Eagle Kammback

What is the stock coil voltage on my 95 F150 XLT 302 Auto?

herb1

The haynes manual I have says "ignition(run) supply voltage" between 6 and 8 volts

Eagle Kammback

What? The original coil on my Eagle was about 18000 volts. I think you misunderstood me or something?

wde3477

Couldn't find the specs for the OEM coil, but there are several aftermarket jobs advertising 40K+ volts, so I would suspect the OEM would be in the 25-30K volt output range.

The need for voltage increases with compression ratio and spark gap.

Actual output voltage is determined by many factors, some of which are the turns ratio of the coil, the rate of decay of the input current, and the efficiency of the coil windings - all of which should be taken into consideration during the design phase.

herb1

lol...I guess I should have read a little further down the page...sorry for the mis info

wde3477

Suggest that the primary side voltage info given by 'herb1' is probably correct. Many ignition systems roll back off the nominal battery supply voltage during normal running operations.

Just has to be careful what one asks for :-)

Eagle Kammback

What is the highest voltage coil the rest of the ignition can safely handle? Any upgrades so it can handle more?

94'snap

What are you planning on doing? You could upgrade everything with some MSD things.

Eagle Kammback

I just want the truck to get better mileage, and a hotter spark will do that, right?

wde3477

Suggest that if there were significant gains to be made with hotter sparks, they would be standard OEM fare for boasting privileges and reduced emissions. IMO, don't think the money spent on upgrades would be recovered in gas savings, even at $3+ per gallon.

It's my understanding that one of the driving forces for hotter spark is for those who run the motors up towards the high end of the RPM range, where the coil output voltage tends to fall off since the coil has less and less time to recharge for the next cylinder pulse.