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1 hole Vs 4 hole injectors Sat Nov 15, 2014 8:24 pm
Holister
Life time member
If anyone can correct me or add some relevant information on this topic, please jump in. I'm no authority, I've just been reading up and I'm just posting this info here to get some discussion going. I just want to know whether a 4 hole injector will work properly in a K100 engine.
There's been discussion here and on other forums about upgrading to 4 hole injectors to possibly get a performance boost. Fuel from these injectors is properly atomised by the 4 fine holes which also creates an efficient dispersal pattern. There doesn't appear to be a 4 hole injector specifically designed for the K100, so finding a substitution is the problem.
The table below is one I've put together covering injectors that are relevant this topic or have been discussed here or somewhere else on the web in relation to the K100.
[EDIT: PSI and Bar pressures above are working pressures for each injector not test pressure]*
Because air is measured as a mass, Bosch refer to the measurement of fuel mass in grams not cc's. However when bench testing an injector it's easier to measure the volume in CCs.
Note: 1gram of fuel does not equal 1cc of fuel
Some interesting reading from Bosch.
http://www.bosch.com.au/car_parts/en/html/4554.htm
Sections a,b,c,d - fuelinjectors.pdf
The first injector 0280150210 has been designed to run in the K100 engine and these are the parameters for the engine and ECU to operate within. The 'Pressure %' column is my calculation and refers to the available pressure provided by the fuel system divided by the required pressure for that injector. This injector requires 36.25psi to operate. The K system provides 36.25psi so therefore it's getting 100% of its required pressure.
0280150705 could be substituted. It has almost identical specs. It's been designed to run in a BMW 4 cyl 1.0 litcar engine*. [EDIT: This is the OEM injector for K1 & 16v Ks]*
However when you get into the more modern 4 hole injector, things start to change.
0280150715 (4 hole) delivers slightly more fuel, but it's normal operating pressure is 43.5psi and in a K100 (at 36.25psi) it's only getting 83% of its required pressure, so therefore it's working with a 17% drop in pressure. These injectors require the higher operating pressure to get proper atomisation of the fuel. But if you want to go for a 4 hole injector then this is probably the one to buy as its the closest to the standard specs BUT is it operating efficiently??
0280150415 (4 hole) is an injector being sold on US ebay as the injector upgrade for K machines (the listing doesn't state the OEM# but I messaged the seller for that info). As you can see this injector requires a much higher operating pressure (50.75psi) but will only get 71% of that required pressure from the K100 fuel system. It's working at a nearly 30% drop in pressure. Pressure and flow are directly related so that would mean that the flow rate would come down to 91grams/min. Thats a 12% drop in fuel delivery and a 30% drop in pressure. That cannot be efficiently atomising the fuel. Poor atomisation... poor air/fuel mix... poor combustion... drop in power. IMHO this injector is a bad choice.
I read posts online from people who have fitted these and it really does seem unclear whether this injector makes any difference. Any percieved difference "may just be due to the fact that their old injectors were stuffed anyway" was one comment. It may be difficult to determine any changes in power output under normal use so I would be very interested to see dyna results and fuel consumption data before and after fitting these injectors.
If the above assumption is correct, could a solution be to regulate the fuel at a higher psi by fitting a different fuel pressure regulator?
Would you then need to install a pump to accommodate the higher operating pressure? The K fuel pump provides a head of pressure around 60psi.
With increased fuel will the air regulate accordingly or do you get a richer mix?
How would this affect the performance of the ECU?
I'm just putting this out there and looking for feedback. I've tried to approach this logically but from what I can see we're probably better off sticking to the standard 1 hole injector. That's disappointing because I really wanted to upgrade.
Any thoughts
Cheers
There's been discussion here and on other forums about upgrading to 4 hole injectors to possibly get a performance boost. Fuel from these injectors is properly atomised by the 4 fine holes which also creates an efficient dispersal pattern. There doesn't appear to be a 4 hole injector specifically designed for the K100, so finding a substitution is the problem.
The table below is one I've put together covering injectors that are relevant this topic or have been discussed here or somewhere else on the web in relation to the K100.
| Bosch OEM # | Type | Nozzle | Length | Ohms | Gr/Min | PSI | BAR | Pressure % | Application |
| 0-280-150-210 | EV1 | 1 (pintle) | 60.5 | 16.2 | 103.10 | 36.25 | 2.50 | 100% | BMW Motorcycle |
| 0-280-150-705 | EV1 | 1 (pintle) | 60.5 | 15.9 | 104.60 | 36.25 | 2.50 | 100% | BMW 4-1.0l, 4-1.1l, 4-1.2l, |
| 0-280-150-715 | EV1 | 4 hole | 60.5 | 15.9 | 116.50 | 43.50 | 3.00 | 83% | BMW 4-1.6l, 4-1.8l, 6-2.5l, |
| 0-280-150-415 | EV1 | 4 hole | 60.5 | 15.9 | 130.00 | 50.75 | 3.50 | 71% | BMW 6-2.5l, 3.0l |
Because air is measured as a mass, Bosch refer to the measurement of fuel mass in grams not cc's. However when bench testing an injector it's easier to measure the volume in CCs.
Note: 1gram of fuel does not equal 1cc of fuel
Some interesting reading from Bosch.
http://www.bosch.com.au/car_parts/en/html/4554.htm
Sections a,b,c,d - fuelinjectors.pdf
The first injector 0280150210 has been designed to run in the K100 engine and these are the parameters for the engine and ECU to operate within. The 'Pressure %' column is my calculation and refers to the available pressure provided by the fuel system divided by the required pressure for that injector. This injector requires 36.25psi to operate. The K system provides 36.25psi so therefore it's getting 100% of its required pressure.
0280150705 could be substituted. It has almost identical specs. It's been designed to run in a BMW 4 cyl 1.0 lit
However when you get into the more modern 4 hole injector, things start to change.
0280150715 (4 hole) delivers slightly more fuel, but it's normal operating pressure is 43.5psi and in a K100 (at 36.25psi) it's only getting 83% of its required pressure, so therefore it's working with a 17% drop in pressure. These injectors require the higher operating pressure to get proper atomisation of the fuel. But if you want to go for a 4 hole injector then this is probably the one to buy as its the closest to the standard specs BUT is it operating efficiently??
0280150415 (4 hole) is an injector being sold on US ebay as the injector upgrade for K machines (the listing doesn't state the OEM# but I messaged the seller for that info). As you can see this injector requires a much higher operating pressure (50.75psi) but will only get 71% of that required pressure from the K100 fuel system. It's working at a nearly 30% drop in pressure. Pressure and flow are directly related so that would mean that the flow rate would come down to 91grams/min. Thats a 12% drop in fuel delivery and a 30% drop in pressure. That cannot be efficiently atomising the fuel. Poor atomisation... poor air/fuel mix... poor combustion... drop in power. IMHO this injector is a bad choice.
I read posts online from people who have fitted these and it really does seem unclear whether this injector makes any difference. Any percieved difference "may just be due to the fact that their old injectors were stuffed anyway" was one comment. It may be difficult to determine any changes in power output under normal use so I would be very interested to see dyna results and fuel consumption data before and after fitting these injectors.
If the above assumption is correct, could a solution be to regulate the fuel at a higher psi by fitting a different fuel pressure regulator?
Would you then need to install a pump to accommodate the higher operating pressure? The K fuel pump provides a head of pressure around 60psi.
With increased fuel will the air regulate accordingly or do you get a richer mix?
How would this affect the performance of the ECU?
I'm just putting this out there and looking for feedback. I've tried to approach this logically but from what I can see we're probably better off sticking to the standard 1 hole injector. That's disappointing because I really wanted to upgrade.
Any thoughts
Cheers
Last edited by Kaptain Holister on Mon Nov 17, 2014 6:20 pm; edited 4 times in total (Reason for editing : *corrected info)
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1989 K100RT VIN 0097367 (naked) 1996 K1100RS VIN 0451808 |  | Fuel: 95 Octane Engine Oil: Nulon Full Synthetic 15W50 Gear Box Oil: Nulon Synthetic 75W90 |
-o: 
"
1988 K100RS SE/ABS
