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

 

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

 

"SetUp : 13B REW Large Extend/Turbo Port, 3mm PTS Apex Seals, Dowelled & balanced.
Match ported REW intake manifolds & emisions & sec butterfly removed.
1680cc Secondaries & 880cc Primaries, 2 bosch 044 pumps feeding surge tank &
1000Hp SX main pump feeding engine.
Turbo is to be changed to either BW362 or BW366 with extended tip & possibly
race cover. Wastegate is 45mm Turbosmart, 20psi, plumbed back into 3" Exhaust.

We are changing over to E85, and are unsure as to what fuelling (ie injectors) we will need for a projected 550RwHp @ 20psi, (or if this is even possible with the turbos we are looking at & psi.)
We are looking to change to a 4" exhaust, if this would help."

road racing presents significant challenges as nowhere is hp under the curve more important. the ideal turbo for road racing makes 400 rwhp at 5500 rpm. ports have a lot to do w making the number.

i have a compressor map for the BW 362.
the cold wheel is 62 X 86 or 6.291 average are in sq inches.
it makes 59 pounds at one pressure ratio (14.7) and 68 at 20 psi.

59 = 854 CFM or 445 rw rotary hp
68 = 984 CFM or 513

the Garrett GT3582r
61.4 X 82 or 6.386 av sq inches
56 pounds at 1 PR and 62 at 22 psi
56 = 422
62 = 467

as you can see neither of these turbos will get the desired top tick 550 done. i do think that finding 400+ at 5500 and 500 tops will win any road race given the FDs immense chassis advantage.

if you step up to a larger turbo, the 67 MM class (PT67, GT500 ASpec, TO4Z) the compressor wheel is 7.003 sq inches and you will be trading more top end for a bit less midrange...

here's a dynosheet from a motor i built & ported running another turbo that i really like... i believe it is actually a BW turbo and it has also been marketed as an R85 and TEC300.

compressor is 61.5 X 84.7 or 6.667 av sq inches. this turbo has a rotor friendly huge hot side turbine which is 6.93 av sq inches. compare to the S362 at 6.7 and the GT35r at 5.171. ASpec markets a similar turbo, the GT3574 that i llike because they use a large turbine wheel (5.89) on the Garrett GT35 compressor.

anyway here's the sheet. hp is in the more understated SAE correction:



IMO, this is what you want for road racing.

now let's do the math:

500 rw rotary hp using E85.

road racing generates huge cumulative heat and CCP. the alcohol will deal with it.

500 rwRhp requires 960 CFM (500 X 1.92)
960/14.471 = 66 pounds per minute

at a max rich AFR of 10 that's 6.6 pounds per minute of gasoline times a duty cycle max of 85%

1/.85 = 1.176 X 6.6 pounds = 7.764 pounds of gasoline

7.764/ 6.35 (pounds per gallon) = 1.222 gallons

1.222 gallons X 116,090 BTUs per gallon = 141,953 BTUs needed to do 500 rwRhp

BTUs per gallon:

gasoline 116,090
Ethanol 76,330

at 85/15: 82,293 BTUs per gallon from E85

141,953/82293 = 1.725 gallons per minute of E85 to make 500 rwRhp

1.725 GPM = 6529 CC/Min

you have 5120 and will need additional injector capacity.

i do like your battle plan and it is always great to see FDs on the type of track for which they were built.

Howard

 

"If we take that case to the stock turbos: then are we running the optimum injector size to maximize hp? Let's assume for the sake of arguement that stock turbos/ports plus intake/exhaust/pfc maxes out safely near 350rhp..."

since there really aren't any compressor maps for our stock setup (yes i have one but it doesn't disclose the numbers) let's just reverse into it...

assume 350 rwRhp...

350 X 1.92 = 672 CFM / 14.471= 46 pounds per minute.

46 pound of air

4.6 pounds gasoline X 1.176 to correct for 85% max duty cycle = 5.41 pounds fuel/
6.35 = .8519 gallons per minute = 3224 CC/Min

the FD has 2800.

255 flywheel hp X .85 to correct for rwhp = 217

217/350 = 62%

.62 X 3224 = 1998... (needed for stock 255 flywheel output)

we have about 800 CC/Min additional injector capacity. (good for 300 rwRhp)

if 217 requires 1998 then 400 requires 1.8433X or 3683 CC/Min

howard

 

here's the executive summary:


...................gross...................net
..................gasoline............gasoline.... .....Energy.........Cooling...Addit'l Cooling BTUs
rwRhp........CC/min...............CC/Min..........BTUs.............BTUs...........from water AI

217 (stock)....2018...............1559...........47,82 3............392..............640........ 300 CC/Min

300...............2790...............2156......... ...66,128............542.............854.......... 400 CC/Min

400...............3720..............2875.......... ...88,172.............723.............854......... .400 CC/Min

500...............4650..............3593.......... ..109,741...........900..............1068......... 500 CC/Min

600...............5580..............4311.......... ..132,258..........1084..............1495........7 00 CC/Min

fuel requirements assume we can deliver at a 10.0 AFR at 85% max duty cycle.

column 2 is required max nominal injector capacity the stated hp level using above assumptions.

column 3 is the fuel required to make stated hp (net of the 85% duty cycle and using an 11 to 1 AFR)

column 4 is the BTUs to make the stated hp

column 5 are BTUs of cooling in the gasoline

column 6 is the additional BTUs of cooling from the introduction of water.

column 7 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 88.

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

 

these engines are incredable, just got off youtube, PR and OZ have multiple 1000HP 13B ,two rotors, and runnin in the hi 6second range.

how can that be possible??

 

geese howard...I'll have to finish the second half of this in a couple hours... my brain hurts.. haha. How about using C02 to further cool the intake charge? or is that even necessary?

 

Manny is correct Howard!!
so much numbers and info leaves a person cold,
as such they dont read it, you put so much into math that it loses the simple facts of fast car modifications.
most mods were developed by just trying things till they worked , the same old HOT-ROD stuff that has made top-fuel dragsters run 300+.

stop and think,, how many PR-OZ guys are math wizards, and work things out by numbers,(not many)

 

and if you make it to the Texas Mile , email me , im about 2hrs from there.

i did watch a 1987 turbo RX7, blow its lunch all over the track (back 2weeks ago), 1 mile is a long time at full boost, espiecally the last 1000ft, where top speed is important.

 

The rotary doesn't have a VE problem at all, quite contrary, it does however take a penalty due to lower thermal efficiency, hence the heat and cooling problems.

 

the simple facts of fast car modification... so many want to slap on parts without thought, and just go. why not take advantage of the physics and science available to us? to have a car make power, to develop a powerband that you so desire, to track or drive as you want it to, is all an equation. the variables change depending on your needs. the more you understand, you better you can tailor the car to do exactly what you want.
theres nothing wrong with spendng years and years figuring out what works best for you, but when you can take a minute (ok... more than a minute) and figure it all out... before you cut into metal, or turn a single bolt.
I guess i'd rather understand and be able to manipulate as much as possible to achieve optimum results, than waste time, effort, and money on a guess, or because "someone else did it."
More people need to take this approach if they expect to move ahead or make progress.

Howard, you missed out on the open track at RA this past weekend.... I expect to see you there this June!

 

Since water is used to "steam" clean the engine, is it possible to put a larger amount of water to clean the inside of the engine? Or just running a water injection system for a longer time the same thing?

 

"The rotary doesn't have a VE problem at all, quite contrary, it does however take a penalty due to lower thermal efficiency"

i probably should have used Brake Specific rather than VE. VE can refer to a number of things but BSFC is really the bottom line... i also need to stipulate that i am talking (only) turbo'd rotaries as the thread title states.

that said:

here's the BSFC for the turbo rotary calculation...

BSFC is expressed as FLYWHEEL hp. we are going to solve for a 500 rwhp rotary.

588 FWHP is 500 rwhp after a 15% deduct for drivetrain loss.

500 X 1.92 = 960 CFM/ 14.471 = 66.34 pounds of air per minute.

using 11.3 AFR 7.4963 pounds per minute of gasoline would deliver 11.3 AFR

7.4963 pounds per minute is 449.778 pounds per hour

588 FWHP/ 449.778 pounds of fuel derives a .765 BSFC

turbo'd piston motors normally are between .6 and .75

the rotary requires 13.3% more fuel to make equal power to the midpoint on the turbo'd piston scale and 27.5% more based on the best (.6) piston performance.

in addition, keep in mind that i have used what i consider the max numbers for rotary hp given the airflow. most rotaries won't make the number.

hc

 

Can one simply measure the compressor/ turbine inducers & exducers and get an accurate turbo flow rating?

Or, in order to have the flow rating (CFM) do you need to have a compressor map.

I'm going to be pulling my BNR Stage III sequential turbos apart to take measurements.

Also: can these numbers be restricted substancially from exhaust back pressure?

Since I'm running sequentially, I'm wondering if there are more limiting factors than just hte compressor/ turbine.

I found this page to be quite helpful:

http://www.turbobygarrett.com/turbob...o_tech102.html

 

Still looking for some imput on this question.

Also, this thread is helpful SO FAR for injector selection.

But

What about pump selection?

I know I know, Bosch 040, 044, etc or APEXi BNR blah blah blah.

but there is so much more to a fuel system than pumps & injectors.

what about pump/ injector parameters (optimal fuel pressures to run for both the injectors or pump) so as to not overly strain the pump.

I would think you would have to see what the reccomended fuel pressure is for the pump & at what fuel pressure rating the flow measurements are taken.

Fuel viscosity? Gasoline vs Pre-mixed gasoline vs E85 Vs pre-mixed E85?

Whit changing the density/ viscosity of our fuels from premixing, is our injectors actually flowing what they were originally measured at?

most injector flow bench testing is done with mineral oil...

ID injectors actually flow test using gasoline (so their flow numbers vary greatly when third party flowbenching is done) their 1000cc injectors flow 850cc with mineral oil.

target injector duty cycle?

FPR's?

pump location/ or feeds?

im thinking twin Bosch 040's feeding to a surge tank and surge tank feeding to a Bosch 044 inline pump would be optimal.

Filter selection & placement (Micron count????) post pump/ pre fuel rail placement of filter?

More than one fuel filter?

substrate selection of fuel filter?

I like this thread, but it is under developed.