used JSpec motor blew 1 mile after installed. -- vent thread
 

front rotor seems to have no compression. i made a wot pass in 2nd gear , afr was pegged to 10.0:1, ignition timing was around 18 degrees and split was about -8, suddenly the car sounded like it was running on one rotor. checked for compression just using my hand, and there are strong pulses coming from the rear rotor, but really weak ones coming from the front rotor.

if this is how sensitive the rotary is, i'm going to the dark side. expect a major part out thread coming soon. :icon_tdow

cya then, forced induction is the same for any vehicle but only slightly more sensitive in the rotary.

why were you WOT boosting a fresh engine with only 1 mile on it? you know you'll get flamed for that but i think you want it, except for this case it only furthers the bad name of the rotary engine.

keep in mind you can have rich AFRs but that means NOTHING! do you know that both injectors were firing at 100%? one can be working properly dumping fuel and keeping AFRs within target after mixing with the second rotor which could be running excessively lean. unless you either had the injectors serviced and the shop did in fact put the right injectors in the package to send back, your wideband is accurate and your injector clip didn't simply pop off at a really bad time then ANY motor probably would have let go under the same situation.

i feel your pain but don't blame the motor for something that probably isn't its fault. there is good reason why there is also a break in period. burrs in the rotor apex slot can bind a seal in boost where it would lap in normally with simple miles driven in other cases. we have no idea how liberal you were with your cleaning and spec'ing of the engine.

i see engines blow all the time while in the target AFR range, then after testing the injectors low and behold one is 15% out of spec. this won't show on your wideband, unless you have dual widebands(which no one does because they will cook to death).

i see all this bullshit all the time, people swapping to V8s for not being dilligent during rebuilds or maintenance. try something different if forced induction is obviously not for you, build a naturally aspirated 3 rotor.

there, now you have me ranting too..

Why would you go WOT on a motor that has 1 miles? That's stupid. ^ like stated above, could have been a lot of thing that = to operator error.

I agree. I always wait at least 20 miles before going WOT to redline. depending on new or used bearings/metal seals/housings.
:lol:

it wasn't a fresh motor. it was 29k mile used jdm motor which had 100psi compression roughly on both rotors. all injectors were serviced and balanced. the injector clips didn't pop off. the engine was running for a long time ~10hours idle + revving before it was taken for a cruise to be tuned.

same with other engines? i have to disagree. i have a turbocharged 4g64 9:1 that was beaten up worse than this (22psi on a 35r with aem ems).

Who did the compression test? I will never rust a JDM motor or a motor that I can't verify its history. Even on my Honda days I will not trust this after going through 2 motors in less than 3 month.

What mods are you running and how much boost?

I think you need to change the post title. This is not a 1 mile engine.

even worse thing to admit then and be pissed about. many threads have been disclosed about jspecs which have been sitting in the elements for years, then shelved, then set outside and buried 6 feet under, dug up, pressure washed off then wrapped and sent to you.

run time means nothing as well, have you ripped the motor apart to see what actually happened to it yet? i have had more than one customer who accidentally dropped a nut/bolt down the intake, ran the engine for 30-45 minutes perfectly fine then once they hit a bump with some throttle "hiccup, fart, pop!" the motor sounds like a lawnmower as the bolt/nut gets sucked in.

your 4g is argumentative how? we don't even know what caused this 15 year old shelf motor to fail..

listen, one time in my car i cracked a rear plate from overboosting. i pulled out the motor and replaced the rear iron, while the motor was out i fixed a leaky wastegate issue but failed to adjust the boost controller back down to compensate enough. i took the car out, made a right turn and went WOT, left a trail of oil down the street and right back into the bay that i just pulled out of. who could i be pissed at? the motor? no, i smacked myself and went back to work. shit happens, if you're smart enough you never make the same mistake twice and eventually all of that pain pays off.

i verified the compression pulses myself when i went to go pick the engine up. i saw the car it came out of. gt3582 1.03 a/r t3, 550/1680cc injectors, 8.7psi (was just trying to tune one row of the boost comp map slowly)


what are the chances i flooded one rotor? 10:1 is pretty rich.

after blowing my first engine due to the fuel atomization plates breaking, i was meticulous in making sure there was nothing that could fall or break. (i removed all atomization plates)

Do another compression check and check your coolant levels. JDM engine could have good compression but a bad coolant seal that could have gave way when you when WOT, log shot but possible. You could also have a stuck injector flooring the front housing. When you felt the pulses, was there fuel coming out?

i'll just give you an example of how much a 15% discrepency in low output from one injector can cause AFR wise.

say you have one injector firing 100% spray pattern producing a 9.5:1AFR, then you have a second rotor injector that has 15% low out put spraying 85% flow with an output of 11:1 AFR, your wideband will read the average of the 2 at 10.2:1.

of course it would have to be further than 15% out to cause a failure with your wideband reading 10.1:1 but i still listed it as a possibility anyways not knowing if you did have the injectors serviced or not.

This could have attributed to your problem I believe.

i pressure tested the coolant system before putting it into the car
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/homemade-coolant-tester-953769/

the front rotor plugs were really wet when i pulled them out. i cranked the car a bit and a bit of fuel came out (i made sure to WOT the throttle to inject no fuel). after a while it all seemed pretty dry. but the pulses dont seem strong still.

i'll compression test it soon and get the numbers

doubtful, atomizers are mainly for fuel economy and a slight increase in torque(hah, i said torque).

You bought an old engine and blew it apart. Very unlikely it had 29K. Very likely it sat around for a long time. Whats the point of this thread? To tell people not to buy JDM engines???

front rotor 0-0-0
rear rotor 95-92-94

you put a JDM junkyard motor in your car and then you wondered why it blew up. Old 3 piece apex seals is just asking for it on a single turbo.

if you had pulled that motor apart it may have had a lot of good useable parts. it could have been a good base to build up properly. now you have a trashed rotor and a trashed housing at least

This unfortunate event could have been avoided if the setup was properly taken care of. A compression test, data-logging 0 psi and perhaps small increments in boost to isolate any weak wiring/defective injectors/fpr or even a bad batch of fuel.

Anyway, sell me the short-block. Sorry for your loss...

Seem that your motor was on it way out when you got it. Post picture when you take it apart. Would like to see the seal and housings.

This right here! There are so many other factors that causes rotarys to blow that easily get over looked during rebuilds. If you never source the problem that took out the previous engine, I don't care if the newer engine is built by the hand of God, it's gonna suffer the same fate. I mean seriously I don't see how some rotary shops offer the warranty they do. Customer sends in a blown core for rebuild. Shop sends rebuilt engine back with 1 year warranty. Customer blows engine again because of improper flow differences between the injectors or a freyed wiring harness that cut power to one of the injectors. Customer try to send engine back for warranty repairs. Warranty get denied. Now customer is slamming the shop and the rotary to all his friends. Rotary's reputation gets worse due to customers own IGNORANCE. I'm with you Krack! I can keep on ranting too!

:mad:

The compression test really means nothing with an aged used rotary engine. The compression test will never tell you the state of carbon inside the engine. These engines are always carbon infested (especially after sitting up for years on end). The factory 3 piece apex seals also get very brittle. What do you think happens when carbon chunks finally fall of the rotor face and start jamming those brittle apex seals? The engine goes snap crackle and pop! If you don't check the used engines state of carbon before installation, your asking for trouble. Period! When I bought my 20b back in 2003, that was the 1st thing I did was remove the turbos to inspect for carbon build up. I've already had a 12a engine carbon lock before. Originally I was afraid to open the engine so I figured a way to clean out the carbon (which I did). Engine went from have no compression to having compression in the 90's on all three rotors. At that point, I was confident enough that if I ever got that engine running that nothing would be falling off any rotor face to destroy my engine.

Pretty misleading thread title....

+1. why on earth would you buy a used engine on a car that is renowned on the internet for blowing engines and expect it to be any better than the blown up motor you already have?

I am very sorry for your luck, but it makes me thank my engine builders. I trashed my previous rear rotor/ housing when it blew. Got a jdm motor and had it rebuilt and it's great. Then again I'm mostly stock. Hope it works out for you.

I can attest to the ridiculous amount of carbon that builds up in the engines here. For the average owner there's not many places where you can just go WOT and run the car hard to keep the carbon down.

The engines themselves typically have low wear though. I just bought a used engine about 6 months ago, rebuilt it and got it back on the road a couple months ago. Yesterday I took it for a compression test, result was 115 front 118 rear. OMP is deleted so carbon won't build up during daily driving. I've got AI but have yet to install it as I wanted to get the engine broken in and test everything first. During the rebuild everything was tested and injectors were cleaned.

Why not spend the time and effort to verify all the internals are good and put in new seals and rebuild it right instead of just putting one in and hoping it would be ok. Lot of wasted time and effort just dropping in an engine that seems ok.

I'd love to see pics of it as well once you open it up.

will post up pics. pending on what the reason of the blow up was, i'll decide whether its time to move on or actually spend more time and effort on the rotary engine. it's kinda tiring after 3 years of dealing with this shit :\ i myself deleted the omp and was running premix in the tank, but I guess that doesn't do anything about the carbon that was already inside the engine. it's so odd, I actually inspected the apex seals through the exhaust ports and they were nice and springy, with no sign of carbon build up.

Why are you guys slamming him for buying a used engine? Tons of people do this because the used Japanese engines are known for being in great condition and low miles. But every once in a while there is a bad egg. It's true they usually don't ever get over 30k miles. But it's a lot of stop and go traffic. So yes there is bad carbon build up. And you don't know if the previous owner was drifting or abusing the engine otherwise. So it's a bit of a gamble but even a rebuild is a gamble. He just had some bad luck. It doesn't mean you shouldn't buy used engines.

Either way I feel your pain Zeeshan. That really has to suck especially after it was running just fine.

+1

Not to mention that he never stated the engine only had 1 mile. It decided to go 1 mile AFTER INSTALLING IT. It's amusing when the new guy isn't the ignorant one.

We are aware of this, after he clarified it. Going WOT on an unknown engines is asking for it. Just because was idling ok and was able to be rev, doesn't mean it will be the same when under load. He should have taken it easy and slowly work his way up till everything seem fine. I have 2500 miles on my current engine and I haven't gone WOT yet.

Doing what he did is like going to Thailand and jumping in bed with the first piece of ass you see.

What's wrong with that? hehehe

i guess i just needed to vent. oh well. not knocking the rotary, but it's not for me.

*runs*

Well, it might have a sausage in it's pants for one thing.

Buying a used engine is ok. If you get a used block though why not crack it open? Verifying the coolant walls, bearings, etc etc is just the smart thing to do on something that requires so much work to replace. Spec everything, buy some new seals, put it back together and you KNOW the condition of the engine.

Buying a used one, dropping it in and crossing your fingers is just not a good idea. There are a ton of posts where people have done this, and it seldom ends well. then of course they blame the "damn JDM engines". The JDM engines are put together the same as one built in the US, it's not like the build is any different.

would you buy a used gun and put ammo in it and just start firing without checking it out?

lol

I changed the thread title to make it more accurate.

originally it did state that it blew after one mile. Let's leave the statements of ignorance out of this, ok ;)?

Dual egt, its the only way to fly, afr is great and all but without egt what do you really know.

I'll be waiting for the part out thread. Interested in some parts.

You vulture lol

all jspec motors have 30-40k miles magically lol

The reason why they are advertised that way is because the taxes and other fees in Japan create a financial incentive for owners to junk or otherwise get rid of their cars with that kind of low mileage.

it was a front clip, unless someone tampered with the digital odometer, it had 29k miles which is 45,000~ km

This is true.

I believe the mileage. You must have gotten an engine that was severely abused. If you think about, they're really popular vehicles in the "racing scene" in Japan so I wouldn't be surprised if that engine came out of a car that was used for drifting.

Im no engine builder but I have heard countless stories of engines with perfect compression blow. Its either a tuning error or driver error. Or something else was wrong with the car, NOT engine related.

Can't always blame the engine when it goes cause it had a bad rap. Assumptions like those ARE the reason they got a bad rap.

shoulda rebuilt the engine or made sure it was good before heavily modifying it. throwing in a used rotary engine that has been sitting for years, is probably not in the best shape. I've had a used S5 13BT engine before that is still alive after 60k+ miles. And I've also received a seized S5 13BT engine before. as well as put in a used S4 13BT engine for one of my customers that had good compression but bad coolant seals. I have yet to blow a Rotary engine after 8 years of hard driving on many of em that I owned from S4, S5 NA or Turbo, and used JDM FD engine. Knock on wood, hope it doesn't happen to me now. But one thing I do to try to prevent it, is make sure everything is working and fuctioning 100% and maintenance it. Good luck with your next motor, whether its Rotary or LS1.

If you think about it the only place that engine would've come from is a crashed car. And just about the only reason they wouldn't sell it here is if someone died in the crash. There is a law here about that sort of thing and if one person dies in the accident you are required to inform the next buyer. Even if they just died idling in a parking lot from a heart attack. So usually you cannot sell that car so they are auctioned off to foreign buyers. It's just as hard to find used 13B REW rotary engines here as it is in America so they just don't auction them off for nothing. Especially with the exchange rate how it is right now they catch a better price in Japan than America. These engines are still useful even beyond 30,000 km.

About the Shaken.

Every 24 months there is a 60 point inspection the car has to pass and you need 8 documents to pass it. You can actually do it yourself and bring your own vehicle to the inspection center. This is called User Shaken and there's a whole club for it:

http://www.asahi-net.or.jp/~EP7Y-TMT/

Older cars are more expensive (if you're paying a shop to do Shaken for you like %99 of people) because before 1995 there were more inspection points on the list. So a 1996 RX7 only has 60 points of inspection, but a 1995 has more (I don't know how many).

Costs break down:
JCI (Japanese Compulsory Insurance): This is determined by the average rate of accidents in your prefecture. It's currently 22,470 yen in Tokyo for a passenger car and 18,890 yen for a Kei car. Everyone in the prefecture pays the same so it doesn't matter how old your car is.

Weight tax: 25,200 yen per half ton. So it's around 75,000 yen for an FD. If your car is less than 18 months old, a kei car, or a hybrid you get big discounts here. I mean this is almost $1,000 every two years so it's important. If you have a kei car it's only 7,600 yen. Besides that the mileage doesn't matter, only the age beyond 18 months.

Test fee: 1,700 yen, 1,400 for kei cars.

Application form fee: 35 yen.

I'm not sure if they are still charging the recycling fee. There was a problem with people abandoning cars that they could no longer afford to keep so they started charging you at the time of registration for the disposal and recycling fee of the car.

Engine displacement tax:
69,000 for two yeas on the rotary engine. They measure it as 1300 CC. If you have a kei car it's ridiculously cheap, same for a hybrid and there's discounts for new cars. But they add %10 if your car is older than 10 years. But again nothing to do with the mileage.

Here's a link to a story in English about someone doing user shaken:
http://www.bigdaikon.com/mystory-20030305.shtml

So beyond the small additional fee's and taxes that are added for an older vehicle, the primary reason they are more expensive is because of maintenance. Most people are paying shops and auto repair is on par with dentists here in terms of perceived professionalism and cost. So if you need to change a turbo in your FD you might as well just buy a new FD. But there are those people who are truly enthusiasts and maintain their vehicles very well, even doing the work themselves. For those people it's no problem to pay the %10 more on the engine tax. They've already put thousands into the car otherwise.
So realistically if you have a wrench and know how to work on cars you can do user shaken and not really pay much over $2,000 every two years. It might actually be under 200,000 yen total.

i'm honestly betting a bolt made it's way into the intake during assembly.

Did you even open this engine before you installed it? An ounce of prevention...