Hi Guys

On the dyno tuning for higher boost we are getting spark blowout at high rpms . Or else we think ?

Anything over 15psi boost at around 6000 rpm we can hear a sharp pop pop sound .

Its not pinging , The cars making around 500 rwks through a 300 stalled auto. But we know there is more in it.

The plugs were Tr6s gapped at .8mm , We changed to TR7-ix and it didn't fix the problem .

New leads , Same problem , Although on one of the leads there is a hot spot the boot Slighly melted , But it seams fine , I changed the heatshields

The leads are Magnacore KV85 with high heat angled boots .

We tried LS2 coils , And its the same ?

Anyone have any ideas ???
Before anyone asks ,Background on the car :

Motors a 408ci Twin Turbo with a 4L80e Trans .
Eagle Crank Rods ,Diamond pistons .AFR 225 Mongoose Heads Pac Dual Springs , Titanium retainers, Morel Lifters T&D Shaft Rockers.

Auto is a Craigs Automatic built 4L80e Dominator 3000 Stall.

Fuel System is 80 lbs Siemens injectors , 2x 044 pumps, Surge tank and a Aeromotive Fuel reg, ( The reg is not boost referenced, Set always at 60psi)

 

.8mm = .031 inches, which is quite a bit. try more like .022- .025 which is .55 - .63 mm

 

Close the gap more. Is the fuel pressure dropping?

 

The Tr7-IX plugs are gapped at .8mm , .030 thou .

Pressure isn't droping .

 

That's interesting that it's happening to you. I run up to 25PSI with no issues at all. My spark plugs are the NGK BR7EF's. I do use a pretty close gap that I've tweaked over the last 2 years that I use. I kept moving the gap further out and was losing MPH so I went the other way and found a sweet spot but don't have access to my gapping tool to tell you what it's set to. I'll look when I get home tonight.

I also index my plugs. Lots of folks say they don't see any difference but I definitely get better MPH by facing the open end towards the top of the head. It's not much but when you're tapped out on injector size you look for any hidden HP you can find.

I also use stock 1999 coils with a stock 1999 PCM with HP Tuners custom OS in there. Nothing magical at all. Everthing works just fine. I'll be watching to see what the culprit it on your motor. I'm stumped.

 

Close the gap down.

.030" is too much on many cars. Go down to .025" and try it. I use BR7EF out of the box.

 

I noticed this event on my dyno tune and was unsure what it was, i also logged no knock but right bank was popping will pull my plugs to check gaps.
Can you post if you find reducing gaps solves your issue

 

I went through this and you need to go-over the tune carefully. It wasn't the plugs on mine, but I thought it was too.

 

I run TR6's gaped at .030''. Been to 20psi and 6800RPM. Sometimes gaping the plug can be a little tricky. I use a .030'' feeler gauge, I don't use a gaper. Also check your coil wiring harness, I had bad insulation on a wire and caused a similar incident. What CR is the engine?

 

+1

 

Where at on your wiring harness did you have an issue?

 

It was on the coil harness there was a wire where the insulation was cracked just pased the tape part.

 

+1 on plug gaps...anything over 20 psi you should be at or less than 25.

Also, run an MSD or KB BAS to help with spark output if blow-out continues.