Blower Thermodynamics

[78Eliminator]

Question: I am reading a book that Blown472 sent me on blowers. I was reading last night that the purpose of a blower is to create a denser charge (obvious). When you compress air, it heats up, thus working against the purpose, which is to condense the charge. An example they used is that if you had a box, which was totally sealed and you stuck a pressure gauge in the side of the box and then put the box over a flame, it would heat up. As the air expands, it will create pressure (boost), which would show up on the gauge. ItÂ’s misleading since most people think that the more boost you make, the better. One way people solve this is by adding an intercooler like the "superchiller".
My question is: do any of you blower guys have blower specs that include the ratio of compression to heat. Theoretically, if you get a blower that will compress the charge and not heat up the air as much as the next blower, you are ahead of the game. Anyone know this info?

[Infomaniac]

Whipples and screw blowers are very effecient. Centrifugal blowers - turbos etc are more effecient than roots blowers.
A roots blower does not compress the air inside the blower. It provides the engine more air than it can use so the pressure is increased inside the intake manifold.
A dyno will tell you at what point a roots blower is defeating it's purpose. You plot the boost curve along with the power curve.
At the point the boost is increasing and the power is decreasing shows you where the air is expanding due to heat.

[78Eliminator]

Infomaniac:
Whipples and screw blowers are very effecient. Centrifugal blowers - turbos etc are more effecient than roots blowers.
A roots blower does not compress the air inside the blower. It provides the engine more air than it can use so the pressure is increased inside the intake manifold.
A dyno will tell you at what point a roots blower is defeating it's purpose. You plot the boost curve along with the power curve.
At the point the boost is increasing and the power is decreasing shows you where the air is expanding due to heat. So really, the best method is to take the engine to a dyno with a set of pulleys and determine which combination is the best for your application (engine set up)?

[Liberator TJ1984]

I read in a Street Rodder Mag. where they tested different power adders,Blower,Turbos ,NOS, but I will stick only to the Blower section they stated that a roots style blower is good for 12-15 psi before it actully starts to Rob power from its application.what you know on this INFO..???? smile_sp

[Infomaniac]

Justin - Honestly I do not think you would reach that point on a pump gas deal. Unless you are running a very small blower without intercooler.
you would not be able to work an intercooled 8-71 or 10-71 on pump gas hard enough to reach that point.
Buy a Whipple if you just want the most effecient blower.
[ January 15, 2003, 10:43 AM: Message edited by: Infomaniac ]

[78Eliminator]

Infomaniac:
Justin - Honestly I do not think you would reach that point on a pump gas deal. Unless you are running a very small blower without intercooler.
you would not be able to work an intercooled 8-71 or 10-71 on pump gas hard enough to reach that point.
Buy a Whipple if you just want the most effecient blower. Ok Info. The book I'm reading is just kinda scaring me. With all the heat they're talking about, you can really rattle your bottom end. With an intercooler and the biggest radiator at your disposal, I suppose this wont be much of an issue. Thanks for your input as I try to get up to par in the "Blower World"....
J

[Infomaniac]

Don't just take my word for it. Wait for all the other replies.

[78Eliminator]

Infomaniac:
Don't just take my word for it. Wait for all the other replies. But you're the "Infomaniac"! :D

[Blown 472]

And I thought Bill Nye the sceince guy was off the air??

[bigq]

Infomaniac:
Whipples and screw blowers are very effecient. Centrifugal blowers - turbos etc are more effecient than roots blowers.
A roots blower does not compress the air inside the blower. It provides the engine more air than it can use so the pressure is increased inside the intake manifold.
A dyno will tell you at what point a roots blower is defeating it's purpose. You plot the boost curve along with the power curve.
At the point the boost is increasing and the power is decreasing shows you where the air is expanding due to heat. Sounds good.I will add I believe that at the point where boost is increasing and no power is gain is where the point the engine is maxed out for the air coming in, which causes the heat. If you added bigger port heads maybe changed the cam design you would gain more power and the boost could actually read lower, but more power.
Or you could just give it a shot of NOS and compress with a cooler charge. :D J/K dont try that at home kids.

[Blown 472]

Or run it fat, so the fuel helps cool?

[bigq]

Blown 472:
Or run it fat, so the fuel helps cool? That could help too. Have a nice running idle circuit and primary with fatty secondaries for the higher end. It is hard to get it too fat on the top end, at least the application I had, a lot of air.I don't know how much more fuel would cool it, but I know it does have a cooling affect on the air charge.

[Schiada76]

First off I have NO IDEA WHAT I"M TALKING ABOUT!
Other than that it sounds like you want to know what's going to give you the least heat gain in a roots blower. Bigger blower heats the air less, plus inna boat you have a GIANT radiator to keep things cool. :D
Happy to be of no service!

[Schiada76]

BradP:
First off I have NO IDEA WHAT I"M TALKING ABOUT!
Other than that it sounds like you want to know what's going to give you the least heat gain in a roots blower. Bigger blower heats the air less, plus inna boat you have a GIANT radiator to keep things cool. :D
Happy to be of no service! Didn't I see somewhere you were looking for 700 to 750 horsepower? I got 756 on the dyno (first pull) on my 496 w/871 no intercooler

[058]

78Eliminator:
Question: I am reading a book that Blown472 sent me on blowers. I was reading last night that the purpose of a blower is to create a denser charge (obvious). When you compress air, it heats up, thus working against the purpose, which is to condense the charge. An example they used is that if you had a box, which was totally sealed and you stuck a pressure gauge in the side of the box and then put the box over a flame, it would heat up. As the air expands, it will create pressure (boost), which would show up on the gauge. It’s misleading since most people think that the more boost you make, the better. One way people solve this is by adding an intercooler like the "superchiller".
My question is: do any of you blower guys have blower specs that include the ratio of compression to heat. Theoretically, if you get a blower that will compress the charge and not heat up the air as much as the next blower, you are ahead of the game. Anyone know this info? The answer is 7 degF for each pound of boost with no outside influence such as heat created by the blower or the engine. If your blower makes 15lbs of boost the discharge temp will be raised 105 degF above ambient temp. Roots blowers are the least efficient of supercharging. They only have about a 45% rating whereas turbos are 65-70% efficient. I don't know the rating of the Whipple but its got to be close to that of the centrifical.

[Hotcrusader76]

Effeciency = Actual divided by theorectical mult.by hundred
Ok...nuff said, back to studying.
[ January 15, 2003, 03:50 PM: Message edited by: Hotcrusader76 ]

[Whipple Charged]

Q58, at 15lbs of boost with a roots, running gasoline through the supercharger, depending on brand, age, rotor design, would be much closer to 300-350 above ambient temp. A screw compressor would be somewhere near 120-140 above ambient as well as a centrifugal.
To all:
The purpose for supercharging is to raise the density of the air charge, this increases the air mass trapped and then compressed in each cylinder firing. In simple terms, the more air and fuel you can shove into the cylinder, the efficient the engine is (more power).
Blower thermodynamics are much more complexed. First, on roots, the temp rises dramatically as boost increases. Every supercharger has an "efficiency" curve that can be plotted out like a map. This is based off of three varibles, compressor rpm, airflow and manifold psi. There are a few ways to figure efficiency, adiabatic efficency and volumetric are the most common. Volumetric measures how much air per rev. If your supercharger was 2.3L and it had a VE ration of 100%, then you would get 2.3L of air per rev. AE is the measure of the input power to which is wasted in raising the charge temp. Think about this, the blower has a discharge area on the bottom, when the manifold pressure gets positive, where is the air naturally trying to go? Simple, right back through the supercharger. This causes air to be recirculated time and time again which continues to heat up. The longer you hold the engine in positive psi, a roots will never stabilize temp and will continue to grow. Racers use nylatrol strips to actually seal the superchargers up to decrease leakage, but that causes a tremendous amount of power to operate since the surfaces are touching and so on.
So, to answer your question (78Eliminator), its depends on supercharger make, and model (such as rotor design, discharge size and design, compressor size) as well as inlet air flow, etc. Roots doesn't really have a rule of thumb, 7 degrees per lb, thats what you would see on a 15 second sweep test on a dyno, not the real world in a boat or towing in a car. The curve is not linear.
It's very hard to speak in general terms of superchargers for these reasons. Weiand is different than B&M, Kuhl is different than Littlefield, etc.
Thanks,
Dustin

[Nstigator74]

I'm not trying to confuse anyone, but does running methanol keep you charge temps cooler?

[Badboat1]

Whipple Charged, Very well said. Whipple is the strongest I have seen on the dyno and can run some boost and it will stay together.
Badboat1

[Fiat48]

Nstigator74:
I'm not trying to confuse anyone, but does running methanol keep you charge temps cooler? Yup. And 15% more horsepower by pouring it in the tank and up to 30% more horsepower if the engine is "optmized" for alcohol. wink
K.I.S.S. method:
An engine is an air pump
A blower is an air pump
There's 14.7 PSI atmospheric pressure available at 0 elevation (sea level) and 60 degree's temperature.
Basically every time you put in 14.7 lbs of boost you double the horespower compared to sea level. (less the power required to drive the blower).
Bump the blower overdrive till you feel no real gain in performance. Blowers vary a bunch.
Running the engine fat is not the way to cool: creates extreme exhaust temperature and dilutes your engine oil. My 2 cents (overpriced). :D
[ January 15, 2003, 09:03 PM: Message edited by: Fiat48 ]

[058]

Dustin, With all due respect please re-read my post. With no outside influence [rotor design, brand, age, size of outlet, ect,] The mere act of compressing the air will raise air temp 7 degF for every pound of compresson. No other factor considered including the adiabatic and volumeteric efficency. Thats all I was trying to point out because thats what I thought "78Elim" was asking.

[hulshot]

i am going to just put on a 14-71 and forget it. It will make more power by running it slower and not having such a hot intake charge.

[bigq]

Fiat48:
Nstigator74:
I'm not trying to confuse anyone, but does running methanol keep you charge temps cooler? Yup. And 15% more horsepower by pouring it in the tank and up to 30% more horsepower if the engine is "optmized" for alcohol. wink
K.I.S.S. method:
An engine is an air pump
A blower is an air pump
There's 14.7 PSI atmospheric pressure available at 0 elevation (sea level) and 60 degree's temperature.
Basically every time you put in 14.7 lbs of boost you double the horespower compared to sea level. (less the power required to drive the blower).
Bump the blower overdrive till you feel no real gain in performance. Blowers vary a bunch.
Running the engine fat is not the way to cool: creates extreme exhaust temperature and dilutes your engine oil. My 2 cents (overpriced). :D 2 questions, how does the alcohol create a cooler charge and how does it mix with the gas? Will it burn more fuel because of the alcohol?
OK that was three questions.

[bigq]

Running the engine fat is not the way to cool: creates extreme exhaust temperature and dilutes your engine oil. My 2 cents (overpriced). :D
Diluting the oil, that would be just a tad to "fat". :p
[ January 15, 2003, 11:50 PM: Message edited by: bigq ]

[Fiat48]

Alcohol creates a much cooler charge. It really doesn't mix well with gas. I was referring to straight alcohol. You burn about 2.2 times more alcohol for a burnable mixture than gasoline so you do burn a lot more fuel. :)
But it smells better and made in America.

[Snowboat]

Dustin: I know what you do for a living, but I don't understand. If my boost guage read 14psi and it was 100 degrees out that day, then my intake charge is at 400 to 450 degrees? Quote "Q58, at 15lbs of boost with a roots, running gasoline through the supercharger, depending on brand, age, rotor design, would be much closer to 300-350 above ambient temp." End quote. A screw compressor would be somewhere near 120-140 above ambient as well as a centrifugal. Isn't that above the flashpoint for gasoline?

[Snowboat]

Dustin: I know what you do for a living, but I don't understand. If my boost guage read 14psi and it was 100 degrees out that day, then my intake charge is at 400 to 450 degrees? Quote "Q58, at 15lbs of boost with a roots, running gasoline through the supercharger, depending on brand, age, rotor design, would be much closer to 300-350 above ambient temp." End quote. Isn't that above the flashpoint for gasoline?
[ January 16, 2003, 09:13 AM: Message edited by: Snowboat ]

[bigq]

Fiat48:
Alcohol creates a much cooler charge. It really doesn't mix well with gas. I was referring to straight alcohol. You burn about 2.2 times more alcohol for a burnable mixture than gasoline so you do burn a lot more fuel. :)
But it smells better and made in America. Ok that clears it up. I didn't think you could mix it. I had a friend that ran a 2 stroke ATC on straight alcohol, hauled ass. Anyway, I don't know much about it except it can create a lot of HP and no emissions. I am always woundering why we don't run all the cars on this and forgo using the oil based gas.

[78Eliminator]

Infomaniac:
Don't just take my word for it. Wait for all the other replies. You run on alcohol, right? Do you just have the small racing pill for a tank or do you have the 15 gallon stainless tanks stuffed in the sponsons? What has to change in your carbs and motor to run alcohol?

[Jordy]

I dont know if it would work on a blower application, but theoretically it should follow the same principles as a turbo motor, but you could have the motor run gas and then set up a boost enrichment system that trickles alcohol into the motor to cool the charge when you're getting after it. I suppose it would have to be set up a bit different on a blower as you're seemingly always producing boost versus a turbo motor that can run without the boost in the case of just cruising. Any thoughts???

[Blown 472]

jordanpaulk:
I dont know if it would work on a blower application, but theoretically it should follow the same principles as a turbo motor, but you could have the motor run gas and then set up a boost enrichment system that trickles alcohol into the motor to cool the charge when you're getting after it. I suppose it would have to be set up a bit different on a blower as you're seemingly always producing boost versus a turbo motor that can run without the boost in the case of just cruising. Any thoughts??? Only time you are making boost with a blower is when the motor is under load, blowers are load sensative.

[Blown 472]

78Eliminator:
Infomaniac:
Don't just take my word for it. Wait for all the other replies. You run on alcohol, right? Do you just have the small racing pill for a tank or do you have the 15 gallon stainless tanks stuffed in the sponsons? What has to change in your carbs and motor to run alcohol? Drill out the emulsion tube holes, throw the rear jets away, jet the primaries to start at 100, increase the volume of fuel. Oh yeah drill out the tubes to the boosters.

[Infomaniac]

78Eliminator:
Infomaniac:
Don't just take my word for it. Wait for all the other replies. You run on alcohol, right? Do you just have the small racing pill for a tank or do you have the 15 gallon stainless tanks stuffed in the sponsons? What has to change in your carbs and motor to run alcohol? I have 2 11.5 gallon side tanks and 1 5.5 gallon "T" tank. It is a lake boat. The injection was designed for alcohol. I starve it for fuel on the ramp after pulling it out of the water. I drain the system from the "T" tank and WD-40 the pump and barrel valve after I use it. I have a Holley pump to keep the "T" tank full. I drain and WD-40 it also after each use. It is not designed for alcohol and has lasted 2 seasons so far.
[ January 16, 2003, 11:32 AM: Message edited by: Infomaniac ]

[78Eliminator]

Infomaniac:
I have 2 11.5 gallon side tanks and 1 5.5 gallon "T" tank. It is a lake boat. The injection was designed for alcohol. I starve it for fuel on the ramp after pulling it out of the water. I drain the system from the "T" tank and WD-40 the pump and barrel valve after I use it. I have a Holley pump to keep the "T" tank full. I drain and WD-40 it also after each use. It is not designed for alcohol and has lasted 2 seasons so far. So you're saying the injection system is designed for alcohol but the cam, compression, and fuel system etc. is not? How many hours can you run? If you are light on the pedal, can you go 50 miles?

[Infomaniac]

78Eliminator:
Infomaniac:
I have 2 11.5 gallon side tanks and 1 5.5 gallon "T" tank. It is a lake boat. The injection was designed for alcohol. I starve it for fuel on the ramp after pulling it out of the water. I drain the system from the "T" tank and WD-40 the pump and barrel valve after I use it. I have a Holley pump to keep the "T" tank full. I drain and WD-40 it also after each use. It is not designed for alcohol and has lasted 2 seasons so far. So you're saying the injection system is designed for alcohol but the cam, compression, and fuel system etc. is not? How many hours can you run? If you are light on the pedal, can you go 50 miles? Cam and compression are not. When the pistons or cyls wear I will up the compression to 11:1. Maybe this winter. I have not taken it apart yet. I will though. I have ran it 2 seasons without looking at the inside of it. Right now it is about 9:1. The cam is very conservative and not specific to blown alcohol. I may change it and I may not. Depends on funds.
It runs very well the way it is. If I up the compression it will require pistons, rods and crank. I am still running GM crank now and ran Eagle rods for 2 seasons. They will not hold up to the extra power of more compression. If I have enough left over I will buy a new cam. I did change the roller lifters and springs before this last season.
Oh yea: It is about 1 1/2 - 2 miles from the ramp to the island where we hang out. I can make it there and back, make a few passes and use about 10 gallons of Methanol
[ January 16, 2003, 12:56 PM: Message edited by: Infomaniac ]

[78Eliminator]

Infomaniac:
Oh yea: It is about 1 1/2 - 2 miles from the ramp to the island where we hang out. I can make it there and back, make a few passes and use about 10 gallons of Methanol Holy Cow!!!!! I think I am going to stick with pump gas or super blue. Geez!!!!!

[Infomaniac]

What do you mean? It's only about $13.00 worth of fuel and 12 beers. Not bad for a day at the lake.

[78Eliminator]

Infomaniac:
What do you mean? It's only about $13.00 worth of fuel and 12 beers. Not bad for a day at the lake. I had no idea it was that cheap.....

[Blown 472]

You keep a 55 gallon drum in your truck at the landing??

[Liberator TJ1984]

That is not too bad ,Blowers love fuel . One day of moderate running I'll burn 40 gals .. eek! which translates into maybe 2hrs.run time cry
Gopherrr

[Fiat48]

Infomaniac: Try a product called Pro Blend Alcohol lube. 1 can to 55 gallons. It works so well, that I only WD40 the system when the engine sits 3 months or more. I don't even drain the tank between races. I discovered how good it was by total accident. We left a race with the alcohol still in the system, was going to WD40 the system when we got home. We had an engine failure in our tow vehicle in the middle of nowhere. In all the confusion, the alcohol got left in for 6 weeks before we remembered. System was clean, no damage, no corrosion. wink

[GofastRacer]

Fiat48:
Infomaniac: Try a product called Pro Blend Alcohol lube. 1 can to 55 gallons. It works so well, that I only WD40 the system when the engine sits 3 months or more. I don't even drain the tank between races. I discovered how good it was by total accident. We left a race with the alcohol still in the system, was going to WD40 the system when we got home. We had an engine failure in our tow vehicle in the middle of nowhere. In all the confusion, the alcohol got left in for 6 weeks before we remembered. System was clean, no damage, no corrosion. wink Wow, 6 weeks!! eek! where do you get this stuff??, if it's that good, F*&K the gas, I'm switchin to alky!!... eek!

[Infomaniac]

Thanks guys. When I buy a drum of alcohol it has a bottle of top end lube mixed in. Choice of cherry or grape. I use the WD 40 anyway. May not even need to. I will buy some pro blend and give it a try. Thanks
You know I run it every week sometimes twice. Regular use like that does not even require much maintenance. When it sits and absorbs mositure is when it really becomes corrosive.

[Nstigator74]

Fiat, I'm using Redline top lube, does work as well as Pro Blend?

[Badboat1]

And yes Info does have a 55 gallon drum in the back of the truck he did when he came to Texas any way
Badboat1

[Fiat48]

I am not sure about Red Line's lube. I was winning the Pro Blend through contingencys in the Alcohol car so that is the only brand I tried. Free was a good price. I have not used any other Pro Blend products but have heard good about them. I'm not much of a "bottle magic" guy. But I like the Alky lube.
Info and can buy here http://www.pro-blend.com/tech8400.html
[ January 16, 2003, 08:45 PM: Message edited by: Fiat48 ]

[Whipple Charged]

Q58, sorry, didn't read your message clearly.
hulshot, just putting a 1471 does not mean it's going to be cooler. Blower speed is not the major componet to temp as much as leakage is. A 1471 has more clearance because the longer rotors, as well as a larger discharge opening lending itself to more leakage than something near a 1071, so pick a supercharger that is going to fit the motor better, a 1471 should only be used on 1300hp + engines or race engines.
Roots blowers typically cannot run the teflon/nylatrol strips because it either heats up and expands too fast, therefore seizing up, or losing clearance within a short time. Example is that drag racers, especially the top fuel teams changes strips every 2 runs.
An example of methanol cooling the air charge, with our race supercharger when drag racing, we saw boost levels around 60lbs and discharge temps were in the area of 100-110 degrees where a roots hi-helix 1471 would be around 300-350 degrees, so methanol is a incredible conductor of heat.
As for the flashpoint of gasonline, ignition temp is near 752F for premium gasoline, methanol is 842 while av gas is 932, it's more dependent on the air fuel ratio to light the fuel. Think about putting a cigarette in a puddle of fuel, it won't light, thats because theres too much fuel to air, a rich condition, with vapors, theres far less fuel and closer to 18:1 or lower. Now the hotter the fuel or air around it, the more tendency it has to light, but it's more predicated on the air fuel ratio.
Stoich #'s:
Gasoline 14.7:1
Methanol 6.47:1
Ethanol 9.0:1
Toluene 13.5:1
Benzene 13.27:1
If methanols water content gets to a certain mass, it will become a acid that will eat through virtually any surface, thats why most "pickle" the engines with gas or WD40 after running, because it can eat through anything.
Thanks,
Dustin

[Unchained]

Dustin, Thanks for all that tech info.
I have a question,
To make 15 lbs boost at 6000 rpm in a 500 ci engine how much HP does it to drive a,
Screw blower
Roots blower
Centrifugal blower
Or what percent of the power output does it take to drive it?

[Unchained]

Does anybody have an answer to the
"How much horsepower does it take to drive the blower" question that I posted above?

[Whipple Charged]

Unchained,
This really depends on blower design, blower size, etc, but in an ideal situation, this would answer your question in rough form:
screw:75
roots:225
centrifugal:90
Thanks,
Dustin

[ACCEPTENCE]

[/qb][/QUOTE]I have 2 11.5 gallon side tanks and 1 5.5 gallon "T" tank. It is a lake boat. The injection was designed for alcohol. I starve it for fuel on the ramp after pulling it out of the water. I drain the system from the "T" tank and WD-40 the pump and barrel valve after I use it. I have a Holley pump to keep the "T" tank full. I drain and WD-40 it also after each use. It is not designed for alcohol and has lasted 2 seasons so far. [/QB][/QUOTE]
I got a question?????

[ACCEPTENCE]

Fiat48:
Infomaniac: Try a product called Pro Blend Alcohol lube. 1 can to 55 gallons. It works so well, that I only WD40 the system when the engine sits 3 months or more. I don't even drain the tank between races. I discovered how good it was by total accident. We left a race with the alcohol still in the system, was going to WD40 the system when we got home. We had an engine failure in our tow vehicle in the middle of nowhere. In all the confusion, the alcohol got left in for 6 weeks before we remembered. System was clean, no damage, no corrosion. wink Dear Sir, Where to get this wonder stuff??? Thanks, Greg

[Unchained]

Whipple Charged:
This really depends on blower design, blower size, etc, but in an ideal situation, this would answer your question in rough form:
screw:75
roots:225
centrifugal90
Thanks,Dustin [/QB]Wow, What a range of drive HP's required . I had no idea the roots blower could take that much HP to drive it.
Thanks, Mark

[78Eliminator]

Unchained:
Whipple Charged:
This really depends on blower design, blower size, etc, but in an ideal situation, this would answer your question in rough form:
screw:75
roots:225
centrifugal90
Thanks,Dustin Wow, What a range of drive HP's required . I had no idea the roots blower could take that much HP to drive it.
Thanks, Mark [/QB]I find this hard to believe. You're saying if an engine doesn't pump out 225 HP, it won't spin a roots blower? I can spin the thing with my hand. I must be a lot stronger than I think...

[Liberator TJ1984]

Justin there is a relative curve it takes..boost# is a big factor I read somewhere if you run a roots blower under 15# it is effecient once you start getting over that is when it starts to "eat up" some of the power it is actually making say instead of producing 200hp you are getting 150hp taking 50HP just to make desired boost...wish someone in here could come up with a grap to illustrate this ??? a blower has alot more mass to move than say a belt driven turbo and therefore robs more HP.
[ January 21, 2003, 10:37 AM: Message edited by: Liberator TJ1984 ]

[Infomaniac]

I honestly doubt those numbers are all under the same engine operating conditions.
For example put the screw blower on a specific engine - test it - put the roots blower on the same engine etc.
I know a roots blower can take 220 HP to turn but the HP required to turn the others in the same conditions?
If I am wrong I will gladly admit so and shut up.

[Fiat48]

ACCEPTENCE:
Fiat48:
Infomaniac: Try a product called Pro Blend Alcohol lube. 1 can to 55 gallons. It works so well, that I only WD40 the system when the engine sits 3 months or more. I don't even drain the tank between races. I discovered how good it was by total accident. We left a race with the alcohol still in the system, was going to WD40 the system when we got home. We had an engine failure in our tow vehicle in the middle of nowhere. In all the confusion, the alcohol got left in for 6 weeks before we remembered. System was clean, no damage, no corrosion. wink Dear Sir, Where to get this wonder stuff??? Thanks, Greg Info and can buy here http://www.pro-blend.com/tech8400.html

[Whipple Charged]

The question was, 500ci engine, 15lbs. of boost, but under ideal conditions meaning properly sized compressors, proper amount of airflow on the inlet. Turning a supercharger by hand gives you little information about 15lbs. of boost. A roots should never be run at a level above 12lbs., typically speaking, you will not gain anymore HP with anymore than 12. You will net more torque, but not HP. At 40lbs, theres over a 300hp differential between the properly sized screw vs. roots on a 500ci engine. That would be comparing a high helix/teflon stripped roots. It's been proven many, many times.
Dustin

[Blown 472]

Whipple Charged:
The question was, 500ci engine, 15lbs. of boost, but under ideal conditions meaning properly sized compressors, proper amount of airflow on the inlet. Turning a supercharger by hand gives you little information about 15lbs. of boost. A roots should never be run at a level above 12lbs., typically speaking, you will not gain anymore HP with anymore than 12. You will net more torque, but not HP. At 40lbs, theres over a 300hp differential between the properly sized screw vs. roots on a 500ci engine. That would be comparing a high helix/teflon stripped roots. It's been proven many, many times.
Dustin Dont the fuel cars run roots at 40 to 50 psi??

[Infomaniac]

They used to. I think they are screw blowers now.

[Blown 472]

Thanks info, can I come live at your house till you get that motor done?

[Infomaniac]

Come on over. It will be boring during the day when I am at my real job. I would have you clean parts but everything is brand new. You can help me take pics and post progress.

[78Eliminator]

Infomaniac:
Come on over. It will be boring during the day when I am at my real job. I would have you clean parts but everything is brand new. You can help me take pics and post progress. Well, that's good and dandy, but you still need a test driver. I am more than qualified. I have a strong right leg and my left one is good to brace myself. Whattayasay?????!!!!!! wink

[Blown 472]

78Eliminator:
Infomaniac:
Come on over. It will be boring during the day when I am at my real job. I would have you clean parts but everything is brand new. You can help me take pics and post progress. Well, that's good and dandy, but you still need a test driver. I am more than qualified. I have a strong right leg and my left one is good to brace myself. Whattayasay?????!!!!!! wink Bring you depends, I have a feeling when you hammer tha throttle you are going to shit your pants. :D

[Whipple Charged]

Top fuel cars run standard style roots blowers. Screw compressors are not allowed, there trying to limit the HP, not make more at this point. They don't even run the hi-helix roots, it's against the rules as well. The alcohol classes all run screw, where it positevely blew away the standard and hi-helix roots including the thousands of retrofits.
Some top fuel cars run up to 60lbs. of boost. The alcohol cars run up to 65lbs. with screw compressors. Typically speaking, if you installed a screw on the top fuel cars, you could lower boost to approx. 45lbs. and make the same power because of less parasatic losses and denser air charge, but at the same time, you can run the boost back up and make a incredible amount of torque and hp.
Screw compressors are less likely to blow off, are more cost effective, last longer, are all the same (every roots in racing varies in flow and efficiency) and are safer, but don't get me going on NHRA rule makers :mad:
Dustin

[Infomaniac]

Same with top fuel drag boats?
This is why a lot of times I answer with "I think" or "I am pretty sure". If you speak up as much as I do, you are bound to be wrong or say something stupid sooner or later. cry
[ January 23, 2003, 05:14 AM: Message edited by: Infomaniac ]

[78Eliminator]

Blown 472:
Bring you depends, I have a feeling when you hammer tha throttle you are going to shit your pants. :D B472, did you look at my profile? My interests include scaring myself. :D

[DEL51]

Whipple Charged:
The question was, 500ci engine, 15lbs. of boost, but under ideal conditions meaning properly sized compressors, proper amount of airflow on the inlet. Turning a supercharger by hand gives you little information about 15lbs. of boost. A roots should never be run at a level above 12lbs., typically speaking, you will not gain anymore HP with anymore than 12. You will net more torque, but not HP. At 40lbs, theres over a 300hp differential between the properly sized screw vs. roots on a 500ci engine. That would be comparing a high helix/teflon stripped roots. It's been proven many, many times.
Dustin I disagree on part of that statement. I went from 11.8 lbs of boost to 13.5 and gained about 70 H.P.,1471 Littlefield with no bells or whistles.Gaining torque at a specific rpm cannot happen without a corresponding increase in horsepower,check out the formula for horsepower.Lets also consider Power versus price.What is the cost of a whipplecharger vs a good ole roots? I would like a cost comparison.Not on a 65 psi deal but something more relative to performance lake boating.Thanks,Chris

[Whipple Charged]

picked up 70 hp from 11.8 to 13 with a 1471? Was that steady state? Thats pretty rare in a marine roots blower.
And, yes, you can pick up torque and not hp, not at the same rpm, thats not what I said, but at a lower rpm while not making much hp. To give you an example, figure the cost of 100+hp on that same engine with 13lbs. of boost, not to mention you can achive a higher psi before detonation because of the cooler air charges. Not only that, it doesn't vary over time, they last longer, smaller, more compact, quieter, etc.
There is no comparison, call up Littlefield, he has to run a screw compressor on the alcohol car that he runs because the roots is no wear near competitive, even though it has major rule advantages with weight and engine size.
Thanks,
Dustin

[Whipple Charged]

Example of approx. price:
Whipple quad rotor (will make 700-1600 hp on pump gas, more on race, 2000 on methanol): Retail pricing $5000-6500
Roots 1471: $3000-6000
Approx. pricing, theres also race compressors, etc. A new race supercharger from SSI or Kobelco runs near $10,000.
Thanks,
Dustin

[DEL51]

Whipple Charged:
picked up 70 hp from 11.8 to 13 with a 1471? Was that steady state? Thats pretty rare in a marine roots blower.
And, yes, you can pick up torque and not hp, not at the same rpm, thats not what I said, but at a lower rpm while not making much hp. To give you an example, figure the cost of 100+hp on that same engine with 13lbs. of boost, not to mention you can achive a higher psi before detonation because of the cooler air charges. Not only that, it doesn't vary over time, they last longer, smaller, more compact, quieter, etc.
There is no comparison, call up Littlefield, he has to run a screw compressor on the alcohol car that he runs because the roots is no wear near competitive, even though it has major rule advantages with weight and engine size.
Thanks,
Dustin

[DEL51]

Whipple Charged:
picked up 70 hp from 11.8 to 13 with a 1471? Was that steady state? Thats pretty rare in a marine roots blower.
And, yes, you can pick up torque and not hp, not at the same rpm, thats not what I said, but at a lower rpm while not making much hp. To give you an example, figure the cost of 100+hp on that same engine with 13lbs. of boost, not to mention you can achive a higher psi before detonation because of the cooler air charges. Not only that, it doesn't vary over time, they last longer, smaller, more compact, quieter, etc.
There is no comparison, call up Littlefield, he has to run a screw compressor on the alcohol car that he runs because the roots is no wear near competitive, even though it has major rule advantages with weight and engine size.
Thanks,
Dustin I have no reason to call him, a blown alcohol drag application is not my intended use, it is cool though.I paid 2500.00 for my 1471 add 500 for accessories.So I am at the low end of the roots cost estimate.That is still 4k under the whipple.The dyno session was a ramped pull on a DTS dyno. No steady state comparison.Final power number was 1166 @ 6500rpm.Tis was with the air cleaner on and 110 octane fuel.This motor was 1117 on pump gas@ 11.8 lbs of boost.My point is that excellant power can be made with old technology. This is comparable to a different 572 whipplecharged engine referred to in a previous post in this forum. No dual drive belts or belts popping off. I think your product is good but not when the price and looks come into play. Assuming I had the money to spend for a new whipple quad rotor, I would be better off going with a twin turbo/EFI setup similar to what Unchained is doing.It is VERY hard to beat a simple roots setup for great power and price.If he were to start out with a roots he could convert to one of your whipples when he has the money.I am curious about steady state dyno pulls. Do they yeild different numbers than a ramp type test?Thanks for posting the comparisons,very informative. When the screw blowers become more competitive price wise I will consider them as an alternative.These are my opinions and I do not want to seem dismisive of your good points.Thanks for responding
[ January 29, 2003, 05:35 PM: Message edited by: DEL51 ]

[Infomaniac]

A "sweep" test usually shows a higher number than a "step" test.

[DEL51]

Infomaniac:
A "sweep" test usually shows a higher number than a "step" test. On the bottom of my dyno sheet it says," inertia factor .96".I wonder if this may account for the difference.When you dyno your project engine what type of test will you run? and what are the pro's and con's of each?

[Infomaniac]

It will be a sweep because 99 % of them are.
The computer controls the acceleration of the sweep test.
A step test gives a few seconds for everything to stabilize at each RPM tested.
In the early days a manual operated dyno used the step test. It is nearly impossible to do a sweep manually. I have tried. And If you did no two would be the same.
Maybe someone else will add to pro and con issues.

[Badboat1]

As I would call a ramp test and a steady state test.IT is about 15-25HP down on a ramp,but you need to make 4 or 5 ramps and average them for a good reading the dyno will spike some numbers at times.The ramp will allways be lower than a steady state pull. just my 2 cents been doing this shit for over 20 years.I will post some steady state pulls for you tommorow.What Rpm per sec.you talking also.
Badboat1
[ January 29, 2003, 09:19 PM: Message edited by: Badboat1 ]

[Whipple Charged]

Theres certainly still power in older technology, but I think you might be missing the point, there is a huge difference, not a minimal difference. Also, there are not dual belts, just one that runs on two blowers. It's also a very quiet serpentine vs. the short lived and noisy 8mm/cog. For the amount that we've sold, we have had little belt problems.
The difference in dyno test and power numbers provided are different for every engine, but with a roots, steady state will continue to fall in power as the temp increases, a 10-15 second swept test is no comparison to a full throttle run in a stable boat. Temps will continue to increase through the rpm range. With todays computer controlled dynos, you can do a lot longer swept test, something closer to 45 - 60 seconds for a typical boat run and 10 minutes WOT for endurance testing. Mercury racing does 20 minute WOT runs on the big motors to give an example.
But when your refering to the amount of money spent, on that exact motor, we could get another 100-150hp (not saying it's needed) without breaking a sweat and gaining durability, not losing. So depending on what your starting with, getting that extra power on the desired octane gas could be cheaper. Maybe somebody built the same motor as yours, but wanted to run 91 octane and make the same power, they could lower boost, etc. Otherwise they were stuck running higher octane or bigger ci or heads, etc. Maybe somebody wants to make 1000 hp on a 500ci motor with pump gas, etc. Either way, theres always alternative soloutions, some are turbos, some centrifugals, some roots, etc.
Dustin
[ January 30, 2003, 12:56 AM: Message edited by: Whipple Charged ]

[Infomaniac]

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