Feeding the Turbo Rotary: Horsepower, Airflow, Fuels
01-16-10, 12:32 PM
#1
Racing Rotary Since 1983
Thread Starter
iTrader: (6)
Feeding the Turbo Rotary: Horsepower, Airflow, Fuels
Much of this post can be found scattered around this board but i thought it would be a good idea to put it all together and add in alternative fuels such as ethanol and methanol.
The rotary is, of course, unique and as such it would be a big mistake to use piston metrics when planning setup.
How unique?
Let's talk airflow:
A piston engine can generally make ten hp for every pound per minute of air, so a 70 pound per minute turbo can make 700 piston hp. As we navigate the web looking at turbos we often see a hp tag... for instance a 73 pound per minute TO4Z/GT500/PT67 is often rated at 730 hp. If you are looking for 730 you'd best look elsewhere because they are talking PISTON lingo.
Should you wish to translate to rotary you'd take the pounds per minute, or the estimated HP number, and divide by 1.3.
73 pounds per minute is 561 ROTARY rwhp.
BTW, that doesn't mean the rotary takes a back seat to the piston engine. While it does take a discount due to lower volumetric efficiency (VE), it makes up for lower VE by being able to flow more air V displacement.
O K, let's get into it starting with airflow and hp.
FDs are all about airfow from turbos.
Most turbos have a compressor map which sets forth maximum airflow in pounds per minute and other metrics such as efficiency and airflow at differing boost levels etc. (see Sean's How To Read a Compressor Map thread sticky in the Single Turbo Section).
This thread is about properly sizing the fuel system(s) so let's just focus on the maximum air as set forth on a commonly used GT3582R compressor map.
Airflow is represented in pounds per minute. The GT35 makes approx 62 pounds per minute max.
Rotaries require 1.92 CFM (cubic feet per minute) to make one rear wheel hp. Transposing pounds per minute to CFM, we multiply by 14.471.
14.471 times 62 = 897 cubic feet per minute.
Now that we have CFM we divide by 1.92 to get rear wheel rotary hp.
897/1.92 = 467 max rotary rwhp.
TO4Z, GT500, PT67 turbos make 73 pounds per minute.
73 X 14.471 = 1056 CFM/1.92 = 550 max rotary rwhp
The GT4294 puts out 85 pounds per minute.
85 X 14.471 = 1230 CFM/1.92 = 641 max rotary rwhp
Now that we have an understanding how to get CFM from pounds per minute and then rw rotary hp let's move on to solving for fuel requirements from air generated.
AFR
Air Fuel Ratio... 10 to 1, 11 to 1, 12 to 1. These ratios are for air and fuel measured in POUNDS.
Back to the GT35r and let’s calculate fuel injector sizing.
I suggest we use a couple of "givens."
"Given" we want to have enough fuel to run 10.0 to 1 AFR if necessary.
"Given" we want to run our fuel injectors at no more than 85% capacity (expressed as duty cycle).
Assuming 62 pounds per minute of air, at a 10 to 1 ratio we need 6.2 pounds per minute of gasoline.
62 pounds air
6.2 pounds gasoline
We wish to limit our fuel injectors to 85% duty so we divide 1 by .85
1/.85 = 1.1764
We now take our adjuster (1.1764) and multiply it times our 6.2 pounds per minute of gasoline.
1.1764 X 6.2 = 7.294 pounds per minute of fuel delivery capacity.
The next step is to convert the pounds of gasoline to gallons. Gasoline weighs 6.35 pounds per gallon.
7.294 pounds / 6.35 = 1.14868 gallons per minute
Off to my favorite "converter" website (http://online.unitconverterpro.com/u...ha/volume.html)...
Select “Gallon” converted to “Cubic Centimeter” (CC) and find that 1.14868 gallons is 4348 CC
So 4348 CC/Min at 85% delivery is 3695 CC/Min net of duty cycle.
That number will produce fuel necessary to service the max air GT35r at a 10 to 1 AFR.
Given the above calculations we can now answer some common FD injector questions…
“If I run my 550s as primaries what do I need as secondaries with my GT35?”
4348 - 1100 = 3248 CC/Min needed in addition to 550 primaries
Run a couple of 1600s and you are fine!
“How about 850 primaries and 1300 secondaries?”
4348 required…
(850 X2) = 1700
(1300 X2) = 2600
Total = 4300… fine.
Moving up to the larger 73 pound per minute turbo... Let’s do it simply by just multiplying by the increase in air delivery V the GT35r..
73/62 = 1.1774
4348 X 1.1774 = 5119 CC/Min
“Will 550s work as primaries?”
5119 - 1100 = 4019 required for secondaries so given our assumptions the 1600s won't work.
“What do I need w 850s as primaries?”
5119 - 1700 = 3419 CC/Min. 1600s will probably be O K, especially considering 1600s generally flow 1680 each.
“How about a GT4294 at 83 pounds per minute?”
83/62 = 1.3387
4348 X 1.3387 = 5820 CC/Min
“What do i need in addition to my 850 primaries?”
5820 - 1700 = 4121 CC/Min
As I understand, the Bosch 1600 injector is no longer being made. There are a few new injectors that have become recently available. I believe there is a Siemans injector that is around 2000+ CC/Min and there is at least one brand of aftermarket injectors that offer increased deliverability w good spray pattern.
Additional injector option info welcomed.
So far, we have been talking gasoline.
We also need to understand two other fuels since either they, or water, must be introduced into the combustion process or we will be destroying our turbo'd rotary in short order.
Fuel, whether gasoline or some derivative of alcohol (ethanol or methanol), is really about BTUs.
A combo of oxygen and BTUs creates energy as in Torque and HP.
BTUs per Gallon
Gasoline (any octane)..................................116,090
Ethanol (alcohol)......................................... .76,330
Methanol (alcohol)......................................... 57,250
E85............................................... .................82,293
Gasoline wins the energy per gallon contest, so why would we want to run methanol or ethanol?
Alcohol delivers immense cooling compared to gasoline. Cooling is expressed as “latent heat.” The bigger the number the higher the cooling capacity. (BTU/Gal)
Gasoline.......................952
Methanol.....................3136................. ..........3.29 times more cooling than gasoline
Ethanol........................2398............... ............2.52 times more cooling than gasoline
E85.............................2180.............. ...............2.29 times more cooling than gasoline
The immense cooling provided by alcohol allows boost to be raised without encountering motor destroying knock. Note that methanol delivers 31% more cooling than ethanol which is why methanol is the non gasoline fuel of choice amongst many pro racers.
Real world proof is provided by Jose LeDuc's 13 B-REW (two rotor) 1000+ rear wheel horsepower drag racing RX3. Powered my methanol alone, the 1150+ flywheel horsepower two rotor doesn’t even use an intercooler! The upper intake manifold is freezing to the touch after a 180+ MPH quarter.
An excellent indicator of rotary health is absence of knock. Low knock equals low CCP Low knock equals less calls to your engine builder. Running about 20% methanol with 93 octane pump gas my 507 SAE hp FD shows less than 10 knock at 20 psi! My motor ran in this state of tune for four years and generated it’s highest compression just as I decided to pull and examine it. (Purely out of curiosity) All was well inside thanks to the methanol.
Rotaries generally fail due to warped apex seals (loss of compression), broken apex seals from knock or blown out coolant seals from too much CCP/heat. Alcohol ‘s ability to defeat heat solves the problems.
Another benefit of alcohol is that it’s autoignition point is much higher than gasoline.
gasoline...........................495 F
methanol..........................867 F
ethanol.............................793 F
E85...................................748 F
Methanol ignites at a 75% higher temperature than gasoline. This delivers important benefits should a piece of carbon decide to glow in the motor.
Our 159 cubic inch 2 rotor motors routinely put out 300, 400, 500 rwhp w the help of turbocharging. Corrected to flywheel hp this is 345, 460, 575 flywheel hp and is 2.16, 2.89, and 3.61 hp per cubic inch! These are all stratospheric compared to the $300,000 AMG hotrodded twin turbo SL65 Benz at 1.81 or the $106,000 Corvette ZR1 at 1.69.
That's why it is necessary to use either water or alcohol derivatives to cool our motors at higher output/boost levels. (please see my thread "the Fix" in the 3rd Gen section for the details.)
Let's get back to the details relative to ethanol and methanol so you can properly size your total fuel needs...
BTU content is the key.
We know what we need as far as gasoline to make "X" hp from above. Since gasoline contains 116,090 BTUs and meth is 57,250 BTUs per gallon, if we are to replace, say 20%, of our gasoline w meth we need to replace it on an equal BTU basis.
Back to the GT35r…
3695 (net of 85% duty cycle) CC/Min Max gasoline is .9761 gallons per minute. (thanks converter site).
.9761 gallons times 116,090 BTUs/Gal = 113,315 BTUs.
Let’s assume we want to take our gasoline injector duty cycle from 85% to 70% using methanol.
That’s a drop of 21.1%. We would be removing 21.1% of the BTUs. .
.211 X 113,315 = 23,996. BTUs removed by cutting base fuel (gasoline.)
To replace those BTUs…
One gallon of methanol has 57,250 BTUs.
23,996/57,250 = 42% of a gallon which is 1586 CC/Min. I run two FJO 700 CC/Min injectors to deliver my meth and am around 76% duty cycle on base fuel w 850/1600 injectors at 11.3 AFR.
As you can see it is a pretty simple procedure to dial in fuel combos. Since the alcohols are “fuel” you can run as much or as little as you wish. I suggest around 1000- 1400 CC/Min.
Finally, there’s water, which can also be an important solution to rotary longevity and increased power.
Water of course is not a fuel, and as such adds no energy.
Water’s big attribute is subtractive! It subtracts/removes heat in a big way.
Heat (BTUs) removed per gallon
Gasoline....................952
Ethanol....................2398
Methanol..................3136
Water.......................8087
Three things jump out.
Water, as far as cooling, is king.
Methanol is king of fuels as far as cooling
Gasoline is lame, very lame. This underlines the inefficiency of purposely tuning to a rich AFR with gasoline. A rich tune carbons up the motor and adds little cooling-wise compared to water or methanol. In addition, both methanol and water clean carbon from the rotary interior.
The addition of water is not unlimited since it doesn’t burn. FD tuners generally use between 300 and 500 CC/Min to cool CCP. Should you be wishing to raise boost and make more hp, water in the amount of 700+ CC/Min, has been utilized and 700 rw rotary hp has been made using water and pump gas. An uprated ignition system is required as you start using more than 400 CC.
The purpose of this thread is not to get into the nuts and bolts of AI rather to lay out a specific understanding of how to tailor your fuel needs.
Howard Coleman
The rotary is, of course, unique and as such it would be a big mistake to use piston metrics when planning setup.
How unique?
Let's talk airflow:
A piston engine can generally make ten hp for every pound per minute of air, so a 70 pound per minute turbo can make 700 piston hp. As we navigate the web looking at turbos we often see a hp tag... for instance a 73 pound per minute TO4Z/GT500/PT67 is often rated at 730 hp. If you are looking for 730 you'd best look elsewhere because they are talking PISTON lingo.
Should you wish to translate to rotary you'd take the pounds per minute, or the estimated HP number, and divide by 1.3.
73 pounds per minute is 561 ROTARY rwhp.
BTW, that doesn't mean the rotary takes a back seat to the piston engine. While it does take a discount due to lower volumetric efficiency (VE), it makes up for lower VE by being able to flow more air V displacement.
O K, let's get into it starting with airflow and hp.
FDs are all about airfow from turbos.
Most turbos have a compressor map which sets forth maximum airflow in pounds per minute and other metrics such as efficiency and airflow at differing boost levels etc. (see Sean's How To Read a Compressor Map thread sticky in the Single Turbo Section).
This thread is about properly sizing the fuel system(s) so let's just focus on the maximum air as set forth on a commonly used GT3582R compressor map.
Airflow is represented in pounds per minute. The GT35 makes approx 62 pounds per minute max.
Rotaries require 1.92 CFM (cubic feet per minute) to make one rear wheel hp. Transposing pounds per minute to CFM, we multiply by 14.471.
14.471 times 62 = 897 cubic feet per minute.
Now that we have CFM we divide by 1.92 to get rear wheel rotary hp.
897/1.92 = 467 max rotary rwhp.
TO4Z, GT500, PT67 turbos make 73 pounds per minute.
73 X 14.471 = 1056 CFM/1.92 = 550 max rotary rwhp
The GT4294 puts out 85 pounds per minute.
85 X 14.471 = 1230 CFM/1.92 = 641 max rotary rwhp
Now that we have an understanding how to get CFM from pounds per minute and then rw rotary hp let's move on to solving for fuel requirements from air generated.
AFR
Air Fuel Ratio... 10 to 1, 11 to 1, 12 to 1. These ratios are for air and fuel measured in POUNDS.
Back to the GT35r and let’s calculate fuel injector sizing.
I suggest we use a couple of "givens."
"Given" we want to have enough fuel to run 10.0 to 1 AFR if necessary.
"Given" we want to run our fuel injectors at no more than 85% capacity (expressed as duty cycle).
Assuming 62 pounds per minute of air, at a 10 to 1 ratio we need 6.2 pounds per minute of gasoline.
62 pounds air
6.2 pounds gasoline
We wish to limit our fuel injectors to 85% duty so we divide 1 by .85
1/.85 = 1.1764
We now take our adjuster (1.1764) and multiply it times our 6.2 pounds per minute of gasoline.
1.1764 X 6.2 = 7.294 pounds per minute of fuel delivery capacity.
The next step is to convert the pounds of gasoline to gallons. Gasoline weighs 6.35 pounds per gallon.
7.294 pounds / 6.35 = 1.14868 gallons per minute
Off to my favorite "converter" website (http://online.unitconverterpro.com/u...ha/volume.html)...
Select “Gallon” converted to “Cubic Centimeter” (CC) and find that 1.14868 gallons is 4348 CC
So 4348 CC/Min at 85% delivery is 3695 CC/Min net of duty cycle.
That number will produce fuel necessary to service the max air GT35r at a 10 to 1 AFR.
Given the above calculations we can now answer some common FD injector questions…
“If I run my 550s as primaries what do I need as secondaries with my GT35?”
4348 - 1100 = 3248 CC/Min needed in addition to 550 primaries
Run a couple of 1600s and you are fine!
“How about 850 primaries and 1300 secondaries?”
4348 required…
(850 X2) = 1700
(1300 X2) = 2600
Total = 4300… fine.
Moving up to the larger 73 pound per minute turbo... Let’s do it simply by just multiplying by the increase in air delivery V the GT35r..
73/62 = 1.1774
4348 X 1.1774 = 5119 CC/Min
“Will 550s work as primaries?”
5119 - 1100 = 4019 required for secondaries so given our assumptions the 1600s won't work.
“What do I need w 850s as primaries?”
5119 - 1700 = 3419 CC/Min. 1600s will probably be O K, especially considering 1600s generally flow 1680 each.
“How about a GT4294 at 83 pounds per minute?”
83/62 = 1.3387
4348 X 1.3387 = 5820 CC/Min
“What do i need in addition to my 850 primaries?”
5820 - 1700 = 4121 CC/Min
As I understand, the Bosch 1600 injector is no longer being made. There are a few new injectors that have become recently available. I believe there is a Siemans injector that is around 2000+ CC/Min and there is at least one brand of aftermarket injectors that offer increased deliverability w good spray pattern.
Additional injector option info welcomed.
So far, we have been talking gasoline.
We also need to understand two other fuels since either they, or water, must be introduced into the combustion process or we will be destroying our turbo'd rotary in short order.
Fuel, whether gasoline or some derivative of alcohol (ethanol or methanol), is really about BTUs.
A combo of oxygen and BTUs creates energy as in Torque and HP.
BTUs per Gallon
Gasoline (any octane)..................................116,090
Ethanol (alcohol)......................................... .76,330
Methanol (alcohol)......................................... 57,250
E85............................................... .................82,293
Gasoline wins the energy per gallon contest, so why would we want to run methanol or ethanol?
Alcohol delivers immense cooling compared to gasoline. Cooling is expressed as “latent heat.” The bigger the number the higher the cooling capacity. (BTU/Gal)
Gasoline.......................952
Methanol.....................3136................. ..........3.29 times more cooling than gasoline
Ethanol........................2398............... ............2.52 times more cooling than gasoline
E85.............................2180.............. ...............2.29 times more cooling than gasoline
The immense cooling provided by alcohol allows boost to be raised without encountering motor destroying knock. Note that methanol delivers 31% more cooling than ethanol which is why methanol is the non gasoline fuel of choice amongst many pro racers.
Real world proof is provided by Jose LeDuc's 13 B-REW (two rotor) 1000+ rear wheel horsepower drag racing RX3. Powered my methanol alone, the 1150+ flywheel horsepower two rotor doesn’t even use an intercooler! The upper intake manifold is freezing to the touch after a 180+ MPH quarter.
An excellent indicator of rotary health is absence of knock. Low knock equals low CCP Low knock equals less calls to your engine builder. Running about 20% methanol with 93 octane pump gas my 507 SAE hp FD shows less than 10 knock at 20 psi! My motor ran in this state of tune for four years and generated it’s highest compression just as I decided to pull and examine it. (Purely out of curiosity) All was well inside thanks to the methanol.
Rotaries generally fail due to warped apex seals (loss of compression), broken apex seals from knock or blown out coolant seals from too much CCP/heat. Alcohol ‘s ability to defeat heat solves the problems.
Another benefit of alcohol is that it’s autoignition point is much higher than gasoline.
gasoline...........................495 F
methanol..........................867 F
ethanol.............................793 F
E85...................................748 F
Methanol ignites at a 75% higher temperature than gasoline. This delivers important benefits should a piece of carbon decide to glow in the motor.
Our 159 cubic inch 2 rotor motors routinely put out 300, 400, 500 rwhp w the help of turbocharging. Corrected to flywheel hp this is 345, 460, 575 flywheel hp and is 2.16, 2.89, and 3.61 hp per cubic inch! These are all stratospheric compared to the $300,000 AMG hotrodded twin turbo SL65 Benz at 1.81 or the $106,000 Corvette ZR1 at 1.69.
That's why it is necessary to use either water or alcohol derivatives to cool our motors at higher output/boost levels. (please see my thread "the Fix" in the 3rd Gen section for the details.)
Let's get back to the details relative to ethanol and methanol so you can properly size your total fuel needs...
BTU content is the key.
We know what we need as far as gasoline to make "X" hp from above. Since gasoline contains 116,090 BTUs and meth is 57,250 BTUs per gallon, if we are to replace, say 20%, of our gasoline w meth we need to replace it on an equal BTU basis.
Back to the GT35r…
3695 (net of 85% duty cycle) CC/Min Max gasoline is .9761 gallons per minute. (thanks converter site).
.9761 gallons times 116,090 BTUs/Gal = 113,315 BTUs.
Let’s assume we want to take our gasoline injector duty cycle from 85% to 70% using methanol.
That’s a drop of 21.1%. We would be removing 21.1% of the BTUs. .
.211 X 113,315 = 23,996. BTUs removed by cutting base fuel (gasoline.)
To replace those BTUs…
One gallon of methanol has 57,250 BTUs.
23,996/57,250 = 42% of a gallon which is 1586 CC/Min. I run two FJO 700 CC/Min injectors to deliver my meth and am around 76% duty cycle on base fuel w 850/1600 injectors at 11.3 AFR.
As you can see it is a pretty simple procedure to dial in fuel combos. Since the alcohols are “fuel” you can run as much or as little as you wish. I suggest around 1000- 1400 CC/Min.
Finally, there’s water, which can also be an important solution to rotary longevity and increased power.
Water of course is not a fuel, and as such adds no energy.
Water’s big attribute is subtractive! It subtracts/removes heat in a big way.
Heat (BTUs) removed per gallon
Gasoline....................952
Ethanol....................2398
Methanol..................3136
Water.......................8087
Three things jump out.
Water, as far as cooling, is king.
Methanol is king of fuels as far as cooling
Gasoline is lame, very lame. This underlines the inefficiency of purposely tuning to a rich AFR with gasoline. A rich tune carbons up the motor and adds little cooling-wise compared to water or methanol. In addition, both methanol and water clean carbon from the rotary interior.
The addition of water is not unlimited since it doesn’t burn. FD tuners generally use between 300 and 500 CC/Min to cool CCP. Should you be wishing to raise boost and make more hp, water in the amount of 700+ CC/Min, has been utilized and 700 rw rotary hp has been made using water and pump gas. An uprated ignition system is required as you start using more than 400 CC.
The purpose of this thread is not to get into the nuts and bolts of AI rather to lay out a specific understanding of how to tailor your fuel needs.
Howard Coleman
Last edited by Howard Coleman; 01-22-10 at 08:53 AM.
The following users liked this post:
EZAS (08-11-19)
01-16-10, 01:27 PM
#2
deja-vu? what happened to all the posts? Great Info here!
as I mentioned in another thread, Injector Dynamics High Impedance injectors ID1000 for the primaries and ID2000 for the secondaries or up to 6 ID2000 can be used with the Xcessive LIM given that they are supposedly linear enough at low duty cycles to be able to idle correctly... They demonstrate the idle in a 4cyl 120hp integra engine running 4x ID2000's.
or if not so much fuel is needed then 2x ID2000's in the primary location with a simplified fuel system althought they said that fuel stratification may occur due to low air flow in the primary ports.
http://www.injectordynamics.com/ID2000.html
as I mentioned in another thread, Injector Dynamics High Impedance injectors ID1000 for the primaries and ID2000 for the secondaries or up to 6 ID2000 can be used with the Xcessive LIM given that they are supposedly linear enough at low duty cycles to be able to idle correctly... They demonstrate the idle in a 4cyl 120hp integra engine running 4x ID2000's.
or if not so much fuel is needed then 2x ID2000's in the primary location with a simplified fuel system althought they said that fuel stratification may occur due to low air flow in the primary ports.
http://www.injectordynamics.com/ID2000.html
01-16-10, 03:00 PM
#3
Racing Rotary Since 1983
Thread Starter
iTrader: (6)
i like your Injector Dynamics suggestion preliminarily... based on some calculations from my original post it looks like i will be running racegas and water injection for my 200 mph project at the Texas Mile.
i will get the energy BTUs from the racegas and the cooling from around 1000 CC of water. i think i will swap out my 1600s for the Injector Dynamics.
hc
i will get the energy BTUs from the racegas and the cooling from around 1000 CC of water. i think i will swap out my 1600s for the Injector Dynamics.
hc
01-18-10, 03:54 AM
#5
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Very good post. I can confirm that with a decent amount of water (Im running 550cc) and rich a/fs (10s) you will have problems even with a Twin Power. I do. I am going to try and lean it to about 11a/fs @ 20psi and see if that helps. It worked out great on my other setup.
01-18-10, 11:12 AM
#6
I've noticed a lot of people have had trouble running water, high boost and rich afrs. I've never had a problem with my setup. Twin power, high 10's, greddy race plugs, 10mm wires, 23 psi, and 600cc of water. Although maybe if I was closer to mid 10's or low 10's I would start having issues.
01-18-10, 02:21 PM
#7
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I've noticed a lot of people have had trouble running water, high boost and rich afrs. I've never had a problem with my setup. Twin power, high 10's, greddy race plugs, 10mm wires, 23 psi, and 600cc of water. Although maybe if I was closer to mid 10's or low 10's I would start having issues.
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01-18-10, 05:07 PM
#8
Yeah If I were doing the system over I would probably go with something else, but its working for my needs and was a very easy install. Personally I see no reason to be that rich, I aim for 11 flat and have zero knock. Not much more you could really ask for.
01-20-10, 08:02 AM
#9
Racing Rotary Since 1983
Thread Starter
iTrader: (6)
here's the executive summary:
..................gasoline............Energy...... ...Cooling................Addit'l Cooling BTUs
rwRhp........CC/min...............BTUs.............BTUs........... ............from water AI
217 (stock)....2018...............61,899............50 8................................640........ 300 CC/Min
300...............2790...............85,578....... .....702................................854....... ..400 CC/Min
400...............3720..............114,105....... ....936................................854........ ..400 CC/Min
500...............4650..............142,018....... ...1165..............................1068......... .500 CC/Min
600...............5580..............171,158....... ...1404..............................1495......... 700 CC/Min
fuel requirements assume we can deliver at a 10.0 AFR at 85% max duty cycle.
column 2 is required injector capacity at the stated hp level.
column 3 is the total BTUs of energy required to make the stated rotary hp level.
column 4 is the inherent cooling ability in negative BTUs from the gasoline.
column 4 is the additional cooling from the introduction of water.
column 5 is the amount of water.
note that the water adds approximately 100% additional cooling. this is not small potatoes. remember, we are easily running 10% more gasoline in an effort to cool our motors courtesy of Mazda.
at the 400 hp level 10% of the gasoline cooling BTUs is 94.
the introduction of 400 CC/Min of water adds 854 cooling BTUs!
win win win.
lose the gasoline and it's carbon
cool the CCP by an additional 9X
steam clean the carboned up motor.
hc
..................gasoline............Energy...... ...Cooling................Addit'l Cooling BTUs
rwRhp........CC/min...............BTUs.............BTUs........... ............from water AI
217 (stock)....2018...............61,899............50 8................................640........ 300 CC/Min
300...............2790...............85,578....... .....702................................854....... ..400 CC/Min
400...............3720..............114,105....... ....936................................854........ ..400 CC/Min
500...............4650..............142,018....... ...1165..............................1068......... .500 CC/Min
600...............5580..............171,158....... ...1404..............................1495......... 700 CC/Min
fuel requirements assume we can deliver at a 10.0 AFR at 85% max duty cycle.
column 2 is required injector capacity at the stated hp level.
column 3 is the total BTUs of energy required to make the stated rotary hp level.
column 4 is the inherent cooling ability in negative BTUs from the gasoline.
column 4 is the additional cooling from the introduction of water.
column 5 is the amount of water.
note that the water adds approximately 100% additional cooling. this is not small potatoes. remember, we are easily running 10% more gasoline in an effort to cool our motors courtesy of Mazda.
at the 400 hp level 10% of the gasoline cooling BTUs is 94.
the introduction of 400 CC/Min of water adds 854 cooling BTUs!
win win win.
lose the gasoline and it's carbon
cool the CCP by an additional 9X
steam clean the carboned up motor.
hc
01-20-10, 10:56 AM
#12
Yes refering to the ignition system. My first goals were 400 hp with no thought of water. Twin power is great for that. Now im over 500 with high boost and water. Its still working for me, but based on others experience it probably won't handle much more. I generally like to over build so i don't have to do things over.
01-23-10, 01:53 PM
#13
Howard instead of calculating rwhp by going back and forth with different formulas, couldn't you just multiply lb air by a smaller number? Piston engines make 10 hp per lb of air, you said rotaries make 1.3x less. 10 divided by 1.3 =7.7 hp per lb rounded. 73lbs air x 7.7= 562 rwhp
That seems like an easier way to calculate it.
That seems like an easier way to calculate it.
01-23-10, 02:30 PM
#14
Here's a calculator I made for calculating turbo size or estimating RWHP
http://www.wannaspeed.com/rotaryhpcalculator.html
Howard, one thing I just thought of is that these calculations don't factor in whether the rotary is ported or not. A ported engine would make more power with a given turbocharger compared to a stock engine.
I used 7.55 X lb/min for the calculations. 7.7 seemed a bit optimistic
http://www.wannaspeed.com/rotaryhpcalculator.html
Howard, one thing I just thought of is that these calculations don't factor in whether the rotary is ported or not. A ported engine would make more power with a given turbocharger compared to a stock engine.
I used 7.55 X lb/min for the calculations. 7.7 seemed a bit optimistic
01-23-10, 04:41 PM
#15
Updated the calculator to include fuel usage based on Howards calculations the new calculator can be found at www.wannaspeed.com/hpturbocalculator.html
I might add to it some more if I can think of other data that would be nice to have.
I might add to it some more if I can think of other data that would be nice to have.
01-24-10, 07:19 AM
#16
Howard you do realise that methanol will use more then two times the amount of gasoline correct.
You can't compare btu per gallon unless you also figure that amount of fuel required.
Methanol makes more power because there's more total BTU's then gas. Cooling is also a factor but not the primary reason for added power..
You can't compare btu per gallon unless you also figure that amount of fuel required.
Methanol makes more power because there's more total BTU's then gas. Cooling is also a factor but not the primary reason for added power..
01-24-10, 07:30 AM
#17
Also on the hp vs lb per minute calculations.
Yes the numbers are usually based on piston engines since that's the majority of engines out there.
But a major reason why a 70lb turbo won't make the same power on a rotary vs a piston is due to the fact that backpressure will be much higher on the rotary since the turbine side of the turbo being to small.
A properly size turbo that flows 70lbs per minute will make alot more power on a rotary engine.
Yes the numbers are usually based on piston engines since that's the majority of engines out there.
But a major reason why a 70lb turbo won't make the same power on a rotary vs a piston is due to the fact that backpressure will be much higher on the rotary since the turbine side of the turbo being to small.
A properly size turbo that flows 70lbs per minute will make alot more power on a rotary engine.
01-24-10, 08:51 AM
#18
Racing Rotary Since 1983
Thread Starter
iTrader: (6)
"Methanol makes more power because there's more total BTU's then gas."
total energy (BTUs) per gallon...
Gasoline (any octane).....................................116,09 0
Ethanol (alcohol)......................................... .. .76,330
Methanol (alcohol)......................................... 57,250
E85............................................... .................82,293
BTU content per gallon provides the simple answer as to why we have to run more alcohol V gasoline.
combine the energy content (BTUs) w the proper amount of oxygen and you have max Tq/hp. max out any of the above fuels and the power will be exactly as they relate BTU-wise.
since we can raise gasoline octane to the sky we can run big boost... along w water and dry ice intercooling etc ect. it's just expensive.
as to backpressure/rotary... i do agree w you. we need larger hotsides because we have to flow more air to make the same hp as a piston... so we need a bigger hotside.
part of the reason i built my twin TO4 setup was to have a larger hotside total. i ran two stage 5 wheels for an average area of 10.816 sq inches of turbine. comparatively a GT4202 (75/82) has 7.527 sq inches and a S475 (88/95,7) has 10.292. a stock GT35r (62/68) has 5.171.
my digitally logged backpressure was 24 psi at 20 psi boost. for a number of reasons i never did dyno it at more than 20 psi where it made 507 SAE on 93 pump and 1400 CC/Min meth. the engine did love the absence of backpressure.
the edge alcohol has is the immense cooling V gasoline which allows even higher boost/CCP.
after all is said and done we are still saddled w the fact that methanol has 49% of the BTUs as gasoline. that's why 1000 rwhp 2 rotors run as many as 14 injectors for their meth delivery.
another plus on the alcohol side is that the autoignition temp V gasoline:
gasoline 495 F
methanol 867F
i am not knocking any of the fuels but just pointing out their characteristics.
hc
total energy (BTUs) per gallon...
Gasoline (any octane).....................................116,09 0
Ethanol (alcohol)......................................... .. .76,330
Methanol (alcohol)......................................... 57,250
E85............................................... .................82,293
BTU content per gallon provides the simple answer as to why we have to run more alcohol V gasoline.
combine the energy content (BTUs) w the proper amount of oxygen and you have max Tq/hp. max out any of the above fuels and the power will be exactly as they relate BTU-wise.
since we can raise gasoline octane to the sky we can run big boost... along w water and dry ice intercooling etc ect. it's just expensive.
as to backpressure/rotary... i do agree w you. we need larger hotsides because we have to flow more air to make the same hp as a piston... so we need a bigger hotside.
part of the reason i built my twin TO4 setup was to have a larger hotside total. i ran two stage 5 wheels for an average area of 10.816 sq inches of turbine. comparatively a GT4202 (75/82) has 7.527 sq inches and a S475 (88/95,7) has 10.292. a stock GT35r (62/68) has 5.171.
my digitally logged backpressure was 24 psi at 20 psi boost. for a number of reasons i never did dyno it at more than 20 psi where it made 507 SAE on 93 pump and 1400 CC/Min meth. the engine did love the absence of backpressure.
the edge alcohol has is the immense cooling V gasoline which allows even higher boost/CCP.
after all is said and done we are still saddled w the fact that methanol has 49% of the BTUs as gasoline. that's why 1000 rwhp 2 rotors run as many as 14 injectors for their meth delivery.
another plus on the alcohol side is that the autoignition temp V gasoline:
gasoline 495 F
methanol 867F
i am not knocking any of the fuels but just pointing out their characteristics.
hc
01-24-10, 09:06 AM
#19
Well I think you should run Methanol. Don't waste your time with gasoline. your trying to find ways to convince yourself why it's better when in the real world it isn't..
Here's something to think about..
Gasoline is for cleaning parts.
Alcohol is for drinking
Nitro is for racing!
Here's something to think about..
Gasoline is for cleaning parts.
Alcohol is for drinking
Nitro is for racing!
01-24-10, 09:57 AM
#20
Racing Rotary Since 1983
Thread Starter
iTrader: (6)
enzo,
"you should run Methanol"
i agree w you and BTW recognize your rotary accomplishments
Alcohol is for drinking... that'd be ethanol and i raise a glass to YOU.
methanol, since it is poisonous i suggest we run it in our rotaries.
Nitro... i haven't quite gotten there yet.
regards,
howard
"you should run Methanol"
i agree w you and BTW recognize your rotary accomplishments
Alcohol is for drinking... that'd be ethanol and i raise a glass to YOU.
methanol, since it is poisonous i suggest we run it in our rotaries.
Nitro... i haven't quite gotten there yet.
regards,
howard
01-25-10, 03:51 PM
#22
BDC Motorsports
"Methanol makes more power because there's more total BTU's then gas."
total energy (BTUs) per gallon...
Gasoline (any octane).....................................116,09 0
Ethanol (alcohol)......................................... .. .76,330
Methanol (alcohol)......................................... 57,250
E85............................................... .................82,293
BTU content per gallon provides the simple answer as to why we have to run more alcohol V gasoline.
total energy (BTUs) per gallon...
Gasoline (any octane).....................................116,09 0
Ethanol (alcohol)......................................... .. .76,330
Methanol (alcohol)......................................... 57,250
E85............................................... .................82,293
BTU content per gallon provides the simple answer as to why we have to run more alcohol V gasoline.
What's the difference in cooling BTUs from 800cc/min of gasoline vs. 1600cc/min of alcohol?
combine the energy content (BTUs) w the proper amount of oxygen and you have max Tq/hp. max out any of the above fuels and the power will be exactly as they relate BTU-wise.
since we can raise gasoline octane to the sky we can run big boost... along w water and dry ice intercooling etc ect. it's just expensive.
as to backpressure/rotary... i do agree w you. we need larger hotsides because we have to flow more air to make the same hp as a piston... so we need a bigger hotside.
part of the reason i built my twin TO4 setup was to have a larger hotside total. i ran two stage 5 wheels for an average area of 10.816 sq inches of turbine. comparatively a GT4202 (75/82) has 7.527 sq inches and a S475 (88/95,7) has 10.292. a stock GT35r (62/68) has 5.171.
my digitally logged backpressure was 24 psi at 20 psi boost. for a number of reasons i never did dyno it at more than 20 psi where it made 507 SAE on 93 pump and 1400 CC/Min meth. the engine did love the absence of backpressure.
the edge alcohol has is the immense cooling V gasoline which allows even higher boost/CCP.
after all is said and done we are still saddled w the fact that methanol has 49% of the BTUs as gasoline. that's why 1000 rwhp 2 rotors run as many as 14 injectors for their meth delivery.
since we can raise gasoline octane to the sky we can run big boost... along w water and dry ice intercooling etc ect. it's just expensive.
as to backpressure/rotary... i do agree w you. we need larger hotsides because we have to flow more air to make the same hp as a piston... so we need a bigger hotside.
part of the reason i built my twin TO4 setup was to have a larger hotside total. i ran two stage 5 wheels for an average area of 10.816 sq inches of turbine. comparatively a GT4202 (75/82) has 7.527 sq inches and a S475 (88/95,7) has 10.292. a stock GT35r (62/68) has 5.171.
my digitally logged backpressure was 24 psi at 20 psi boost. for a number of reasons i never did dyno it at more than 20 psi where it made 507 SAE on 93 pump and 1400 CC/Min meth. the engine did love the absence of backpressure.
the edge alcohol has is the immense cooling V gasoline which allows even higher boost/CCP.
after all is said and done we are still saddled w the fact that methanol has 49% of the BTUs as gasoline. that's why 1000 rwhp 2 rotors run as many as 14 injectors for their meth delivery.
another plus on the alcohol side is that the autoignition temp V gasoline:
gasoline 495 F
methanol 867F
i am not knocking any of the fuels but just pointing out their characteristics.
hc
gasoline 495 F
methanol 867F
i am not knocking any of the fuels but just pointing out their characteristics.
hc
B
01-25-10, 05:37 PM
#23
BDC Motorsports
There's something else I'd like to add to this discussion besides delving more into the water and alcohol thing. I'd like for this to get drilled into the heads of all of the rotary enthusiasts reading this: compared to the piston engine, this rotary, even though it has a decidedly better weight-to-power ratio to that of its counterpart, suffers from the problem of heat creation. For its relative displacement and its size, given the amount of air it's able to easily consume, it generates far more heat compared to the piston motor. Besides the fact that this engine doesn't seem to be too terribly resilient to heavy engine knock, 'd say it's the reason why so many of these blow up even though we wind up running less boost than (for example) your typical piston-powered street car.
It's also the main reason why I believe auxiliary injection is so paramount especially for a pump-gas driven car. I think every one of us ought to be pursuing this. The benefits of alcohol and especially water are plainly apparent. There's basically nothing that either of these could do to hurt a setup even if either were applied to an engine setup in a simple, static (constant spray) format just for the purpose of adding some engine reliability.
Once I get my new engine and setup going, I plan on adding a simple water injection. I plan on running about 350-500cc/min through an external air atomizing nozzle (thanks, Brent) just shy of the throttle body inlet for the purposes of seeing a difference in both chambers' EGT's. I want to get some before and after data, at the same boost (probably 25psi), on the same hot-air setup with the 70/30 pump gas to methyl alcohol ratio I run (M30). I doubt I'll change the target AFR at first (about 10.50:1) but probably will once the car is parked on a dyno.
My thought on water, even though I've not given it the credit it deserves in the past, is that it should be used strictly as a chamber coolant. I'm still not settled on the whole benefit of injecting pre-turbo thing but since I'm a heavy alcohol user I could care less about trying to use water as something to drop IAT's. I'm beginning to believe the notion, aside from the possibility of it occurring pre-turbo, that it's unlikely atomized water injected into the intake is going to have a drastic effect on dropping IAT's as compared to alcohol. I think water is best served as a chamber coolant. Get it atomized and into the compression stroke and let it do its job there more effectively than anything else will. Anybody disagree?
Alcohol Injection - I think it needs to be injected as early into the intake plumbing as possible to allow it all to fully flash into a gas, taking advantage of its low flash temperature (52*F) and high latent heat of vaporization to yank heat out of a turbocharger's discharge air. I've seen this first-hand on my setup (when it did not work with the alcohol nozzles just before the throttle body) what happens when the injection point is moved well upstream. With them upstream, my intake air temps at 25psi of boost were right at 100*F (non-intercooled). Prior, they were quickly climbing to 155*F+ and above at 10psi of boost less with an engine sounding like a rattle can. This is something to keep in mind for you guys aspiring to use alcohol.
Latent heat of vaporization:
http://www.engineeringtoolbox.com/fl...eat-d_147.html
No surprise, water is at the top of the list.
It's also the main reason why I believe auxiliary injection is so paramount especially for a pump-gas driven car. I think every one of us ought to be pursuing this. The benefits of alcohol and especially water are plainly apparent. There's basically nothing that either of these could do to hurt a setup even if either were applied to an engine setup in a simple, static (constant spray) format just for the purpose of adding some engine reliability.
Once I get my new engine and setup going, I plan on adding a simple water injection. I plan on running about 350-500cc/min through an external air atomizing nozzle (thanks, Brent) just shy of the throttle body inlet for the purposes of seeing a difference in both chambers' EGT's. I want to get some before and after data, at the same boost (probably 25psi), on the same hot-air setup with the 70/30 pump gas to methyl alcohol ratio I run (M30). I doubt I'll change the target AFR at first (about 10.50:1) but probably will once the car is parked on a dyno.
My thought on water, even though I've not given it the credit it deserves in the past, is that it should be used strictly as a chamber coolant. I'm still not settled on the whole benefit of injecting pre-turbo thing but since I'm a heavy alcohol user I could care less about trying to use water as something to drop IAT's. I'm beginning to believe the notion, aside from the possibility of it occurring pre-turbo, that it's unlikely atomized water injected into the intake is going to have a drastic effect on dropping IAT's as compared to alcohol. I think water is best served as a chamber coolant. Get it atomized and into the compression stroke and let it do its job there more effectively than anything else will. Anybody disagree?
Alcohol Injection - I think it needs to be injected as early into the intake plumbing as possible to allow it all to fully flash into a gas, taking advantage of its low flash temperature (52*F) and high latent heat of vaporization to yank heat out of a turbocharger's discharge air. I've seen this first-hand on my setup (when it did not work with the alcohol nozzles just before the throttle body) what happens when the injection point is moved well upstream. With them upstream, my intake air temps at 25psi of boost were right at 100*F (non-intercooled). Prior, they were quickly climbing to 155*F+ and above at 10psi of boost less with an engine sounding like a rattle can. This is something to keep in mind for you guys aspiring to use alcohol.
Latent heat of vaporization:
http://www.engineeringtoolbox.com/fl...eat-d_147.html
No surprise, water is at the top of the list.
01-25-10, 06:13 PM
#24
BDC Motorsports
Carl Byck's old 2nd gen road race car: PT67 compressor w/ 0.81 A/R turbine housing, made 506.5hp to the wheels at roughly 24psi of boost. Injectors were 680/1680 and static rail pressure was 40psi. Datalog shows duty cycles at 7500rpm of 90%. That calc's out to ~4250cc/min of fuel output. Was running 110L race gas at an AFR of about 11 flat:1.
If we were to shave a point of that and go from 11:1 to 12:1 (an 11.1% reduction in fuel injection), that would be a removal of 472cc/min. What's the difference in the cooling BTUs of gasoline to water at 472cc/min?
B
If we were to shave a point of that and go from 11:1 to 12:1 (an 11.1% reduction in fuel injection), that would be a removal of 472cc/min. What's the difference in the cooling BTUs of gasoline to water at 472cc/min?
B
