SPOautos

Hey guys, I was wondering if anyone is familair with Whipple Supercharges or if anyone in here runs one? What I'm wondering is boost pattern. I HEAR they make FULL boost at about 2500rpms and carry it to redline. I dont understand how this is possible with it being belt driven but I hear it has some type of bypass setup or something like that. Supposedly its the only SC that does this, all the others build boost with rpms and dont get peak boost till redline.

Anyway if anyone KNOWS about the boost pattern of a Whipple and can tell me how this is achieved (if its true), I'd greatly appreciate it

Thanks,
STEPHEN

Kenku

Yup, that's pretty much true. The reason it works is because whipples are positive displacement blowers instead of the centrifugal blowers we're used to with turbos. What that means is that one revolution of a whipple will move the same amount of air through it no matter what; it's an air pump. Well, at lowish RPMs, there's a bit of leakage because stuff is going so slowly. Centrifugal blowers move more air the faster they're spinning; it's an exponential curve vs. compressor RPM, whereas the whipples have a line.

Here's how to think of it. Say you have a 13B and a positive displacement blower that moves 160 cubic inches of air per revolution. If they're turning at the same speed, the blower will be forcing twice as much boost into the engine as it would take in NA. If you change the pulleys so it's turning 50% faster than the engine, it crams in three times as much air.

Roots blowers work similarily, but less efficiently; they have teflon tips to seal everything whereas the whipples don't *actually* have anything touching. The screw type superchargers also have a lot higher compressor efficiency than the roots type blowers.


Hope that answered some questions; not too scientific, but it's the gist.

SPOautos

So how does it keep flowing the same amount of air and say 10psi at 3000 and at 8000? Why doesnt the boost and flow go up with rpms? Doesnt it spin faster???

I dont understand how it makes the same boost and flow at 3000 as it does 6000 or 8000

I guess my next question would be has anyone tried to run one on a rotary and how did it work out? OR why hasnt anyone tried to run one on a rotary?

STEPHEN

Kenku

Well, it's not the same amount of air, it's the same proportion. If the supercharger is geared for one atmosphere (for convenience's sake) it's pushing twice as much air as the engine is taking in, because it's geared that way. As the engine spins faster it will be taking in more air, but the supercharger will be spinning faster and it will still be moving twice as much air as the engine is taking in, for one atmosphere of boost.

Imagine hooking a 1.5 liter engine up to a 3l one that is just acting as an air pump. Both spin the same speed, but the 3l one is always going to be forcing twice as much air into the 1.5l one as it would be taking in normally.

SPOautos

Ahhhh, I understand what your saying.

Hmmm, thats very interesting. Do you know if they heat up the air to an extreme degree like a turbo does? In other words do you have to intercool them and such to run say 15+psi of boost?

Is there any downside to them? Why dont more people run them instead of turbos? My main complaint about sc'ers is that you dont hit peak boost till around redline.....but it seems like that is now not true.

Has anyone tried running one on a rotary?

STEPHEN

rotarygod

iTrader: (1)

Your concerns about superchargers are true in regards to centrifugal superchargers such as those from Paxton, Vortec, and Powerdyne. Eaton (roots) superchargers and Whipple superchargers are diiferent and like Kenku said positive displacement. They will always provide the same proportion of air to the engine regardless of RPM. If the positive displacement supercharger had no loss at low rpms than you would theoretically have full boost at idle. However since tolerances are close instead of zero there are some losses at low rpms.

The traditional roots supercharger such as the Eaton have two "rotors" inside them of either 2 or 3 lobes. The Whipple supercharger has twin screws. Due to the twisted screw configuration there is much more area available to grab air. The screw design unlike the roots design also compresses the air inside it. Like a turbo or centrifugal supercharger this is much more efficient and heats up the air less. The roots style does not compress the air inside it but rather blows air into the engine hence the term blower. The air compresses inside the intake manifold itself and this causes greater air heating. Roots style blowers are typically around the 30% efficiency range. Turbos can exceed 80% efficiency and the whipple superchargers are a little less than that at around 75% or so. These numbers vary some with size and style. The roots style superchargers are not as good at high rpms but are nice in the low and midrange. The centrifugal superchargers are nice from the midrange and up. The whipple superchargers are nice everywhere.

Since their efficiency is approaching that of a turbos they will obviously produce more power than a roots supercharger. Any forced induction system should run an intercooler if possible. Any high boost application requires one unless it is running on alcohol. The most popular form of intercooling for roots and whipple superchargers is a liquid to air intercooler mounted directly underneath the supercharger. These usuall blend in well with the intake manifold and sometimes are a part of it.

The disadvantages of Whipple superchargers is that first no one makes one for the rotary. Everything will be custom fabbed by you including the intercooler. You will need to figure out a way to make a pulley system work. Next they do rob power off of the eccentric shaft. It takes power to spin them. Obviously a turbo spins from exhaust gas but these usually are a restriction in the system as well but do not use power to the extent of the supercharger. However, the whipple supercharger would be my top choice in supercharging. My car insurance agent drives a Ford Lightning (poor guy!) that comes with an Eaton roots style supercharger. He recently replaced it with a Whipple unit. He said that his truck at 7 psi on the Whipple supercharger is still much faster than 10 psi on the Eaton unit. Efficiency is everything.

Many people will get on here and start spouting off how turbos are better and easier. This may or may not be true. Just ignore them. Whatever is best is what works best for you. Install what you like and don't worry about what anyone else thinks. You'll have one of the coolest engine bays around. Everyone has a turbo rotary under their hood. What's so original about that? Good luck!

rynberg

I see a few problems with a supercharger install (with an FD for example):

1) Superchargers are not mounted low in the chassis like turbos are, so center of gravity is raised.

2) Possible increased weight with a supercharger (not at all sure about that).

3) Power drain to operate. All the good supercharger installs have bypass valves so the supercharger is not sucking up engine power in cruise situations. This would need to be fabbed up. The power drain with big superchargers is ENORMOUS. The 55 AMG cars with 490 bhp spend 100 horsepower to run the supercharger.

4) I prefer the "whistle" to the "whine"...

chairchild

Just had a quick browse on google to find them http://www.whipplesuperchargers.com/ and it appears that they have some sort of automatic bypass already built into them. It also says on one point, that they only require around 1/3 Bhp at idle.

But if you have an NA car, and slap a supercharger on, of course it's going to be heavier rvnberg

but these things are BIG - and I think you'd need to make a few alterations before it could fit in a stock engine-bay - but hey, I'm getting one as soon as I can afford it now

rotarygod

iTrader: (1)

I agree with the raised center of gravity comment. Of course also consider that if it is over the engine the center of gravity is in the "center" and not off to the right side of the car as it is with the stock turbos.

Weight may or may not be an issue. A big supercharger will weigh quite a bit. The stock turbos with their manifold probably weigh more than you think though and big single turbos get downright heavy. Also consider the fact that many people add bigger heavier intercoolers to the front of the car farther away from the center of gravity whereas the supercharger is inside the wheelbase. Even the intercooler in the stoclk position on the 3rd gen is in front of the engine and not over it (but the 2nd gens is) closer to the centerline of the car. the factory intercoolers are pretty light though. The effective weight difference is probably negligable.

I do agree that the power drain at full boost is quite a bit. It is low at idle because the bypass valve is allowing air to flow around and the supercharger is not working hard to compress it. At the same token the stock turbos on a 3rd gen (even a 2nd) gen are very restrictive but don't effect the engine at idle. The stock exhaust manifold on a 2nd gen as compared to a proper header on the same engine can equal near 30 hp. That is alot. Consider also that the stock nonturbo exhaust manifold is also less restrictive than the 2nd and 3rd gen turbos in line. Also since the turbo compressor housing heats up due to being the same unit that touches the exhaust it heats up the intake air even more which affects power. These reasons are why a full exhaust equipped nonturbo 2nd gen can just about keep up with a stock T-II that has boost. It needed the boost to overcome the restriction in the exhaust. There is more to it than that but I will not get to it here. I'm not saying that the supercharger doesn't take more power to operate than a turbo system. It does, but depending on which turbo system we are comparing it too the disadvantage may be slight.

The Whipple Supercharger is the quietest supercharger on the market. At all but the highest rpm's you probably will not hear it at all. The turbo whistle does sound damn good though!

I'm not trying to make anyone mad here or get personal. This is just a fair comparison to a stock setup and even some modded products on the turbo equipped RX-7. Obviously there are turbo kits that will walk all over this but a good supercharger system can be made and have much greater power than many people realize. It is really only when someone is using a nonintercooled Roots style system or a centrifugal system that they are not getting anywhere near the full potential. The Whipple is a wonderful style of supercharger.

SPOautos

WOW, thanks for the info guys. Also, let me say this....I wasnt really wanting to swap over to a s'cer. The reason I'm asking about all this is I'm helping my brother with a persuasive speech on why turbos are better than s/cers.

It was a easy speech till I ran up on the Whipple haha.

So really the only benifit a turbo has over a whipple is the turbo is about 80% efficient and the whipple is about 70% efficient (according to some online reading). Also, in addition to the 10% less efficient the whipple also robs more power from the engine than a turbo. BUT can anyone find any good source to prove this? We cant just spount out unproven "facts" in his report.

What would be nice is dyno numbers comparing the same car with a whipple or other s/cer and turbo

STEPHEN

rynberg

You're not making me mad...

Thanks for pointing those things out. Nice to have a respectful talk between enthusiasts instead of the flame war these types of threads normally turn in to....

MikeLMR

Whats the difference between a whipple supercharger and a Lysholme supercharger. at first glance the whipple looks just about the same to me.

mike

KevinK2

mabe an old roots type used by a young big daddy G was 30%, but modern eaton SC's are a modified roots, with a 60 degree screw like twist, and efficiency of around 60% based on publised data. the whipple is a screw compressor, with less internal 'slip', and a little higher thermal efficiency. it likely has higher parasitic losses since it still does some compression along the screw length, even in bypass mode. Turbos may hit 80% at peak torque rpms, but stocks are usually blow 70% at max hp. just my $.02

Kenku

Whipples are a brand of Lysholm type superchargers.

Well, see, I actually *FOUND* a site with some maps for the Eatons... and... well, they're annoying and list temperature rise in terms of delta T. For argument's sake, looking at the M90, at the tip speed limit of 12k RPM on the blower input shaft, at 10psi it's sucking 44hp and generating a 190 degree temperature rise. They only have that published for 5 and 10 psi, unfortunately.

It's quite well known how much the roots-type Eatons heat intake air up. Interesting fact is that Ford went to a Lysholm type compressor on the GT...

infinitebass

rotarygod, you have it backwards. Whipple style (screw type) don't compress the air, but roots do. Thats what a roots style needs an intercooler to be more efficient, because it DOES heat the air due to the compression.

The compression of the air causes it to heat up, and the Root's actually compresses it between the lobes, whereas the twin screws simply move it.

http://www.whipplesuperchargers.com/....asp?PageID=68

Blake

Kenku

Sorry, nope. And there's not really anything on that page that supports your conclusion.

http://corradog60.tripod.com/scoverview.html is a reprint of an article I've seen in various places.

KevinK2

adiabatic rise for thet 12k case, based on 85F ambient and no ic or intake losses, would be (460+85)*(24.7/14.7)^.286-(460+85)=87F. compr eff is 87/190 = 46%. 51% at 10k rpm. modest boost os 5 psi gives 60%. no real data provided for the whipple .... but should be a bit more efficient. IC's mittigate the diff in efficiency.

Kenku

Thanks, didn't want to go to the trouble of looking up how to do that. Point is that it's still 60% or less compressor efficiency (rotarygod claimed 30, not I ) and yeah, that can be overcome through intercooling but... for a given intercooler setup, something with better compressor efficiency is going to end up with cooler charge air, y'know?

Also there's the issue of higher boost than 10psi. I don't claim to have data for that, just bringing it up as a question.

rotarygod

iTrader: (1)

Yeah admittedly I was basing that efficiency number on the old ones. That number is pretty close to the Camden supercharger. It only has 2 straight lobes per rotor. The Eaton has 3 lobes per rotor with a twist and should be more efficient.

It is the Whipple that compresses the air not the Roots.

SPOautos

Right, the Roots style is called a blower cause it just "blows" the air then the air compresses into the manifold......it doesnt actually compress in the blower like it does in a whipple.

Also, I was reading something interesting about a roots. It was saying they always force a fixed amount of air into the engine. So that at very low rpms your getting high boost but as the rpms go up and you start sucking in more air the boost drops cause you using all that air up.

Is that true? Anyone know?

I found a good website that compared them all, I'll try and post the link if I can find it again.

STEPHEN

infinitebass

Look at the chart at the bottom. It mentions the heat buildup in the Roots is high, but low in the Whipple...

I did A LOT of research (as in several months and almost actually bought one) on positive displacement superchargers. I'll see if I can find the old sites. There's one in particular one that has an animation of the Roots that shows exactly why it compresses air.

Blake

Kenku

The heat buildup in the Roots is higher than the Lysholm compressor because the Lysholm is more efficient. The Lysholm will compress air when turned in free air though, while the Roots will just move air. Both compress air when flowing into a system that flows less than they're moving; PV=NRT and all that. If you force twice as much air into a system as it takes in normally, you will have (ignoring heating) one atmosphere of boost. Period, bar none, whether it's a Roots, Lysholm, centrifugal or axial flow compressor.

http://www.grapeaperacing.com/GrapeA...supertypes.cfm Another link, because it looks like the other link went down.

Well... Roots and Lysholm compressors force a fixed amount of air *per revolution*. As the engine spins faster, the blower gets spun faster as well... so blower flow stays pretty much proportionate to engine flow.

SPOautos

Here is some good reading material on superchargers...

http://www.coloradocobras.com/whippl...induction.html

If you scroll down and look to the right you'll see links for different types of superchargers. There is quite a lot of info there.

STEPHEN

SPOautos

I have a questions I'm still not TOTALLY understanding about positive displacement superchargers.

If they always flow the same proportion of air per revolution (like lets say double what the engine can take in which would be 14.7psi of boost...right?) do they have to be matched perfectly for your engine?

In other words, lets say I take in 100cfm at idle 400 at 5000rpms and 700 at 8000rpms. How is the supercharger "matched" to that particular flow pattern so that its always doing exactly double?

Or does your boost jump all over the place as the engine becomes more or less efficient???

STEPHEN

Kenku

First off, you'll note in your example that it's pretty close to a constant VE.

Anyway, yeah, it "jumps all over the place"... that's part of why there's bypass valves, to prevent a weird situation of that sort where it would be making a lot more boost than it should. I know that people have killed engines because of that issue... In practice, the changes in VE aren't *that* severe, normally.