keeping fuel injections cooler

[Clem Z.]

Re: keeping fuel injections cooler

Clem is right on, as usual. Keeping the hot oil off the bottom of the manifold is important. The oil splash shield that GM designed for big blocks way back in the mid 60's works. Big blocks splash a LOT more oil around the valley than small blocks but they all do it.
The trick is to keep the lower section of the splash shield far away from the manifold as possible, yet still function as a shield to make sure the oil doesn't get by on the sides.

The cyl heads are always hotter than the temp of the coolant that is exiting at the front of the manifold. The coolant is only warmed to the temp of the surface of the cast iron. Not the core. The core of the cast iron is always 10* to 20* hotter in most areas and a LOT hotter around the exhaust port. That heat travels by convection to other areas of the casting.
That's another reason why cooling systems often boil AFTER the engine is shut off. The coolant temp immediately begins to rise to the core temp of the casting when it stops flowing.
That heat also travels from the cyl head to to the intake manifold after an engine is shut down.

the intake side of the heads run cooler when the engine is running because if the flow of the gasoline. we have used epoxy in the intake ports to change the shape or volume that could not be used on the exhaust ports because of the heat. with all these new cylinder heads available with different volume intake runners you no longer have to do the epoxy thing.

[Michael H.]

Re: keeping fuel injections cooler

the intake side of the heads run cooler when the engine is running because if the flow of the gasoline. we have used epoxy in the intake ports to change the shape or volume that could not be used on the exhaust ports because of the heat. with all these new cylinder heads available with different volume intake runners you no longer have to do the epoxy thing.

Yes, the first few inches of intake port would benefit a bit from that but down deeper, the temp was hotter because of convection from the exh port side even though they didn't come in contact.
Amazing, all the different temps that would show up in different areas of a cyl head casting when the engine was under full load.

I well remember those days of "bigger is better for intake ports". The BEST thing we ever did to early big port big block aluminum heads was build up the intake runner floor and make the port smaller. Everyone else was grinding everything in sight and giving away HP.