How often do engines fail because of FI?

[Xxyion]

So question i had. I have found during my research that you generally dont want to go above 300 whp or above 10 psi on stock internals otherwise your engine will blow.

Now while i dont really dispute that claim i am curious.

How often, or what is the percentage of failure on cars where people have pushed past the recommended limit? I think it would be beneficial to see some good hard numbers or at least a rough estimate of this.

I'm not trying to push my luck this is purely curiosity.

A big reason i ask is due to the fact that everyone seems to make out the FA20 to be this super fragile engine that as soon as you try to add more power it just explodes. However i always hear about how people have old 93 Integra's or Civics pushing like 600 whp on stock internals. Were those engines just better built? I find it hard to believe as those cars costed next to nothing even for those days.

I also see many posts of people saying "I'm at 450 whp on stock internals!!" or something similar and the only response they get is "your on a ticking time bomb" but with no real evidence to back it up.

So yeah does anyone actually know the real numbers behind this? Or is this something that has been assumed because a few early boosted motors blew up at a certain limit when the car came out?

[gramicci101]

Subaru engines back then could so the same. The old closed deck STi blocks were monsters. It isn't because engines were built to be stronger out of any desire for performance; it's that materials testing and production methods weren't anywhere near as developed as they are today, so everything was overbuilt just to be sure. Car manufacturers are in business to make money, so if they can cut materials by having their 200hp engine be built lighter to hold 250hp instead of 600hp, they spend less and make more.

[Xxyion]

Originally Posted by gramicci101

Subaru engines back then could so the same. The old closed deck STi blocks were monsters. It isn't because engines were built to be stronger out of any desire for performance; it's that materials testing and production methods weren't anywhere near as developed as they are today, so everything was overbuilt just to be sure. Car manufacturers are in business to make money, so if they can cut materials by having their 200hp engine be built lighter to hold 250hp instead of 600hp, they spend less and make more.

that makes sense. It's a little disappointing going to be honest, and also knowing that their profit margin technically went up because they get to spend less but charge the same. But they are also in the business of making money and i cant fault them for that.

[Yoshoobaroo]

Originally Posted by Xxyion

that makes sense. It's a little disappointing going to be honest, and also knowing that their profit margin technically went up because they get to spend less but charge the same. But they are also in the business of making money and i cant fault them for that.

Manufacturers have to spend much more on safety items and electronics now. Overall their profit margins have stayed the same, and I'd argue that we get cars that are much more value for money now. Our cars go for under 30k, about 18k in 1993 money. That's exactly what a 240SX went for, but our cars are significantly more powerful, handle better, are more refined, and from a safety point of view they make the 240 look like a box made of aluminum foil.

The NA 300ZX would be closer (not quite) to the performance of our cars, but they are heavier and started at 30k. That's 50k today.


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[cdrazic93]

Originally Posted by gramicci101

so if they can cut materials by having their 200hp engine be built lighter to hold 250hp instead of 600hp, they spend less and make more.

Hehe this engine is still f'kin heavy too

[gramicci101]

Originally Posted by cdrazic93

Hehe this engine is still f'kin heavy too

Sorry, built less durable.

[cdrazic93]

Originally Posted by gramicci101

Sorry, built less durable.

I know thats the problem

[COO86L]

I pushed the limits and ran 18 PSI on stock internals with a Borg Warner EFR 6758. That was after running a Sprintex 210+ or SPS kit on 69mm pulley. All tuning completed by Delicious Tuning.

People will say it's a ticking time bomb but really, the amount of boost etc means nothing. I had a friend who blew his engine up N/A just driving normal. I've heard of cars sitting on cruise control on the highway bending rods. I know amazing tuners that have only run 7 PSI on theirs and bent a rod (that particular one was a track vehicle though)
There's a tuner in Aus near Sydney who runs about 313kw and 500nm to the hubs and tracks his car and hasn't had an issue.

[Calvin27]

Maybe a better way to gauge this is to somehow compile engine failures and what exact part failed and under what conditions. A lot of boosted 86's here in Aus run street only.

I haven't heard of smashed gearboxes, so I think drive line is ok. Which basically leaves engine. Spun bearings are relatively common for this engine (suspected oil pump failure possibly) but I don't know that this has an relation to boosted cars. If anything boosted cars probably don't get revved as high and almost all run oil coolers. Actually come to think of it, I haven't even heard of any boosted cars failing other than crap tune or being totalled . No stories of bent rods or anything.

[COO86L]

Originally Posted by Calvin27

Maybe a better way to gauge this is to somehow compile engine failures and what exact part failed and under what conditions. A lot of boosted 86's here in Aus run street only.

I haven't heard of smashed gearboxes, so I think drive line is ok. Which basically leaves engine. Spun bearings are relatively common for this engine (suspected oil pump failure possibly) but I don't know that this has an relation to boosted cars. If anything boosted cars probably don't get revved as high and almost all run oil coolers. Actually come to think of it, I haven't even heard of any boosted cars failing other than crap tune or being totalled . No stories of bent rods or anything.

Maybe we can just say that Australia is Number 1 boosted 86 country? ;D

I have a few boosted brothers that snapped CV shafts. One other kept running into spark plug issues of some description but not sure exactly.

I know of a few engines that went bang but the owner expected them to blow up as they were pushing the limits.

[Calvin27]

Originally Posted by COO86L

Maybe we can just say that Australia is Number 1 boosted 86 country? ;D

I have a few boosted brothers that snapped CV shafts. One other kept running into spark plug issues of some description but not sure exactly.

I know of a few engines that went bang but the owner expected them to blow up as they were pushing the limits.

Lol, that's because we get shafted on Australia tax on every other car!

CV shafts sound about right, but spark plugs happen due to heat - which also happens on NA cars with untreated headers.

[Hags86]

Bent two rods with 240 rear wheel KW. Engine was 60,000km old with plenty of track days under it's belt before the turbo install. Lasted 7,000km after boosting it. Only had one track day after the turbo went on and that was taking it easy on a shakedown.

[majixmatrix]

I really wish we could compile a list of data for bent rods etc. like the nice forum for the classic p0018 codes...

[Hags86]

Originally Posted by majixmatrix

I really wish we could compile a list of data for bent rods etc. like the nice forum for the classic p0018 codes...

So the symptom of the bent rods is the air/fuel ratio changing. I had some problems with the A/F drifting over a few weeks and the ECU needed to perform a lot of fuel trims to try and compensate. We couldn't figure out why. Faulty MAP sensor or Lamba sensor? Changing the engine efficiency table an it would be sweet, and then drift away again.

Turns out the compression ratio was changing as the rods bent and lowered the CR. All 4 rods were in fact bent - the photo is just the worst two of the four.