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 :teehee: im looking for real world Miata owners feedback, thanks ! :mrgreen:

[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 :shrug:

[Hyper]

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

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. :]

[Slampen]

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

My NA got an NA engine, where boost is NA. :)

[kung fu jesus]

In my experience, and I have run turbos and a s/c on the same car, the turbos took more attention to control the heat. The Greddy one especially, but the custom one that I pieced together from an FM3 manifold and gt2554 was easier. I believe that was because the FM manifold locates the turbo much lower in the engine bay, among a few other things.

Still, the JRSC I installed later wasn't as hot as either turbo. A lot of that depends on how fast you spin up the s/c, though. I ran mine at the kit's stock 6psi, then 8 with a crank pulley overlay. At 8, it did make the s/c hotter, but still nothing like the turbo. Still, I suppose you could make the case that the S/C blocks or soaks the heat from the exhaust manifold directly below it. I used a manifold blanket with the S/C and it helped a lot.

I remember a few times with the turbos, despite a turbo blanket and shielding, I saw steam rising off the hood right over the spot the turbo sits when it rained. :)

11829

[mini_fd]

To help out with my heats oak engine bay running 13lbs of boost, I added the oem under tray which dramatically reduced my water temps. I am constantly reading them on my gauge. I am also installing proper lava heat wrap on all radiator hoses near and around the turbo/exhaust manifold. I am also rerouting the cooling system with m-tuned coolant reroute system with gold adhesive relative tape on the fire wall along with the aluminum 8 inch pipe flyin' miata included in there turboII KIT right before the throttle body where the iat sensor is located in. I added royal purple's rain additive (forgot the actual name) into my cooling system. Silicone hoses also help reduce heat soaked air temps with my intercooler other then using regular metal piping. I do plan to get a vented bonnet of some sort whether it be GV or on made by my body guy.

[I<3flippyheadlights]

I have a SC and a turbo on my car so my input might be worthwhile.

My intake temps have been lower with a turbo compared to the SC. Yes, a turbo can glow red hot after very serious driving. So can your headers. The fact is that hot exhaust is running through a turbo the same way it runs through an exhaust. But the Roots style SC makes a ton of heat with the two screws spinning next to each other.

My coolant temps have been the same though between the SC and turbo. I run around 205 degrees in the middle of day heat. (That isn't over heating. Your gauge lies to you.)

To give you an idea of heatsoak and how it affects your car. In the middle of a Florida afternoon, it can be in the 80s and 90s. On a NA car, my intake temps were around 120-130 degrees. When I had the SC installed WITHOUT an intercooler running 5 psi, I had intake temps of 220. It was stupid.

[DK Wolf]

It's not the heat of the actual part that will increase intake temp guys.. the air is blasting through super fast anyway that it isn't going to be increased by much. Compressing air period will yield an increase in temperature. However with a supercharger, you're exposing more air to more heated material for a slightly longer duration in time, meanwhile by design of the turbo the hot air isn't being compressed for so long in the actual housing and significantly less air at any one moment is exposed to the hotter housing. Which is why down the line you'll see on higher boost applications turbos will usually yield lower AITs.


However all those issues can be mitigated with appropriate steps.

Anyway, heat soak is when certain component critical to the breathing capability of the engine become hot. Most people I've talked to don't seem to think an intake piping being hot matters much since the design of intake piping isn't to cool the air anyway and the distance traveled is so short it hardly matters. But when you start throwing in an intercooler who's job it is is to cool the gases then you start to lower it's ability to do the job correctly since it no longer has a larger disparity between it's cold temperature to the hot temp of the gases.


I'd recommend buying the book Maximum Boost by Corky Bell, it's what I have and it may have been written ages ago but the theory behind the application remains unchanged. I'd highly recommend getting that book.

[kung fu jesus]

Ditto on 'Maximum Boost'