Improving Forged Engine Longevity w. Coolant Pre-heaters (i.e. Webasto, Eberspächer)

[Enlight]

As detailed in another UOA I posted, it looks like I will be looking for a new shortblock for my turbocharged '05 Subaru Legacy GT soon. I began by only considering OEM replacement options because I wanted a long-lasting engine; that is before I discovered engine coolant pre-heaters. While I'm aware of freeze plug and oil pan heaters, I'm primarily interested in getting the entire engine's internals closer to operating dimensions before the engine ever turns over. My understanding is that the primary reason forged engines suffer shorter lives is because of thermally contracted pistons at startup. Following that logic, solutions that actively circulate coolant throughout the entire block will pre-heat the internals more evenly. Both the Webasto and Eberspächer will heat coolant up to 80°C or 176°F.

All other factors being equal, are there any reasons why an engine with forged internals would not last as long as one with cast internals with a coolant pre-heat system?

According to this neat chart I've found from Engine Builder Magazine, raising temps to 176°F get 4032 and 2618 pistons less than halfway to their final (approx. 572°F) operating dimensions.

 

[BMWTurboDzl]

The only time I've ever read about pre-heaters is with F1 because the tolerances are so tight. I can't imagine how any other engine would benefit. There are plenty of high power engines with forged internals which have no need for this complexity.

 

[john_pifer]

Interesting…

With that level of obsessive-compulsiveness, you definitely belong here on BITOG!

Cool car. Can we see some photos?

 

[Bjornviken]

pre heating is only necessary in cold climates

 

[kschachn]

Yes we need pictures.

 

[atikovi]

I will be looking for a new shortblock for my turbocharged '05 Subaru Legacy GT soon.

Why? Makes no sense to replace the engine on a 17 year old Subaru unless this is a pristine low mileage example. But then, why would it need an engine?

 

[FastLane]

LS swap it. Chevy V8 doesn't care how cold it is........

 

[wpod]

I would like to ask what are you expecting to gain in engine life. Race cars are prewarmed because they aren't driven easy to reach operating temps. What about a pre luber?

 

[Popsy]

I thought the pre-heating of F1 engines was especially important for valves guides clearances?

 

[PontiacHO]

Forged pistons do shrink (cold) and swell (hot) but if you got that many years (17) it doesn’t matter to that configuration.
Concentrate on the specific oil required and drive easily until full operating temp. Then let her rip…

 

[JoelB]

I would say you have gone too far down the rabbit hole at this point.

 

[SubLGT]

....Both the Webasto and Eberspächer will heat coolant up to 80°C or 176°F.

Is this a complicated, expensive installation process?

 

[UncleDave]

I never had a longevity problem with a forged engine without preheating.

We use them all the time in boating where the duty cycles and loads mangle cast pieces.

 

[Exhaustgases]

? So is the car used near the arctic circle? Maybe a nice multi viscosity oil would help. Cast piston clearances are tighter so ?

 

[Vermess]

@Enlight you're over complicating things. To install new pistons, you're going to have to split that block, machine it, etc. It's not a process many engine shops are familiar with.

Search eBay for ej20x/y. Got one in the same model and year car as your son going strong for the last 80k miles. Got it for $695, $150 shipping. Another 300 in fluids and consumables, including a new oil pan and he's well on his way.

Process is simple. Swap your intake and exhaust to the new/used shortblock and you're done.

You can have it swapped and driving in 4-6 hours.

 

[Vermess]

I never had a longevity problem with a forged engine without preheating.

We use them all the time in boating where the duty cycles and loads mangle cast pieces.

Boxer and flat engines are a different animal compared to v or inline engines(I'm assuming it's what you use in the marine application).

Boxer/flat engines use dumb tight ptw clearances.

 

[UncleDave]

Boxer and flat engines are a different animal compared to v or inline engines(I'm assuming it's what you use in the marine application).

Boxer/flat engines use dumb tight ptw clearances.

Eager to learn something new here.

Marine engines are simply the ones Ive done the most of and always have to do.

I've built all kinds of forged engines including flat / boxer style VW and Bru sand rails.
I had a Subaru rail with an out front (formerly outback) subaru turbo-no pre heater , I4's for Motorcycles (gs1100's particularly) , V8's.

So far the formula is identical - You set them up loose (slugs anyway) and warm them into place.

Never used a pre heater or had a premature failure that wasn't caused by my own right foot colliding w physics.

 

[Vermess]

Eager to learn something new here.

Marine engines are simply the ones Ive done the most of and always have to do.

I've built all kinds of forged engines including flat / boxer style VW and Bru sand rails.
I had a Subaru rail with an out front (formerly outback) subaru turbo-no pre heater , I4's for Motorcycles (gs1100's particularly) , V8's.

So far the formula is identical - You set them up loose (slugs anyway) and warm them into place.

Never used a pre heater or had a premature failure that wasn't caused by my own right foot colliding w physics.

You can set the slugs loose in boxer application, no problem. They will run a bit noisy and sometimes "oily" as some oil will get past until the piston and rings expand. That's not an issue in your application of off road.

2 things. 1. This is an on road app with cat. 2. What are the chances regular people have the know how and patience to let it come up to temp. That's why I pitched a jdm engine. Cheap, easy, runs.

Last time I wanted to put in a set of "drop in" forged slugs in my 05 STI(at the time), I ended up with a sleeved, closed deck, rods, pistons, 6262 rotated, 2250cc injected, cammed, dual disc'ed, haltech controlled car....cause....."I WAS IN THERE ANYWAY"

 

[Enlight]

Thanks for the warm welcome, @john_pifer! Here is a photo from when I visited Tail of the Dragon on August 30th. The camera setup you see is for a passion project where I record scenic roads. I installed riv-nuts in the hood for a hard mount so I don't need to worry about it ever coming loose (or losing suction). RibbonWork was going to be the name of my YouTube channel before I decided on something else. I am the fourth owner of this car, third in its (mostly) current form after it received a 6MT swap and other upgrades. This car has had two other owners on the LegacyGT.com forums where you can find its build thread. This car is my project car and one that I hope to hold on to indefinitely. I bought it in Humboldt County, CA and drove it back East - that profile picture of mine was taken in Monument Valley. I learned most of my shadetree skills, replaced my first timing belt, clutch, and fuel tank on it.

@Vermess, here's my UOA thread showing that I likely have bearing failure and blown head gaskets. In addition to taking this car filming on road trips, I also track it and would like to get into autocross. I've been speaking to a few reputable builders in the Northeast and exploring my short block replacement options.

The added benefit of a coolant pre-heater is that it also provides heat to the interior of the cabin. When I'm on my filming trips I sometimes decide to sleep in the wagon and it can get quite cold in the winter. @SubLGT , the most involved aspect of the pre-heater is installing a standpipe into the fuel tank. Do you have an LGT too? Ideally, we can install the standpipe through the fuel pump access doors. Dropping the rear subframe in order to drop the tank is not fun.

I know this pre-heater idea is overkill for most people, I come from a long line of males who come up with harebrained ideas so it's a congenital condition. Interestingly, when I browse European eBay I see that these units come from the factory for economy cars like the VW Golf. In either case, this is just an idea that interests me.

From what I read, it seems like most 2618 owners report 50-75k from their engines before they need to be refreshed for excessive compression loss. 4032 experiences are harder to find, but Rallispec told me that they used to be used in OEMs until emission standards became more stringent. @UncleDave, how is a marine engine's lifetime measured?

 

[UncleDave]

You can set the slugs loose in boxer application, no problem. They will run a bit noisy and sometimes "oily" as some oil will get past until the piston and rings expand. That's not an issue in your application of off road.

2 things. 1. This is an on road app with cat. 2. What are the chances regular people have the know how and patience to let it come up to temp. That's why I pitched a jdm engine. Cheap, easy, runs.

Last time I wanted to put in a set of "drop in" forged slugs in my 05 STI(at the time), I ended up with a sleeved, closed deck, rods, pistons, 6262 rotated, 2250cc injected, cammed, dual disc'ed, haltech controlled car....cause....."I WAS IN THERE ANYWAY"

I know well the domino effect of spend. I figured once the OP starts changing rotating assemblies its on him not fat hand it.

@UncleDave, how is a marine engine's lifetime measured?

In hours. Way to few of them if you are making big HP.

A "typical" Mercury 525 will get 5-700 hours out of the short block and 250-350 on the top end.

Guy I know running pre heater are all diesel guys in the Northern climes.