Is backfire dangerous?

[rjyentsch21]

So...I finally worked all the of the demons out of my electrical system, and a new KA-T is on the road. Just using it for short hops to town and back until I trust it more (and until I get an exhaust on the SOB). Now that I'm running, I do have a few questiosn for the wise men around here:

I backfire upon throttle off decel...loud. It's usually only bad if I was running pretty hard before, but its always there just a little bit. I'm running open downpipe right now, so that sure as heck isn't helping, but my real question is this: is backfire dangerous? Once I get a muffler on there, I'm sure I can handle the noise, but can I actually hurt my 02 sensor, hot side of the turbo, or anything else from backfire?

How long should I give the engine as a "break in" period after rebuld? 500 miles? More? I'm trying to keep my foot...mostly...out of it until it's had some time to heal...

My set up is as follows:Rebuilt engine w/ 8.5:1 compression, forged rods, new gaskets, bearings, all clearances checked, etc. etc. Compression is where it should be on an unbroken in engine.Enthalpy tuned ECU (16 bit daughter board)50 lb. fuel injectors255 lph fuel pumpadjustable FPR (currently set to the stock ~43 psi)tubular manifoldT3/T04E turbocharger2.5" open downpipenarrowband O2 sensor and gaugeboost gaugeoil pressure guageaftermarket temp gaugeblow through stock MAF on the cold sideBlow off valve on the hot side (open)wastegaterelocated batterynew clutchone stage colder than stock plugs gapped to .035MSD coil

I'm running around 7lb boost at peak on 93 octane @ 15 degrees timing. My AFR's are decent on the narrowband, just a tiny bit rich under throttle. She pulls wonderfully and runs fine now what she's had a little bit of road time.

I'll try to post a picture or two after I get the engine cleaned tonight (sitting for three months while I was at school didn't help the appearance any).

[480sx]

Back firing wont really hurt anything except your ears if your running open DP heh.

You should just recirc your BOV if at all possible, your rich condition on decel will go away if you do. No more backfires this way.

How did you break your motor in?

Pretty nice build, but why do all that and keep the stock maf..?

[rjyentsch21]

Recirculating the BOV is neither possible nor...hopefully...necessary at this juncture: I have the BOV on the hot side and the MAF downstream on the cold side, so that any air blown off has not yet been metered.

Haven't yet broken the motor in, which is the question: How long (how many miles) should I give a newly rebuilt KA-T before I start giving the car any real hell?

I know what you mean about the MAF...when I originally did the build, my goals for power did not exceed 250 BHP at the time, because I didn't really have to funds to do a full rebuild of the motor, so from what I read the stock MAF would work just fine for those goals. Once I blew the motor, I'd already purchased injectors. They limited me to about 300 BHP, so there was really no point in going up in MAF size unless I bought new injectors and at that point I might as well get a new cam, and at that point I need to do...blah...blah...blah... So for right now, this ought to be just fine for the 275 horse I want to be able to make. I'm sure it wont' satisfy me forever, but hey...it will do until I finish grad school and get a real job.

[s14tan]

pics of the set up?

How does the blow my MAFs work?sorry for thread jack.

[rjyentsch21]

Here are the pictures that I promised, at least as she stands now (always changing something)

The car itself: and no...for several years I don't plan on making it pretty...I don't even plan on making it look decent

Next is the engine bay as a whole. Note the cheapness inherent in everything I do, being that half the car is scavenged from crap I found in my dad's garage:

Here is the hot side where you can see the BOV. Whenever I get around to it, I've got the piping to move the filter down next to the BOV to get some of that good, cold air in the fender.

Here is the cold side where you can see the MAF. I think I'm pretty much done with this side for a while (as long as no leaks develop).

Here is why you should never purchase an e-bay manifold: it places the turbo too close to the firewall. I had to remove the massive stock brake booster for clearance (you get used to it) and rig up a heat shield until I get the exhaust finished and some wrap on the downpipe. Those brake lines were getting just a little toasty, but they seem to be ok now.

That's pretty much it. Any CONSTRUCTIVE criticism is always appreciated