having a really heavy flywheel? If I want to downshift quickly does it hinder the engines ability to change revs?

It always seemed that way in our factory sc Mini Cooper. But that may just be factory tune.

I guess it depends on the type of SC. My experience with a Centrifugal Rotrex is that you dont even notice it.

The 2-scroll Whipple on the Manic Miata doesn't seem to affect rev response at all except in a good way. It's got a light flywheel and the revs fall off instantly if you clutch, and so I usually heel-toe my downshifts, but overall I don't see it as an issue.

Yeah, on the supercharged Wreck Racing miata, I don't think it's too noticeable. The car has a pretty heavy flywheel, essentially an OEM MkIII supra unit, and an M90 supercharger and it revs pretty freely/quickly all the way to redline.

I think with most roots-type superchargers the polar moment of inertia is so low (ie: the diameter of the root packs is small and more of the mass is towards the rotational axis), that you don't get a significant effect.

This is all just my impression though. It should be pretty quick and easy to actually calculate and compare the effect vs additional flywheel mass if you were really concerned about it.

I drove an M62'd NB Miata a week or so ago... Seemed to rev a bit less "free" than my MSM, and was certainly less powerful out of boost.

It didn't "ruin" the car or anything, though.

I've driven many supercharged cars, mainly Mustangs with different sorts of blowers from the factory roots on the '03-'04 Cobra or Roush Stage 3's, to a whipple to a centrifugal, never noticed anything weird about the revs falling or anything like that. I ALWAYS heel-toe, but it was never noticable on any of the cars. Of course it wasn't something I was REALLY looking for when test driving them, I was mainly concerned with driveability and problems. This was all at the performance shop I worked at.

Drove a RunX (FWD hatch with 2ZZ engine) with a roots-type supercharger once, it was still very free-revving both ways.

Why would someone want a clutched s/c? The IRL(Saturn) I had was rev happy, dropped revs quickly, and had good response.

MPG reasons, i would guess. I know higher boost and higher revs are sort of competing interests with positive displacement superchargers because generally you gear them with more over drive for higher boost, which lowers the engine rpm where the blower hits its max rpm. So if you wanted both very high boost and very high rpm you'd end up with a very large blower.

yamaha wrote: Why would someone want a clutched s/c? The IRL(Saturn) I had was rev happy, dropped revs quickly, and had good response.

The 4agze had a clutch on the supercharger in the MR2. A little light would turn on when the supercharger was... supercharging.

I had one, and I'll mirror his statement since I've never driven a car without one.

Thanks for weighing in guys, sorry I neglected this thread as OP. Glad to hear the responses I was looking for! Definitely looking at Whipple twin-screw types, positive displacement. I don't really see the value in a centrifugal over a turbo.

I love how helpful this board is

mr2peak wrote: Thanks for weighing in guys, sorry I neglected this thread as OP. Glad to hear the responses I was looking for! Definitely looking at Whipple twin-screw types, positive displacement. I don't really see the value in a centrifugal over a turbo. I love how helpful this board is

Whipple for the win!! Best combination of all the traits you want and very little negative. Great compressor, pretty much instant boost, no spool up time, and it is MUCH cooler than a roots type supercharger when it comes to air intake charge temeratures.

What's this going on?

Value of a centrifugal over a turbo is it's less complicated to make the powerband very linear, which is great for when you ALREADY have a lot of torque and dont want any surprises mid corner, etc. I think centrifugals have their place, but it isn't on small motors!

Vigo wrote: Value of a centrifugal over a turbo is it's less complicated to make the powerband very linear, which is great for when you ALREADY have a lot of torque and dont want any surprises mid corner, etc. I think centrifugals have their place, but it isn't on small motors!

Personally I think the "surprise mid-corner" thing is overstated. WIth a well-sized modern turbo system (no 1970s turbo 911s, for example) it's just not a problem.

The main benefits to a centrifugal over a turbo are price and ease of installation.

I never noticed any rev difference with my MP62 installed on my miata. When I added the IC I felt maybe a little more "cushion" but that was due to the added throttled volume. No big deal. I think all the problems stated with blowers and turbos is way overstated. When I'm driving mine (250 to the wheels), the last thing I'm thinking about is how hot the intake air is or how much power my SC requires for my engine to spin. I'm enjoying the driving experience too much to care. Same goes for the turbos and supposed lag; in the real world on public roads, sometimes theses things don't matter.

-Hamid

Vigo wrote: Value of a centrifugal over a turbo is it's less complicated to make the powerband very linear, which is great for when you ALREADY have a lot of torque and dont want any surprises mid corner, etc. I think centrifugals have their place, but it isn't on small motors!

Iono.... this looks like a berkeleying riot!

http://youtu.be/poR3NSgGG5E

Swank Force One wrote:

Vigo wrote: Value of a centrifugal over a turbo is it's less complicated to make the powerband very linear, which is great for when you ALREADY have a lot of torque and dont want any surprises mid corner, etc. I think centrifugals have their place, but it isn't on small motors!

Iono.... this looks like a berkeleying riot! http://youtu.be/poR3NSgGG5E

It sounds better than it moves. Granted, it's not slow, but the only upside of that vs a turbo as far as the powerband goes, is the rotrex car might be easier to modulate power and have less underhood heat. I have a local friend who just sent me a video of a 119mph 1/4 mile pass in his miata on a $129 turbo. Torque/dollar ratio blows goats on a centrifugal 4cyl. Some cars dont need a lot of torque and some spenders don't need a lot of value return, so that's fine. But there are definitely certain 4cyl cars and owners out there that would be poorly served by a centrifugal.. although my original point was actually defending them.

I don't notice any weirdness on my Vortech V3Si Supercharged Corvette. Other than 300 ft/lbs at 2000 RPM and 400 ft/lbs at 3500 RPM. Which is not weird, just awesome.

Conquest351 wrote:

mr2peak wrote: Thanks for weighing in guys, sorry I neglected this thread as OP. Glad to hear the responses I was looking for! Definitely looking at Whipple twin-screw types, positive displacement. I don't really see the value in a centrifugal over a turbo. I love how helpful this board is

Whipple for the win!! Best combination of all the traits you want and very little negative. Great compressor, pretty much instant boost, no spool up time, and it is MUCH cooler than a roots type supercharger when it comes to air intake charge temeratures. What's this going on?

It will be going on my E30 M50 swap car. $ to HP points to a supercharger over S50/52 swap. More potential, and the cool factor is beyond the basics. Plus, I can always swap out to a larger displacement motor in the future and the same kit should bolt right on with a new tune.

Personally I think the "surprise mid-corner" thing is overstated. WIth a well-sized modern turbo system (no 1970s turbo 911s, for example) it's just not a problem.

Well, modern factory systems usually use VERY small turbos that are fully spooled by 2000 rpm and dont do anything dramatic after you're moving. Likewise, an aftermarket system with a properly setup and electronically controlled wastegate can be made to have a progressive buildup of power. But if, for example, you take a typical aftermarket DIY turbo system on a 4cyl, let's say using a ball bearing turbo that spools between 3500-4k rpm, controlled using a basic manual boost controller, the difference in torque between 3500 and 4000 rpm can be 100%. It really DOESNT matter when you're going straight.. but it could be highly irritating on track.

Vigo wrote: But if, for example, you take a typical aftermarket DIY turbo system on a 4cyl, let's say using a ball bearing turbo that spools between 3500-4k rpm, controlled using a basic manual boost controller, the difference in torque between 3500 and 4000 rpm can be 100%. It really DOESNT matter when you're going straight.. but it could be highly irritating on track.

I own a Miata with a 2560 (Flyin' Miata FM2 kit), it hits full boost around 3400 RPM. The torque curves grows quickly, yes, but it's not doubling in 500 RPM.

It's really not that big a deal on the track.

Smallish, early-spooling (probably non DBB) turbo.. does not match my example. But that just goes to show that if you plan ahead, you can build around it so it's not a problem.

mr2peak wrote: It will be going on my E30 M50 swap car. $ to HP points to a supercharger over S50/52 swap. More potential, and the cool factor is beyond the basics. Plus, I can always swap out to a larger displacement motor in the future and the same kit should bolt right on with a new tune.

Seriously? Turbo the berkeley out of it......2.5's LOVE turbos

Vigo wrote: Smallish, early-spooling (probably non DBB) turbo.. does not match my example. But that just goes to show that if you plan ahead, you can build around it so it's not a problem.

So... you're talking about incorrectly sized turbos in your example?