Anyone with supercharged expierence?

[Kr0n1k]

Due to what my project will be used for, I began looking at centrifigul superchargers. Looks like a turbo basically, but how do you go about mounting such a thing? It would obviously have to have a bracket of some sort, and mount up so that it is lined up with the pulleys and custom piping made to go from the blower to the intake. Also, what pulley would you run it off of? There's also the roots type, but I dont even want to begin to imagine how much the fab would cost on a custom intake minfold and all that. The centrifigaul looks to be the most inexpensive way, but I have 0 expierience with either type. Any ideas?

[TrunkMonkey]

everyone say it with me...

a roots blower does NOT need to be attached to the intake manifold!a roots blower does NOT need to be attached to the intake manifold!a roots blower does NOT need to be attached to the intake manifold!

sorry. i just had to get that out of my system.

-demetrius

[Kr0n1k]

yea, thanx for all your help. seems how the objective of the post was to learn about centrifigaul superchargers... also stated the fact that I have zero experience with either. How does it connect? I see alot of kits for roots blowers that come with a new intake manifold for Ford and Chevy trucks. I know that a centrifugal does not have anything to do with any type of manifold, which was why I was interested, and wondering what would have to be fabricated to make it work properly.

[madbouncy]

I think most of the reason they mount it on the intake is because they're using them on v6's and v8's where the intake is in the center. So it gives you an easy place to mount it plus if you don't run an intercooler it feeds directly in. Though if you look at the supercharger kits for like a miata, they mount it on the exhaust side.

Any specific reason you want a centrifugal one? You said it was because of the project, just curious what the main goal of that project is that you want a centrifugal for. As far mounting it, the only thing I can think of is if you moved the intake piping over to the battery side(and moved the battery to the trunk), or just incredibly short intake piping, then you put the super infront of the engine. If you try and put it where younormally put a turbo, your distributor is going to get in the way. Do you have any idea how big it is? If you knew you could get an idea of where you could place it to avoid stuff. You can run it off any pulley you want. however, if you have an underdrive pulley on already, you should put a pulley on the crank one and run it off that, otherwise yo'll make less boost than you're expecting. Just try and find a kit as close to what would work for you and see how it works. If you plan on running a front mount intercooler I'd keep the super on the exhaust side, that way you feed into the intercooler and then it exits on the intake side, otherwise you have to loop it all the way around to the other side of the engine bay to get into the intercooler.

[madbouncy]

Oh yeah, forgot one thing. You should look at twinscrew superchargers. They're like the roots but with a lot better highend. Whipple and Kenne-Bell are the major ones I know of. If you think it could handle the weight, you could get a hotshot header and mount the super onto that, then run the snout under the distributor to reach the pulleys. I know with the kenne-bell superchargers you can mount them any way you want as far as angle. So you could have it upside down or slanted to mount it a little bit further down the headers to get it to get under the distributor.

I hate centrifugal superchargers though, so I'm going to be kind of biased on the issue. Like people say, it takes the bad side of a turbo and mixes it with the bad side of a super. You get low boost at low rpm, almost like turbo lag, plus you have parasitic loss from it running off pulleys, and ontop of that, you have to change the pulley to change boost.

[Kr0n1k]

Well, a couple of the goals would be:

a) Unique power upgrade (for the 240)b) Streetability (least amount of lag from boost as possible)

Other factors come into play. From driving a supercharged (Jackson Racing) Civic I enjoyed the instantaneous power that the supercharger provides. My buddy that owns the car drives it everyday, and I could see why from driving it for about 15 minutes. The power is always there. I understand that turbochargers are more efficent and etc. etc. because they use exhaust gas to propell the turbine, but I would much rather have that power on tap. Now, the one I've never heard of before, the twin-screw, that may be something I'll have to look into. Like I said, I have zero experience with superchargers. I just felt that it would better suit the KA's powerband, and the centrifugal was the first I brought up because it basically looked like a belt driven turbo, although after what you've said, I don't think I want the worst of both worlds. Thanks for your help Madbouncy, going back to research...

[madbouncy]

http://www.kennebell.net/techi...l.htm

You can look around there, the kennebell site has a lot of dynos comparing what the superchargers are like. Roots and twinscrew pretty much just bump the torque curve up however much you decide. It doesn't slowly come on, you just get like 50+tq all the way from start to end. However, the roots has a tendencey to die at higher rpms. The twinscrew does the same at lower rpms but it keeps going strong well into 6000+ rpms. The centrifugal, just builds up boost as you go, linearly obviously. So a turbo would hit max boost sooner I think, for higher psi anyways. But a centrigual will havea little better low end than the turbo. I still don't like them though, turbos are the best for high horsepower and boost. Turbos are a lot cheaper because there's plenty of options for it and it's been done a lot so there's a lot of resources to get help from. You'll pretty much be on your own with a supercharger.

[H.D.HUMPERDINK]

centrigual superchargers don't hit whatever the peak psi is until near redline, if not at redline. I think the only real advantage of them is that thry don't create alot of heat.

roots and twinscrew blowers make alot of heat, but you can put an aftercooler on them and keep the temperatures down. plus you can get a eaton blower off of a gtp or a thunderbird for dirty cheap.

If it was up to me I would build a roots set up, but its your project. there is a guy on here that had a centrigual supercharger set up, and if you search you might be able to find a post about it.

[nissanfanatic]

I believe a centrifugal produces just as much heat as a roots, twinscrew, turbocharger, or pretty much any type of compressor at the equivalent efficiency and boost level. Compressing air just creates heat. Enthalpy.

[TheOne]

i'd look at the kennebell, if it wasn't cause the 240sx stopped bein produced, maybe you could've been their project car:).since the miata has the same shape(as in rwd with exhaust at 1 side and intake at other) it would be a good place to start.or look at the other kits like the 1 that summit racing sells for the I4's, its mounted right up of a custom intake.

[Ubernoober]

Eaton twisted-roots: Good efficiency, instant boost from 1500 RPM, can be mounted anywhere, belt driven. Good to 15 PSI where the efficiency radically drops off.

Whipple/Kenne Bell (Lysholm): efficiency near that of a turbo compressor, instant boost from 1500 RPM, mount wherever, good through 15 PSI, belt driven.

Centifugal supercharger: The compressor half of a turbo driven by belt. Boost and efficiency rises with RPM, which means incredibly poor low end power. Easy to tune since a rising FMU will increase fuel delivery along with the device (not perfectly, but close enough, look at how the V8 boys work it). Light and small, easily mounted, good to stupid levels of boost. Makes an obnoxious whine from the internal gear drive, though you may find that appealing.

Turbo: must be mounted in the exaust path. Very efficient, but turbo must be chosen to match boosting and engine goals. Boost threshold and max boost based on user design.

All can be intercooled. Water or air. You ALWAYS drive the belt driven units off the crank pulley if at all possible.

[madbouncy]

nissanfanatic: Yeah they all create heat, but the more efficient ones will make less heat. Also, a roots blower isn't a compressor, it's just an airpump, the twinscrew is a comperssor which is why it holds up better at higher levels.

Ubernoober: As far as it being only good up to 15psi, where did you hear that from? I'm not saying your wrong, all I know is what their website shows. I just figrued it would be able to put out a lot more and hold efficiency pretty well. I'll look around for some dynos on higher psi ones. Though they offer plenty of high boost pulleys, I didn't see any dynos of them, so it wouldnt suprise me if they do fall out that quickly.

[TheOne]

kenne bell's 2.4L supercharger is good up of 20psi, ppl have done 24 or so on 03/04 mustang cobra svt's.(this is just to say that twinscrews can go up of 15psi efficiently, even their 1.7L can do 15-16psi).

anywayz, if you do some research, somebody here in the forum though about taking out i think the a/c then putting a custom mount for a mercedez kompressor.

[Kr0n1k]

hmmm... 20 psi you say? boost comes on at 1500 rpm you say?

[TheOne]

boost does come around 1500rpm.and can get 20 or more psi.look for kennebell supercharged 03/04 mustang cobras.......and you'll see what am talkin about.(i like that car, but am stayin with my 240....i just like it so much)

[Ubernoober]

Yup, the Lysholm (Kenne Bell) is a true compressor and as such can reach high boost numbers efficiently. You just have to watch out for the overall screw speeds and choose your size carefully. I guess I should have said "good beyond 15" instead of "through". Sorry.Since the Eaton "twisted Roots" is not a true compressor, it suffers from efficiency problems. Note that NONE of the graphs on Eaton's page show the delta-T at more than 10 PSI. In fact, what they don't show you is that 15 PSI isn't 50% worse, it is actually twice as bad as 10 PSI. One solution is to of course drive a larger supercharger at slower speeds to gain back some efficiency. The problem comes from the device working against discharge pressure. Again, its a modified air pump, not a true compressor. One benefit of the Eaton over the Kenne Bell is that it takes less HP to drive and with a bypass, will draw less than 2 HP, meaning you still get great mileage. The Lysholm is a tad less friendly in this regard since without a clutch (hint hint, see Mercedes and their clutched Lysholm) you are constantly compressing and then blowing off the boost. Also, the Eaton is HUGELY easier to find and buy. Hell, just go to a junk yard and pull the M-90 off a Thunderbird Super-Coupe. Tada, more size than you will ever need (thats what my girlfriend always says).

[hamsturbation]

a cenrifugual blower will make more power at a given PSI than a turbo, all other things equal, since it dont have hot exaust flowing though half the turbo, and its not sitting on top of a hot exaust manifold/header ect..

roots blowers dont compress air, you just get pressure from heatalso, for a centufigal blower you can just have a machine shop mill you a bracket/tentioner and a crank pully, if you have the $$if you have a high rpm motor, or just want a dyno queen a centrufigal blower will work fine

you guys alos need to stop looking at PSI, and look at how much air the damn thing flows..

[TrunkMonkey]

a cenrifugual blower will make more power at a given PSI than a turbo, all other things equal, since it dont have hot exaust flowing though half the turbo, and its not sitting on top of a hot exaust manifold/header ect..

the "a supercharger will produce more power because doesn't have hot flowing exhaust gas passing through it and it isn't attached to a hot exaust manifold" is an age old defense used by old school V8 guys...it's lame, it's incorrect, and it needs to die. i have yet to see a centrifugal supercharger make more power than a properly sized turbocharger at the same psi. at low boost levels they'll produce close to the same. but the more boost you run, the more the turbo excels.

Quote »you guys alos need to stop looking at PSI, and look at how much air the damn thing flows..[/quote]nope. even if a supercharger were to push more air at a given psi than a turbocharger, what good is all that air if it's 2-3 times hotter? bad efficiency only robs power. you can't substitute quantity for quality in this case.

-demetrius

[Ubernoober]

*Edit* In reference to Hamsturbation*No.Why are you throwing out all this misinformation? Nothing you said is meaningful or helpful. About the only thing worth merit is mentioning that the belt-driven centrifugal doesn't transfer exaust heat. The rest is just wrong.

Airflow is important, but efficiency at a given pressure ratio is far more accurate. We have been using PSI because it seems people understand that more readily than pressure ratio.We never said roots blowers compress air. We said they were air pumps.You don't get pressure from heat in any open system. In fact, I cannot even comprehend what you are trying to describe here.If a shop can make you a bracket for a belt-driven cetrifugal, they can make you one for any of the others. I mean, WTF? Really now.

I am sorry if this seems harsh, but every time a boosting thread comes up, people seem to feel the need to contribute even if they don't know what they are trying to say. It just spreads confusion, and the same questions get asked again and again as a result.

I may have misread what you are trying to add, and if so, I apologize. Maybe you could clear it up a bit?

[Kr0n1k]

Who said anything about dyno queen? I've driven both a supercharged (read above) and turbocharged vehicle in the past, and really enjoyed the supercharged vehicle ONLY because the power came on much quicker and smoother than the trubo cars. I'm not looking to race anybody (well, maybe a drag or three) or autocross or anything like that, I was more interested in a more subtle (driving wise) power add-on. Ok, so, twin-screw and mounting on or near the exhaust manifold. Only problem I can see is heat soak. However, I've found the Miata kits, and that's right where the 'charger sits, but underneath (or behind, which ever) the exhaust manifold. Price is also a BIG issue. Some of these kits are 4 grand?? It is a kit with other things included but c'mon. And it also doesn't help me because I need just the supercharger itself. Maybe I will make a trip to the junkyard... and find a Thuderbird super-coupe. What year are those again Ubernoober?

[Ubernoober]

The supercoupe was available over the same time span as the S-13/14. 1989-1997. Obviously the later years will have revisions to the plumbing and perhaps the supercharger itself that make them more desirable. I suggest you do a simply google and go from there. The problem is that the supercharger is a tad large for our 2.4L application. Still, its cheap.

BTW, how cheap do you want to go?Heres uber-cheap....Used supercoupe charger. Piping from a muffler shop (nobody cares about mandrel bending when you get it for pennies), or Home Depot. If you want to intercool (highly advisable) you can just get a core from the same donor car as the charger. Fuel control with a 8:1 rising rate FPR. Retard spark by backing the distributor off 3-5 degrees. Pull your AC and use the block mounting location to build your bracket. Don't forget to include and idler pulley that forces the drive belt to run at least 180 degrees over the charger pulley. If later (s14's) 240's came with a serpentine setup, you might be able to convert over to get the advantage of a superior drive belt and an easier install (since most factory pulleys for the chargers are of the wide multi-groove and not the V-belt kind). Kepp the boost below 7 PSI and you won't need a piggyback, but you had better make sure the FPR matches your fuel needs.

Super ghetto, but assuredly cheap. The hardest part would be the bracket and pulley fab. It might be worth it to simply pay someone else for the fitting. Better that someone else get the migraines and pay for the mistakes and re-do's. Just negotiate a fixed cost before work and don't let them run up the costs if they screw up. They bid on the job, so fixits come out of their pocket.

[Ubernoober]

You know what? Now that I think of it, be sure to get all the gobbledygook that comes attached to the SC. That would include the throttlebody (you don't need it), all the bypass tubing and intake tubing (you DEFINITELY want this) so that you do not have to re-create your own. It should include all the aluminum castings that feed into and out of the rear of the SC. It will make your life a million times easier.

Also, for cheap, I think this would be a hot-s**t way to go fast. At 7 PSI the car will definitely by tail-happy all the way up to the torque peak.

[dfw240_EE]

Another advantage for a centrifugal/Lysholm/whatever is that you don't have a reversion problem.

It's something I read about in my turbo book. We all know that as RPM and flowrates increase you start to build up pressure in the exhaust manifold. This is from the fact that the flow rate exceeds what the turbo can handle. At a certain point this pressure exceeds the intake manifold pressure. At this point exhaust gasses can flow back into the combustion chamber during valve overlap. The solution to this is to design the system to have a large enough turbo to handle the high RPM flowrates and have a low overlap cam profile.

Since the supercharger doesn't run off the exhaust manifold, you could run as wild of a cam as you wish (or is practical). In fact a high overlap cam might be preferrable. During the transition from Exhaust to Intake strokes the supercharger would be blowing fresh air from the intake side through the combustion chamber, and out the exhaust side. Thus clearing the chamber of exhaust charge.

[madbouncy]

http://www.kennebell.net/techi...g.pdf

That's a quick compare of the heat given off at different PSI for a twin screw and a roots. I'm sure it's a little biased towards the twin screw. However, I think for lower psi, it's better to do what ubernoober said and get a junkyard roots type. Frankly, for the small difference at low boost, I don't think the $1500 (smallest of the whipple ones) justifies that. Though some people have to have the best.

I was wondering about that clutch thing that you mentioned, I've been trying to find info on it. I'm going to look for it some more, would like to see how well it works and everything.

The statement about a centrifugal being better than a turbo sounds like complete bull. The only real restriction I could see from turbo is maybe some extra back pressure before it spools. However, the extra heat is mostly removed by the intercooler. Either way though, the parastic loss from a supercharger is pretty much always higher than running it off the exhaust. Maximum Boost said you'll get abuot 10-15% more power from a turbo than from a supercharger because of the parasitic loss.

[dfw240_EE]

There is also backpressure like I mentioned at high RPM, especially on small exhaust turbines which are quick to spool. I think the VW's turbo system used small turbines.

Personally, I am leaning more torwards turbocharging. Back pressure at high RPM should be no problem if I size the turbo right. The problem of plumbing the exhaust to the turbo is already well-solved, as manifolds are easy to come by.

[Kr0n1k]

Ubernoober = the MAN. Thanks for all the help. I thought it might be cheaper than a basic turbo setup, as long as I wasn't out to get the newest, most expensive supercharger. I just can't imagine what this thing will be like stop light to stop light. This has now become my mission. And raising/lowering boost depends on the pulley size, right? So shouldn't I pull the pulley and tensioner off of the T-Bird to make sure I'm getting the correct size pulley and tensioner made up? I don't think the T-Bird runs anymore than 8 PSI but I'll have to look that up. Anyways, more reading, and thanks for all the help Uber.

[madbouncy]

I'd be careful with the pulleys. The T-Bird uses a bigger engine, so if you get the same size pulley it'll be running more boost on your 240 than on the T-Bird. I don't know the formula for it off hand, but I'm sure somebody will chime in with it. Basicaly it's because the supercharger flows a specific amount of air, so say it pushes 3.0L, if that was on a 3.0L engine, that would be like having a 6.0L engine and would be equal to about 2 bar (assuming no loss.) Where as if you run that 3.0L super on a 1.5L engine, that be around 4.5L total, which is 3 bar. So you have to be careful. It's all just ratios of the pulley sizes and engine sizes. I'll see if I can find a formula before somebody else mentions something, I'm sure uber has it, so far he's our best resourse.

[madbouncy]

Theoretical Boost = Supercharger Size * Pulley Ratio * 29.4 / Engine L - 14.7

crank pulley / supercharger pulley = pulley ratio

[Ubernoober]

Hey thanks. This is probably the only time I have been useful on this board.

Anyway, it is almost exactly like madbouncy described. The supercharger for the T-Bird was designed to make 12 PSI on a 3.8L engine (BTW, it is essentially a Ford 5.0 with 2 cylinders hacked off). So just as you thought Kronik, the pulley must come off the front and a pulley must be found or made to turn the SC to the speeds you want for the boost you want. The pulley on the T-Bird looks as if they all came with a serpentine, which our 240's did not. The easiest thing might be to get a crank pulley made that has all the normal v-belts with an extra nose for a multi-rib serpentine belt. Cheap and it keeps the SC belt out front abd separate from the rest of the system. It will also allow you to simply buy a new pulley for the SC from the millions that are available. Don't forget an idler. I'd pull the idler off the T-Bird and make a bracket for it. You might be able to get away with just making an adjustable bracket for the SC and running no idler. Might be easier that way, but get the idler with the SC anyway, they won't charge you for it. I think.

Its hard to find info, but I am pretty sure the T-Bird SC is an Eaton M-90. It displaces 90ci per revolution (thats 1.5L to you and me). That makes it pretty huge for your low boost application. Here is a complication though. All Eatons have a gear drive up front and I do not know whether it is direct drive or not. In other words, I do not know if one revolution of the pulley = one revolution of the rotors. You would have to find one and turn the pulley to find out. This of course affects the pulleys you need to size. At any rate, with this monster, I would run an intercooler. The volume this thing pushes will move air through it rapidly and the benefits seriously outweigh the negatives.Raising or lowering boost depends on the pulley ratio. It is like saying "size", but a bit more descriptive and accurate.The formula madbouncy gave doesn't seem right. I get all kinds of goofy numbers using it.

For some reason I was using this one:(SC displacement in L * Pulley Ratio * 14.7 / Engine L) - 14.7 = Boost in PSI

That doesn't take into account efficiency losses.

Anyway, I think the Eaton M-62 would be a better match. Maybe we can find one off a different car. Try doing a search on:Buick GSBuick RivieraBuick Park Avenue UltraPontiac BonnevillePontiac Grand Prix GTPOlds LSS

Maybe one comes with a 62. The problem is that they are almost all certainly going to be more expensive that the older T-Bird stuff.

One thing is for sure, the M-90 can take you to much big boost numbers, Hondo.

[madbouncy]

Ubernoober, I was looking up the numbers on the different eaton superchagers, mostly the m45 and the m90. The m45 is like .75L and the m90 is 1.5L. I looked at the stuff and obviously, at the same speeds the m90 puts out more heat and has alot bigger parasitic loss. However, i figured, if the super is twice the size, it would probably only turn half as fast to put ou the same amount of air. Which would put the m90 ahead of the m45 as far as efficiency. That sound right to you? I'm really new to superchargers and supercharging in general, as you've noticed since all my knowledge has come from that one single website.