I had NGK's for 15000 miles and replaced them with Niponseno Iridium as everyone raved about them. I blew my motor 6 weeks ago and just had the motor torn down this week. (3 broken rods). No detonation at all, pistons were black/brown on top and no ring land issues or blow by or pitting. When the shop doing the motor disassembled the heads they pointed out to me that 3 plugs had cracked insulators. The plugs were in for 1000 miles. The plugs were brown and no signs of being too hot or too lean at all and had the top 1/8"to 3/16" of the insulators missing. I read about a month ago a thread with similar issues and dismissed it. I would just recommend that you beware and if nothing else save the cash.
I'm not blaming the motor failure on the plugs, but they do not appear to be up to a blown motor making power and surely not for a nitrous motor.
I was running a 55hp wet shot (Zex Kit) for the 1st time at the track when it blew.

It will be reassembled with Eagle Rods, Manley Pistons, FMS Oil Pump, ARP Studs, Stainless Valves, Decent Valve Springs, Ported Heads and NGK TR7 plugs in the next few weeks.

 

Sounds like too much heat and I will guess detionation. With the nitrous I will guess you had some detionation and this is what kills the rods. You will not see it in the pistons but the rods are the weakest link. When you have detionation it forces the piston down while it is still on it's way back up this puts lots of stress on the pistons and rods. In our case the rods are the weakest link.

 

I've cracked insulators on the denso's due to some detonation. I agree the iridium plugs have little forgiveness. I prefer NGK plugs for daily driven low boost trucks. I used NGK plugs in my 99 for 20k miles and never changed the plugs. I ran NGK TR6's in my 94 Lightning w/ a Vortech and they performed perfectly also. I am running Denso IT24's right now and I am currently looking for an alternative to test.

The Denso's do serve they purpose and perform well when all things are perfect. You just have to be careful and watch for detonation.

 

were you running a nitrous program? on your chip? how aggresive was the chip that you were running? timing? if i had to guess you were running way to much timing for the nitrous.

 

You meant NGK BR7EF 's not TR7's didn't you?

Dan

 

I meant BR7's. I see no evidence of detonantion. If it were detonating enough to break 3 rods in the 1/8th mile it would dhave been pretty violent and shoudl surely show in either the top of the pistons, the heads, valves or plugs in the form of pitting, inconsistant coloring of carbon on the pistons, valves etc. I have had many high perf vehicles and racing cars and cycles and boats that I have become pretty sensitive to the sound and feel of detonation and I felt none of it at all. It ran perfect until it just let go. I ran a std JL chip that ran fine on pump gas. I ran 94 octane Sunoco this run and the 55hp wet shot does not require any advance change according to Zex and everyone I talked too prior to installing the Nitrous, including Sal, thought I should be OK. The only issue is the , depending on who you talk to, rods on the 01's can only handle 450-500 hp max and I dynoed at 400 before the upper pulley, muffler change and the Nitrous so I was surely over the 450hp range and possibly closer to 500.

 

This is very possible but the ZEX paperwork also is looking at it as if the truck was at the stock timing curve.

Way back I was running only a 6# pulley and broke 2 rods (no nitrous) on a bad tune. The pistons did not show any sign of detionation.

 

Whatever it was the rods are junk. Ff the Cobra gets Manley's from Ford they must know something we seem not to know. We make more power, put more load on the engine and have heavier pistons. I have never heard of anyone with Manley or any other decent Rod breaking them for any reason including bad tune or nitrous, etc. MAybe they have, but I just haven;t read about it.

 

I think the Cobra's get better rods because they turn more RPM's.

 

And maybe, just maybe that the Lightning's have proven the rods are a weak link?