F/I Blowing motors facts
 

Hey everyone I just want to put a few facts out there for you new F/I guys who are not really tech savvy on this platform or to the people that are considering F/I. I don't mean to offend anyone but I am sure I will because someone always knows more or has their own opinions.


Here it goes, THE NUMBER 1 REASON the fa20 blows up under F/I is THE RODS SUCK they are nothing more than TIME BOMBS under the STRESSES that F/I PUTS OUT!!!!!!!!! PERIOD the END!!!!! Will the rods hold up to 8000 to 8500RPM N/A sure they will no problem oil will be the issue then at that RPM if it stays at that rpm for while. So to drive this point home their is no real way for anyone to claim a certain psi is safe. NO WAY!!!!! A gt45 at 18 psi and a GT28 at 18 psi are completely different. And the stress that goes with the bigger turbo are harder on a stock engine.. Sure you have companies out there telling you its all good no worries go for it but they sell products its there job to sell. I don't know of any company that will replace your engine if it pops and that should tell you something... I personally know guys pushing 500 whp on stock motors for close to 2 yrs with no problems. I also have friends that popped around 325 to 350 hp.. Its a roll of the dice.....
Which leads me to the next point. Please please please for the love of whatever you love, stop blaming the tunes....If a rod went its most likely not the tune if you have a huge hole in your piston it could be the tune but it could also be mechanical. Faulty fueling like a bad pump bad injectors. Please find the source before placing blame it's the right thing to do. Their are some really great people on this forum that have years of experience with this craft and have tremendous knowledge about this platform that are more than willing to help you. Most of them for free... Just ask..... So is it safe to boost a stock engine well that depends on what you call safe. Can it be done at a low psi and live for awhile? sure it can but don't' expect it to go 200k and not have a problem.... My thought are this if I bought a new frs/brz the first thing I would do is boost it to 300hp for everyday driving. That's my personal feeling of remotely safe and a risk I would take to have a car that feels amazing to drive... Anything above 300hp I would replace the rods and pistons. Just be aware that the 6k you invest in your boosted fa20 and what the truth is behind F/I
One more quick thing don't get caught up in the numbers game, 30psi or 650hp. Do what feels good to you and stop, numbers are for bragging smiles are where its at. If you get a big cheesy grin at 300hp that's all you need and your car will last a lot longer.. Trust me 640 hp on the street isn't much fun so I just dial my boost down and cruise along. I only run wastegate springs set at 5 psi on the street that's all I need. I hope this helps some of you new F/I guys. Peace and let the flaming begin lol






EDIT:


Tomei compared rods on the factory FA20 to the Factory FA20T and discovered the FA20T rods were a heavier design. Also the pistons were heavier design even tho they were 10.6 compared to the 12.5 FA20


http://dsportmag.com/the-tech/tomei-...a20-flat-four/




I guess Subaru engineers didn't feel safe pushing FA20 stock rods to even 268hp @6700rpm at the crank was safe.


THIS THREAD GETS TOTALLY SIDE TRACK FOR THE NEXT 13 PAGES IF YOU WANT TO READ SOME TOTAL B.S. PROCEED AT YOUR OWN RISK!!!!

So if you made 300hp NA, you would replace the rods and pistons... got it.

I disagree.
You should mention what part of the rod. And why.
You mention oil, so oil starvation? bearings? caps? bolts? WHERE?

If a fa20 could make 300hp n/a on a stock bottom end I would faint!!!

The rods usually break off at the big end and swing around and cut the block in half (ok not in half but put big windows in the top of your block)

rods beginning to fail here(they should not have a bend in the middle lol)
http://www.ft86club.com/forums/showthread.php?t=98229


Element tuning goes into great detail about oiling issue


http://www.ft86club.com/forums/showt...oil+starvation

So what it is? Failure because of weakness or failure because of oil starvation? Two different symptoms, one part. Oiling can be addressed with some work.
What specific part are you talking about? the rod cap? the rod? the bolt? the nut? the bearing? LOL you aren't clear on your "theory" it is just as bad or worse than saying "the tune" as it is "the rods"

Sorry I wasn't clear on what you were asking the rods are weak and can not take the extra forces that high boost puts on them. As you can see in the pictures they deform under boost conditions and break off. IF you want to discuss the tune causing a failure please ask a specific question as I'm not sure what you want to know. Are we talking about lean conditions or spark knock, injector pulse? I have no problem backing up my "theory" with facts..

No, I don't want to talk about tunes, I want to talk about your "theory"
Snipped from one of your links-
"What we're thinking is either a severe overheat due to sustained high speed/high boost operation without an oil cooler on pump gas, or possibly too tight of ring gaps from the factory leading to this failure when combined with the high temperature condition."

Cooling issue is not a rod issue, it just caused damage to the rod.
Piston ring gap is not a rod issue.

So explain your theory again? Weak rods because of too much power? or? What evidence do you have to back this up? Because those links BOTH say oil/heat issues.

Ok now I understand what your saying, I apologize if I was short.
In the link I only was referring to the pictures as a reference my mistake for not saying that. In his failure you can see obvious piston scuffing I would venture to lean toward misgapped rings causing a drag on the cylinder from increased cylinder temps do to boosting or a possible piston pin failure or small end rod bushing failure. I can not say for sure without personally inspecting it myself and measuring everything.
Now with that said I base my findings on all the rods that I have seen that snap off with no piston scuffing. In all the cases that were not catastrophic to the point I could not take the big end off the crank and check the bearing I found all the breakage was in close proximity. There is no sign of oiling or heat being a issue either. I never sent the rod out for a hardness test but from all other indications its weak by design. As you can see they are a basic rod design. Not like a Pauter rod or a H-beam. All in all I would venture to say its the material they are made of is brittle from the manufacturing process of the cracked cap design. Then again they were never designed to be boosted in the fa20 at this compression level. So in closing boosting lets say 20psi in a 12.5 compression motor creates a compression level close to if not over a diesel engine and the rod simply can't take it.


You are running 20 PSI of boost at an altitude of 500 feet. Your motor's static compression is 12.5 :1. At this boost level and altitude your effective compression ratio is 29.41 :1, and without altitude correction your compression ratio would be 29.51 :1.


Boost and Altitude Correction to Compression


You are running 15 PSI of boost at an altitude of 500 feet. Your motor's static compression is 12.5 :1. At this boost level and altitude your effective compression ratio is 25.16 :1, and without altitude correction your compression ratio would be 25.26 :1.



Boost and Altitude Correction to Compression

You are running 10 PSI of boost at an altitude of 500 feet. Your motor's static compression is 12.5 :1. At this boost level and altitude your effective compression ratio is 20.90 :1, and without altitude correction your compression ratio would be 21.00 :1.


No way with these ratios can that rod survive


Now lets do a wrx FA20DIT


Boost and Altitude Correction to Compression

You are running 15.9 PSI of boost at an altitude of 500 feet. Your motor's static compression is 10.6 :1. At this boost level and altitude your effective compression ratio is 21.97 :1, and without altitude correction your compression ratio would be 22.07 :1.


As you can see its a huge difference and the wrx is throwing rods too.


My 1997 Dodge 5.9 Cummins is only 16.3.1 compression and those rods are huge in comparison

I am done here. I will let others chime in.

So what evidence do you have for us, since you've seen it by you own eyes? How many of these motors have you seen? So you've seen more motors blown than the entirety of the forum
come on man put your big boy pants on and act like a adault


So in your opening post you say 20psi on one turbo isnt the same as another, yet you still make that same assumption that psi is psi? LOL

Yeah, sure....


Are you saying Im wrong about that? Do you expect me to sit here and put all example for every turbo made? Really


Everyone ALREADY knows that most mechanical failures(besides the tune/owner/heat) is due to the RODS(power), Bearings(due to oil starvation/heat) pistons(tune/power/heat), or head gasket(tune/power/heat), and for MOST engines in general. That is why a basic block build usually has those items. If you are building a motor and replacing the rods, usually you replace all those other parts....



You are wrong people everyday ask for help where you been??


But the number 1 reason(by numbers) was and still is.... THE TUNE. People do dumb shit all the time like raise boost without adding fuel, or just bad tuners who have no idea how to tune a Direct injection 12.5:1 compression engine with TURBO. Go find me some blown motors with a supercharger(at lower power levels) on an off the shelf tune with an oil cooler. No many, I would say it is hard to find. Edelbrock has a 30k(or 36k) mile warranty if you use their tune.



Ive never scene a tune put a hole in a block what proof do you have on that theory...
Doesn't a low boosted s/c motor putting out 7 psi make less compression (kinda goes along with what Im saying huh less boost less pressure rod will live)
Edelbrock warranty lol







COVERAGE DETAILS




• Terms are 3 years (36 months) or 36,000 miles, whichever occurs first – Time is measured from the vehicles original in-service date and the mileage is measured from zero (0) on the odometer


the reason for boom is-- too much power for what the engine was designed for. There is no reason for the factory to overbuild rods when the intention was to make NA power.

Didn't I basically just say that????


the number one reason a fa20 blows up, besides a bad tune, driver error, install error, or cheap parts.... is.... the rods, and usually from trying to make more power than the engine was designed for


Some people would argue with a fence post SMH

Sounds good no sense arguing when you probably have a stock motor anyway

I'm not sure what the point of this post is.... I'm pretty confident that everyone that has gone FI has done so with the knowledge that you have bestowed in your OP. Did you have a friend not do his due diligence and blow up @ 19psi of boost?

Boosted or not all high volume manufacturers have engine failures. Sometimes they don't even make it from the dealership to home. The FA20 has proven both durable and fragile depending on which thread you want to read.

I think its relatively common knowledge these rods aren't meant to handle boost and are relatively weak above 300-350 whp... on the frs ( and even on the wrx, at these power levels). Tunes can contribute too as well as how the power comes on. But regardless these engines weren't designed for boost and hearing "it was the tune" does get annoying. Yeah it happened after the tune sure...you know what else happened? You boosted the car tripling its intended power output. Things go boom exponentially quicker when additional stress is added.