Page 2 of 2
Re: Does anyone know how to simplify a Gems 4.6 p38a cooling system for a classic car?
Posted: Tue Jul 08, 2025 11:22 am
by Bigwallace
FBW wrote: ↑Mon Jul 07, 2025 8:25 pm
That looks good, though. Are those larger funnels?
The thermostat should open at 82°C. The P38's only opens at 88°C, which is too high and bad for the engine.
Does the engine have T-liners?
Hi bud! Yep, the inlet was enlarged to 45mm, port matched to the cnc Terminator heads. Top hat liners, pocketed pistons, Stealth cam, balanced rotating assembly with 6kg flywheel, 36-1 trigger wheel, Yella Terra roller rockers, 72mm inlet, etc. 7,000rpm redline. The cam comes in at 1,700rpm & runs out at 6,700rpm. The torque curve will no doubt be further up the revs before it comes in!
Regards.
Leigh.
Re: Does anyone know how to simplify a Gems 4.6 p38a cooling system for a classic car?
Posted: Wed Oct 29, 2025 2:58 pm
by SuperV8
Bigwallace wrote: ↑Mon Jul 07, 2025 8:01 pm
The thermostat housing and inlet manifold base.
Someone's modified that - it's not how GEMS were originally.
GEMS versions had a remote thermostat housing on the lower radiator hose - some call it a cows udder!! one of the pipes is a feed from the manifold to the back of this remote thermostat to give the stat accurate engine temp coolant - so it can open when required, and when it does gradually open it controls the temps of the coolant entering the engine - rather than controlling the temps of the coolant exiting the engine!
I switched from the old in manifold thermostat to a remote thermostat in the bottom hose and found it better controlled my temps.
There are different versions of these remote stats with different temperature openings, and also with pressure relief as well - so they open from temps of higher flow. One of the strategies they used to help with k-series head gasket issues was to go to this type of stat arrangement to better control temps.
I'm using a grey one from a Disco 'I think'.