Kyle F

I was doing some research here at work and I found a chart that gives the performance characteristics of centrafugal blowers like the Paxton and Vortech superchargers. Anyways I was wondering what CFM they move and at what RPM the internals spin at. Say we are talking the motor is a 2000rpm, as if you are launching. From the chart I can see how much HP it takes to turn them. I am wondering if at lower RPMs you are actually losing HP until you reach a certain RPM in the motor.
If you can give me the conversion factor for the engines RPM to the Blowers RPM that would be awesome, well back to my real job now.
Hey if I concect a leaf blower to my car and run a 100mile long extension cord, do you think I can shave a few thnths in the quarter? J/K

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86 Trans Am 355 TPI Rebuilt 700R4 with Corvette servo, modified valve body, and a B&M Torque Converter (2000 rpm stall w/ lock up), 87 350 block bored .30 with new crank. Reworked 305 heads with 3-angle valve job. Added in the rebuild was an SLP TPI cam, BBK 58mm Throttle Body,MSD 6A, Hypertech Power Coil, 1.5 Crane roller tipped rocker arms, SLP Intake Runners and Port matching in upper intake including fully ported plenum, TPIS adjustable fuel pressure regulator @ 46psi, Hooker shorty style headers w/ Thermotech heat wrapping, Custom 3” exhaust with Flowmaster muffler and chrome quad tips, Hypertech Thermomaster Computer chip, K&N open element cone filter on modified MAF per TPIS specs, MSD Wires, removal of A/C hardware and added a 1LE firewall cover installed. Also there has been a PST front suspension kit with Hotchkis strut tower brace added. Soon to have Intrax lowering springs.
http://geocities.com/SunsetStrip/Garage/9548/kyle.html

Kills:
95 Talon TSI, 96 Probe GT, 91 T/A L98, 89 RS, 86 Mustang GT, 88 Mustang LX 5.0, 92 Thunderbird V8. couple or ricers that I think were Civics or Preludes not sure what year, 95 Celica GT-S, 94 Chevy 1/4 ton 350, one of those NASCAR F150's

The Third Gen Will Never be Forgotten

The ODB

blower rpm compared to engine rpm is a direct function of the internal gearing of the blower and the pulley ratio.
You will need to contact the blower manufacturers for specs like CFM on each particular blower model... they have many.

you should not lose power with a blower. Blowers work, they are just very inefficient.

definately use the gas-powered leafblower vs the electric. The track officials would kick you off for creating a tripping hazard with the cord.

Kyle F

So does anyone have the specs on thier blower. I know they work Im not trying to disprove that, I am just wondering hom much HP you use to run the thing. Like sasy you only gain 10hp at 2000 rpms, but it takes 12 hp to run the thing then you net -2 hp, but at 4000rpms your gaining 75hp and losing 15 you net 60hp. Right, you get my idea now, Im just seeing what the effect are on the engine.

Blown 305 TBI

Here's some Paxton specs.

Model SN-93

Weight - 23 lbs

Boost - 5-7 lbs
w/HP impeller - 5-10 lbs

Air flow - 850 CFM
w/HP impeller - 1,100 CFM

Max. impeller speed 38,500 rpm

--------------------
Novi-2000

Weight - 23 lbs

Boost rating - up to 25 psi

Air flow - 2,200 CFM

Max. impeller speed - 55,000 rpm

These numbers are straight out of my Paxton service manual. And that all the info I have. It doesn't say anything about what CFM is made at what RPM, so, sorry I can't tell you.

Mike

Kyle F

Yea that RPM range is off my chart, but just a guesstamate from extending the graph it looks like at max specs on the paxton unit without HP impeller it looks like it is using around 10-15hp to run the thing. I am guessing though this would be at WOT at the Superchargers max RPM, which does not mean the engine is actually getting it there. So yea it is inefficient, so why do they cost more than turbos?

Grim Reaper

What's your point? Nobody worries about parasitic loss; they are concerned with net gain.

How much HP do you loose from piston friction? How much power do you loose by "blow-by" around the rings on forged pistons vs other types of pistons? How much power do you loose from because of the turbo clogging up your exhaust over a good set of long tube headers?

And before you say "turbos don't waste power", disconnect the turbo's boosted intake and leave it in the exhaust "freewheeling" and then compare it to the same engine with long-tube headers. I guarantee the turbo will loss power by sitting there in the middle of the exhaust with all its required tubing.

Bottom line: people are interested in the net gain.

[This message has been edited by Glenn91L98GTA (edited February 23, 2001).]

IROCKZ4me

10-15 HP sacrifice to gain 75-100+...

I can live with that. LOL


The paxton SN series is internaly geared and externally pullied as shipped in the F body kit to achieve it's maximum impeller rpm at 4850 engine RPM.

Inefficient? Not to bad. As I said above I can live with the difference. Glenn has a good point on turbos, but don't just discharge the air into the atmosphere. Blow it through a jet before release to the atmosphere to apply back pressure to the impeller. You will see some loss there too, I' sure at least 5 or 10 HP. Part of the reason a turbo car is quieter out of the exhaust is the backpressure from the turbos turbine. It's like running an extra muffler. The loss won't be as much with a turbo as the supercharger but it is still loss.
Until some of our "super genius" scientists can bend the rules of physics a little more that is just the way it is.

As far as why they cost more than turbos I wasn't aware that they did.

If you add up the price of everything needed by either you will find that they are somewhat comparable. Some turbos are cheaper, and some supercharger kits are cheaper.
On a side note there aren't any "bolt on" turbo kits for 3rd gen F bodies yet and might not ever be.
Also turbos a a little more tempermental about application and externals like exhaust & intake ducting, cams etc. than superchargers. Bottom line there is that you can get by with more "screw ups" and incompatabilities with a supercharger than a turbocharger.

------------------

Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro
"Cogito ergo zoom"

• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

My IROC-Z
EFI Performance Club on Yahoo
Club IROC-Z


[This message has been edited by IROCKZ4me (edited February 23, 2001).]

Grim Reaper

IROCKZ4me is very correct about the availability and cost of a turbo for 3rd gens. They are not readily "bolt-on" for 3rd gens thus you must get it "custom".

"Custom" is an automotive term for "expensive".

Kyle F

Ok Flamers, I asked a Tech question to satisfy my curiosity. Now all I get is no one cares about this. Look it gives us more HP and there is no other form of forced induction for our cars so it doesn't matter. Though a question like can my V6 F-body out run this or that if I do this and change that ends up getting 180 replies. This all makes perfect sense to me.
To those who helped me satisfy my curiosity Thanks, the info was greatly appreciated. To all others just leave it alone if you don't want to answer the question.
I know that a Turbo is a restricion on the motor and causes some losses just as a supercharger does, but it has been proven that turos are a little more efficient that a supercharger. Thats why I wondered why the superchargers were more expensive than turbos. This was not a question on if they work or not or which one is better, just a question of curiosity.

------------------
86 Trans Am 355 TPI Rebuilt 700R4 with Corvette servo, modified valve body, and a B&M Torque Converter (2000 rpm stall w/ lock up), 87 350 block bored .30 with new crank. Reworked 305 heads with 3-angle valve job. Added in the rebuild was an SLP TPI cam, BBK 58mm Throttle Body,MSD 6A, Hypertech Power Coil, 1.5 Crane roller tipped rocker arms, SLP Intake Runners and Port matching in upper intake including fully ported plenum, TPIS adjustable fuel pressure regulator @ 46psi, Hooker shorty style headers w/ Thermotech heat wrapping, Custom 3” exhaust with Flowmaster muffler and chrome quad tips, Hypertech Thermomaster Computer chip, K&N open element cone filter on modified MAF per TPIS specs, MSD Wires, removal of A/C hardware and added a 1LE firewall cover installed. Also there has been a PST front suspension kit with Hotchkis strut tower brace added. Soon to have Intrax lowering springs.
http://geocities.com/SunsetStrip/Garage/9548/kyle.html

Kills:
95 Talon TSI, 96 Probe GT, 91 T/A L98, 89 RS, 86 Mustang GT, 88 Mustang LX 5.0, 92 Thunderbird V8. couple or ricers that I think were Civics or Preludes not sure what year, 95 Celica GT-S, 94 Chevy 1/4 ton 350, one of those NASCAR F150's

The Third Gen Will Never be Forgotten

jRaskell

Superchargers are also arguably more street friendly, relatively speaking. I say arguably because you can take any statement on these boards and find somebody to dispute it. I still believe that is one of the primary reasons why commercial superchargers are more popular (and by commercial I mean kits that we the consumers can buy and install in our cars) It could be argued that they are easier to install and tune (though some of the stories I've heard from some of the members make the installation of these kits sound pretty terrible)

As for your horsepower question, keep in mind that the amount of horsepower consumed by the supercharger while your engine is running at 2000rpm and the amount of horsepower consumed while it's at 5000rpm are entirely different. High impeller speeds require more horsepower to reach. You also need more horsepower to reach higher boost levels. So the horsepower consumption is dependant on a number of variables. A number I've heard thrown around for the Vortech and ATI superchargers is 70 horsepower to drive them. This is 70 horsepower at peak RPM and peak boost, NOT at idle or low RPM. You will still have a very significant overall net gain in this situation. 20-30 of that horsepower is required to compress the air and generate the boost. The rest is the parasitic loss in the belt drive and transmission inside the supercharger. A turbo will have the same 20-30 horsepower loss as a result of generating the boost, there's no way around that. Turbos have no belts and transmissions though, but they do induce a horsepower loss as a result of exhaust backpressure. How much, I don't know, but it's less then the loss from a supercharger.

In my own opinion though, if I can reach my goal with either setup, then the SC is the best option. My experience with power adders in general isn't nearly as extensive as the regulars on this board.

ps. I didn't get the impression there were any flames in this thread, nothing blatant enough to require a direct response anyways. The info provided by everyone who responded in this thread should still be useful, if not directly applicable to the questions you had. Just weed out the info you want and take the rest as nothing more then views from others as to what is or isn't important.

Kyle F

I got upset at the response... What's your point? Nobody worries about this.
Yea nobody worries about this, its ****ing curiosity. So whatever. I got some info that I needed and like I said it was appreciated. Im surprised you don't need to custom burn a Prom to read the HP chart I have. Hmmm I bet the graph would work better with one anyways because nothing works without a custom prom.

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86 Trans Am 355 TPI Rebuilt 700R4 with Corvette servo, modified valve body, and a B&M Torque Converter (2000 rpm stall w/ lock up), 87 350 block bored .30 with new crank. Reworked 305 heads with 3-angle valve job. Added in the rebuild was an SLP TPI cam, BBK 58mm Throttle Body,MSD 6A, Hypertech Power Coil, 1.5 Crane roller tipped rocker arms, SLP Intake Runners and Port matching in upper intake including fully ported plenum, TPIS adjustable fuel pressure regulator @ 46psi, Hooker shorty style headers w/ Thermotech heat wrapping, Custom 3” exhaust with Flowmaster muffler and chrome quad tips, Hypertech Thermomaster Computer chip, K&N open element cone filter on modified MAF per TPIS specs, MSD Wires, removal of A/C hardware and added a 1LE firewall cover installed. Also there has been a PST front suspension kit with Hotchkis strut tower brace added. Soon to have Intrax lowering springs.
http://geocities.com/SunsetStrip/Garage/9548/kyle.html

Kills:
95 Talon TSI, 96 Probe GT, 91 T/A L98, 89 RS, 86 Mustang GT, 88 Mustang LX 5.0, 92 Thunderbird V8. couple or ricers that I think were Civics or Preludes not sure what year, 95 Celica GT-S, 94 Chevy 1/4 ton 350, one of those NASCAR F150's

The Third Gen Will Never be Forgotten

IROCKZ4me

As far as custom PROMs go you're right there.
For any given application there is one "perfect calibration". Anything different isn't as good. The closer the calibration is to what would be "perfect" the better off you are. A lot of Guys use a "Fuel Management Unit" (FMU) to compensate for a PROM with a calibration that is lacking enough fuel while in boost. FMUs are also often used to compensate for injectors that are too small to supply the needed fuel at normal fuel pressures. If you don't know, an FMU is a fuel pressure regulator that is vacuum/boost oriented like a stock regulator, but unlike a stock reguator it is not 1:1 biased. A stock regulater increases fuel pressure 1 PSI for each PSI of boost. An FMU has higher ratio and many are adjustable.
In my opinon propperly sized injectors and a correct PROM calibration is a better way to go.

It suprizes me how many people run a PROM that isn't even close to what they need, and they think their engines running good. Then when they do get a custom PROM that is closer to what they need they can't believe how much better it is.

------------------

Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro
"Cogito ergo zoom"

• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

My IROC-Z
EFI Performance Club on Yahoo
Club IROC-Z

Kyle F

Dude I wasn't talking about the PROM in the car or a fuel management system or anything like that. I was making a sarcastic remark to Glen, because even though I know he knows his **** about the proms and burning them he doesn't need to put it into every thread. Though it seems like everytime I see his name he is talking about some BIN or something about Proms and I got a little pissed at his response to my question. I mean I know superchargers work... everyone knows that. I was just curious to how much HP it takes to run the things. Because in the High Performance A/C bussiness we have to figure out what blowers to use to move a certain cfm through a given air space and what HP it is going to take to move enough air to make the pressure drop. Kinda like say you need 7PSI boost to get you 70 More HP you want. Well basically what this graph would calculate is the amount of HP you need from an electric motor to make the boost within the given perameters. Anyways I was just being curious.

------------------
86 Trans Am 355 TPI Rebuilt 700R4 with Corvette servo, modified valve body, and a B&M Torque Converter (2000 rpm stall w/ lock up), 87 350 block bored .30 with new crank. Reworked 305 heads with 3-angle valve job. Added in the rebuild was an SLP TPI cam, BBK 58mm Throttle Body,MSD 6A, Hypertech Power Coil, 1.5 Crane roller tipped rocker arms, SLP Intake Runners and Port matching in upper intake including fully ported plenum, TPIS adjustable fuel pressure regulator @ 46psi, Hooker shorty style headers w/ Thermotech heat wrapping, Custom 3” exhaust with Flowmaster muffler and chrome quad tips, Hypertech Thermomaster Computer chip, K&N open element cone filter on modified MAF per TPIS specs, MSD Wires, removal of A/C hardware and added a 1LE firewall cover installed. Also there has been a PST front suspension kit with Hotchkis strut tower brace added. Soon to have Intrax lowering springs.
http://geocities.com/SunsetStrip/Garage/9548/kyle.html

Kills:
95 Talon TSI, 96 Probe GT, 91 T/A L98, 89 RS, 86 Mustang GT, 88 Mustang LX 5.0, 92 Thunderbird V8. couple or ricers that I think were Civics or Preludes not sure what year, 95 Celica GT-S, 94 Chevy 1/4 ton 350, one of those NASCAR F150's

The Third Gen Will Never be Forgotten

askulte

Before y'all get your panties all wrinkled up, I think he (Kyle) took a look at a generic pump curve for centrifugal pumps. What this curve will show is an industry accepted efficiency of the air pump at its respective rpm, airflow, and pressure ratio range. The hp shown on the curve is strictly to spin the impeller, and does not account for the fact that our superchargers have step-up gears of almost 10:1.

Here is the compressor map for the Vortech S-trim



It's efficiency is from 65% to 72% in the intended operating range. This means 65% of the hp needed to spin the compressor goes to compressing the air, the other 35% goes into heating the air further through friction. What your pump curve shows is how much hp it takes to generate the X amount of boost at Y rpms and Z CFM. If you spin a supercharger by hand, you need a pretty firm grip on the pulley - it's not all that easy (i.e. doesn't really freewheel too well). Just imagine the impeller spinning around 40,000 rpms. I don't have concrete numbers, but Vortech does. Give them a call, and ask to speak to engineering. Say you're doing a school report or something (otherwise they might not give it out). Ballpark - 75 hp for a 7 psi system. I'd say half is for the drive inefficiency, and the other half is to compress the air.

BTW - the hp loss from flow doesn't really begin until you get boost, so under 2k, it would be just the drive inefficiency. I hope this was the kind of answer you were looking for.

Finally - if you weren't looking at a pump curve, then ignore my response (which I'm sure most do anyway!)

Andris "The Rambling Engineer" Skulte

Kyle F

Actually you gave me more info than I was looking for but its what I needed. Yes this is a generic chart for cetrafugal blowers, but it X is CFM and Y is the Pressure drop(or Boost) Plotted on the curve is the effeciency of cetrafugal blowers based on RPMs. Showing the efficient operating range. Which not one curve is a straight line. Then also plotted on the cuve is HP ranges. Well it looks a lot like what the Vortech S trim graph but mine has the HP ratings for driving them. This graph is not an ideal graph it is a lab experimental result graph, though the blowers we use only run at about 4,000 rpms max. THough the graph goes higher for blowers. I also have a sweet program called whirl wind that cvalculates all thsi info for you if you have the proper information.

Grim Reaper

Funny, I don't recall me saying ANYTHING about a prom in this thread?

I don't know where I flamed you Kyle, but I sure can see where you have done so to me.

[This message has been edited by Glenn91L98GTA (edited March 01, 2001).]

PROCHARGED89Z

LOL dam right
On the topic of superchargers using hp to turn.I dont think they use any if not a little when they are not in boost conditon.I think they tend to rob crank hp when the impeller has the force of back pressure to deal with.Just my 2 cents

Grim Reaper

Procharged89Z, I've heard from a number of people with superchargers, that when just "cruising" that they actually experienced an increase in gas mileage, which would tend to indicate an overall increase in the engine's efficiency. If the engine was suffering from siginificant parasitic loss, they'd also experience a drop in gas mileage too.

WOT is another matter entirely. High HP needs fuel.

PROCHARGED89Z

Glen I totally agre with you on that one.When I had my p600B system on the first time I noticed the car was a little stronger in out of boost acceleration,light acceleration and such.Must be doing something oter than robbign hp in off boost situations.I dont think,even though I have no data to back this up,I feel the blower will only start to rob hp under boost,when the impeller has to push against the air backing up.I can turn my blower with a little 1/4 hp angle drill,to about 1500rpm the rate on the motor,with no problem what so ever.So i fell their is no robbing of hp what so ever in any other condition besides boost conditions.Someone pointed out it is a good trade off,I agree,seeing the system can be installed by any competent person.I dont know what the gains are in relation to hp but with my car for example,with the times I ran I estimated the crank hp to around 400hp this is over a 230hp stock.Not bad,I gained I dont know around 150-170 hp at the crank.What would be my losses?40hp - 50hp.I can live with that,I was only pushing 9lbs.

IROCKZ4me

here's something to help back that up...

›Boost is just a measurement of back pressure in the intake.

›Boost is measured relative to atmospheric pressure.

›Atmosheric pressure is just under 15 PSI at sea level.

›Absolute vacuum is 0 PSI

›Manifold vacuum is another way of saying "manifold absolute pressure" or MAP, where 0 inches of vacuum = atmospheric pressure (15 PSI).

›A manifold absolute pressure above 15 PSI = boost condition.
A MAP of 25 PSI would be equall to 10 PSI of boost.

›Also a MAP of 12 PSI or any other MAP under 15 PSI would not have "boost".
<hr>
The point is you are increasing the manifold absolute pressure even when the MAP is not exceeding 15 PSI (showing boost). So, you can increase airflow even when not in "boost" conditions because the actual manifold pressure is indeed higher, just not higher than atmoshperic pressure. The more efficient the impeller is and the more air it flows at low RPM the better the effect on "nonboost" power & efficiency.

There is of course some resistance do to friction of parts. This increases proportionatly with RPM.
On ball drive type superchargers this type of drag is higher than on gear driven types. The big culprit is indeed the drag caused by pressure on the impeller imparted by boost. The higher the boost is the more drag on the impeller.



------------------

Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro
"Cogito ergo zoom"

• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

My IROC-Z
EFI Performance Club on Yahoo
Club IROC-Z