Well I’ve been bummed for a few weeks now... but I’m going to try and lay it all out. This will be a long post so bear with me. My intent with this thread has always been to help folks learn from my mistakes, so hopefully you won’t screw up like I have....
Mid-November I took the car in for the final full throttle tune. It turns out these new Hemi’s don’t like a lot of timing. In fact it made max power at only 24 degrees of timing (not 32 - 36 like the old engines I’m used to). It made 401 hp and 428 torque at the wheels which is ~460 hp at the engine if you believe 15% drivetrain loss. It did smoke a lot on decell and always has (even the first time I took it to the dyno). I thought maybe I didn't have the breathers right or something..... Here’s a dyno video.
Here’s the dyno chart:
After getting the car dyno tuned it was running great. Smooth, tons of power and driveability was really good. I was almost home when I punch it from a start go through the gears and shift to 5th. After that I noticed that it was popping out the exhaust. I limp it home and it was popping at random even at idle.
So I pulled the plugs on a Friday and the first thing I notice is the plugs on the #1 cylinder are smashed (bottom 2 in this picture). Oh crap.
Just for the heck of it I put new plugs in on the drivers side cylinders (passenger side ones were fine) and started up the engine. It ran fine like nothing had ever happened.
That night I drank some scotch and was trying to convince myself that maybe something goofy happened with the spark plugs and that the engine was actually fine. I woke up the next morning and said I had to know for sure so I decide to pull it apart. When I pulled the driver’s side head off this is what I saw....
Yep, all 4 pistons on the drivers side are broken at the top ring land. The #1 piston in particular is a mess with scratches and embedded metal. You can actually see the top piston ring on some of the cylinders.
Even the combustion chamber of the #1 cylinder is a mess. Thankfully the other ones are fine.
So obviously I'm looking at a total rebuild of the engine. I thought about just doing the bare minimum and replacing the broken pistons especially since the engine has so few miles on it but I was so upset with all this that I said screw it and I might as well do a stroker 426 cubic inch motor. So I’m going to go with an all forged bottom end plus a larger cam and ported heads. After doing a lot of reading on the LX forums I decided to have Inertia Motorsports in Texas build the stroker. They specialize in the Gen 3 Hemi. So out comes the engine.
I got a pallet and used 4x4’s screwed in to the pallet to brace the engine at the oil pan rail so it wasn’t sitting on the oil pan.
Then I wrapped the thing in a bunch of layers of shipping plastic shrink wrap.
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Then I strapped it down with a couple ratchet straps and sent it freight to Texas.
Anyway it sucks.... I don’t have a good answer why. I'm guessing all of the damage was caused by all the miles I put on the car without a tune? Probably in particular in the summer heat. Since it started up and ran fine with new plugs, who knows how long the damage had been done. I’m wondering if this is why it’s always smoked so much on decell on the dyno?
It's strange that the damage was only on the driver's side. When I first got the car running I only had a crossover fuel line in the rear connecting the fuel rails (like the stock fuel rails). Later on I also added a front crossover. Perhaps before I did that it was running lean on the drivers side? Perhaps I need to go with a full return fuel system (even though the stock Hemi are a returnless system)?
Reading the forums the top ring land is the weak part of these engines. Folks that run boost in the LX cars have seen very similar failures. In my case one of the downsides to the FAST system is it doesn’t use the Hemi knock sensors, which perhaps if I was running a stock computer with factory knock sensors it might have saved the engine?
So that’s where I’m at. I’m still depressed about the whole thing. Plus before this happened, I was all set up to attend a private road course track day but obviously I had to miss out on that as well.
I had always planned on doing a cam and ported heads, I just didn’t think it would be this soon....... If there is any positive out of all of this its that when the stroker is done it should be good for 475 - 500 rwhp. So I’m now glad I put in the heavy duty clutch.
The other lesson learned for anyone planning a Gen 3 Hemi swap; when I bought this engine in 2007 buying it direct from Dodge was pretty much the only game in town. Now there are a number of vendors that will either rebuild a junkyard motor into a forged stroker motor or even sell you a long block outright without a core for not much more than what I paid for the original crate motor. Check with Modern Muscle (a sponsor on here), or Interia Motorsports, or Arringington Performance or Performance Werks Racing for options.
Travis
72 Cuda
