paw140

Well, I think you can add me to the list of people on their second engine.

I was doing a little joy riding tonite, nothing too hard. I really wasn't driving the car too hard at all. For some reason I thought to myself, "I wonder at what RPM I get full boost at?". So I have it in 3rd gear, doing about 35 to 40 mph, and I floor it. I hit 10 psi somewhere in the 3000 rpm range, and all of a sudden I have no power. I didn't hear any detonation or anything (I had the radio on though). The engine sounds like **** (like its missing very badly). And I figure I blew an apex seal.

So I was able to drive it home, in 2nd gear, doing about 45 mph for about 5 to 7 miles. The car had enough power to accelerate at about 4000 rpm, but thats about it. I never let it idle the whole way home, afraid I would not be able to restart it. I finally got home, pulled it into my garage, and as soon as I let it idle, it dies.

So I popped the hood and checked the obvious (MAP sensor). It's fine. I tried to restart the engine, and it does start if I hold the gas to the floor. It idles at around 500 rpm and shakes the whole car. I'm getting about 2 in of vacuum. When I crank the engine over, it sounds like it's not getting compression half the time.

Sounds like an apex seal, right? I hope it didn't take out my turbos. They didn't sound too good on the way home, but I don't know if that was because of the engine. I could still get 5 to 7 lbs of boost...

Finally, after 91,000 miles on the original engine, it's time for a rebuild. My only performance mods are an HKS downpipe and K&N drop in filter. And all the maintenance has been done (fuel filter, plugs, wires, etc.).

Paul

paw140

You know, it's funny, but I really don't feel too bad about it. I've been really looking forward to pulling the engine and doing something with it... I've been considering the Hinson V8 conversion, but I think thats out of my price range right now. Anyway, I finally get to tear apart a rotary and see the insides in person, and I can clean out my engine bay and do some other things to the car that I've been wanting to do.

Trexthe3rd

Good luck man, I just replaced mine with a Mazda reman, and plan on rebuilding/porting the one I took out on spare time and keep it as a spare.

pp13bnos

iTrader: (1)

Thats a healthy and good way to look at it.

My FD ony has 48k miles on the motor. But every time I drive it, I expect the motor to let go. This is good, because, when it does let go, I wont be so bummed out. Although, if things go to plan, by the end of this summer, I should have a ported motor from Rob@Pineapple, and some BNRs. CJ

yzf-r1

iTrader: (1)

your motor is toast

mine did the same thing, only it had better power and better vacuum....one of the apex seals on the rear rotor let go at 15 psi on a cold night

cold weather like this will give you more boost, you really have to watch it....if you had a dp with the stock ECU you likely hit fuel cut and/or ran lean

put a streetported Mazda reman in there from Malloy Mazda....my reman engine is beautiful, new housings and the rotors are like new....then strip the emissions crap off, put a new clutch in, clean and flow the injectors, buy a used Pettit ECU and a used M2 IC, and say hello to 330 hp at the wheels

say goodbye to annoying F bodies

r_ed_line53

...one you need to understand in a turbocharged motor is that you have to be at or above the power band of each gear... what happens is that the turbo's will spool up faster than your motor can wind up... meaning @ 55 mph you were already at full boost and over working the motor by trying to push in and letting out too much air... the power band for third gear is AT OR ABOVE 80 mph... your third gear will get up to 110-115 mph, depending on your set up, before you reach the power band for fourth gear... the power band for fifth gear is past 155mph... and so on... or TO BETTER PUT IT YOUR AIR/FUEL RATIO IS NOT THERE!!!!! These two must be balanced at all times.... PFC

if you were to do a poll... and asked the people on the forum where and when do they blow their motors? you'll find that most, if not everyone will say, on the street rather than on the track. on the track you're always going to be in the power bands of each gear, right? on the street, you downshift, thinking that it will make you go faster, not keeping in mind the power band in which the gears need to be at...

you know when you downshift or shift and the cars jerks or 'bogs', you're producing enough power, so you shift to a lower gear or you just step on the gas until it finally reaches its boost or power band...

this is just my findings after going thru quite a bit of motors... but you learn the hard way.... just know that air and fuel must be balanced at all times, and when you're boosted it's even more critical to keep up with the air intake to your fuel intake.......



well have fun... looks like you're going to be on your back for a while... man i miss those days...


see ya,
car 53

Rx-7$4$me

interesting 53, I never thought about that... IT makes sense to me now, but It sucks some time. Im 17 and while I do have money for a new engine, id like to keep mine for as long as possible( although I do look forward to looking at the internals when it does blow ).

I just got my SBC-ID boost controller, and after installing it, I was doing some tuning with it. I didnt want to miss the boost building up, so I could fine tune the wastegate, so I Was doing exactly what he was doing and when I was doing it, I was thinking about how it seemed to be hard on the engine. So in cases such as that, where u dont want to floor it at to high an RPM when starting tuning, so not to spike and such, what can you do?

So basically the best thing to do in any gear, is not floor it unless your above 3000 rpms so your past the rpm level where your turbos reach full boost? ( except first of course)? or just for higher gears, such as third 4th and 5th be at least near transition?

Thanks! Great info

Steve

r_ed_line53

it all depends on how it's tuned, but basically... try it out and you'll see what I mean... as far as tuning for spiking is concerned, you can't rely on the stock ecu. you definitely need to meet the needs of your air vs fuel.... and a stock ecu won't do it... or even a piggy back (more delicate tunig is involved to make this work)... the only thing that I haven't put on the motor are the 1300cc secondaries and a boost dependant fuel regulator...

another thing is evey car and driving techniques are different... you want to make sure you apply these towards the power output of your 7....

hey on a side note... there's talk of a turbo charged rx-8 in the works and the design will be of that close to the 7... i can't wait for that.... woooo hooooooo


see ya,

car 53

Rx-7$4$me

well, my mods are listed, Im not in the stage of tuning yet ( *tear* ), but I just keep my boost near 10 psi with my SBC-ID, and I only drove it like that when I Was tuning it. I generally when Im downshifting to floor it, I'll be up in the rpms , so I mean, I dont understand why this would happen in the first place......

maybe its just late, and im not thinking right

where did u hear about the Rx-8???

Steve

Rx-7$4$me

everything I do on my engine I do myself at age 17 haha
and Its still running strong, and I'd like to do as much as I can to keep it that way.

Rx-7$4$me

I think im going to shut up seeing as I dont make sense to myself right now lol

paw140

I'm still not sure what I'm going to do, as far as engine mods. I'm going to pull the engine and tear it apart, but I have a feeling that with 91K miles, the rotor housings are going to be pretty worn. I'll probably end up buying a Mazda reman. But then the question is, should I street port it? If I do that, then I need to get an ECU, then if I run more boost I need better IC, bigger injectors, then.... you see what I mean? At that point, I should just put in an LS1.

I'm tempted to buy a reman and keep it stock. I was also thinking about a mild street port, and just leave the stock ecu and everything else the same. That way, if later I wanted to add an ECU and IC, or whatever, I'd have a much stronger platform to build from.

paw140

I want this car to be reliable. If I street port it, and then buy a Pettit or M2 ecu, can I still run just 10psi boost? Do you see anything wrong with this? I'm not sure I want to push it up to 12 psi.

r_ed_line53

do you plan on smogging the car? if so, don't port the motor at all...

mine is slightly polished, but nothing major... i run anywhere between 10 and 12lbs of boost on the street. on the strip it's betwee 13-15lbs of boost. reliability stems from your driving habits... you want to tune accordingly to that... definitely do all the bolt ons, injectors, and ecu upgrade, but the stock form of the motor will handle high 11's consistently with proper tuning...


see ya
car 53

Street King

I wouldn't do injectors unless you get a stand alone ECU. The chips won't know what CC you are using and you are just going to run really REALLY rich.

my .99 cents

vosko

iTrader: (4)

i'm not sure exactly what redline was trying to tell you but, it depends how hard the car was driven. you can wear an apex seal down to nothing in 90k miles..... you can simply wear out the seals in it. my FD engine lasted 87k miles but i only had blown coolant seals and oil control rings. anyway if you want to stay stock and keep it reliable. i'd suggest putting in the reman and getting a M2 or Pettit ecu. the car should be VERY reliable and could go for another 90k miles

paw140

Do you think there is any advantage to putting a petit or m2 ecu in with a stock engine and only a downpipe?

vosko

iTrader: (4)

yes there is. if for some reason you spike past 12psi. you won't hit fuel cut and detonate your engine

paw140

Well, I checked to see if I was getting any compression, and check which rotor blew an apex seal. First I removed the rear trailing plug, cranked the engine over, and heard nothing. No pulses at all. Next, I took out the front leading plug, and cranked it over. I got nice, solid whooshes from the front rotor.

I must have blown 2 or more apex seals on the rear rotor.

SleepR1

My motor failed from worn out o-ring seals. 102,543 miles. I replaced motor with KDR street port, reman, added Apex Power FC, Greddy 2-row FMIC, Nippondenso Comp fuel pump, 1300-cc secondary injectors, Greddy Airinx intake, engine torque brace...awaiting word for pick-up at the Rx7 Store.