Pre Tune Information

by Michael Decipha Ponthieux
Posted: 8-17-2013
Last Updated: 11-13-2015

Before inquiring about an EFIDynoTuning Custom Tune, be sure you have verified the following for best results.

Rotating Assembly

A forged crankshaft is not recommended for stock blocks (excluding modular blocks and 6 cylinder engines). For small block ford applications, a cast crankshaft is typically able to support 900hp and is often stronger than the limitation of the stock block. For modular v8 applications, the stock cast crank should be replaced with a forged crank after exceeding the 450rwhp. This does not apply to V6 engines, V6 engines are more susceptible to crankshaft harmonics and thus forged crankshafts are recommended on all performance oriented V6 engines. A factory sbf 302ci block is good for approx 550rwhp, a factory sbf 351w block is good for approx 900rwhp. A factory modular ford block is good for approx. 1500rwhp. Aftermarket blocks should be used for all engines that exceed these ratings. Factory rod bolts should be replaced with ARP high strength rod bolts in all boosted applications. Gapless rings should not be used in any application, all boosted engines should have at least .006" per inch (of piston diameter) regardless of the piston manufacturer's recommendations. The second ring should be gapped at no less than the gap of the top ring, again regardless of the manufacturer's specifications. Highly boosted and/or heavy-nitrous injected engines should have at least .008" per inch (of piston diameter). All coyote 5.0L engine's subject to nitrous and/or boosting, MUST have the factory ring gap of 0.008" opened to at least 0.016".

Cylinder Heads

Factory SBF E7 heads should be the absolute first component replaced in the engine. All engines should have MLS head gaskets and ARP head studs. This is neccessary for all boosted engines.

For all modular engines converted to DOHC (cobra-heads) the block MUST BE DRILLED for the additional water jackets. Failure to do so will result in heat spots and engine damage. It is not recommended to use Felpro 1250 intake gaskets as they are designed for temporary use only. Only use O.E. equivalent gaskets.


An OEM stock distributor is required for all high performance engines that use a ford TFI ignition system. Aftermarket distributors CANNOT be used for high performance applications and ARE NOT RECOMMENDED regardless. OEM ford distributors are manufactured with a precision cut 0.002" tolerance on the reluctor wheel. Its not uncommon for aftermarket reluctors to be up to 0.100" off causing SIGNIFICANT spark variances per cylinder. Many aftermarket EFI distributors are also not designed for EFI use. This is evident by the oil drive shaft typically being 1/2" too short and the shaft diameter too small for a roller cam gear to have an interference fit. I highly recommend using ONLY genuine ford hall effect sensor pickups and modules. Aftermarket sensors are never recommended. If using an aftermarket sensor, it is highly recommended to keep a known functional spare replacement in the vehicle at all times for quick replacement when it does fail; which it will. If using an aftermarket harness for TFI ignition modules, the ignition ground MUST be grounded to the distributor case and engine block. Failure to provide adequate grounding can result in ignition signal noise.

See the
Ignition Systems Reference Data for more details.

Spark Plugs

Spark plugs will be dependent upon the CYLINDER HEAD, in all cases, ALWAYS compare the thread reach and washer design from the old plug to the new plug. If your spark plug currently has a washer present, the new spark plug MUST have a washer present as well. All DOHC cobra engines MUST have a washer present.

The following is a list of typical spark plug specifications, for boosted applications up to 15 psi and n2o up to a 100 shot.
Engine TypeYearHeadCIDLitersN/A Plug - Gapw/ Boost - Gapw/ n2o - gapNote
SVO83 - 88SVO4 Cyl2.3APP104 - .054APP103 - .032
Pushrod SBF89 - 95E73025.0APP 25 - .054APP 24 - .040
Pushrod SBF93 - 95GT40 / GT40 P3025.0APP104 - 0.54APP103 - .032
Pushrod SBFGT40 Y3025.0AR 94 - .028
Pushrod SBFTFS Twisted Wedge3025.0Autolite AR3924 - .050APP 3923 - .032
Pushrod SBFRHS3025.0APP3924 - .054APP3923 - .032NGK R5671A-8
Pushrod SBFEdelbrock Performer RPM3025.0APP 23 - .028
Pushrod SBFCanfield3025.0APP 3922 - .030
Pushrod SBFAFR3025.0 Motorcraft AGSP32CK (3924) - .0563923 - .032
Pushrod V689 - 95 SCEssex SC2313.8APP 5144 / APP 2544 - .054APP 103 - .044
Modular93 - 04SOHC2814.6APP 764 / APP 104 / NGK TR55 - .054NGK BR7EF - .032(Do not recommend TR6 but is OK)
OEM is 1/2 thread
Modular97-04SOHC3295.4APP 103 - 0.064
Modular92 / SVO / FRPPSOHC2814.6AGSF-32CAGSF-12EESVO / FRPP & (SOME early 4.6L)
Modular93 - 04DOHC2814.6.035.030
Modular93 - 04TFS Track Heat2814.6NGK (copper heat=6) - .030
Modular05+3 Valve2814.6APP 5143 / Bosch 8120
Duratec V62000+SOHC1833.0Motorcraft 8GFF32WX - .044
GM BBEdelbrock RPM 60054287.0Autolite 3924 - .045
Note: The above AP numbers are AUTOLITE part numbers, in all cases, read your plugs and adjust the heat range and gap as needed.
For nitrous applications up to a 75 shot the N/A heat range typically works well. For every 50 shot above 75, reduce 1 heat range.
If your engine currently has CHAMPION plugs they MUST BE REPLACED prior to getting your engine tuned.
NEVER, use a half thread plug in a full thread head!!!
However, using a full thread plug in a half thread head is acceptable.
Always reuse washers if they are present on the plugs being removed.

Anatomy of a Spark Plug
Half thread VS Full thread plugs


Boosted engines should not have high overlap and duration. The stock camshaft is typically most ideal for turbocharged engines. A slight performance gain can be ascertained by retarding the stock camshaft by -4 degrees (PTV clearance shouldn't be an issue unless pistons are above the deck). Custom camshafts for turbocharged applications often lean on the exhaust for a slight decrease in spool time. It is not recommended to replace the camshafts on DOHC or VVT engines . For VVT engines, any replacement camshaft that has more lift than the factory cam's MUST have phase limiters installed to prevent accidental PTV clearance issues due to faulty tuning / hydraulic lag.

Intake Manifolds

Ported stock GT40 intakes are most ideal for all SBF engines BOOSTED making up to 400rwhp. For highe HP applications, 'bread-box' style manifolds are highly effective. Ideally the throttle body should be located in the center front of the engine (not typicaly possible).

Inlet Air Temperate Sensors

If your intake manifold is designed to accept an IAT/ACT sensor, it should be plugged and the IAT/ACT sensor relocated to the inlet piping.
ACT/IAT sensors located in the manifold are prone to heat soak and cannot accurately represent the actual air charge temperature.
Note: When relocating the IAT/ACT to the inlet piping, the ACT fuel, spark, and VE modeling SHOULD be corrected in the calibration.


It is imperative that your ECU and FUEL PUMP relay's are in 100% functional operating condition. If the relay's are more than 10 years old or if their age is unknown they must be replaced. A faulty/failing ecu or fuel pump relay will cause unstable fueling and can lead to engine damage. It is highly recommended to upgrade the alternator charging post to the battery terminal using at a minimum 4ga wire. It is also highly recommended to add a ground cable from the battery negative terminal to the transmission bellhousing (nearest the starter) using at a minium 4ga wire. Note: The all components must be grounded through the chassis for filtering to prevent ground loops. The only grounds that should be ran to the battery are chassis and engine grounds. NO OTHER GROUNDS must be allowed to be ran to the battery or ground loops can occur.

Oil and Filter

Make sure you have fresh oil in your engine before getting it tuned, if you have a new engine use proper break-in oil such as straight 30w with high zinc content (specified off road use only). Use only Champion-labs (STP, BOSCH, MOBIL1, K&N) or Wix oil filters. DO NOT use FRAM fiters, if you have a fram filter on your engine, replace it prior to getting a custom tune. All high horsepower drag race engines >1500hp should have a magnet attached to the oil filter with a large capacity filter (1 quart). Recommend using fully synthetic 20w-50 oil after proper break-in is completed. If your engine has been running at an idle AFR richer than 11:1 for more than 5 minutes, it is REQUIRED to change your oil to prevent engine damage. The excess fuel can 'wash-down' the cylinders and contaminate the oil, fuel does not lubricate and will damage the engine. If you are unsure if your oil is contaminated, the dip stick can be checked for any fuel odors, this is not always a good indication and fuel may still be present in your oil. If in doubt, change your oil and filter.

For turbochargers, it is imperative that an oil restrictor be used on all ball bearing turbo's. Failure to use an oil restrictor will result in turbo failure and engine damage. This applies to ball bearing turbo's only. Journal bearing turbo's do not require oil restrictors and and should not an oil restrictor present.

Coolant System

For initial break-in, the engine should be operated with water only (if you live in a climate where freezing is not a concern). After the engine has been broken in, the coolant should be drained and replaced with GREEN anti-freeze coolant. If you live in an area where freezing is common, it is highly recommended to use GREEN anti-freeze for engine break in. DO NOT use the red DEX-COOL even if factory equipped. Water wetter can be added to your coolant system if desired. Verify all radiator hoses are in like-new condition and do not have any cracks or dry-rotting present. Squeezing the hoses is a typical method to check for wear. When filling the coolant for the first time, the vehicle should be at a slight angle with the front end (radiator) higher than the engine. The lower radiator hose should be pinched repeadily until all air bubbles are purged from the coolant system. All factory THERMOSTAT BYPASS hoses should be blocked off and a 195+ degree thermostat WITH BYPASS HOLES should be installed. All race engines and high performance street engines should have a high pressure water pump with a high pressure radiator cap and an adequately sized overflow reservior. The fan must be properly shrouded to the radiator with the lower air dam in place for best results.

Serpentine Belt

Verify your belt is properly tensioned and that all pulleys are spinning in the correct direction. Some water pumps are reverse directional. Proper tension can be checked by placing a socket on the alternator pulley and turning the serpentine belt which cause the crank pulley to turn if adequate tension is present. The belt should be checked for cracking / dry rotting, and should be in like-new condition.

Brakes / Wheels

It is imperative that your brakes are functioning at 100% of optimal performance prior to getting your vehicle tuned. All wheels must be hubcentric, aftermarket wheels must have hubcentric rings. The lugnuts are not load bearing and should not support the weight of the vehicle. Wheel spacers cannot be used for racing applications. Make sure your tires are not dry-rotted and they are inflated to the appropriate pressure. Street tires should not be any less than 35psi unless otherwise specified. Slicks should be aired up to manufacturer's recommended pressure during the initial tuning phase.

All slicks should only be pressured up with nitrogen only.
The maf sensor can be cleaned by simply removing the HOUSING from the inlet piping and using electrical parts cleaner to spray the maf sensor element.
DO NOT unbolt the maf sensor from the housing on 90mm ford sensors, this will usually strip the housing and the sensor will not reseal.
Using a q-tip to swab the element is not recommended but can be done if extreme caution is used.
Be sure to let the sensor sit overnight in a warm and dry area for all residual traces of the cleaning solvent to fully evaporate.
Failure to do so may cause sensor damage upon power up.

Inlet / MAF

Be sure your intake piping is completely sealed with no sharp bends or transitions. Airflow does not like to bend anymore than 15 degrees at a time, although thats almost impossible to follow in an automobile, you want the minimal amount of bends as possible. DO NOT place your air filter in the fenderwell where it can suck in water. All inlet piping should be of the same diameter as the MAF sensor and throttle body. High flow Slot style MAF sensors are recommended for all applications. If using the stock MAF sensor with a 'calibrated' MAF housing, I only recommend purchasing a MAF housing "calibrated" for 60lb injectors, REGARDLESS OF YOUR ACTUAL INJECTOR SIZE. It is recommended to install a screen on all MAF setups, however, If you are using larger than 3" piping, it is REQUIRED to have a screen installed before the MAF sensor.

A screen can be made by using screen door mesh available from your local Lowes, Home Depot, or home improvement store. If possible, it is recommended to have a screen BEFORE and AFTER the sensor element (when applicable).

Note: a 75mm throttle body is adequate to support 500 hp naturally aspirated. This does not apply to configurations where the throttle body is a pre-supercharger restriction such as MN12 and Terminator setups.

MAF Placement
The MAF must be in a blow-through configuration such that the meter ONLY measures airflow entering the engine, thus the BOV must be located BEFORE the maf on all turbocharged applications (that use one). Ideally the MAF should be in the center of the longest straightest length of pipe available, this is typically the charge pipe that runs from the outlet of the intercooler, through the factory air box opening, and up to the throttle body.

"Clocking" the MAF
Slot style sensors are most ideal and measure airflow from the central portion of the piping, thus, they do not typically benefit from "clocking". Older MAF designs that utilize a sampling tube can be 'clocked' to improve MAF accuracy by simply loosening the coupler clamps and twisting the maf housing until the HIGHEST MAF VOLTAGE is ascertained.

Cold Air Intakes

Cold air intakes that REPLACE the stock MAF housing, such as most all 2005+ Mustang CAI kits, must have the MAF transfer calibrated. Never use a CAI setup that places the filter in the fenderwell where it can suck up water. This can lead to hydrolocking the engine when driving through a puddle.

PCV / Breather

Be sure your PCV system is completely sealed, the crankcase should be under vacuum when the engine is running, this will reduce emissions while improving throttle response and increasing power. A faulty PCV or unsealed PCV setup will result in windage and will cost power. NEVER use a filter type breather vent on the valve cover. The PCV system MUST be completely sealed. For boosted engines, a check valve is required to be installed between the valve cover breather and the inlet/suction side of the turbo/supercharger. The check valve must be mounted in reverse so under non-boosted conditions, the PCV will evacuate the crankcase and suck the check valve shut. Use only PCV valves that have internal checks and will lock to prevent backflow or bleeding of boost pressure into the crankcase. With this configuration, during boosted conditions, the manifold reference PCV valve will lock and the check valve on the breather line will open from the inlet vacuum to evacuate the crankcase. For race engines, it will be necessary to install a catch can to prevent oil from entering the intake.

Fuel System

if using a ford ecu other than the SVO 4cyl ecu, be sure you have high impedance 12+ohm injectors only. Proper injector size can be calculated using the following formula.

INJSIZE x NUMBER OF INJECTORS x 1.6 = MAXIMUM RWHP (multiply again by 0.8 for boosted applications)
for quick reference typical injector size horsepower limits are given as follows:
Injector SizeColor4 Cyl N/A4 Cyl Boosted
or N/A w/ E85
6 Cyl N/A6 Cyl Boosted
or N/A w/ E85
8 Cyl N/A8 Cyl Boosted
or N/A w/ E85
8 Cyl Boosted w/ E85
24Dark Blue150120230185305245196
36Light Blue230185345275460370296
80 Black 500 400 760 615 1,000 820 656
Note: The 17lb injectors used on ford's typically have a base fuel pressure of 65psi making them effective flow approx. ~21.25 lbs/hr.
The ford 42lb injectors only flow 34.5 lbs The values given above can be increased by 15% (x 1.15) by increasing fuel pressure to 55psi.

I highly recommend using no less than Siemens Deka High Impedance 80lb injectors in ALL ENGINES (excluding split port).


Adjustable fuel pressure regulators are not needed and should ONLY be used when you have borderline injector capacity. However, if an adjustable fuel pressure regulator is installed, it MUST have a check valve present to prevent pressure drop when the pump is powered off. Kirban regulators are known to have check valves. Many aftermarket regulators do not have check valves. Be sure to VERIFY your regulator holds fuel pressure after the pump has primed. FMU's should not be used, however if one is present, it should be set to raise fuel pressure by using the 6:1 disc only so long as the fuel pressure does not exceed 75psi at maximum boost levels.

Fuel Pumps

Fuel pump(s) must be adequate to support the horsepower of the engine. Fuel pump requirements can be calculated by using the following formula:
fuel pump LPH x 2.8 = horspower limit of pumping capacity. Verify your fuel pump has a check valve to prevent pressure drop after priming.

For those in the UK with pump flows listed in Imperial GPH (UK gallons), 1 GPH = 4.55 LPH
A typical 255 LPH pump is capable of supporting 700hp N/A 570 hp boosted and is adequate for most street vehicles. Be sure you are using a high pressure pump if your engine is boosted or if fuel pressure is raised due to small injector size. All drag racing setups with a return style fuel system must have a fuel cooler.

Returnless Pumps

For returnless style fuel systems such as 99-04 modular fords, the stock basket should have holes drilled to help prevent fuel starving. A cobra twin hat is highly recommended for all 99-04 engines making over 400rwhp The cobra hat will support 700 rwhp with a boost a pump voltage amplifier and wiring upgrade. Ford GT Supercar pumps are not recommended and will require FPDM and line modifications. The walbro returnless specific pump requires cutting of the basket and is not recommended. The stock 05+ Mustang GT pump is adequate up to 450rwhp.


It is highly recommended to fill up with fresh fuel. It is common for vehicles to sit for extended periods while being worked on. This usually results in fuel degradation and solid deposits at the bottom of the fuel tank. The fuel pump and fuel filter should be replaced if the vehicle has been sitting for more than 3 years or if any fueling issues arise during the tuning process. Remember only use the highest grade PREMIUM fuel, unless otherwise discussed. Failure to use high octane fuel can result in engine damage. If you forget to fill up with high octane fuel, you do not need to drain your tank. Simply drive the vehicle like a normal human keeping the throttle below approx. 35% until your next fill up. REMEMBER, always FILL UP before going to the track or autocrossing, fuel slosh is serious concern and can cause your engine to run lean. Always keep a full tank of fuel when racing your vehicle. The little bit of weight savings is not worth damaging your engine over. Also note, most aftermarket fuel pumps have a shorter operating life when not completely submerged in fuel. It is highly recommended to keep no less than a half tank at all times.

For replacement pumps,
Treperformance has quiet and quality pumps at a very resonable price.


It is critical that your exhaust is leak free and that your o2 sensors are new and are functioning properly. Only the front two oxygen sensors control fuel mix, the rear two o2 sensors are not needed unless required to maintain emissions testing. For vehicles equipped with catalytic converters, be sure you specify that you have cats present in the vehicle info sheet or on the tune application. High flow catalytic converters often do not flow more than most OEM catalytic converters. Proper size exhaust length and piping is necessary for proper delta pressure. If your exhaust is inadequate it will typically result in the engine reaching MBT ignition timing much lower than practical, this will cause a loss in engine performance. For all naturally aspirated engines making less than 500 horsepower, 2.5" dual exhaust is adequate. A single 3" pipe flows approximate to dual 2.5" pipes. For turbocharged applications, all piping past the turbo will need to be doubled as compared to a naturally aspirated engine.

Note: X-Pipes will require that your tune be updated to disable the 2nd hego; due to cross scavenging, a full explanation can be found by

WBo2 & o2 Sensors - HEGOs

As outlined above ^^, you should have new and fully functional o2 sensors in order for your vehicle to be properly tuned. A wideband is recommended for higher horsepower engines but is not usually required. I highly recommend the AEM 30-4110 widebands. Be sure to set the wideband to report LAMBDA on the gauge by setting the adjustment screw on the backside to mode P1. The best pricing on the AEM widebands I have found thus far is from
MAPerformance which is less than $160 shipped. If you find better pricing please do let me know. In all cases, the wideband and hegos must be mounted after the turbo in the downpipe with the sensor installed at the top most area of the pipe. More details can be found at the HEGO Write Up.


The MINIMUM recommended turbo sizes are as follows:
Engine CylindersEngine SizeTurbo FlangeTurbo SizeARMax HP
41.5 - 2.5T-370mm.68550
63.0 - 4.0T-470mm.96550
84.6 - 5.8T-476mm.96700

Header "hot-side" piping can be easily calculated by multiplying the pipe diameter by 1000.
1.25" header is good for 1250 hp
1.50" header is good for 1500 hp
2.00" header is good for 2000 hp
2.50" header is good for 2500 hp
3.00" header is good for 3000 hp

For turbocharged applications the cold side exhaust needs (downpipe) are doubled as per naturally aspirated. All race turbo engines should have a cut out present. All turbo's should have a heat blanket and all hot side piping should be wrapped. It is highly recommended to keep a fire extinguisher in all turbocharged vehicles.

It is highly recommended to get a larger than neccessary AR housing and using a restrictor spacing plate between the turbo header T-flange and the turbo's exhaust AR housing.

Blow-Off Valve

For all turbo applications that utilize a BOV, verify the BOV is CLOSED AT IDLE, Part Throtte, and WOT. The BOV must ONLY open when there is more pressure in the inlet piping than the intake manifold. Any BOV that opens during normal driving is faulty or incorrectly installed and must be resolved before the vehicle can be tuned properly. A BOV is not required or recommended for turbochargers that have 'surge vents' in the casing such as airwerks / borg warner.


As boosted levels are increased, the wastegate requirements are reduced. The wastegate discharge should be piped into the downpipe and not vented to atmosphere for all street vehicles. The discharge piping should be of equal to or greater size of the wastegate discharge. The placement of the wastegate should be so positioned that it is in direct flow of exhaust gas with no bends directly before or after the wastegate valve. If the placement of the wastegate is such that it is at an angle greater than approx. 70* to direct flow, the hp suppression begans to reduce. In all applications the wastegate must be COMPLETELY closed until manifold pressure (boost) exceeds the wastegate spring threshold. The table below gives an approximate hp suppression for typical sized wastegates. The HP suppression is the amount of horsepower (calculated from airflow) that the wastegate is capable of bypassing. For example, if your turbocharger is capable of moving enough airflow to support 1200hp, and your desired hp limit is 800 due to your engine components, you must have a wastegate that is capable of 'suppressing' at least (1200-800) = 400 hp.

SizeHP Suppression
60 mm~1600hp
50 mm~780hp
48 mm~600hp
46 mm~520hp
44 mm~450hp
39 mm~320hp
38 mm~290hp
36 mm~220hp

Note: The above values are approximate, there are just too many variables to
have a definitive answer, as a general rule of thumb, when in doubt go larger.


The following applies to vortech superchargers only. Vortech makes the following pulley sizes.
generally, you can assume 1 psi per .1" pulley change, of course this is not exact size but a general rough estimate
Vortech Blowers Flow Ratings
S-Trim628 hp
SCi-Trim659 hp
Si-Trim722 hp
T-Trim753 hp
YS-Trim942 hp
YSi-Trim1005 hp
Note: The V1,V2,V3,V7 all fit the same mounting brackets.

...continue on to the
Initial Tune Instructions

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