As the title askes will they fit? I realize the connectors might be differant but are there any other problems to overcome? What kind of HP will they support safely?

 

in a S4 they fit unless your have a N333 ecu, that you need a 10 watts, 10k resistor but if you have a N332 they fit like stock. and on a S4 you diont need to change the plug unless you break the plug

 

the ecu does not determine the impedance, it just sends the power pulses out. the harness is what determines what impedance you can use. for an 86-early 88 cars, they fit and work just fine. for late 88, you'll need to add resistors and file off the centering tab on the injectors. for 89-91, you need to add resistors and change the injector connectors.

 

Thats what I thought from reading through some stuff, thanks for confirming the info.
What is SAFE max HP?

 

depends on what mods you have.

 

88 TII 61k on clock.
Racing Beat turbo back exhaust, expensive but sounds damn good and for sure car has more power.
Fuel cut defender
K&N filter on HKS adapter.
FD fuel pump still to be installed.
Megasquirt just pulled from my GXL still to be installed.
Everything else is stock.

 

It'll be just fine. Read what EDDIE said.

 

RacingBeat in their catalog have long recommended using the 680's in the secondary positions for years for upgraded engines. The ECU matters not in the series four.

 

What is a safe max HP with what I got.

 

probably like 230-240whp?