Bosch High Flow Injector Information for the 403 model @ 503 cc/min
by Anthony Hyde, Australia © 5/2002, Updated 1/2005
High flow electronic fuel injectors like the Bosch 403 & 400 are a popular choice for performace 4 cylinder turbos, and are OEM on some USA V8 engines.
Injector control by a programmable engine computer will enable optimum fuel and ignition settings.
- This unique web page gives specific information, pictures, and discusses related injection issues 0280150403 -

Bosch injector # 028050
403 straight from
the box - with unusual non clip ends

Fitted up with EFI parts - pintle cover,
O-Rings and nylon washers

FEATURES of the 403 # 0 280 150 403 - GREY in color/colour, / Low impedance / Coil resistance 2.6 Ohms / Peak and hold type / common L-LE Jet 2 pin electrical connector / unusual ends / length dimensions as per standard EFI injector (65 mm c/c between O-Rings) / single pintle.
Flow rate - Charts show
503 cc/min (49.3 lbs/hr) @100% duty cycle, presumed at a pressure of 3 Bar (43.5 psi). USA based and others show a higher flow 55 lbs/hr @ 45 psi. (Feedback from P Bradley) -403 injectors - had them cleaned and flowed. At line pressure of 43.5 psi, they flow about 59 lb/hr or about 600 cc/min at 100% duty cycle, flat out. Wide open they flowed 114 cc after 11.4 seconds, and pulsed flow 102 cc after 21.2 seconds.

Idle pulse width - On my engine at 900 rpm idle the shortest steady pulse width obtainable is between 1.2-1.3 ms which is pretty good for a big injector. (Pulse width - the length of time an injector is open and squirting fuel).

Smaller brother to the big grey #0 280 150 403 is the #0 280 150 400 being BLUE in color, at 3 bar PSI approximate flow rate 437 cc/min (42.8 lbs/hr).
Even smaller brother is the 402 model, reportably 32 lbs/hr at 3 bar PSI used on 6 cyl engines.

The Demon Tweeks (UK) motorsport parts catalog lists injector upgrades for the Ford Cosworth Turbo.
The Bosch GREY 503 cc/min injector (reviewed here) is the model #0 280 150
403 - described as "Competition Only - power outputs up to 420 hp".
BLUE 437 cc/min injector model #0 280 150 400 is described for "power outputs up to 370 hp".
Referring to the model
400 injectors were originally fitted to USA Ford Mustangs 5.0L V8 engines, mid 80's Crown Victoria, Lincolns etc.

INJECTOR CHANGES required to suit a European style injector rail:
'Fuel IN' end - the European fuel rail normally holds injectors into place by a 'clip-into plastic groove' arrangement. The 403 and 400 injectors have no grooves for clips, basically a plain round metal shaft that is the correct diameter to fit a standard EFI O-Ring and nylon washer. Therefore, ensure the fuel rail can be tightened down properly with the injectors and seals firmly in place. Take no risks whatsoever with any fuel pressure leaks or dodgy sealing arrangements, ask for advice or a second opinion if in any doubt. I used one washer and two viton O-Rings on the top shaft as leak security when fitting the 403 into the fuel rail.

'Spray OUT' end - before the injectors can be fitted into the inlet manifold bore, the long blue plastic pintle cover (pic1) needs to be carefully removed before new seal parts can be fitted. Look for a thick lip that clicks the cover into the injector just near the spray end, and carefully cut through the plastic lip area, the rest will come off relatively easily. The shaft is the correct diameter to fit standard EFI parts; nylon washer, viton O-ring and a large pintle cap. The yellow pintle cap recommended to me was Bosch? #1 280 423 883.

Road Figures: With the large Bosch 403 injectors fitted to a 2.3L 4 cylinder Volvo (B230FT) turbo engine run up to 14-15 psi boost, the following figures were obtained on two similar engines using modern engine management systems (different software and map settings).
Haltech E6K - the maximum
pulse width was 7.3 ms at a duty cycle of * 70 % at 4,800 rpm. * (additional enrichment of about 4% was added via a cockpit adjustable Haltech fuel-trim module.
MoTec M800 maximum 'Fuel actual pulse width' was 15.4 ms (15.4 / 2= 7.7 ms). Maximum duty cycle was 61% at 4,800 rpm. Fuel pressure 61 psi@15 psi (200 kPa) boost

Idle ms - With these large injectors thankfully the engine idles well with a pulse width around 1.28 to 1.3 ms. This is getting close to the minimum pulse width this large injector can obtain.

Bosch LH type low impedance injector assembly with the 'black body cover removed'

There is more to buying an expensive injector than selecting a suitable flow rate, so before ordering, try and find out things like : tail fitting type (hose, O-Ring, clip-in), injector length (if in doubt), electrical connector type (L Jet, D-Jet).
There are a growing number of injector charts on the web, a great source for a flying head start, but look closer & notice a number are incomplete in important areas like tail type or connector plug type. Some lists are just copies of others that still contain 'original' mistakes. Double check.

The most comprehensive INJECTOR PAGE listings are DIY EFI or

(a good fundamental description - original author unknown)

Pulse width or pulse time - "The length of time an injector is open and squirting fuel is called the "pulse width" and measured in milliseconds (ms).

Duty cycle or pulse period - As rpm increase, an injector can only be held open for so long before it needs to be held open again for the next engine revolution - this is called its "duty cycle" expressed in % (percent). [Or measurement of the amount of time a component is on]

Even though a fuel injector's flow rate is measured at its maximum duty cycle (100%), fuel injectors should never be operated at 100% duty cycle. Instead, a typical maximum duty cycle is around 80%."

Comment reproduced with kind permission of Todd Kirkwood,
If you're turbo charged, you're better off staying on the low side of the
duty cycle range (45%). Here's why: Under Turbo boost the fuel has to overcome the extra pressure in the intake manifold. Injectors are rated by using 45 pounds of fuel pressure (PSI) (~3 Bar), so this means that to maintain the same rated flow while under boost, the fuel pressure would have to be 45 PSI higher than the boost pressure. A fuel pressure that high would overburden the pump, so what you want to do is use a larger injector that can flow more fuel at a lower fuel pressure. An injector operating at 45% of it's capacity should be a good starting point. In this case a 45 pound/hour injector will work and you could lower your fuel pressure to 25 PSI to get enough flow.

FUEL PRESSURE REGULATOR (FPR) - TURBO: For example a Turbo Volvo F.P.Regulator is a 1:1 unit regulating at 3 Bar or 43.5 psi, and connects via a hose to the inlet manifold to sense vacuum or (boost) pressure changes. Using even figures, if the manifold pressure rises to 10 psi, then the FPR also rises (43.5+10) to 53.5 psi at the fuel rail & hence into the injector. ** However, it should be noted that the actual pressure at the tip of the injector is at the original 3 Bar or 43.5 psi due to 10 psi pressure inside the manifold acting aginst the injector spray tip - (balanced by the increased fuel rail / injector pressure).
If working correctly, the fuel delivery pressure should be constant and not vary so the injector flow rates remains stable.

A RISING RATE (RR) FPR has a ratio greater than 1:1, eg 2:1, 4:1. and will increase fuel rail pressure after a certain boost point eg 12 psi and upwards. The rising rate reg will ensure rail pressure rises at a greater rate eg 2x, 4x with boost, and injectors will flow more fuel. In this case the net effective fuel pressure would be greater than the standard 3 Bar. Rising rate means fuel flow rises at a greater rate than manifold pressure. A RR FPR is suitable to increase flow from smaller injectors (to a point), or, for the case where a manufacturers non programmable computer can't compensate for big injectors at lower rpm's.

Lorcan in the USA has used Bosch 403 (grey) injectors on his 760cc alcohol drag bike. "I used 8 injectors with a DTA ECU. I agree with your page in that I found 1.2 - 1.3 ms to be the minimum on time for a reasonable idle. Obviously these are very large injectors for a 760cc engine. I got them used for $15 each from Cosworth Racing in the US (I am in the UK) in 1997. My website is .I ran 8.69 @ 162mph for the quarter mile with this setup. Base fuel pressure was 66psi, boost was 23psi. Our team has since been able to bore these injectors to flow 800cc/min."
VOLVO TURBO specific information / VOLVO information / VOLVO TURBO specific information / VOLVO information

TurboBricks member consensus: The B230T idles quite well with big 500 to 750 cc/min low impedance peak and hold injectors, as long as a aftermarket quality programmable engine management system is used eg, MoTec, SDS, Autronic, Haltech etc. An example of a big injector is Bosch #0 280 150 731 low ohm, 700cc, standard fitings.

CONFIRMED flow specs for standard Volvo turbo injectors:
740T - B230FT green injectors - 300 cc/min (29 lbs/hr) @ 3 bar (43.5 psi) Bosch #0 280 150 357 (Volvo #133233) - B230 ET,FT,GT to 1989. Note -> ballast resistor pack is different between 740T and 940T. After 1989/90 see Volvo 940T
B200ET - 271 cc/min @ 250 kPa (36.25 psi) Bosch #0 280 150 802 or Volvo # 1346699
940T (1991-) B200FT and B230FT both - 310 cc/min @ 3 bar (43.5 psi) Bosch #0 280 150 804 (Volvo #3517283) -1990-onwards. 940T Low boost turbo injectors are a bit lighter green in colour/color than the green 740T type.
What can be confirmed is that the late model 940 injectors work fine on an LH 2.2 car when matched with the late resistor pack,
thanks Philip Bradley. Flow rate of the 804 at 100% duty cycle is 320cc @ 3 bar and 372cc @ 4 bar - thanks Mike Aaro. 310cc by RC Engineering, (supports 210-230 hp) thanks Philip Bradley

Mentioned above are Bosch injectors 802 (Volvo T) and 804 (Volvo T). Looked up 803 (Porsche) 4.8 ohm 388cc (40 lbs/hr) standard fittings, therefore an next-step-up possibility.

Larger Injectors on a 740 Turbo ?
A number of people have tried larger (eg. 370 cc/min (std 300)) injectors with little success using the standard LH-Jet 2.2 Turbo factory fuel computer and separate EZK ignition. It seems the engine sensor / mapping parameters cannot compensate enough for the increased injector flow and the system runs very rich both during idle and running - Probable reason for rich running - the computer still delivers the same mapped injector pulse width, it doesn't know your using a 66% larger injector. Bill Watson reports that at 11 psi boost in his 87 745, he measured no more than 82% duty cycle. Juha in Finland reports no rich problems with his B230ET model, but the ET uses an early Motronic system where ignition and EFI talk to each other.

Peter Linssen writes: Bosch / Volvo LH 2.2 cannot deal with injectors larger than 310cc. Bad idle and poor drivability is the result.
LH 2.4 however will adapt for injectors up to 370cc and offer good performance. However because the LH 2.4 system is adaptive it will trim itself to compensate for the richer mixture it offer very little if any advantage. If you want to run larger injectors with the stock fuel system you have to modify the signal from the MAF sensor to compensate.

LATEST DESIGN - 'R' Injectors

Info from JP Styling Web Page
There is a very popular modification among Volvo engine tuners in Sweden; blue "R" injectors. These injectors are used on Volvos high output engines, such as S60T5. We have tested these on B200 & B230ET/FT engines with Motronic and LH Jectronic injections with great results. They flow 391cc/min and are good enough for over 300 horsepower. Could be good with an aftermarket ECU.

The following is of interest to Volvo modifiers:
Racetronix - Siemens / Mototron Deka 4, 60 lb / hr Injector Mototron Part # INJGAS003A00 (aka L107) Static Flow Rate: 60 lb/hr @ 43.5PSI (300kPa) = 630cc/min / Coil Resistance: 12 Ohms / High Impedance / High-Z (No ECM driver modifications required) Gain: 0.11ms/mg, Offset: 0.055ms, Turn on time: 1.14ms @ 14VDC, Turn off time: 0.85ms @ 600KPa.

Boris Mohar (the Volvo knock sensor guy) uses 63 lb/hr injectors on his developed 740T - Racetronix - - My duty cycle is 63% at 18lb boost. Idle is fine and car has much livelier response. They are high impedance so the ballast resistor has to be bypassed. The mechanical fit is dead on. No modifications of any sort. Engine management is Megasquirt and Spark.

Conversions: 1 atmosphere = 14.7 psi, 1 atmosphere = 101.3 kPa ,1 atmosphere = 1.013 BAR, 1 BAR = 14.51 psi

Volume Conversions: [ lbs/hour = Cubic centimetres (cc) per minute (divided by) 10.2 ] ; [ cc per minute = lbs/hour x 10.2 ]

cc per minute = HP x 5 , HP (per injector) = cc per minute / 5 , HP = lbs per hour x 2.04

Other web reading:

Comprehensive Injector information by Russ Collins, R.C. Engineering - Excellent

SDS EFI , Modern Engine Controls by Jeff Taylor -

Not official - If these injectors produce 500cc @ 100% duty cycle, then sticking to a safe 75% duty cycle, 500cc at 75% duty is about 375 cc/min. At 375 cc the injector is good for about 85 hp each. 85x4= 340 ? hp on 4 cyl engine

Optimum Injector Size Equation:

(BHP * BSFC) / (No. of Injectors * 0.8) = Injector Size (Flow Rate)

BHP = Maximum Brake Horsepower

BSFC = Brake Specific Fuel Consumption at peak horsepower

Maximum Horsepower with a Given Injector Size

(Flow Rate * No. of Injectors * 0.8) / (BSFC) = HP

Convert cfm to Estimated Injector Size

(CFM * 0.44298) / No. of Cylinders = Estimated Injector Size

Sidenote: Mike Aaro writes, The time available (window) for an injector "to inject" is 10 millisec's @ 6,000 rpm/100rps, and 7 millisec's @ 8,000rpm/133.3rps, i.e. the time spent for one crank revolution. In theory, a fully open 300 cc/min injector would inject 5 cc/sec and finally ?0.0375cc/rps, i.e. in each engine revolution.

SIZING - needs completing - Before purchase I did the calcs ...per ..websites...In my case I felt a little disappointed that my homework did not compare to reality.

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