KillerRons - James Monroe
KillerRons - James Monroe


Mechanical fuel injection is (MFI) is referred to as a “constant flow” system.  Just as the name implies fuel is continuously being sprayed into the intake runner without interruption.  The amount of fuel is variable with engine RPM in relation to the pump speed.  A change in pump speed increases and/or decreases the volume of fuel and its pressure.  As you may guess, at low RPM’s the fuel pressure and volume is low but at midrange and higher RPM’s it becomes much higher.  Due to its constant spray, mechanical flow injection is not known to be fuel efficient at idle and low RPM’s (even when the intake valve is closed) so it is not recommended for street-driven use.  But at mid and higher RPM’s the fuel becomes highly atomized and the time the intake valve is closed becomes insignificant so it becomes excellent for high performance use.  This highly atomized mixture is injected close to the combustion chamber and is the reason why injection offers incredible throttle response.  An in depth explanation of how these systems work can be read about on our
“Fuel Injection 101” page.

The answer is "yes" but unfortunately it isn't that simple.  KillerRONS.COM specializes in providing fuel systems that not only are fast but are trouble free and consistent.  With that said gasoline doesn't fit mechanical fuel injection well.  This is due to gasoline's narrow tuning window which would require frequent recalibration when even small atmospheric (temperature) changes take place.  In our opinion the best way to successfully run gasoline is to use a carburetor or an expensive electronic fuel injection system that can manipulate the fuel curve at many points throughout a run.  We feel that alcohol is the best fuel to use with mechanical fuel injection but there are alternatives.  E85 is gaining popularity and works well with MFI along with being available from the "pump" in some areas.  E100 or pure ethanol is also a good alternative.

At KillerRONS we believe the reasons are many to choose alcohol over racing gasoline for your engine.  Your engine will run cooler and in most every case the engine will make more usable horsepower and torque.  In a drag racing application your race car will be more consistent from pass to pass when using alcohol over gasoline.  A large percentage of the most successful bracket drag racers in the country choose alcohol as their fuel.

Alcohol allows an engine to operate at cooler temperatures than gasoline and it doesn’t build excessive heat during the pass and on the return trip to the trailer.  This makes between round temperature control much easier especially when bracket racing in the summer heat.  It is particularly advantageous in multiple entry or round robin type events. With the use of a belt or cam driven fuel pump; it is not uncommon for the ignition and water pump to be the only accessory requiring voltage during a pass.  Due to these facts between rounds battery charging and engine cooling are significantly diminished.  This lack of necessary maintenance allows the driver to focus on the things important to winning the next round.  Things such as reviewing time slips, making delay box setting decisions and devising a game plan for winning the next round become the main focus of the driver.  We have been told many times by racers that the alcohol and mechanical injection actually made them a better driver.

Alcohol is a more stable fuel for bracket racing due to its high oxygen content.  This makes it significantly less prone to react to the atmospheric changes throughout a long race day.  During a long race day the temperature usually exhibits the most frequent and dramatic changes of the various atmospheric conditions.  Whereas barometric pressure and water vapor will typically change only a small amount.  Alcohol is least affected by temperature and most affected by the barometric pressure and water vapor.  Gasoline is most affected by temperature and barometric pressure and least effected by water vapor.  Temperature is the key variable here if you hadn't noticed.  This means that burning alcohol will make your race car a more consistent performer from morning to afternoon and afternoon to evening.  Not to mention day to day or during changes to the season.  In fact, our customers typically report being more concerned with track temperatures than they are the atmospheric changes.  To learn more about this please visit read our “Why Alcohol is More Consistent” technical bulletin.

Alcohol lowers elapsed times and increases speed.  There is much debate about peak horsepower levels with alcohol versus gasoline on various dynos.  In our testing this is a "hit or miss" proposition.  Some combinations make more peak power, some make less peak power and some are about the same.  What is hardly ever in question is an alcohol’s ability to outperform gasoline on the track in virtually every new system that is sold.  Common gains are in the neighborhood of two tenths more than a couple of MPH when switching from a gasoline carburetor to alcohol fuel injection.  Of course, these results vary due to the efficiency of the engine and caliber of the carburetor replaced.  Heavier racecars with lower compression engines see as much as a half-second of elapsed time improvement and “tweaked-out” combinations in lighter cars may only see a tenth gain in ET. 


We want our customers to make an informed decision whether to stay with a carburetor or switch to MFI.  There are so many opinions from friends, at the track and on the internet that sometimes it is hard to make any sense of it.  With that said, we will outline here what we believe to be the “pro’s” and “con’s” of MFI.  We hope this will help you make an informed decision.

“Pro’s” of Injection
PERFORMANCE - Mechanical fuel injection does not utilize a venturi (restriction) to draw fuel into the engine as a carburetor does.  This is why the flow numbers of a throttle body are considerably larger than you are accustomed to seeing with a carburetor.  Without the restriction and with no heavy fuel to deal with in the intake plenum and runners the engine is able to pull in more air at a higher rate of speed.  The fuel is mixed in as a last step before the combustion process.  This is the reason that MFI has incredible throttle response.  More importantly than that, the increased air intake allows the tuner to increase the fuel delivered.  This is why increased on-track performance is realized in almost every race car where MFI takes the place of a carburetor.  Average gains are in the neighborhood of a tenth of a second no matter who modified the methanol carburetor.

MAINTENANCE – If you have ran an alcohol carburetor for any significant amount of time it is almost guaranteed that you have experienced a problem with the engine flooding because of a needle/seat problem or a float problem.  You most likely have also experienced a bog or hesitation due to a faulty accelerator pump or squirter or poorly calibrated fuel metering circuits.   MFI eliminates the typical failure prone carburetor parts such as accelerator pumps, pump squirters, needle-n-seats, floats, power valves, air bleeds and gaskets.  This means that MFI is less likely to have a failure that could ultimately cost you a round or a race win.  Moreover, mechanical fuel injection virtually eliminates the age-old transition problem from the idle to power circuit (no more "walking into the throttle and hoping it doesn't stumble).  MFI will respond instantly each and every time.  Mechanical fuel injection has only a handful of moving parts, no gaskets, is hard anodized inside and out and has only a couple of sealing o-rings.  From an induction standpoint, this makes it less necessary to use top lube with methanol.  We estimate that 50% of our customers do not use top lube and they see no residual effects of this in their engine.  A mechanical fuel injection system utilizes a fuel shutoff cable that allows the user to starve the engine of fuel at the end of the day preventing alcohol from lying on top of the piston between races.  This makes it unnecessary to “fog” the engine with WD-40 after each race.

CONSISTENCY - Mechanical fuel injection is a constant flow system meaning that a mechanical pump and fixed orifices (bypass pills and nozzle jets) deliver a pre-determined and exact amount of fuel at a specif RPM, no matter how much the atmospheric conditions change.  These same atmospheric changes will cause a methanol carburetor to draw varying amounts of fuel into the engine. Thus with MFI the only variable in this consistency equation is the atmospheric changes throughout an event. This alone will make an MFI system more consistent than a carburetor.  There is more.  As discussed in the above bullet point, one of the things that affects methanol the most is water vapor in the air.  Methanol MFI is less affected by water vapor because the fuel is delivered close to the chamber whereas a methanol carburetor allows the water vapor to dilute the fuel immediately upon entering the manifold plenum.  Granted, this is a small advantage but in today’s racing every thousandths of a second of increased consistency is important. 

“Con’s” of Injection

Mechanical injection isn’t without its flaws.  There are a few minor things that can be thought of as “con’s” for MFI.  The good news is that there is a way around all of these with just a little effort.  The bad experiences you hear with MFI are typically from people that didn’t have either the knowledge or the parts necessary to utilize a system properly.  Unfortunately or fortunately, we consider these circumstance as our main competitor; not other companies or forms of induction.

HARDER STARTING – Mechanical fuel injection does not start as easily as a carburetor.  This is mainly due to a couple of reasons.  The first being that it doesn’t have accelerator pumps.  The second reason is because the barrel valve and injector hoses have to be filled with fuel before it can be delivered to the chamber.  Ultimately, this means that with a properly adjusted/tuned system and starting technique it will normally take a few seconds of cranking to restart a warm engine.  Starting a stone cold engine the first time of the day normally takes a bit more effort.  In this case a squirt bottle or a can of carburetor cleaner needs to be on hand to assist in priming the mechanical fuel pump in delivering fuel to the barrel valve.  All of this can be eliminated with a primer system which can be viewed here.  A Basic Primer gives the driver a way to give the engine a squirt of gasoline to aid the starting process.  A Primer Plus adds the ability to idle on gasoline for the ultimate in starting, fuel savings and heat building.  A primer will have your MFI engine starting like a carbureted engine.

GREATER FUEL CONSUMPTION – Compared to a carburetor mechanical fuel injection must utilize a richer idle mixture.  This is because it doesn’t have accelerator pumps to help transition from idle to wide open throttle.  The richer idle mixture helps give MFI its incredible throttle response but also causes it to use more fuel.  A great part of this can be offset but using the fuel shutoff cable to lean the fuel mixture while the engine idles.  The addition of a Primer Plus gasoline idling system will almost eliminate this “con”. 


The answer to this is that it is absolutely unacceptable to have contaminated oil in any alcohol burning engine.  If you are experiencing this with our system (or any other) it needs to be addressed and rectified immediately.  In respect to our systems there are two criteria to be met that will ensure your oil is as pure as possible at all times.  Those being the idle mixture and proper use of the shutoff cable included with each system.  First the idle mixture needs to be adjusted so that the engine is clean off idle with no hesitation but not excessively rich.  This can be accomplished with a leakdown procedure (preferred with a Ron's Fuel Injection tester) or a visual setup described elsewhere on this site.  The fuel shutoff cable is often overlooked but is extremely important in this process.  Once the engine is running the shutoff cable should be pulled until you hear the engine RPM's tweaking up to 2,000-2,500 RPM.  This ensures that the engine is a little on the lean side which will allow it to build heat quickly save fuel and make the oil look great.  In a drag racing application it is good policy after a pass is to see how much temperature you can gain before returning to the pits in preparation for the next pass.  If you can reach 170-180* ANY and ALL moisture that is present will be eliminated in the oil and valve cover area.  It is also good practice to remove the header evacs or vacuum pump hoses from the valve covers at the end of the race day.  This will allow the condensation to get out of the engine as it slowly cools down. 

Generally speaking the answer to this is no.  A typical camshaft selection that is working well in an existing gasoline engine will work well with a methanol MFI engine.  Alcohol is known for great bottom-end and mid-range gains as it effectively lowers the RPM band of an engine.  In almost all cases of persons switching from gasoline to methanol in drag racing applications the results are quicker elapsed times and faster speeds, regardless of the camshaft specs.  That being said, there are camshaft characteristics to pay attention to when selecting a profile that will help optimize a methanol engine’s performance.  We suggest selecting a cam with a few degrees more exhaust duration and/or a little wider LSA when compared to a perfect gasoline camshaft.  This helps a methanol engine run better in the upper RPM band and it helps the extra power “hold-on” a little longer.  The forgiving nature and broad torque curve of alcohol may tempt a person to try a camshaft with more intake duration as a way to increase upper rpm power.  Doing this may sacrifice too much mid-range and is normally not recommended by KillerRONS.COM.  It is preferred to increase the effectiveness of the intake lobe by increasing the lobe lift as alcohol generally reacts well to this.  As much as a specific fuel can dictate a camshaft selection, your engine components such as cylinder heads, stroke, cubic inch and type of induction will continue to play their traditional roles and should take precedence in these matters.  Please be aware that the above recommendations are based solely on the use of mechanical fuel injection as the choice of induction.  If you are using a methanol carburetor these recommendations may not be appropriate for your engine.  When selecting a new camshaft we suggest speaking to someone familiar with the engine combination and induction you are utilizing.  Once this is done and you still have specific questions please fill out
this questionnaire and we will help guide you further. 


Our systems are priced as complete units and include the throttle body, combination barrel valve (pill holder, fuel shutoff and distribution block), injector hoses, injector bodies, nozzle jets, fuel pump, fuel pump mount and drive kit, fuel shutoff cable, fuel filter and assortment of bypass pills for fine tuning.  The only parts you will need to add to the primary system are the hoses and fittings to and from the fuel cell.  An average changeover will cost in the $1,900-$2,300 range.  This may sound like a lot to most people but please remember that this is a complete system including the fuel delivery components.  A custom built carburetor along with a top-of-the-line mechanical or electric fuel pump and regulator will cost every bit of this amount.

The Flying Toilet and Terminator throttle bodies are quite different in appearance but they accomplish essentially the same task and that is to facilitate air entering into the engine.  The Terminator is CNC machined and is available in two popular sizes (1475 and 2100 CFM).  The Flying Toilet is a cast aluminum unit available in three sizes (1250, 1435 and 1800 CFM).  Personal taste, ease of installation and specific engine combinations may require the use of one of these throttle bodies over the other.  It may be worth your time to make a call or email to us to discuss these two throttle bodies to decide which is best for you whether it be new or used.  Throttle body aside, the surrounding components of the Flying Toilet and Terminator systems are identical. 


We more than likely do offer a mount and drive kit for your engine make.  We stock kits for virtually all engine makes that includes the appropriate pieces to mount the mechanical pump to your block, the crank mandrel and bolt, both pump and crank pulleys and the appropriate length belt.  All of these pieces are anodized for a great look. 


We will never discourage anyone from purchasing a quality used system from a friend or on the internet.  However, we would like them to make an informed decision on the parts needed for it to be a successful project.  Too often individuals purchase used systems with no comprehension of what they need and this becomes negative not only for the racer but for the product as a whole.  With that being said we treat every customer as if they purchased new from us and do all that we can to make the changeover a favorable experience.  If you are considering purchasing a used system we encourage you to fill out a
questionnaire and let us make a system recommendation for you.  This will allow you to shop for the correct parts as you look for that good deal on a used system.  The number one culprit of poorly running used system purchases comes back to ill-sized nozzle jets and fuel pumps for a particular engine combination.  General tips for looking for a used system also includes making sure that all of the parts are included and are in good working order.

IMPORTANT - Parts that are discontinued and no longer serviced should be avoided such as purple and black barrel valves as well as vane pumps.  This can get expensive in a hurry because not only are the vane pumps discontinued but their mounting parts, pulleys, mandrels and belts are also no longer available.  If any of these parts are bad or missing in a used kit, the pump and complete drive it will need to be replaced totaling $797.

This answer to this question is again absolutely not.  It is estimated more than 1/2 of all alcohol MFI users employ a simple header evacuation system.  It is important that these evacuation systems be free flowing and lack obstructions.  Often times we will ask customers to remove the filter media or “check balls” from the breathers to allow the engine to breathe more freely.

If you already have a vacuum pump system or wish to add one at some point we can supply a fuel pump pulley that will work in conjunction with most mandrel assemblies offered.  If you have a specific question about this please call and ask.  KillerRONS.COM offers complete vacuum pump systems from Star Machine that you can read about by visiting this page.

We recommend using NGK Spark Plugs.  There are many variables that dictate what heat range and plug gap is used in an engine.  As a general rule most of our customers use a “colder” spark plug in the heat range of an NGK-8 or NGK-9.  The plug gap recommended for most of our customers is .030-.035.  Click on our
“Spark Plug Selection” technical bulletin to read all about the factors to take into consideration when selecting a spark plug.

A very large percentage of KillerRONS.COM customers do not utilize any type of hi-speed bypass.  We are aware that a small amount of performance COULD be sacrificed by this policy but consistency is not.  Due to the fact that most of our customers are drag racers who’s engine operates in a narrow RPM band we prefer to set our systems up with a moderately-sized fuel pump to make tuning easier in all conditions. We also believe this to be a secret of most of our customer’s success.

When a hi-speed bypass is utilized in specific engine combinations it is used to tailor the fuel curve to the special requirements of an engine at various points in its operating range.  Most commonly mechanical bypasses are used to “trim” fuel away from the engine at higher RPM’s as the engine’s volumetric efficiency decreases.  This is achieved with a bypass pill at a pre-set pressure value.  An electronic hi-speed bypass is sometimes used as a “dump” at higher RPM’s and it is also utilized on some engines at lower RPM’s. 

KillerRONS.COM considers many factors when recommending an initial tune-up for an engine and car combination.  The basis for a recommendation centers around the kind of power an engine currently makes or is expected to make.  This information can be gleaned from dyno sheets, “desk top” dyno formulas, real world experience or current performance numbers if the engine is already in service.  In simple terms the tune-up recommendation is typically derived from real world experience in the most common engine combinations.  In more exotic combinations we will pull from our extensive database along with referencing some key mathematical equations to derive a tune-up recommendation.  Armed with the knowledge that Ron’s Fuel Injection components are bench tested and flowed individually your technician can give you an excellent starting point for a system.  The ultimate tune-up will come down to testing on the user’s part with performance increase or decrease as the indicator.  This philosophy has been proven successful for many years and is why KillerRONS.COM is widely recognized as the leader in this field.

Occasionally we are asked if a full system flow test is necessary with mechanical fuel injection?  Since all new individual components are tested upon manufacturing we believe it not to be necessary.  We will concede that system flow tests are good for double checking that the system flows an amount of fuel that "theoretically" should work.  This is especially true when trying to put a system back into service with dated and or possibly worn components that may or may not be up to specifications. The system flow test can also be useful when trying to create a fuel curve when utilizing an oversized fuel pump for the engine’s power level.  KillerRONS.COM does not recommend doing this as the use of a properly sized fuel pump for an engine is the cornerstone of our business.  Remember that no matter who recommends your baseline tune-up it is nothing more than an educated guess based upon experience, mathematics and a database of reference and it will be up to the user to determine the ultimate tune-up with on track testing.  There are simply too many variables to factor into the equation.  To name a few things like cylinder head design, camshaft profiles, intake manifolds, headers and even the racer’s geographic location all play in the final tune-up.  It should also be known that system flow tests are quickly becoming outdated with the advent of affordable tuning aids and data logging devices.  For similar pricing a racer can purchase equipment that will allow him or her to see fuel pressure, engine vacuum, engine RPM, exhaust gas temperatures and exhaust gas oxygen trends each and every pass.  This allows the user to tailor the fuel curve no matter the varying conditions from track to track and season to season.













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