what is heat soak?

[johnfett]

I keep reading online about turbos and see the phrase "heat soak" mentioned back and forth with turbos, is this common for all turbo applications? Should I worry about this with my Miata if I go turbo? I think this relates back to my question with the turbo timers. Please no "let me google that for you" replies im looking for real world Miata owners feedback, thanks !

[— kung fu jesus —]

Heat soak occurs when all the parts of the engine become a high temperature, hot to the touch. This includes pieces the intake manifold and associated parts. It decreases performance and power because the hot engine compartment begins to raise the intake charge and other fluids (air going into the motor) much above ambient or normal operating ranges.

You should definitely worry about it if you are going turbo because of a number of concerns:

Hotter air, compressed by the turbo, makes combustion less efficient and more prone to detonation (pinging).

The turbo will be relatively close to important systems such as the brake master cylinder. A turbo is an extension of the exhaust manifold, so it is more mass under your hood that gets really hot in a confined space.

More heat = more stress on rubber and plastic bits under the hood.

Because a turbo use the motor's oil to lubricate, they also can heat the oil more.

The small grill or mouth opening on the front of a Miata is barely adequate for the naturally-aspirated version. The car has known heat soak problems from this AND an odd cooling system route. Remember the engines in these cars were originally designed for FWD applications. They are stout, but prone to heat issues.

A turbo system does need and should have additional system upgrades to counter the heat issues. A larger radiator, coolant re-routing, oil cooler, heat shielding, better systems monitoring, etc. can really add to the reliability and performance.

[— fwdtamiya —]

Heat soak is the unwanted transfer of heat by conduction (touch. the exhaust side of your turbo being bolted to the cold side, making both sides hot) or convection (fluid movement of heat. the air coming off the "cold" side of your turbine wheel, which is now hot, moving into the charge pipe and heating that material). You will probably notice heat soak as a lack of power on a warm day or, in a bad situation, malfunction in your engine.

Problems can be dealt with by isolation (phenolic intake manifold gaskets, turbo blankets, etc.), radiators/intercoolers, airflow tricks and proper tuning by a professional.

[johnfett]

So heat soak is primarily from turbos then? Is there less worry with a SuperCharger since it does not use exhaust gases? I am looking at options for more power but I just want something I can install and kinda not have to worry about since this is my daily driver.

[— kung fu jesus —]

Heat soak occurs either way, turbos accelerate the process. I also ran a s/c on my car, too. They get hot, too, but not like a turbo.

The best piece of advice I can offer when it comes to adding forced induction: do a LOT of homework. Kits are great, bit they are intended to run at a certain level. When you increase that level, the complexity increases and other systems on the car need to be upgraded to handle the increase in power. Chose a power goal and stick to it.

Because it is your DD, you should be aware of how these kits work and how to make diagnosis and repairs. It won't be like taking the car to a normal repair shop if you have troubles. It isn't that forced induction isn't reliable, but they do require more maintenance and vigilance. It complicates things and stuff can go wrong that makes the car less reliable as a whole.

The power is fun, but it is addictive. I know few people who can leave a forced induction kit alone. You may find yourself greedy for extra power or performance while neglecting to upgrade the tertiary systems in regard. This leaves you stuck on the side of the road.

[Hyper]

Heat soak occurs either way, turbos accelerate the process. I also ran a s/c on my car, too. They get hot, too, but not like a turbo.

Actually superchargers create more heat than turbos.

[— Phatmiata —]

Actually superchargers create more heat than turbos.

huuuh? How do you figure that? I have seen glowing red Turbos, but never a glowing red supercharger, just saying

[Hyper]

huuuh? How do you figure that? I have seen glowing red Turbos, but never a glowing red supercharger, just saying

I was talking about roots-type superchargers. The centrifugal superchargers do not generate a lot of heat.

[Andy]

I don't think we should be making blanket statements. How about both can generate a lot of heat and ca heat soak if not properly addressed.

Even NA power can heat soak. That is why a lot of the "cold air" intakes can cause hp to go down.

[mini_fd]

But even cold air intakes only put out minimal hp. It's not even worth having a cold air intake. It only makes a cool noise.

[Andy]

My Jackson racing intake made a noticeable difference. I would do it again.

[mini_fd]

Your butt dyno doesn't count. We're talking no more then 5 hp. I did a dyno on my nb when I was naturally asp. And I had the racing beat cai stock exhaust and just an axle back. Put down a whooping 112 at the wheel. What a shame.

[DK Wolf]

I was talking about roots-type superchargers. The centrifugal superchargers do not generate a lot of heat.

Wrong... traditional centris produce enormous amounts of heat.


The planetary drives however produce much less than other blowers of their type. But still produce a fair amount.

[Slampen]

Your butt dyno doesn't count. We're talking no more then 5 hp.

5 NA hp its a lot.

Can't say heat soaking is a big problem, with my JR CAI.

[mini_fd]

That's the tops and not at all a conservative number. Plus 5hp is nothing once boost kicks in. :]