Discussion
wedg1e said:
There are a few higher-flowing injectors that you COULD fit to the non-hotwire system, notably from one of the Jaguars...
Yes. The flapper Jag injectors flow about 32% more. (Bosch 280 150 153). Fit them with the Jag flapper AFM 280 203 005 and you increase the airflow to match. Interesting what happens on the dyno.
All plugs and parts are compatible..but you will have to alter your AFM bracket a bit for the larger JAG unit.
emog
wedg1e said:
eMog said:
>Yes. The flapper Jag injectors flow about 32% more.
>(Bosch 280 150 153). emog
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>I use Bosch 0 280 150 157. They're from a Jaguar hotwire setup >and have the O-ring type ends, but they can be modified to fit >the older style fuel rail.
Flapper systems were designed by ingenious carb-trained guys. All you need is info and then it's all simple mathematics and common sense.
The primary info is in the flow rates, the pressure required and the ohm rating. The rest is fit. Click www.gomog.com/allmorgan/injectors.pdf Your Hotwires flow at 206 cc at with Bosch parametres (36lbs and 2.4 ohms) and can produce a maximum of 41 hp each. This compares to the stock 3.5 flapper injectors (280 150 227) which flow 171cc. 206/171=120% at 34 lbs and 14 ohms.
As you see from the list, you could have used other Bosch injectors that match the origials (280 150 227) in ohms, pressure but provide more flow and avoided the issues of different recommended pressure and different ohm signal. But with a flapper's flexibility (stock AFM is adjustable and adding on a adjustable fuel pressure regulator) that can be overcome and obviously you have done it. Exoetrts have taken the same path and dealt with it as well. In the end, it all comes to the same place if you adjust to the problems of a non-perfect match and a flapper can do that.
Bigger flapper parts are not Hotwires, they are Porsche or Jag flappers. (Happily these engines had less cylinders (which means bigger flow injectors for each cylinder) and/or bigger capacities, which means larger AFMs.)
In my case, I calculated the capacity difference between a 3.5 and 4.8 (4.8/3.5=137%) Then picked identical injectors (ohms and pressure) with a higher flow (so I didn't have to crank up the fuel pressure). The Jag 280 150 153s turned out to flow 238cc so 171 (the 3.5) versus these turned out to be 238/171= 139%. That was perfect enough in my book.
I then went to a breakers and bought 16 injectors for £6 each. (As a minor note, I don't trust any injectors much. Nothing huge goes wrong with them but their flow rates are all over the place new from the box, therefore providing uneven fueling.)
I then sent these injectors to a small company in the States and had them all completely refurbished and blueprinted. ($12 US each). I used the 8 with closest flow rates (2% variance from lowest to highest) and sold the rest.
emog
eMog said:
Bigger flapper parts are not Hotwires, they are Porsche or Jag flappers. (Happily these engines had less cylinders (which means bigger flow injectors for each cylinder) and/or bigger capacities, which means larger AFMs.)
My injectors were from a recent model Jag, I'm prety certain it was a hotwire injection system... but I bow to your evident experience.
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