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Everything You Needed To Know Aout A Turbo
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| 01-20-2004, 03:27 AM | #1 |
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Member
Join Date: Jan 2004
Location: Nebraska
Posts: 57
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this is from csabaH form clubsi.com
I figured since there seems to be a lot of common questions that are asked in this forum, that sometimes even a search won?t help produce answers for, I?d create a sticky thread w/ some basic boost info. I?ve seen some really nice FAQ?s on some DSM sites that helped me when I had my talon, so I think we should have an informative one as well. SiRacer(Jason), mook (john), myself and a couple of other members came up w/ these common questions and answers. We plan on updating this FAQ but here's what we have so far. Let us know what you think and if you have any other suggestions Recommended Spark Plugs NGK BKR7E (DOHC) Stock No. 6097 or NGK BCPR7ES 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. http://a2.cpimg.com/image/0A/31/1723...-028001E0-.jpg Typical EGT (in farenheit) readings at 5psi on a greddy kit w/ blue box idle.............................................. ....800 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 Summary 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 http://a3.cpimg.com/image/B5/B3/9179...-028001E0-.jpg Type 24 http://a0.cpimg.com/image/72/14/1249...-028001E0-.jpg 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 http://a2.cpimg.com/image/60/FA/2243...-01BF0200-.jpg White????..12v constant White/Black??Accessory 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 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 80? outside and we're shooting for 12psi, your inlet temperature (T1) = 80? + 460 = 540?R 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 = 540?R(26.7 ? 14.7)0.283 = 676?R 676?R = 216?F = ideal oulet temperature. that's a 136? temperature rise. once again, in a perfect world, these formulas work grear. unfortunately, there's our old friend adiabetic effeciency (AE). a 136?F 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, 136? ? .7 = 194? then you add the actual temperature rise to the intake temperature (80?) = 274? 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: (540?R ? 676?R) ? (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 so! 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... |
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| 01-20-2004, 12:57 PM | #3 |
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Senior Member
Join Date: Jul 2003
Location: WestByGod
Posts: 327
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hey, uh, so the title says Turbo, but I was reading and it started saying about SC's, so I got confused and had to stop reading cuz it hurt.
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| 01-20-2004, 03:42 PM | #4 | |
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Join Date: Jan 2004
Location: Nebraska
Posts: 57
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| 01-21-2004, 12:28 PM | #5 | |||
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Location: WestByGod
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| 01-23-2004, 07:08 AM | #6 |
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Member
Join Date: Jan 2004
Location: In this place
Posts: 41
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dude.....I know my stuff about turbos and the like, but damn. Quantum mechanics...thats alright...movius theory...thats ok, but damn.
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