Mr rx-7 tt

iTrader: (5)

Just kidding with you... Hope everything works out for you. When you get it running give me a buzz and we'll grap a beer.
Chris

RedX7

Sounds good to me.

SPOautos

So its interesting that ONE injector shut down, which caused detonation (which how did it get so hot with no fuel?). Then on top of that somehow an apex seal turned into David Copperfield, and magically got to the other exhaust port so it could take out the other turbo as well.

Hmmm, so one injector fails and that caused detonation....eventhough since its stuck shut there is no fuel meaning no heat. THen somehow it took out both turbos eventhough the exhaust port only goes to one turbo.

Maybe you had a bad turbo before this and just didnt know......or maybe the cause isnt the injector and really it just blew from bad tuning and both rotors blew....taking out both turbos

BTW - I'd be curious to hear Daves explanation as to how detonation occured with no fuel (thus no heat).

STEPHEN

rotorbrain

im not understanding how "no fuel" means "no heat" stephen. if youre in the middle of a happy little boost run. . . and all of a sudden you run out of fuel, youll still have heat. . . from all that boost and an engine thats been running hot from boosted runs. makes sense to me. fuel is used to cool down the face of the rotor. so with no fuel the rotor would heat up tremendously. . . causing detonation. how did all those people of years ago come up with the rule of thumb "dont race w/less than 1/4 tank of fuel." they do that cause the tank sloshes and temporarily the injectors get no fuel. if at one second the car has fuel and is in the middle of a high boost run and then another split-second there is NONE, that engine is toast. . . that much is logical. i could see a stuck injector not LETTING you run boost up, but if an injector sticks SHUT while in the midst of a high boost run. . . bye,bye engine!!!!

why in the world does everyone get an FCD??? cause during boost runs, you dont want that rear rotor to lose the fuel it needs to keep on going. . . why??? cause its GONNA BLOW. this is proven. fuel cut in the midst of boost = bad. . . nothing else.

paul

RedX7

It was the front rotor that went. When you compress air (boosting) it heats up-a lot. Driving at 5500RPMs (approx. 90 shaft revolutions per second) and boosting, if an injector goes out-it's over. The heat of the compressed air will detonate. If both turbos are on line, and pieces of the apex seals go flying through, both are going to get smashed.

mjw

iTrader: (1)

No that doesn't seem correct, if there is absolutely no fuel injected into the chamber it will not ignite/detonate because there is nothing to burn.. ie no fuel. He still has primaries though and the small amount of fuel from that would certainly cause detonation if the secondary stuck shut spontaneously.

RedX7

Good point. I forgot to mention the inadequate supply of fuel from the primary injector.

GoodfellaFD3S

iTrader: (213)

Are you serious? Correct me if *I'm* wrong, but aren't you a mechanic at a rotary shop, my man?

rotorbrain

thank you. . . forgot to mention that "small" part of the equation. . .

paul

SPOautos

with no fuel there would be nothing to combust....mjm is right though, I forgot about the primaries that would still contribute fuel if just a 2ndary went out.

BTW - People dont get a fuel cut defender to save thier engine from fuel cut. They get it so they can turn the boost up higher without getting fuel cut cause its hard to race someone when your ecu is cutting the fuel.

STEPHEN

pluto

I don't think 30% of the required fuel would even cause any detonation. Have you try to run the car at 17:1 or 18:1 a/f ratio? it's impossible because there isn't enough fuel to break down oxygen molecule to even make any power. The car would just died and falls on its face instantly. Also, I don't think lack of fuel would make enough energy to create any catastrofic detonation.

These are just my personal experience so I could be way off. Maybe I should connect a switch to my secondary injector so that I could test it myself by disconnecting it?

pp13bnos

iTrader: (1)

Thanks for the info guys. After my car got off the dyno, it ran great. But within 15-20 minutes, it would hit 4,500ish and just fall on its face/pop and snap. I'am running the 1300s, and am going to pull them out and put in some 850 (and do a little reprograming) just to see if thats the case. Looking back, I did have a problem with one injector sticking open when I first picked them up. Thanks for the heads up guys. CJ

BTW, the car made a nice 392rwhp on a mustang dyno. Stock clutch and motor with 49k miles on it!!

Marshall

As others have hinted, I have serious doubts that the injectors alone are at fault....

wonder1and

mine did the same a few years back.

SPOautos

Ummm, arent you Zavier, the head RX7store mechanic?

No matter what kind of turbo it is the exhaust goes thru the turbine wheels before the downpipe. The downpipe is hooked up to the exit side of the turbine wheel. The only exception to this would be if by chance the apex seal went thru the wg. I've seen large singles with apex seal damage on the turbine wheels many times.

STEPHEN

IRPerformance

iTrader: (41)

This is funny... Every motor I have blown has resulted in a damaged turbo from pieces of apex seal hitting the turbine blades. If the exhaust comes out of the motor and goes to the turbo, and out the downpipe, then anything that comes out of the motor has to go through the turbine. I spoke with a rep at Marren Injector a while back and they told me they WILL NOT enlarge any injectors. There is just too high of a failure rate. Go with bosch 1600s. They are less expensive and yo are getting brand new injectors, not bored out stock ones.

books

iTrader: (8)

Did Marren Injector give any explanations as to why enlarging injectors contribute to a higher failure rate?

thanks for any additional info

GoodfellaFD3S

iTrader: (213)

As I understand it, injectors aren't really meant to be taken apart, bored out, and put back together. With turbo rotaries, you're playing with fire messing around with fuel system components. Having said that, I am running 1300cc bored out secondaries for over 3 years with no problems. Back when I purchased them I did not know what I do now. If I could go back I would be running 850/1600 instead of 850/1300.

books

iTrader: (8)

I am still interested in what actually fails and how it is related to the boring of the injectors. I too, have 1300's although I have not installed them yet. I bought brand new injectors and then had them bored, believing/hoping possibly the failure rate is attributed to the age of the injector.
I did speak with RC this week about this topic, perhaps they will enlighten us.

lane_change

iTrader: (20)

Why is everyone going with 550/1300 combos instead of 850/850 combos? And if you need more fuel than that, just get a rail and go with 1600's.....but if this is true and the risk is there to blow your motor due to bored out 850 injectors...well, **** all that. I am going to run 850/850 on my TT car until I go single...at which time I will just switch to Keiths fuel system again like I had on my last single FD.

Crazy to think of this **** happening.....sorry for those of you that did lose a motor/turbo/etc...from a stuck injector.

SPOautos

Honestly I dont think its the fact that they are bored thats hurting them, people have been running the bored injectors for years and years and years. I think the problem is most of these injectors now have a ton of miles on them and if they start to have problems its probably cause they reached thier life expectancy. Remember they are based on your cores you sent in.

As an example, our business has around 6 Ford F350's. The 1600's everyone gets are designed for these trucks and I think the new Duramax also runs them (not sure about the Duramax though). Anyway, the point is that ALL of these trucks have needed every injector replaced around 100K miles. When your 1600's get up in the miles they are going to fail. Why would our factory injectors not do the same?

STEPHEN

artguy

hahaha...a brave man indeed.




j

MichaelFregoe

iTrader: (1)

How many people with stuck injectors add 2 cycle oil to their gas in addition to the stock oil injection? Any comments? I think a little oil might help the injectors as well. Just my 2 cents.

radkins

I think Zavier must have been working some long hours(or someone at the store logged in under his name) cause he was explaining that to me a few months ago when it happened to my turbo.

radkins

When I was stupid a few years ago, I raced my FD manyl times with the fuel light on(smart right?) and in 1st gear it would loose power when the gas would slosh to the back of the tank. Never blew though. I did this a dozen times or more.