yep, my rule of thumb is if the fan motor isn’t drawing more than 20 amps, it won’t cool your car. Not a strong enough motor.
I like Derale stuff, but Spal is supposedly OK too
I have Spal's most powerful 16" and it's even a pusher which a lot of guys on here say can't work, lol, but I didn't have room in the front but anyway never had any issues.