Mike,
As Jack noted in his latest post, the starting current doesn't flow
through the relay.  The solenoid gets its juice direct from the battery
same as before, the only thing the relay does is trip the solenoid from
closer to the battery.  The wire from the ignition switch trips the
relay, which closes and gives you a direct battery connection from the
battery to the ignition switch terminal on the solenoid, which trips the
solenoid which gets its big ol' current draw through the big honkin'
wire to the battery.  I think I'm thinking about this correctly, please
somebody shoot me down if not.

Thanks,
Sean

> 
>   Well I ain't Bob - 
> 
>  First the answer, cause I know you PHD's are busy.
> 
>  Get a relay with a rating for a continuous 30-40 amps and you're 
> alright. Which means the headlight wampus is cool.
> 
>  The Bosch is rated at 35 amps  and the VW is rated at 30.
> 
>  Now the scary stuff: right out of my funky old Bentley.
> 
>  Horsepower: some are .7 and some are .8 hp
> 
>  No Load test - amps:  pooling 3 types, 25 to 50 amps. voltage 12v.
> 
>  Load test: 160 to 200 amps   Voltage pulled down to 9v.
> 
>  Stall torque test:  220 to 300 amps. Voltage pulled down to 6v.
> 
>  
>  If you got this far, let me assure you that there is a big difference
> between a "continuous rating" and a say "30 second rating".
> 
>  The 30 amp continuous relay will handle the 180 average for the 30
> second start with no problem.
> 
>  I think every manual I've ever read says crank for 10 seconds and
> then let it cool off.
> 
>  Those admonishments also are for your starter.
> 
>  You have any idea how big a starter motor would be if it handled 
> those amperages continuously? About the size of your whole engine.
> 
>  west 
> 
>