#7 twice
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Teching In
Joined: Apr 2015
Posts: 1
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From: Shreveport la
#7 twice OK guys have a question.. I have an 05 silverado was a v6 truck that was swapped to a 4.8.. the truck has a intercooled procharger p1 on it with a 3.7 (10lbs) pulley, Walboro 400, and deka 80lb injectors.. sent the truck to be tuned a month later they call saying they don't wanna do its making noises... Short story I went picked it up and #7 was broke ring glands on top.. put a brand new build 5.3 all stock with .030 hypertech pistons stock ring gap.. and truck dynos fine and tunes out great.. high ait's but other than that tunes great (truck had a conservative tune on it as far as timing goes)...15 miles in the drive on the way home get in it hard, truck pops starts knocking and smoaking.. pull it back down and edge of #7 is burnt and piston skirt is broken... had injectors test they tested perfect... now I have bought a 4 way steam port and will be taking the blocksoff off the back of the heads, will be fixing #7, and fitting the top 2 rings on every cylinder... also thinking about going to half race half pump gas or e85... is there anything else I could do to prevent this or has anyone else had the problems and could point me in a direction to save hassles in future...
Ive melted pistons on 2 forged motors so I have some experience. You really are not providing enough info. If you could attach your tune file that would help big time.
The issue is most likely a combo of using pump gas and too aggresive tuning. Probably timing. The 4 way steam ports are a good idea also and running the proper size fuel rail is important.
What I do now that Im afraid of blowing motors up is this.
I run meth injection
When I race the car at the track I put 5 gallons of c16 in the tank.
Run a super cold spark plug, ngk b8efs.
Hooked up the steam ports.
Bought bigger fuel rails.
And probably the biggest one other than fuel is learning to tune or at least learning to understand your tune.
I think by doing this you will have better luck.
The issue is most likely a combo of using pump gas and too aggresive tuning. Probably timing. The 4 way steam ports are a good idea also and running the proper size fuel rail is important.
What I do now that Im afraid of blowing motors up is this.
I run meth injection
When I race the car at the track I put 5 gallons of c16 in the tank.
Run a super cold spark plug, ngk b8efs.
Hooked up the steam ports.
Bought bigger fuel rails.
And probably the biggest one other than fuel is learning to tune or at least learning to understand your tune.
I think by doing this you will have better luck.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
So is the tuner only dyno tuning, and not checking afterwards on the road ?
Have you upgraded any fuel lines or wiring for that Walbro ? They draw insane amounts of current.
But other than that, it does sound like a basic tuning issue for the most part, especially seeing as it happens within such a short time of being tuned.
If it had been 6 months down the line clearly it would be very different.
Have you upgraded any fuel lines or wiring for that Walbro ? They draw insane amounts of current.
But other than that, it does sound like a basic tuning issue for the most part, especially seeing as it happens within such a short time of being tuned.
If it had been 6 months down the line clearly it would be very different.
On The Tree
Joined: May 2012
Posts: 175
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Factory fuel rails or aftermarket? If after market how are they plumbed? I just bought a 5.3 with 129k and most of the bores look good, you can still see cross hatch marks from the hone, except #7, its pretty shiny. Wonder if not much oil gets to the bottom of the piston and they stay just a touch hotter than the rest?
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Where is the meth injected at? Air Distribution to #7 cylinder is typically the worst. If Meth is generally applied through charge pipe I would tune #7 cylinder fatter if you have individual cylinder fuel trim control.
My #7 is always a touch fatter than the other holes with Holley EFI.
My #7 is always a touch fatter than the other holes with Holley EFI.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
In the 12 years or so I've been using an LS in my car, I've never used a factory ecu.
IMO there doesnt need to be a level. You just need, or want an ecu that offers you the features that you want. That is completely irrelevant to power level.
@69, yes you could pull a degree or two of timing from that cylinder, but in this instance from description of damage the problem doesnt really sound timing related. It sounds more like lack of fuel
What Im saying is the setup works well the way it is. There are many other things I would do before an aftermarket ecu. Yes I like many of the features but I dont think they are needed at my point. My goal was a 9 second street car with ac and no restrictions and thats what I have. Maybe next project I will try out a new ecu.
But anyway I want to see a tune file for the op who blew his motor up.
But anyway I want to see a tune file for the op who blew his motor up.
Another possibility - since it's happened twice. What intake manifold is the OP using? If the intake manifold is not seated properly around #7 I wonder if that cylinder is actually going pig rich and rings are lifting.
Pics of that hole would help a lot.
Pics of that hole would help a lot.
Just for conversation...
It would be nice to see the piston. But would you all say that if the piston has broken rings lands, piston cracked, etc that its probably timing related as combustion tried to occur too early or deto? To me, lean AFR would appear to be more of a "burn" or errosion of the piston.
Or too lean maybe causing the deto? I still would like if it was run lean you would see some evidence on the piston. I've seem alot of failed pistons that look perfect other than a clean crack on it...gotta be timing IMO.
It would be nice to see the piston. But would you all say that if the piston has broken rings lands, piston cracked, etc that its probably timing related as combustion tried to occur too early or deto? To me, lean AFR would appear to be more of a "burn" or errosion of the piston.
Or too lean maybe causing the deto? I still would like if it was run lean you would see some evidence on the piston. I've seem alot of failed pistons that look perfect other than a clean crack on it...gotta be timing IMO.