vanillagorilla

iTrader: (1)

Good question, from the way he was desribing it, it seems as though it might be vehicle speed related. That totally confuses me.

If ever really want to find out whats wrong with it, it needs to be torn down now. Because when whatever it is fails, it will take other things with it. Then the culprit will be harder to diagnose. You can get money for those 5.3 heads now (if they're not damaged), but when/if that piston lets go, you'll have no coin to help offset the cost of the 6.0L. JMO.

greentahoe

iTrader: (2)

from what Ive heard that sounds like a piston and most likely #7 as many have already said. What happened?? Did you go lean?? Do you know what your AF was at? Id be more interested in what caused it. Most Ive heard of were from FMU's or just bad tuning.
You probably smoked the motor. I would focus on fixing what did it.

parish8

iTrader: (6)

good point. at only 9 intercooled psi i bet it was too much timing or went lean. did you hear any knock? you almost had too i would think.

Formulized94

iTrader: (68)

what causes the #7 to go? is it a boost only thing, or na also?

1SlowHoe

iTrader: (28)

OK, I read all the post since I left I'll try to answer the ?'s I remember.

I would rather do a swap if the $$ to repair is over, say $700 I'm not going to rebuild a 5.3 for what I can get a 402ci for.

I dont know if I went lean. My injectors were maxed out on top at 128% duty cycle during my dyno tune but, even then I was 12.5 AFR or something close to that. The run that broke the part was the 1st of the night and I heard no pinging or knock until after I pulled off the track.

The knock comes with engine rpm. It goes away around 40mph because thats the only time I get above 1500+ rpm.

I have seen people pull their pistons out of the block and the rings fall apart as well.

The part that will baffle you now is that the knock is GONE! Not even at idle. I never put it under boost but I just drove 50+ miles with no issues at all. Maybe once it cools down I will crank it again and see. Why would it be temp related? I would rather not drive until I figure it out but I really dont have much choice. At least to work and back. 20 miles a day.
Any new ideas as to why the knock had disappeared?

parish8

iTrader: (6)

what kind of dyno?

i keep it richer than 12.5. your injectors can't go over 100% so if the computer was telling them to go 128% they were just wide open. often the dyno(dynojet) puts less of a load on the motor than the real world so your fuel needs end up going up. also weather changes can cause significant changes in your fueling needs. you could have easily been at 13-1 or leaner. most boosted guys shoot for 11.5-12.

1SlowHoe

iTrader: (28)

It was a dynojet. I figured it wasn't a real world load when it said I made 413hp at the wheels but what do I know? Lookat my A/F:


What do ya think?

parish8

iTrader: (6)

i think you blew it up from being too lean. was it prety cool out too?

dynojets are great for geting a number but not for tuning especialy for anything with a power adder.

doesn't the radix come with decent sized injectors? 42's i thought. they should be good for ~500rwhp i would think.

1SlowHoe

iTrader: (28)

I have the flex fuel truck. I used my stock 38# with the radix and I didnt have to add the inline fuel pump. My fuel system was showing its weakness with the 9# pulley. I have a fuel pump voltage booster sitting next to me and 42# ford injectors in transit. I guess they are a little too late.
If I really wanted to go cheap could I just pull it apart, install a new piston and rings and be done?

EDIT: it was about 77 that night. It was in the 90's when we tuned it on the dyno.

parish8

iTrader: (6)

hmm, you may have some cylinder wall damage and likly have some dings in the head. there is a chance you have more damage in other cylinders.

i am not sure but can't you get a 5.3 or for around $500? there must be a member around here that has one siting around. there is probably someone with a stock piston and rings for a 5.3 that they would give away cheap or free if you wanted to try just slaping it in there but who knows if it would be ok or not.