voltage drop at 4500 rpm

[wedgey]

hoping for some help

i have fitted the 2.8 fuel injected 280zx motor

n54 with p90 head flat top pistons and mild cam

into my 71 240z it has an aftermarket computer

the problem i am having is at 4500 rpm i loss voltage

down to 10.5-11 but only over that rpms

noticed when it was on the dyno

one person has advised a surge tank and lift pump

and a few people advise a upgraded alternator

the auto electrician thought that it was charging correctly and losing it after 4500 rpm it is stilling running the 240z alternater 40amps

rob

[SteveJ]

********Wild Speculation Alert************

I have no idea of the duty cycle of the fuel injection system for the Z car. However, could this be a case of the injectors firing so often combined with the current draw of the ignition system? If you didn't upgrade the alternator with the engine, it could be the case.

Also, what is the normal voltage at the battery at idle? Your voltage regulator might not be adjusted properly.