On the basis that cold air intake is good I hope that two cold air intakes are better. I am adding a 1976 ‘over the radiator’ snorkel to my cowl induction 1975. Not straightforward but do-able.
I did some in depth testing using my 99 C5 as a testpig as to effects of quality of hot versus hot air into the cylinder charge
As we know the hotter the airmass brought into the cylinder the worse the charge is, that is an ill effect to performance,
if causing engine knock, or leaner AFR
Mush worse for vehicles that have an engine controller that yanks timing and torque out when knock and AFR occur due
to air/fuel in cylinders being bad quality
We also know that heat raises and that under hood temps are quite high and hotter in some areas than others
In this example, I use a thermal measurement tool that allows up to 5 K type thermal probes concurrently
Probes were placed at:
Master brake cylinder
One of the ignition coils
Case of waterpump
Left fuel injection rail
Exhaust primary for #3 cylinder of header
Test then were recorded when engine at idle, at 40 MPH and then 60 MPH
So you can see where it was the hottest and at what engine mode
Temps are in F and not C
I then made a cold air box that covered a Blackwing aircleaner and put a slot in the radiator shroud so that only outside air was being taken
into the intake manifold
This allows far better quality airmass into the cylinders which greatly reduces engine knock, and then I even was able to adjust the fuel trims
for the cooler airmass and add some timing which increased the torque and allowing leaning AFR
So if adding or making a cold air box system (get away with pre C4s as no engine controller)
Do not design in so that the air is swirling, where at idle the air temps is higher than ambient of weather, and cannot allow water from being brought in and hydrolocking up the engine
You notice I shaped the cold air box so that it was sealed completely so not getting any heat soaked air from engine bay
Wanting to keep everything in the engine bay cooler I then modified the hood and using nature allow outside cooler air flowing in the engine bay and then ports that takes the hotter air and the outside air flow pulls that heat out, so the engine bay overall is much cooler than when stock