No BS: why do they blow engines all the time?

[conehead]

OK, ok. I know there is golden info buried in different threads, but someone please break it down. Why do 86 track cars always have blown engines? Is there an easy solution??


I love them, I own one, I have boxes of autox trophies. I do other racing and this seems like the (much better) successor to the spec miata. People call me to sell one and it ALWAYS has a blown engine. Is this solvable or does it ruin the whole platform as a future budget track workhorse?

[DarkPira7e]

The top reasons I can think of -



Spun bearings from low oil pressure due to high oil temp, or low oil level



Bad tuning causing issues


The track has great potential to be the highest RPM / load for a long duration any car will likely see. Things will break.


Forced induction


J02 Recall


The reason you see them with blown engines is because people are less likely to sell if the engine and car are running harmoniously

[Autoxer62]

My conclusion is that the lack of oil pan baffling and pickup problem are major contributing factors. You can run any oil you want, but if it doesn't get to the bearings at high RPM it's just a matter of time.

Reference link:
https://www.ft86club.com/forums/showthread.php?t=134863

[Tcoat]

First off the term "blown" engine can mean a pile of different things.
Head gasket - Overheating or over boost
Spun bearings - Heat again, oiling issues
Thrown rod - Heat (notice a pattern?), over boost, money shift (no matter how vehemently denied)
Then there is bad tuning issues, defective parts (rare other than sealant), poor setups putting excessive strain on the driveline beyond the design max, just poor driving (see thrown rods) that can cause all sorts of issues up to actually "blowing up" an engine.

As Dark said the number of blown engines is probably not near as high as reading social media or forums may make it seem. There will be thousands of trouble free track cars out there for each one that blew an engine. Also see very, very, very few 2014+ cars with blown engines so it is mostly an early production issue.

[new2subaru]

I've been to the track at least 50 times and seen about a million (slight exaggeration by a bit) 86's and have never seen or heard of anyone blowing an engine.

These are all short technical tracks.

[NoHaveMSG]

As bad of a rap as the FA gets its not fragile. I know of a couple guys who have spun rod bearings. I had a fluke rocker arm ejection which led to a thrown rod.

The main thing I have seen with used cars with blown engines is they are expensive long blocks and a PITA to rebuild since the case halves have to come apart. Short blocks new from Subaru are like 1800 which isn’t terrible. I have been tracking my car for years and have seen my oil pressure gauge drop out under high loads and it’s still fine. A baffle will help a lot.

[conehead]

Thanks for the input. It does always seem to be spun rod bearings. I have read some of the treads with extensive oil passage reworks, but that is way above what I would consider budget friendly.


I guess I should ask it this way, if using a stock engine, bolting on ?????? parts is enough to stop it from spinning bearings. Most cars have have some weak links that need regular replacement, but the whole engine can't be one of them.


Baffles and oil pick up tube? Have people had success with that?

[Matt93SE]

My first engine had baffled pan and don't know what else (I bought it as a built race car with a reliable history.)
I blew the engine the first race weekend after a long left hand carousel holding >1G the whole time.

When I replaced the engine, I reinstalled the baffled pan and had DD Performance port the oil passages on the timing cover and install Toda oil pump. I also installed data acquisition at the same time to record oil pressure.

Took the car to another local track, and even with the above mods, the oil pressure was still going nuts in a few turns- particularly hard lefts after a braking zone.

Sooo I installed a 2 qt Accusump as well. That has improved the situation and the oil pressures are higher in the turns but still ugly.


The issue is that these engines are flat and wide. under hard cornering, all the oil schleps to the outside head and valve cover and doesn't drain back into the pan before the oil pump empties the sump. voila. no oil, spun bearings. done fast enough, it doesn't just spin the bearing but breaks a rod and the rod then turns into an axe and chops the block into pieces.

I'm working on some other ideas on the oiling and will post about them if they work.

[andys_garage]

Originally Posted by Matt93SE

The issue is that these engines are flat and wide. under hard cornering, all the oil schleps to the outside head and valve cover and doesn't drain back into the pan before the oil pump empties the sump. voila. no oil, spun bearings. done fast enough, it doesn't just spin the bearing but breaks a rod and the rod then turns into an axe and chops the block into pieces.

i'm gonna add this to the list of reasons to not spend a bunch of money adding grip to this car.

[NoHaveMSG]

Originally Posted by Matt93SE

My first engine had baffled pan and don't know what else (I bought it as a built race car with a reliable history.)
I blew the engine the first race weekend after a long left hand carousel holding >1G the whole time.

When I replaced the engine, I reinstalled the baffled pan and had DD Performance port the oil passages on the timing cover and install Toda oil pump. I also installed data acquisition at the same time to record oil pressure.

Took the car to another local track, and even with the above mods, the oil pressure was still going nuts in a few turns- particularly hard lefts after a braking zone.

Sooo I installed a 2 qt Accusump as well. That has improved the situation and the oil pressures are higher in the turns but still ugly.


The issue is that these engines are flat and wide. under hard cornering, all the oil schleps to the outside head and valve cover and doesn't drain back into the pan before the oil pump empties the sump. voila. no oil, spun bearings. done fast enough, it doesn't just spin the bearing but breaks a rod and the rod then turns into an axe and chops the block into pieces.

I'm working on some other ideas on the oiling and will post about them if they work.

Interesting. One of our local tracks has a long left we call the carousel, my oil pressure fluctuates a bit but stays just under 40 psi for the most part with no oil pan baffle. It’s a steady 1.2g in my car. It’s a corner I get fuel starve in, especially with e85.

[Lynxis]

Edit: I'm going to preface this with an edit becauset I realize that something I take for granted but is likely the biggest contributor of problems; basic maintenance. Everything written below is assuming your failure isn't related to incorrectly performed or otherwise insufficient maintenance, especially oil changes.

Originally Posted by conehead

OK, ok. I know there is golden info buried in different threads, but someone please break it down. Why do 86 track cars always have blown engines? Is there an easy solution??

Originally Posted by Matt93SE

Sooo I installed a 2 qt Accusump as well. That has improved the situation and the oil pressures are higher in the turns but still ugly.

The issue is that these engines are flat and wide. under hard cornering, all the oil schleps to the outside head and valve cover and doesn't drain back into the pan before the oil pump empties the sump. voila. no oil, spun bearings.

It's pretty well established by now that the issues are typically related to oiling and as Matt93SE points out, this is as much a function of the design of the motor as anything else.

I will say these cars are incredibly popular for track use given their performance, price and relative reliability. I know even at track days with only 20 cars, I'll find at least 3 of these cars which is incredibly high relative rate to all other cars. I don't think it would be a stretch to suggest these are the single most tracked cars in America right now. Just mentioning this because relative numbers are important to keep in mind, if you see 5 blown FA20s for one blown Miata, just keep in mind this is probably proportional to the number of tracked cars out there.

I'll note that the vast majority of people who stick to NA power and street tires (200tw limit) have been driving their cars for years now without a more serious failure than a burnt coilpack. Of the 5 people I personally know who track 2016 or older twins, not one of us has had a blown motor but we've all limited our mods to headers and tune and 200tw tires. I think the higher frequency of issues with tracked cars are largely from people who are adding FI or race slicks and at that point, you should probably be running baffles and sump oiling systems at a minimum but these are the things that are forgotten until a motor explodes.

This is just what my personal, mostly anecdotal experience has to say.

[NoHaveMSG]

Track layout also has a big effect. 3 of my local tracks have sudden elevation and camber changes that drop out oil pressure even on slower tires. It’s usually brief.

[Ultramaroon]

If I were to purpose-build a boxer, I would start with dry sump and go from there. Won't happen, though. I don't want it badly enough.

[Sapphireho]

Originally Posted by Ultramaroon

If I were to purpose-build a boxer, I would start with dry sump and go from there. Won't happen, though. I don't want it badly enough.

That's why my 911 holds 13 quarts of oil in the oil tank.