Archive | Fuel Injectors

Top Feed vs Side Feed Fuel Injectors

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Top Feed vs Side Feed Fuel Injectors

Posted on 15 December 2014 by admin

Most people are lucky enough to have engines than run top feed injectors so upgrades are quite easy (4G63 owners you lucky bastards!) but on the other hand some of us manage to get stuck with side feeds and most commonly all our favourite and easy to find jap turbo motors such as the early SR20, 3SGTE, 1ZJGTE, RB25DET, EJ20 all seem to be side feed.

Side feed and top feed fuel injectors are the two main types of fuel injectors used in our motors, if you have ever had a motor that ran side feel injectors and planned on upgrading your efi system then chances are you would have probably heard people telling you to upgrade you injectors to top feed ones.

Telling the difference between the two injectors is pretty simple as their names sum up the differences pretty well.

SR20 Sidefeed Injectors

SR20 Sidefeed Injectors bolt straight into the fuel rail

Side Feed Injectors:

The fuel will enter through a slot in the side of the injector, the fuel injector sits in the fuel rail and the rail is fixed to the manifold or head.

Because side feed injectors are mounted in the fuel rail and are surrounded by fuel it provides a better cooling effect, in turn you can run a higher duty cycle and push them a bit harder with less chance of failure than a top feed.

Top Feed Injectors:

Fuel enters from the top of the injector, the injector sits in-between the fuel rail and the head.

SR20 Intake Manifold Converted to Top Feed

SR20 Intake Manifold Converted to Top Feed

Upgrading from side feed to top feed:

There are many reasons why you might want to change to side feed injectors but if your car is stock with no modifications there is no point in changing your injection system, it’s a lot easier and cheaper to stick with the side feeds until you actually require a higher flowing injector as there really isn’t any added benefits to a top feed or a side feed, it is just a different way of accomplishing the same thing –injecting fuel! Until then your money is better off spent somewhere else.

However there are many good reasons why you might need to change to top feed, such as:

Side Feeds are expensive!

– Deatschwerks sell 850cc side feed injectors and they cost around $750, Deatschwerks also sell top feed 850cc’s for around $550. That’s around $200 in difference!

You need injectors larger than 1000cc

– Deatschwerks have developed 1000cc side feed injectors, providing your fuel rail can support that amount of flow it might be worthwhile however for anything above this size you will defiantly need to change to top feed! Especially if you are planning on running e85 since it requires around 30% more flow than regular petrol.

Aftermarket intake manifolds

– Most aftermarket manifolds use top feed because replacing the intake manifold is part of an overall upgrade for more power, once you required a bigger manifold then you will need more fuel.

Stock Fuel rail has poor flow

– Unfortunately a lot of stock side feed fuel rails don’t flow the best, some companies offer services to bore out a fuel rail but it’s not always possible and I have never heard of a top feed rail being maxed out. The money spent on boring a fuel rail and buying expensive high flow side feed injectors could have already paid for a top feed conversion.

Due to the different mounting of the injectors and where the fuel flows into the injector the change from side feed to top feed will require a new fuel rail that is designed for top feed fuel injectors, usually you will require an adapotr
Depending on your current brand of injectors you may also have to change the connectors / plugs on the engine loom as different manufactures use different plugs.

Notice the injector bosses  for using the smaller side feed injectors.

Notice the injector bosses for using the smaller side feed injectors.

Top feed advantages:

• More affordable to find injectors over 800cc
• Fuel pressure is usually more stable on a top feed rail
• Top feed rails flow more than side feeds
• More commonly used and available
• Largest size is 2000cc

Top feed disadvantages:

• New rail required if upgrading from side feed
• Fuel doesn’t provide a cooling effect to the injector

Side feed advantages:

• Cooled by fuel as they are mounted in the rail

Side feed disadvantages:

• Expensive
• Limited range of injectors
• Usually restricted by stock fuel rail
• Largest size is 1000cc
• More prone to leaks

What about running a second set of injectors?

Another option that some folks choose is to run a second set of injectors but when you think about it, the time and money it will cost to have a second set of injector bosses machined into your manifold, additional fuel pump and lines, fuel rail and the injectors themselves will cost more than a good set of side feeds or a top feed conversion.
Let’s also not forgot about the stock ecu as it can’t run 4 secondary injectors correctly, it will need to be replaced with something fully programmable with a second set of injector drivers and also the money spent on tuning.

Unless you have a 3000hp motor that requires 2 sets of 1500cc injectors or you just have all the tools and equipment and plan of having fun then its beyond me why people run a second set.

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Fuel Injector Dwell Times

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Fuel Injector Dwell Times

Posted on 11 December 2014 by admin

Injector Dwell TimeI recently installed and tuned an Adaptronic E420c on an 4AGE running ITB’s and after having tuned the car I found the idle to be a bit rough despite any changes to fuel or ignition tables and corrections, I could not really smooth it out and then I realized that I have never set the dwell time or dead time for my injectors!

What is “Dead time” and why do I need it?

Fuel injector dwell time or also called dead time and battery compensation is the time delay between the injector being powered and the injector actually opening. The dwell time (time it takes to open the injector) varies depending on the voltage being supplied, hence why some motors tend to idle rough when a thermo fan kicks in or idle is 100 or 150rpm lower than warm idle.

Getting the correct injector deadtime values set in your ECU is crucial for getting a stable idle and accurate air fuel ratios.
Eg: assuming your dwell time value of 0.50 at 14v is the correct and you also have your dwell time set to 0.50 at 13.0v the the motor will run slightly rough at 13v as a fuel injector takes longer to open when the voltage is lower, setting your dwell time correctly will ensure your motor runs smooth even when cold or under an increased electrical load.

Dwell time impact on tuning

Setting your dwell time correction values will help establish a more stable AFR, failure to correctly set injector dwell time values for each voltage will cause the engine to lean out whenever a drop in voltage occurs.

Dwell time \ Dead Time Chart

Note: Every manufacturer of fuel injectors have a different dwell time, SARD 650cc injectors will have a different dead time to Bosch 650cc, it is best to try and find the dwell time from your manufacturer for your model of injector, below is a list off fuel injectors and their dwell times, if you have any dwell times that I have no listed then please feel free to use the comment form at the bottom of the page so I can add it to the chart.

Injector Part Number Flow CC/min Flow LB/Hr Ohm 10v 11v 12v 13v 14v 15v 16V
Accel 578 55 3 1.24 1.03 0.87 0.73 0.63 0.53
Accel 872 83 3 1.46 1.20 1.00 0.85 0.73 0.62
Honda NSX 240 23 2 0.71 0.56 0.45 0.36 0.27 0.21
Honda Integra 290 28 12 1.28 1.07 0.86 0.70 0.57 0.46
Honda Integra 330 31 12 1.37 1.14 0.95 0.81 0.67 0.55
Audi S4/TT 340 32 14 1.12 0.91 0.75 0.62 0.52 0.42
Blitz 850 81 14 1.38 1.09 0.88 0.71 0.58 0.49
Bosch 1545 147 5 1.71 1.38 1.13 0.97 0.82 0.71
Deatschwerks 600 57 ? 2.00 1.80 1.60 1.50 1.30 1.20 1.20
Deatschwerks 800 47 ? 1.55 1.41 1.32 1.19 1.11 1.04 0.99
Denso 550 52 2 1.24 1.04 0.87 0.75 0.64 0.55
Denso 660 63 2 1.15 0.99 0.86 0.74 0.64 0.55
Denso 720 69 2 1.35 1.14 0.99 0.86 0.75 0.67
Dodge 4.7 273 26 12 1.75 1.44 1.22 1.03 0.89 0.73
Dodge SRT-4 (2003) 525 50 13 0.92 0.68 0.50 0.35 0.22 0.13
Dodge SRT-4 (2004+) 577 55 13 1.62 1.28 1.00 0.79 0.61 0.48
Dodge Viper (96-2002) 336 32 13 2.10 1.77 1.50 1.26 1.09 0.96
Edelbrock 630 60 12 0.76 0.55 0.39 0.25 0.15 0.04
Ford Motorsport 378 36 15 1.15 0.89 0.69 0.53 0.41 0.32
Ford Motorsport 441 42 14 1.14 0.92 0.75 0.64 0.56 0.49
Ford Motorsport 809 77 15 1.78 1.54 1.33 1.17 1.05 0.96
Ford Motorsport 1600 152 5 1.61 1.32 1.11 0.96 0.83 0.72
Ford Motorsport 1680 160 5 1.80 1.51 1.28 1.09 0.94 0.80
Ford mustang (84-95) 200 19 15 0.86 0.67 0.56 0.43 0.34 0.20
Ford Mustang Cobra 252 24 15 0.91 0.73 0.59 0.46 0.36 0.25
Mustang GT (96-03) 200 19 15 1.15 0.94 0.80 0.67 0.54 0.46
Mustang Turbo 315 30 15 0.88 0.68 0.56 0.43 0.33 0.23
Fuel Injector Clinic 650 62 2 1.13 0.96 0.78 0.66 0.54 0.45
Fuel Injector Clinic 850 81 2 1.02 0.87 0.74 0.62 0.51 0.43
Fuel Injector Clinic 950 90 2 1.30 1.05 0.88 0.75 0.65 0.57
Hahn Racecraft 625 60 3 1.19 0.97 0.79 0.69 0.57 0.50
HKS 402-RN011 480 46 2 1.16 ? 0.77 ? 0.48 ? 0.10
HKS 402-RN008 550 53 2 1.17 ? 0.83 ? 0.58 ? 0.40
HKS 402-RZ001 550 52 2 1.63 ? 1.27 ? 0.90 ? 0.54
HKS 402-RN010 600 57 2 0.85 ? 0.59 ? 0.40 ? 0.22
HKS 402-RZ002 680 65 2 1.70 ? 1.40 ? 1.11 ? 0.81
HKS 402-RN009 740 70 2 0.97 ? 0.63 ? 0.46 ? 0.35
HKS 402-RA002 1000 95 2 1.80 ? 1.40 ? 1.10 ? 1.00
HKS 1000 95 2 1.31 1.14 1.04 0.97 0.89 0.79
Holley 788 75 2 1.02 0.86 0.71 0.62 0.54 0.44
Honda Acura CL 240 23 2 0.73 0.64 0.52 0.43 0.36 0.25
Honda civic/crx/prelude/integra (86-91) 240 23 3 0.70 0.52 0.42 0.33 0.27 0.20
civic 92-00 (ex/si) 240 23 12 1.27 1.05 0.92 0.80 0.66 0.50
civic 92-00 (lx/dx/hx) 190 18 12 1.17 0.96 0.80 0.60 0.46 0.34
civic 01+ (EX) 240 23 11 1.04 0.82 0.64 0.53 0.43 0.36
civic 01+ (lx/dx/hx) 215 20 12 1.18 0.98 0.81 0.72 0.60 0.50
civic 03+ / CRV 02+ 290 28 12 1.35 1.15 0.98 0.84 0.71 0.61
Honda Civic 06+ Si 330 31 10 1.20 1.02 0.86 0.69 0.56 0.46
Honda Prelude 92-96 VTEC 330 31 2 0.72 0.56 0.45 0.35 0.27 0.24
Honda Prelude 97-02 290 28 12 1.24 1.02 0.85 0.74 0.63 0.54
Honda S2000 360 34 12 1.27 1.11 0.95 0.81 0.71 0.62
DSM 90-94 Blue 450 43 3 1.11 0.95 0.82 0.67 0.53 0.42
DSM 95-99 Black 450 43 3 1.00 0.81 0.67 0.55 0.45 0.32
Mitsubishi Lancer/eclipse (2.4L) 240 23 15 1.71 1.41 1.13 0.86 0.64 0.54
Mitsubishi Evo VIII 550 52 3 1.13 0.97 0.85 0.75 0.66 0.58
Mitsubishi Evo 9 MR 560 53 ?? 1.03 ?? 0.67 ?? 0.43 ??
Mitsubishi 3000GT (Stealth) 370 53 3 1.07 0.94 0.81 0.73 0.64 0.54
MSD 750 71 2 1.40 1.17 0.97 0.81 0.69 0.58
MSD 525 50 12 1.19 0.94 0.75 0.61 0.49 0.41
Nismo 740 70 11 1.15 0.94 0.79 0.66 0.55 0.44
Nissan 180 sx (88-93) / Skyline (86-88) 270 26 2 1.11 0.92 0.75 0.60 0.49 0.42
Nissan Pulsar Gti-R 444 42 2 1.14 0.96 0.83 0.71 0.60 0.54
Nissan Sentra/200sx/NX/G20 (2.0L ONLY) 259 25 11 0.90 0.75 0.64 0.56 0.47 0.42
Nissan Skyline GT-R 440 42 2 1.35 1.12 0.96 0.85 0.76 0.65
Nissan Skyline GTS-T 380 36 11 1.10 0.88 0.73 0.61 0.52 0.42
Nissan 300zx(95-96) / SR20DET 370 35 11 1.17 0.98 0.86 0.75 0.64 0.57
Nissan 240SX (89-90) 230 22 12 0.94 0.75 0.62 0.55 0.47 0.42
Nissan 240sx (91-98) / Altima (93-01) 250 24 11 1.00 0.83 0.69 0.57 0.47 0.40
Precision Turbo (Rochester) 525 50 12 1.33 1.05 0.84 0.66 0.54 0.45
Precision Turbo (Rochester) 680 65 2 1.56 1.36 1.22 1.13 1.05 0.96
Precision Turbo (Rochester) 1000 95 2 1.38 1.15 0.96 0.81 0.70 0.60
Precision Turbo (Rochester) 1200 114 ? 1.00 ? 0.80 ? 0.80 ? 0.74
Precision Turbo (Rochester) 1600 152 ? 1.00 ? 0.90 ? 0.84 ? 0.79
RC Engineering 240 23 16 1.31 1.10 0.97 0.77 0.62 0.46
RC Engineering 270 26 16 0.89 0.76 0.61 0.49 0.32 0.23
RC Engineering 310 30 16 1.14 0.89 0.72 0.55 0.43 0.33
RC Engineering 370 35 16 0.85 0.64 0.47 0.35 0.21 0.12
RC Engineering 440 42 13 1.27 1.08 0.91 0.74 0.63 0.53
RC Engineering 440 42 16 0.76 0.56 0.42 0.29 0.14 0.03
RC Engineering 550 52 3 0.92 0.81 0.68 0.59 0.51 0.40
RC Engineering 550 52 13 1.07 0.88 0.78 0.67 0.55 0.46
RC Engineering 650 62 12 1.08 0.86 0.69 0.54 0.41 0.31
RC Engineering 720 69 3 1.70 1.48 1.31 1.16 1.06 0.94
RC Engineering 750 71 3 0.88 0.66 0.48 0.32 0.18 0.05
RC Engineering 750 71 12 1.36 1.12 0.92 0.76 0.63 0.50
RC Engineering 900 86 3 1.70 1.48 1.31 1.16 1.06 0.94
RC Engineering 1000 95 3 1.17 0.95 0.80 0.67 0.56 0.46
RC Engineering 1200 114 3 2.55 2.28 2.00 1.79 1.62 1.46
RC Engineering 1600 152 3 1.80 1.46 1.23 1.05 0.92 0.81
Rochester 756 72 2 1.22 1.03 0.87 0.74 0.63 0.54
Rochester 1008 96 2 1.38 1.15 0.96 0.81 0.70 0.60
Sard 700 67 2 0.98 0.80 0.67 0.54 0.44 0.35
Sard 800 76 3 0.90 0.75 0.62 0.52 0.42 0.33
Siemens Deka 578 55 12 1.31 1.13 0.96 0.83 0.71 0.61
Siemens Deka 630 60 12 0.83 0.64 0.50 0.38 0.28 0.17
Siemens Deka 756 72 3 1.41 1.21 1.03 0.87 0.76 0.68
Siemens Deka 872 83 3 1.46 1.20 1.00 0.85 0.73 0.62
Subaru Impreza STI (top feed) 550 52 13 1.23 1.04 0.87 0.74 0.62 0.53
Subaru Impreza WRX 440 42 13 1.25 1.01 0.87 0.74 0.62 0.53
Toyota (00+ 1.5L) xB/xA/Prius/Echo 200 19 14 1.07 0.87 0.68 0.55 0.44 0.37
Toyota (04+ 2.4L) tC/Solaris/Camry/RAV4 330 31 12 1.18 0.97 0.79 0.64 0.51 0.42
Ultimate Racing 440 42 16 0.74 0.57 0.42 0.30 0.19 0.11
Vennom 880 84 12 1.27 1.00 0.77 0.64 0.51 0.45
VW Passat (98-99) Audi A4 (97-99) 220 21 12 0.82 0.62 0.46 0.34 0.24 0.19
VW Passat (2000) 240 23 12 1.05 0.84 0.69 0.60 0.52 0.43

 

 

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