- Engine enamel is for blocks, heads and covers. It burns off a manifold, and every maker says so.
- The ratings run from 140°C to 343°C inside the same shelf. The can decides, not the category.
- An aerosol is quickest, a brush gives the most even finish on a block, and the coverage figures favour the tins.
- Depending on the brand, the engine can run after a day or must wait nearly a week.
- Price per 100 ml is shown on the day from Amazon's figure; the ratings do not move.
What engine enamel is for
Engine enamel is a one-pack paint: no hardener, no pot life, and the tin you opened last winter is still good. It has to stay put at block temperature, shrug off petrol and oil, and survive the degreaser it meets at the next rebuild. That is the whole job, and the paint type page explains how each maker gets there.
What it is not is a manifold coating. The hottest can on this list is rated to 343°C and its maker says in as many words that it is not for exhaust parts. Manifolds and downpipes take a very high temperature coating, which is a different product with a different cure.
The five here are the ones the makers' sheets, the colour reference and the price on the day put at the top of what Amazon UK sells. The shop lists the rest.
The ratings, and the one that surprises
Hycote publishes three service temperatures on one sheet: 300°C for aluminium and matt black, 140°C for gloss black. Same range, same shelf, and the gloss manages less than half the heat. Retail listings often print 300°C against the black can. The sheet is the authority, and it is why Hycote sits fifth with a modest score rather than higher.
VHT gives 550°F, which is 288°C, and calls it intermittent: a peak the film survives, not a temperature it sits at. Eastwood gives 650°F, about 343°C, for its ceramic enamel. POR-15 gives 300°F, about 149°C, and sends anything hotter to a different product. Watch the units: POR-15's 300 is Fahrenheit and Hycote's 300 is Celsius, the same three digits a hundred and fifty degrees apart.
Frost gives 170°C for its own tins. For a block on a road engine that is enough. For an alloy head that runs hotter, or an engine that is worked hard, the two cans above 280°C are the ones with margin.
Aerosol, brush or gun
VHT and Hycote are aerosols. The sheets agree on the method and differ on the numbers: shake for at least a minute, VHT says, and ten seconds more for every minute of spraying; two minutes, says Hycote. Hold the can 20 to 25 cm away, start moving before you press, and keep the coats thin. Applying engine enamel has every maker's figures side by side and draws the recoat windows.
POR-15, Eastwood and Frost are tins. On an engine a brush is a perfectly good tool: POR-15's enamel levels itself as it dries, Eastwood's goes on by brush or gun, and Frost's thins with white spirit for a gun. Only POR-15 publishes a coverage figure, a pint for a whole engine. Aerosol makers publish none, so the first time you paint a block from cans, buy one more than you think you need.
A gun earns its place on a bare block on a stand, or when the colour you need only comes in a tin. The spray gun guide says what size and how much air.
When the engine can run
Dry, handleable and cured are three different states, and only the last gives the paint its properties.
VHT is the convenient one: 30 minutes to touch and an hour to handle by the product page, an hour and three by the data sheet, then either 93°C for 20 minutes in an oven or the heat of the running engine to cure. Hycote can be overcoated after 24 hours, and says full solvent resistance for its 300°C colours comes only after 220°C for 90 minutes, which a block will never see on the car. POR-15 is slowest and most explicit: two to six hours to touch, then four to six days before the engine starts. Eastwood and Frost give drying times on their listings rather than cure schedules.
If the car has to be back on the road at the weekend, that rules the choice as much as the rating does.
What to check before you buy
The colour first. The OEM colour reference says what the factory sprayed on your engine and which of these makers names a colour for it. Frost's tins carry RAL numbers and Ford and BMC names; POR-15 has MG Maroon and Austin Healey Green; VHT's satin and gloss black cover most British blocks of the sixties and seventies.
Then the rating against the part. A block or a cover takes any of the five. An alloy head, or anything near the exhaust side, wants the 288°C or 343°C cans.
Then the primer rule, which is the maker's and not yours. VHT sells one. Hycote forbids one. POR-15 wants its own prime coat on bare metal. The primers page goes through it.
Then the price per 100 ml, which the table shows on the day. A 946 ml tin looks dear until the price is divided by the size.