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

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

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

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

 

Yet another informative post Howard! Great info & overview!!

 

a better suggestion would be put your effort towards getting methanol below $5 a gallon.

 

lol.

I love numbers, im doing all the pre game work for my GT35r on its way to me now. Shying away from meth and doing solely WI until i get a strong grasp of the experience, not just theory. Howard, im going to be photographing my stock port engine that has about 30k miles on it without WI and then reviewing it after ive ran WI for some time. Ill post those in the appropriate thread :-)

 

There should be a "The Howard Coleman" (sub)section with all of your posts. Once again, very well laid out and informative.

You're in Monroe? If you need any help, I live in Dexter and work in Ann Arbor. I'd be game for working on a car on the weekends (provided the garage is heated).

 

"getting methanol below $5 a gallon."

Hmmm, i pay around $2 a gallon.

HC

 

howard, is there any form of calculations to estimate predetonation conditions. I.E. this compression ratio + this quickly + this air temp +this boost is > 495F?

It occurs to me that ive never researched inside the rotary engine itself for detonation conditions.

 

Awesome thread Howard. Love your informative threads that opens up so much more potential for newbies like me. Keep up the good work!

-AzEKnightz

 

"is there any form of calculations to estimate predetonation conditions. I.E. this compression ratio + this quickly + this air temp +this boost is > 495F?"

that's way beyond my pay grade but our knock detectors will let us sneak up on it. there are way too many variables to do it on a calculator.

hc

 

we wish and one of the largest areas of producing methanol is right here in the central valley in california less than an hour from me. don't ask me why i can't find it for less, it used to be under a buck a gallon just a few years ago. sometimes it fluctuates up to over $6 a gallon, too bad when race fuel out of the pump right down the street is $7. although it is still cheaper with AI running methanol it's still annoyingly expensive and out of the question if you had ever thought of running a 100% methanol setup.

 

using the info from post one i thought you might be interested in doing the numbers for my 2010 project.

i plan to enter the 2010 October Texas Standing Mile (http://www.texasmile.net/index.php) with the objective of breaking 200 mph w my 13B FD.

a 550 rwhp FD (built LS7) ran 196 last october. i figure i need about 600 rwhp to get it done.

so let's examine our fueling options...

600 rw rotary hp takes 1.92 CFM per horse... so 600 X 1.92 = 1152 CFM.

1152/ 14.471 = 79.6 call it 80 pounds per minute of air

AFR plan for 10 so you have backup and can run rich if need be...

80 pounds of air

8 pounds of fuel.

8/ 6.35 = 1.259 gallons of gasoline to make 600 rw rotary hp.

since we don't run our injectors wide open and limit them to 85%

1/.85 = 1.1764 to adjust.

1.1764 X 1.259 gallons is 1.481 gallons per minute or 5606 CC/Minute.

that's for gasoline.

total BTU cooling is

1.259 X 952 = 1775 BTUs of cooling from running 100% gasoline

let's run gasoline and add 1000 CC/Minute of water to cool...

1000CC is .2641 gallons

.2641 X 8087 = 2135 BTUs of cooling

so if i run gasoline and water:

1775 BTUs from gasoline & 2135 BTUs from water or 3910 total BTUs cooling from water and gasoline

how about running methanol as a fuel?

we know we need 1.259 gallons per minute of gasoline to make 600 rw rotary hp.

1.259 X 116,090 BTUs per gallon or 146,157 BTUs needed.

methanol has 57250 BTUs per gallon so

146,157/57250 = 2.5529 gallons of meth needed per minute.

2.5529 = 9664 CC/Minute of methanol to make 600 rw R hp

so i would run two 850 CC injectors in my primaries and 4 Injector Dynamics ID2000 (http://www.t1raceparts.com/en/produc...-injector.html) in my 4 secondary ports on my Ground Zero LIM

primary 2 X 850...............1700
secondary 4 X 2200..........8800

total CC/Min......................10,500

10,500 X .85 duty cycle......8925 close

here's the motivation to do the 100% methanol...

8925 CC/Min is 2.3577 gallons per minute

2.3577 X 3136 BTUs = 7393 BTUs of cooling

comparing total cooling:

gasoline......................1775

gas w water AI............3910

methanol.....................7393

the Texas Mile is quite a bit different than a quarter mile where you buzz thru 4 gears in 11 seconds... then you get to back off.

i figure the first quarter will go by in 12 seconds and i will be running around 120. assuming i hit 200, my average speed for the remaining 3/4 mile will be 160. as a rough guess, the last 3/4 mile would take 17 seconds so my motor will have to go thru 5 gears (7500 in fifth w a 3.90) in a 29 second span while making 600 rwhp.

i think i need the cooling. any advice welcomed.

also feel free to ask away re your fuel questions.

hc

 

^ what tranny, rear diff and what size wheels/tires are you running?

 

howard, whats the fastest you have gotten previously? Im not turning this into a MAX mph thread, im just interested in your progress.

 

Here is a theory that not only water is moderating combustion, it's part of the combustion process.

http://www.not2fast.com/thermo/water..._chemistry.txt

************************************************** **************************** Let us take a quick look at ignition. Those who have a Heywood can look it up
- mines on loan so going by memory. The first thing that happens is a plasma
cloud is formed by the arc consisting of super heated electron stripped atoms.
When this cloud "explodes" a ball of high energy particles is shot outward.

The highest energy particles are the hydrogen atoms - and they penetrate the
charge about 5 times as far as the rest of the particles. As they lose energy
and return to normal temps - about 5000 k - they begin to react chemically
with any surrounding fuel and oxygen particles. The effectiveness of spark
ignition is directly related to the availability of free hydrogen. Molecules
containing tightly bound hydrogen such as methanol, nitromethane, and methane
are far more difficult to ignite than those with less bonds.

During combustion - water - H2O ( present and formed ) is extremely active in
the oxidation of the hydrocarbon. The predominate reaction is the following:

OH + H ==> H2O
H2O + O ==> H2O2
H2O2 ==> OH + OH
Loop to top and repeat.

The OH radical is the most effective at stripping hydrogen from the HC
molecule in most ranges of combustion temperature.

Another predominate process is the HOO radical. It is more active at lower
temperatures and is competitive with the H2O2 at higher temps.

OO + H ==> HOO
HOO + H ==> H2O2
H2O2 ==> OH + OH

This mechanism is very active at both stripping hydrogen from the HC and for
getting O2 into usable combustion reactions.

Next consider the combustion of CO. Virtually no C ==> CO2. Its a two step
process. C+O ==> CO. CO virtually drops out of early mid combustion as the O
H reactions are significantly faster and effectively compete for the available
oxygen.

Then consider that pure CO and pure O2 burns very slowly if at all. Virtually
the only mechanism to complete the oxidization ( Glassman - Combustion Third
Edition ) of CO ==> CO2 is the "water method".

CO + OH ==> CO2 + H
H + OH ==> H20
H2O + O ==> H2O2
H2O2 ==> OH + OH
goto to top and repeat.

This simple reaction accounts for 99% + of the conversion of CO to CO2. It is
important in that fully two thirds of the energy of carbon combustion is
released in the CO ==> CO2 process and that this process occurs slow and late
in the combustion of the fuel. Excess water can and does speed this
conversion - by actively entering into the conversion process thru the above
mechanism.

The peak flame temperature is determined by three factors alone - the energy
present and released, the total atomic mass, and the atomic ratio - commonly
called CHON for Carbon, Hydrogen, Oxygen, and Nitrogen. The chemical
reactions in combustion leading to peak temperature are supremely indifferent
to pressure. The temperatures and rates of normal IC combustion are
sufficient to cause most of the fuel and water present to be dissociated and
enter into the flame.

As can be seen above, water is most definitily not only not inert but is a
very active and important player in the combustion of hydrocarbon fuel.
Ricardo and others have documented that under certain conditions ( normally
supercharged ) water can replace fuel up to about 50% and develop the same
power output, or that the power output can be increased by up to 50% addition
of water. This conditions were investigated by NACA and others for piston
aircraft engines. It is important to note that these improvements came at the
upper end of the power range where sufficient fuel and air was available to
have an excess of energy that could not be converted to usable pressure in a
timely manner.

As a side note - Volvo recently released some SAE papers documenting the use
of cooled EGR to both reduce detonation and return to a stoic mixture under
boost in the 15 psi range - while maintaining approximately the same power
output. Notice - they reduced fuel and still get the same power output.

When you consider that EGR consists primarily of nitrogen, CO2, and water ( to
the tune of about two gallons formed from each gallon of water burned ), you
might draw the conclusion that it also was not "inert". They peaked their
tests at about 18% cooled EGR - which would work out to about 36% water
injection and got about the same results under similar conditions that the
early NACA research got.
**************************************

Lots of NACA research also here: http://www.not2fast.com/NACA/

 

I'm guessing a T56?

 

great info, thanks

 

Good information / simplified model about

- maximum amount of water that can be vaporized
- cooling effect from vaporization
- O2 dilution from the vaporized fluid
- Net effect of cooling and dilution

http://not2fast.com/thermo/water_inj...opt_mass.shtml

same site re. post above

- Sandro

 

Poman. I appreciate that link. I love diving into the math only to forget it once the cars on the street.

 

tagged to finish up later.



great info. now I need to do some planning again lol

 

Still awaiting a response to this question: why do you have to run the same pig rich AFRs with water injection (which results in ungodly fuel dilution of the oil)? why can't you run high 12s or even low 13s?

 

I am genuinely interested in the answer to this too. both from a theory and experience basis.

 

You can, RICE RACING(unfortunately banned) run 13B single turbo at ~480rwhp(dyno dynamics) at 13,7 AFR...I think due to the low fuel pressure...but engine run fine....As I understand, ~10,8 AFR+lots of water gives best knock protection without robbing to much power...

Read throught these two papers, lots of history and facts, rather than internet opinions...
http://www.riceracing.com.au/resourc...rinjection.pdf
http://enginehistory.org/Frank%20WalkerWeb1.pdf

 

Also, here is nice thread about what real tuners were able to do back in the day.... https://www.rx7club.com/showthread.p...eripheral+port
Preaching in this thread about how bad pump gasoline is as fuel, is shameful...

 

We need a sticky and go on ahead and put every post Mr. Coleman has done in there haha. Awesome post.

 

Great write up.... Wondering where did the 1.92 CFM/HP come from? Was it an average based on car dynos or a calculated value? I would say that your max WHP/CFM is a little conservative based off of a few GT35 turbo cars that have run 500 whp dynos. Granted there is a lot of error in a dyno. Any thoughts on that?