arghx

iTrader: (3)

in no particular order:

1. Overboosting-- due to a free flowing exhaust with insufficient wastegate flow, or due to problems related to a boost controller.

2. Fuel system failure--clogged fuel filter, failed injector or fuel pump, low fuel pump voltage

3. Tuning problems-- especially when weather changes occur and the tune can't account for it

4. Overheating-- leaks due to old hoses and water pumps, failed cooling fans, or insufficient cooling capacity for the engine's horsepower level and the type of driving

Note that 20+ year old original motors with very few modifictions do eventually fail due to mileage and age, yet turbo engines rarely die a slow death.

Black Knight RX7 FC3S

iTrader: (7)

I would put Fuel system as the number one reason for blown turbo engine though.
Ive seen more blown engines from insuffecient fuel, then overboosting, from pistons and rotaries.
For the noobs thats just starting out on turbo engines, overboosting is definitely a top reason for blown engines lol

j9fd3s

iTrader: (3)

agreed! the old school FC people will tell you the RB turbo back system with the headlights on = blown engine.

which is failure #2

4 happens to any engine. it is VERY important to maintain the cooling system. it is good practice to replace ALL of the cooling system hoses at once, especially when replacing the engine. if 1 hose fails, it can ruin the engine.

we don't see #1 very much in CA, since we have smog a lot of cars are just stock, and the not stock guys are too scared to run more than 10psi. the failure #1 example is the 2006+ Subaru's those just blow up, even stock unabused cars.

#3 is more due to sloppy workmanship. i see a lot of that. bad plug wires, vacuum leaks, misrouted hoses, motors with used (read that as bad) or mismatched parts.... you name it

thejallenator

iTrader: (14)

no the number one reason should be beacuse youre an idiot.

K-Tune

iTrader: (26)

User error during assembly is also a huge factor(won't affect mazda original engines)

as well as oil maintenance.

beefhole

iTrader: (29)

Based on what I've seen/read/experienced the past 7 years.
Tuning problems are a major problem. However, most people never get to the point of tuning, so I would put that last.

Fuel problems. If anything, our fuel problems are the cars run too rich. Sure every now and then a fuel pump fails, or an injector seizes... someone leans out an pops. Has this happened a lot though? I think the problems occur during normal driving over a period of time and are "discovered" via diagnosis. Ultimately these failures initially prevent an overall engine failure.

Overheat and overboost I'd say are nearly on the same level. Overheating will kill ANY engine. It may do it slowly, or instantly, but it's death no matter what. However, people do drive around with engines drinking coolant. Hey, if you keep filling up it will still run right?

Overboost. That will really do it. Why overboost occurs is its own topic. But what it does will break an apex seal and the car is rendered useless.

I'm not an expert and not as experienced as many people here, but this is my list and I hope others get something out of it.

87GTR

iTrader: (61)

I would have to say Sun Spots causing electromagnetic interference with signal from the CAS :P

beefhole

iTrader: (29)

Hehe that's only when you switch to most standalones

incubuseva

iTrader: (13)

I would agree with pretty much what you said. Although *knocks on wood* I overboost, but yet haven't blown up. Yet. My AFR's are still super rich too. I know timing affects this as well, but that's stock also.

gxl90rx7

iTrader: (1)

i believe #3 is the most common.. more specifically people throw a free flowing exhaust on with stock ecu. stock ecu + anything other than stock setup = ticking time bomb

the first go-fast mod anyone should do imo is a proper standalone. ive been running a haltech for years, nice conservative 300whp tune. I give it hell whenever i drive it, and never blown an engine

arghx

iTrader: (3)

On the more mildly modified setups with stock turbo, overboosting and fuel system problems are the most likely killers. Sometimes even a ported s5 turbo wastegate doesn't flow enough to keep boost under control in cold weather. Old injectors and old fuel pump wiring can also cause lean conditions.

On the higher horsepower cars tuning becomes a bigger deal, especially if you have a standalone which does not use an AFM. MAP based systems are even more sensitive to changes in the weather so they need a lot of tuning to stay safe year-round.

Cooling problems can occur on any setup, especially if you have a busted heater hose or failed fan clutch. Setups with front mount intercoolers and electric fan conversions have additional cooling challenges.

Black Knight RX7 FC3S

iTrader: (7)

me personally, I have encountered all the problems, except tuning problems.

I overboosted on the stock turbo by accident when installed a manual boost controller, damn thing went to 20 psi haha, probably stayed there for 5 secs atleast that was what my passenger told me.
ive overheated when my electrical fan just stopped working, temps went to 240-250F for half a mile.
The final thing that finally blew my engine was the fuel. Injectors maxed out on duty cycle and detonation occured, my front rotor has no compression at all only the rear, drove home with just the rear rotor lol
My friend civic running 3xx cc injectors on a 17psi to4e turbo...thats just waiting to detonate, 2 weeks later, it happened.