Originally Posted by
Alternative Auto
As many modern Mustang followers and enthusiast may already know; the 3rd gen 5.0L engine in the 2018+ Mustangs is one of the greatest and most technological Domestic V8s ever produced. Engineered and built with twin-variable cams, 5.0 Liters, 12 to 1 compression, Direct (split injection) and 460hp at the flywheel. It is one of the most powerful naturally aspirated Mustang engines ever produced for the masses.
Sadly though, many of the 2018/2019 Mustangs are plagued with a variety of engine ticks and noises that we’ve never seen happen with any of the previous generation of 5.0L motors since 2011 when the modern coyote 5.0s were introduced.
The motor noises have been labeled from anything from valve train ticks, piston slap, direct injection type ticks, charge motion plates rattling and so on. As of about early 2018 when the new 3rd gen 5.0L cars started to come through my shop, even while still entirely stock; I heard some of these various ticks and noises on several of them. Some of them had what clearly sounded like a old school collapsed lifter type tick coming from the top of the motor, some had what clearly sounded like piston rattle/slap under very light load while motor temps were still cold. Some of these noisy 5.0Ls had gone back to the dealer for fixes while under warranty only to get the car back with no clear answers as to what fixed it, and some even received new motors (under warranty) only to have the ticks or noises return shortly afterwards. So far there has been no definitive word or explanation on what is going on or what is being done (if any) for a permanent fix. As a result people have been a little apprehensive about modifying these new 2018+ 5.0L cars, especially when it comes to adding boost.
It’s become common knowledge and quite comfortable for people to fully accept now days that most modern naturally aspirated cars can handle adding a proper and moderate levels of boost to any motor, and as long as octane and most importantly tuning are in order. They can handle this with no trouble within certain limits. This is common knowledge and practice in the modern Mustang world, which goes all the way back to early days of modifying the older 5.0L in FOX bodies, (where adding superchargers to modern EFi cars gained huge popularity) and from there all the way up to 2017+ Mustangs.
Comfortably and safely adding some boost is not the case unfortunately for stock engines in the 2018/2019 Mustang and its modern 3rd gen 5.0L motors. Sadly it’s not off to a good start for the most part, adding boost to these could lead to engine failure even with proper tuning and octane, and it’s been hit or miss so far.
Our in-house 2018 5.0L Mustang has suffered such a failure after only two conservative initial pulls on our chassis Dyno while sneaking up on the custom tuning once the blower had been installed. At about 10.5psi of boost from a modern Whipple blower kit, with e85 fuel, and an initially soft tune with both A/F and spark, our car developed a engine knock from the bottom end after a second pull on the Dyno, while only making about 640rwhp on e85; which is nowhere near what it should have made as we were sneaking up on the tune initially. The numbers were low due to keeping it under 7k at first, and having less timing then I wanted as we were developing and working our way up on the tune with e85. As a result our car developed what clearly sounded like a hurt piston, piston skirt, or piston pin type noise. It was very clear and obvious that it was coming from under car in the oil pan area. It was the most evident under a light brake TQ situation at about 1100 to 1300rpm.
Although it continued to run perfect and not miss-fire or anything like that… the noise did not sound good. So the decision was made to pull the motor and see what had happened.
Upon further exploration once the motor was completely torn down, sadly we found no conclusive evidence as to what our knock was. We thought for sure we’d find or catch a piston problem, or connecting rod maybe or something along those lines. After several hours of examining the internals, we didn’t find anything that stuck out or was obvious that would cause such a motor knock from the lower end. It couldn’t be more obvious that the tune was just fine. We found zero piston damage, no ring damage, no spark plug damage or anything that would be the usual and obvious problems from either a poor tune, or lack of octane combination. It really is something we’ve never seen and didn’t expect.
So, the decision was made to forge the motor with Diamond Pistons, Manley Rods, and also get away from the Spray bore liner in favor of some drop-in Darton sleeves. Compression will remain at the stock 12 to 1 and no other major changes are happening with the motor’s internals as far as the cylinder heads and camshafts go. It’s all just getting freshened up and put back onto a now forged short block.
Forging the short block this early in the cars life wasn’t exactly the plan. The car only has 5400 miles on it; it was previously tuned for E85 and had an JLT intake on it for about 1000 of those miles. We are keeping our expectations low to figure out the bugs and make sure everything is sorted out before we try and push very serious power numbers.
As explained earlier we know the car has great potential, we upgraded the fuel system (again), and oil cam gear, drive shaft, and the half shafts were already upgraded. We also have full UPR suspension. The car currently has BMR drag springs on it, but the additional weight of the Whipple install it lowered the front end too much. We will be correcting this soon.
We appreciate everyone’s constant support. JoAnna, my daughter and owner of the car is documenting everything on her YouTube channel (@that1320chick). I will be making appearances on the channel as the car gets put back together and we race it though out the season.
Alternative Auto on the 2018/2019 Mustang
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