Reference: Boosted Honda FAQ's

Discussion in 'Forced Induction / Nitrous DIY How-To's' started by Declectic, Nov 8, 2003.

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  1. Declectic

    Declectic SeanJohn1802 Registered VIP Registered OG 5+ Year Member 10+ Year Member

    Feb 12, 2003
    Stockton, CA
    Boosted Honda FAQ's

    We all know that sometimes the search button does not ALWAYS answer your questions. So if you search and dont find it there, you'll probably find it here, and if you dont find your answer here, THEN POST! ;)

    Please Note - This is courtesy of CsabaH from who gave me the permission to share his Honda Boost FAQ on, without further ado:

    This stickty was orginated on with some basic boost info. SiRacer (Jason), mook (John), myself (CsabaH) and a couple of other members came up with these common questions and answers.


    Recommended Spark Plugs

    Stock No. 6097
    Stock No. 3330

    NGK ZFR7F11 (SOHC)


    Recommended Fuel Pump

    Walbro 255lph (also the same as the BBK and Holley fuel pump)
    Model Number GSS342


    Recommended Clutches

    Clutchmasters Stage 3 / 4
    (Stage 3 for lower boost street driven cars, Stage 4 for drag raced or higher boost cars.)


    Recommended Gauges to get when boosting

    Boost Gauge
    EGT Gauge
    Oil Pressure Gauge
    Fuel Pressure Gauge

    Another recommended item that I would get is a shift light. Even though it’s not really a gauge but a simple small shift light can help you be more consistent as well as prevent you from hitting the rev limiter, which could save you from an expensive mess. Hitting the rev limiter in a vehicle w/ high compression can be disastrous.


    What size socket do I need to remove the stock oil pressure sending unit?

    24mm deep well socket


    Where do I tap my manifold for an EGT gauge?

    The best place is the number 3 cylinder runner on the manifold. If you are looking straight on at your engine bay, moving from left (at the distributor) to the right (the cam gear), it’s the second runner from the left. The probe should be placed 1-2" from the flange where the manifold/header meets the head.

    Click here


    Typical EGT (in farenheit) readings at 5psi on a greddy kit w/ blue box

    40mph cruising in 5th gear.........1000
    75mph cruising in 5th gear.........1250
    WOT in 5th gear at 75mph..........1325

    ***Readings will vary based on gearing, mph, temperature outside as well as your a/f mixture. The leaner you are the higher the temps. You do not want to exceed 1400 degrees farenheit because you will be melting things on a honda.


    Turbo Fundamentals

    How turbos work
    the turbine
    The Compressor
    Intercoolers, Blow off Valves and Wastegates
    Turbo Theory Questions
    Turbo vs NA Turbocharged


    What’s the difference between the Greddy Type 24 and Type 31 intercooler?

    The Type 31 requires no modification to your front bumper support, whereas the Type 24 requires you to make a cut on the bumper support to clear the height of the intercooler.

    Type 31
    Click here

    Type 24
    Click here


    Where do I tap in to wire up my {insert any name turbo timer here) turbo timer?

    If you look under the steering column you will see a few set of wires leading from the ignition switch. There is a 7pin connector and 5pin connector

    Here’s a pic from the Helm’s manual
    Click here

    White…………..12v constant
    Yellow………….Ignition 2
    Black/Yellow…..Ignition 1


    What is the Greddy Blue Box

    The Greddy Blue Box is greddy’s fuel control unit that they supply w/ their 99-00 si kits as well as the GSR kit (I believe). I think that the SOHC box is called the black box, but I’m not 100% sure on this. What the Blue Box does is, read map, and when it sees boost it increases the injector pulse. It’s a piggy back that you have to splice into your ecu wires. The unit was designed to be used at stock boost settings. If you up the boost the Blue Box may not compensate w/ enough fuel. Most people that have blown their motors w/ the Greddy Blue Box blew them because they were running more then stock boost. It has been said that some people have opened up and hacked the box to read more boost and compensate more, but this may be difficult if you are not knowledgeable in electronics and don’t have a dyno w/ a wide band near by.


    Should I get a wastegate or a blow off valve?

    Well a wastegate and blow off valve are two different things. A wastegate is on every turbo charged vehicle, whether it is internal or external they all have em. Wastegates are what regulate the amount of boost that your turbo puts out. When a certain pressure or psi is met it bleeds the air off and doesn’t allow it to go into the charge pipe.

    A blow off valve diverts excess air from going back to the turbo charger and causing compressor surge. When you are at WOT and you are boosting you have “x” amount of psi of air in your charge pipe, when your TB closes that air has no where to go but back to turbo. So to prevent this surge of air, you put a BOV on and let it vent out of the piping.


    Do I need a blow off valve?

    At low boost pressures it is not necessary and it may not even function properly under low boost anyhow. At higher pressures however the blow off valve is needed to release pressure in the charge pipes and intercooler between shifts or else that pressure may back up into the turbocharger and cause damage to it. Under 6psi it is not likely to be an issue but over that you really should use a blow off valve of some type. This also applies to centrifugal superchargers like Vortech and Procharger


    Do I need a 3" exhaust?

    Again, depending on boost level you may gain little more than noise with a larger exhaust. A 3" straight through exhaust is ideal for making more boost faster but if you are limiting boost to under 10psi a 3" turbo exhaust will only cause boost to spike fast which could cause overboosting and damage to the engine. You can easily run a standard straight through cat-back exhaust at 8psi with very little losses and it will be considerably quieter. This applies to supercharged cars as well but supercharged cars can run even higher boost with less losses on a standard cat-back exhaust.


    Belt sizes for Vortech users:

    CRV crank pulley > Alternator = 31.5 - 33"
    Recommended belt:
    Goodyear Gatorback : Part # 4PK0800

    CRV crank pulley > 3.125" 10psi Vortech SC pulley w/ AC = 51.5"

    CRV crank pulley > 3.125" 10psi Vortech SC pulley wo/ AC = 41.2"
    Recommended belt:
    Goodyear Gatorback : Part # 4PK1050

    Either crank pulley > Power Steering
    Recommended belt:
    Goodyear Gatorback : Part # 4PK0885

  2. Declectic

    Declectic SeanJohn1802 Registered VIP Registered OG 5+ Year Member 10+ Year Member

    Feb 12, 2003
    Stockton, CA
    MSD distrubitor cap part number for 99-00 Si = Part # 8292


    How to select a compressor size to your application.

    first you need to know how much air it will need to flow to reach your target horsepower. to figure that, you would use the following formula:
    (CID x RPM) / 3456 = CFM

    here's an example of a B16:
    (97Ci x 8000) / 3456 = 225CFM

    of course, if your engine is bored or stroked, you will have to compensate the CID.

    the engine will flow 225CFM at 100% volumetric effeciency (VE). great, in a perfect world. actually VE is about 80-90%. so you'll need to adjust to the VE. 85% is a good number to work with. so addjust your CFM to 191CFM

    next up is the pressure ratio. the pressure ratio is basically the pressure of the air going into the turbo in comparison to the pressure coming out. unless you are running sequential turbos, the inlet pressure will be the atmospheric pressure, which is an average of 14.7. so if you want 12psi, here's the formula:
    (12 + 14.7) / 14.7 = 1.82:1

    now you need the temperature rise. as the compressor compresses the air, it will raise the temperature. there is a formula to figure that rise! there is an ideal temperature rise to where the rise is equivelant to the amount of work it takes to compress the air. here's the formula!
    T2 = T1 (P2 ÷ P1)0.283

    confused yet? of course not! but lets break it down with some back spins and stuff.

    T2 = Outlet Temperature in °R
    T1 = Inlet Temperature in °R
    °R = °F + 460
    P1 = Inlet Pressure Absolute
    P2 = Outlet Pressure Absolute

    easier now huh?

    assuming it's 80º outside and we're shooting for 12psi, your inlet temperature (T1) = 80º + 460 = 540ºR

    the P1 inlet pressure will be atmospheric in our case and the P2 outlet pressure will be 12psi. atmospheric pressure is about 14.7 psi (as mentioned earlier), so the inlet pressure will be 14.7 psi, to figure the outlet pressure add the boost pressure to the inlet pressure.
    P2 = 14.7 + 12 = 26.7 psi

    we now have everything we need to figure out the ideal outlet temperature. now take this info into our original formula ( T2 = T1 (P2 ÷ P1)0.283 ) to figure out T2:
    T2 = 540ºR(26.7 ÷ 14.7)0.283 = 676ºR

    676ºR = 216ºF = ideal oulet temperature. that's a 136º temperature rise.

    once again, in a perfect world, these formulas work grear. unfortunately, there's our old friend adiabetic effeciency (AE). a 136ºF temperature rise is at 100% AE. AE of the compressor is usually 65-75%. so you would use 70% for average. so to figure out the actual temperature rise from the ideal temperature rise, you can use this:
    Ideal Outlet Temperature Rise ÷ AE = Actual Outlet Temperature Rise

    so, 136º ÷ .7 = 194º

    then you add the actual temperature rise to the intake temperature (80º) = 274º

    now you can figure out your density ratio! as the air is heated, it expands and increases the volume and flow. to compare the inlet and outlet flow, you must know the density ratio. the formula for that is:
    (Inlet °R ÷ Outlet °R) × (Outlet Pressure ÷ Inlet Pressure) = Density Ratio

    ok, so our example formula would be:
    (540ºR ÷ 676ºR) × (26.7 ÷ 14.7) = 1.46 Density Ratio

    with all this crap, you can figure out what the actual inlet flow is in CFM. to do this, use this:

    Outlet CFM × Density Ratio = Actual Inlet CFM


    225CFM × 1.46 = 328.5CFM

    that's a 31% increase in CFM, which is a potential for 31% increase in power. ei, 160hp = 209.6hp. of course, that number is directly effected by intercooler, downpipe, exhaust, fuel flow, etc.

    so now you know you need about 328.5CFM to reach your target of 12psi, you now can find compressor maps for different turbos to select the compressor that would best suit your needs. some maps are in CFM, and some maps are in lbs/min. to convert CFM to lbs/min, you would multiply CFM x .069.

    when looking at a compressor map, you match the corrected air flow (22.7lbs/min in our case) to the pressure ratio (1.82:1 in our case). what you are looking to do is plot your graph where it would be most efficient for the turbo. anywhere below 60%, your turbo will spin entirely too fast of a shaft speed rpm and burn itself up.

    here is an example of a compressor map (garrett T03 60 trim):
    when you plot our numbers, they end up in the 75% range, that is good. the turbo will be a perfect match for what we want to do.

    voila! you now can boggle your dates with your infinite mathmetician knowledge...
  3. Declectic

    Declectic SeanJohn1802 Registered VIP Registered OG 5+ Year Member 10+ Year Member

    Feb 12, 2003
    Stockton, CA
    Please Note - This is courtesy of see2k from who gave me the permission to share his add on to the Honda Boost FAQ on, without further ado:

    How about we have something for injectors:

    I.E. Fuel pressure safe levels40 - 60 psi, race levels(70 to 110 psi?), and obscenly stupid levels: 120+ that could cause fuel system malfunction and evidently destroy your engine

    also how about what injectors would fit the stock fuel rail?
    RC and DSM have proven to work, but what about MSD, Blitz, and other brands that are out in the market?
    Additionally, diffences between peak and hold ( < 8 ohm) versus saturated (> 12 ohms) injectors.

    ODBx clips: Which ones work with what.

    For example: RC eng and DSM require the use of ODB1 clips (lower resistance injectors). What about MSD and Blitz, and where can we find such items, fairly inexpensive, other than For Sale Forum.

    How much boost w/injectors?

    Also i know this is big variable, but a very rough estimate of boost levels based on injectors. Forget theory, lets think practical.

    Alot people ask, how much boost can I run with 440cc injectors? Now you're going to ask, what turbo, what engine, what's the ideal Horsepower you're looking for and so on.

    But what about some real general rule of thumb for turbo's that arent huge, that don't cost more than 1500 dollars, and that aren't capable of producing 600 whp with only 15psi.

    As an example:
    B16 TD05-18G, Injector: DSM 450 CC injectors: Maximum boost capability is 14 psi of boost before going over 85% duty cycle.

    what about t3/t4 with 57 trim and so on, they'd almost be identical and could very well fall within the same range. This information could also be volunteered by fellow members to give an overall range of boost to injector capability.

    I know this section contains huge variables, but just something that newbies can see and say, okay, i can't go above this many boost with a turbo of equivalent specs with my peon injectors.

    Should my fuel pump be changed?

    Yes, if you plan to push more than 9 psi, getting a better fuel pump can be necessary, and may result in additional HP gains (claims made by hearsay, and someone saying that it was dyno proven on their car, directly to me.)

    What is Duty Cycle

    Duty Cycle is a percentage of how long an injector stays open in a given time to deliver fuel to the motor. Duty cycles between 80 and 90 percent are considered bad, but tolerable. 90% and higher, and you're looking at unreliable tuning, unpredicatable results, and injector failure.

    If anyone of this is mention is some way unrelated or related just delete my post. otherwise I hope it could add some more frequently asked questions in the boost fawq.

    my 2 shillings.
  4. stealthy

    stealthy 4 Doors For More Whores Registered VIP Registered OG 5+ Year Member 10+ Year Member

    Oct 15, 2003

    An fmu increases fuel pressure at the injectors. If you have a stock fuel pump, its not gonna be able to keep up with the fmu. But if you do have an aftermarket fuel pump, and still have stock injectors, the FMU will create the pressure to the injectors but the injectors arent gonna be able to spray out enough to keep up with the fuel pump. Fuel produces optimal power when atomized, it ignites much better than raw fuel will, and the higher the fuel pressure is the less atomization occurs.

    As someone once said on HMT, think of it like a can of hairspray, if you take the can of hairspray and hold a lighter in front of it and push the nozzle, an atomized mist of hairspray shoots out and makes a big fireball.If you take that same can of hair spray, spray it on the ground in a puddle, it'll burn...but not nearly like the first time.

    Fmu's are out dated devices used by muscle car guys with carbs bc they didnt write a new program for their ecu. The FMU will cause you to run pig rich, and they are no where near being efficient. These are old options nowadays, and who wants toasted injectors and leaned out spark plugs? They are brain dead pieces. Fmu's are by far "old school" considering your ecu chipping options that are available now, not to mention chipping your ecu is not only more effective, usefull and cheaper in the long run.

    Boosting? Do it right the first time, dont skimp. it will cost you major $$$ in the end
  5. Scorchsta

    Scorchsta huh? Registered VIP 5+ Year Member

    Oct 10, 2005
    In case people get confused using this equation, the actual equation is:

    T2 = T1 * (P2/P1)^0.283

    (The 0.283 is an exponent of P2/P1)

    This confused me for a while until I did some research.
  6. Genuine Rolla

    Genuine Rolla Its PETEY PETE, y0! Registered VIP Registered OG 5+ Year Member 10+ Year Member

    Dec 1, 2004
    Amazing post..!
  7. tunerkid7

    tunerkid7 New Member 5+ Year Member

    Dec 7, 2007
    Nor Cal
    great write up
  8. neoc03

    neoc03 I CRAVE CORNERS Registered VIP 5+ Year Member

    Oct 15, 2007
    This is nice as hell. :rocker:
  9. Hkarmy

    Hkarmy Kushboy Registered VIP 5+ Year Member

    Jan 7, 2008
    SOCAL and Norcal
    This thing is old but amazing
  10. DarkCreep

    DarkCreep D16Y8+T Registered VIP Registered OG 5+ Year Member

    Jun 26, 2007
    Pomona, CA
    One of the most amazing write ups ive ever seen.

    PS: How does one register at
  11. Mr.Lx porter

    Mr.Lx porter New Member

    Jun 24, 2011
    quick question i kno its an old thread but i have a Ej6 d16y7 with a little over 300,000 kms and i was wondering if i could turbo it with out blowing it up :twisted:
    it has new plugs wires and a full catback

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