Huge turbo
03-24-2005, 07:28 PM
#46
Race Director
However told you that was not that switched onto it! I am running 82lb (850cc) Siemens with Under drive pulleys, no AC, no ISV, and I dont get an stall. I get stoich idle at 750-800rpm. There are many online calculators to determine the right injector size based on P goals and fuel pressure etc. What are your goals? I think most tuners would suggest 72lb would be fine for 99.9% of applications.
03-24-2005, 08:19 PM
#53
Race Director
Ok, dont buy an AFPR, waste of money if you get the right sized injectors. I have to stock FPR after my APFR failed. I got some sequentially setup resistors from Link. But...
http://www.newark.com is supposed to be a cheap US source.
Originally Posted by Danno
The maximum current-draw on the driver-injector is 16-amps. And you usually don't want to run electrical components at their maximum rating, usually 1/2 is the standard de-rating practice. In the stock configuration with four 5.5-ohm injectors, you have a combined impedance of 1.4-ohms. With a 12v output voltage, you have 12/1.4 = 8.6amp draw.
Using aftermarket 2.0-2.8ohm injectors would require roughly the same overall impedance. So four 2.0ohm injectors gives 0.5 ohms. Driving this with the DME would require a current-draw of 24-amps! Some people have installed one ballast-resistor per injector out by the connector. This allows you to use sequential fueling with aftermarket EFI systems. You'd need a 2-ohm 15W resistor to give the following load:
Injector 2.0ohms + 2.0ohm resistor = 4ohms each
4 injectors in parallel = 4 ohms / 4 = 1 ohm total
12v /1ohm = 12 amp draw
Another way to wire them is in the injector ground wires coming out of the DME. Since there's two lines connected to two injectors, you'll just need two 1-ohm 25W resistors. The scheme would then look like this:
Two injectors in parallel per wire = 2.0 ohms / 2 = 1.0 ohms per ground wire
Each wire 1 ohm + 1 ballast @ 1 ohm = 1.0 ohms + 1.0ohms = 2.0 ohms per wire
Two ground wires per DME = 2.0 ohms / 2 = 1.0 ohms TOTAL
12v /1 ohm = 12 amp draw
Here's some threads of interest:
PelicanParts: 944 turbo injectors
Ballast Resistor Installation?
DME and relays getting hot (good EE posts in this one)
When building your resistor packs, make sure to apply heat-sink compound between the resistors and the aluminum backing-plate, which acts as a heat-sink. Then use male & female 1/4" spade connectors soldered onto the resistors to splice them into the wiring. This allows you to insert and remove the resistors quickly in case you revert back to stock injectors for troubleshooting.
Using aftermarket 2.0-2.8ohm injectors would require roughly the same overall impedance. So four 2.0ohm injectors gives 0.5 ohms. Driving this with the DME would require a current-draw of 24-amps! Some people have installed one ballast-resistor per injector out by the connector. This allows you to use sequential fueling with aftermarket EFI systems. You'd need a 2-ohm 15W resistor to give the following load:
Injector 2.0ohms + 2.0ohm resistor = 4ohms each
4 injectors in parallel = 4 ohms / 4 = 1 ohm total
12v /1ohm = 12 amp draw
Another way to wire them is in the injector ground wires coming out of the DME. Since there's two lines connected to two injectors, you'll just need two 1-ohm 25W resistors. The scheme would then look like this:
Two injectors in parallel per wire = 2.0 ohms / 2 = 1.0 ohms per ground wire
Each wire 1 ohm + 1 ballast @ 1 ohm = 1.0 ohms + 1.0ohms = 2.0 ohms per wire
Two ground wires per DME = 2.0 ohms / 2 = 1.0 ohms TOTAL
12v /1 ohm = 12 amp draw
Here's some threads of interest:
PelicanParts: 944 turbo injectors
Ballast Resistor Installation?
DME and relays getting hot (good EE posts in this one)
When building your resistor packs, make sure to apply heat-sink compound between the resistors and the aluminum backing-plate, which acts as a heat-sink. Then use male & female 1/4" spade connectors soldered onto the resistors to splice them into the wiring. This allows you to insert and remove the resistors quickly in case you revert back to stock injectors for troubleshooting.
03-24-2005, 08:22 PM
#54
Race Director
Oh and I think Delphi are the best. Siemens probably a close second. Just because of the spray pattern being wider on the Delphi meaning atomisation will be better.
03-24-2005, 09:30 PM
#58
I have that same (similar) turbo with the KKK replica hotside. You wont make 400HP at 18psi. I havent run my car but I estimate it will take between 21 and 24 psi to make 400HP. I have chips for 21psi at this point but I am actively contemplating scrapping the DME/KLR and going to a TEC setup. I already have almost 2 years in this car a few more months wont hurt anything.
While we are on the subject you will need larger than 55lb/hr injectors to make 400HP.
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While we are on the subject you will need larger than 55lb/hr injectors to make 400HP.
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03-24-2005, 10:02 PM
#59
Pro
Thread Starter
400hp is not a requirement. If I can break 300+hp that will be plenty in my car considering the wieght reduction I already have. I am also going with the 75 lb injectors. I opted for the stock DME and KLR to keep costs down. The chips that are in it are stage2 APE mapped for 15psi. And I am going to get a Huntley stage 4 or a lindsey MAF. The only thing I have not decided just yet is what boost controller to use.