When do I need engine modifications for Forced Induction?

by | Jul 31, 2017 | Forced Induction 101, Planning Your Build | 0 comments

Engine Modifications and When to do them!

Whenever we are customizing a car that will employ some type of power adder, major upgrades or modifications will become necessary to safely handle the increase in power. What mods and how much will depend on the engine and the application and how much additional power the modifications are expected to make. An engine that’s going into a drag car or some other type of race car may not rack up a lot of miles in a season but the miles it runs will be hard miles at full throttle under heavy load. Street engines, on the other hand, spend most of their time running under relatively light loads and only occasionally are called upon to produce maximum power. They are expected to last tens of thousands of miles without any major problems. So it can be argued that engine durability is just as important for both types of power adder applications, while one of the applications will arguably require far more detailed maintenance and possible rebuilding of certain components on a more frequent basis.

The upgrades that are necessary to handle power adders will depend on the engine and the power level the engine is built to produce and how much power the end game is being designed for. For a typical street application, changes to the stock pistons, rods and crankshaft are usually unnecessary unless a ­customer wants to make insane levels of power. Most stock block V8s can safely handle 150 to 200 extra horsepower on the street without encountering any major problems.

When an engine’s power output exceeds about 600 hp with a small block, or 800 hp with a big block, upgrades start to become mandatory with power adders.  Again, it depends on how the car will ultimately be driven.  A few examples follow.

Let’s take a newer Mustang for example.  The new S550 platform has the ability to handle almost 2X the power without any significant engine modifications taking place.  That means the 2015+ V8 Mustang can reach almost 800 Wheel Horsepower (WHP) with the addition of a supercharger or turbo setup without much of an issue at all.  If the car is being daily driven and spends only a few days at the track, then you will likely not need very much, or any, engine fortifying at all.  However, when breaching that 600-650WHP level, some drivetrain modifications will be needed, as the stock driveshaft and rear axles cannot handle that power for very long before they will break and leave you stranded and embarrassed.

The key to deciding on which modifications to make comes with some consulting time.  We need to fully understand how the car will be used and how you drive it in racing situations.  Some drag racers drop the hammer when the RPM’s are above 4000 when coming off the line, other’s maybe 6000RPM, and some just roll into power from about 2000RPM.  The higher levels create a huge amount of stress on drivetrain components, and they will break.  A stronger 1-piece driveshaft is a must and higher performance axles shafts should also be installed.  It also wouldn’t hurt to change the clutch.  Above 600WHP, the factory clutch will not last or grab and basically burn itself out pretty quickly.  If the car is being treated harshly – severe duty driving, possibly a change to the oil pump gears and timing chain gear should also be done.  Again, this requires a deeper conversation to make a reliable recommendation.  These motors can respectively handle 1000WHP+ with drivetrain modifications and the right fuel system, though longevity and reliability will catch up without a solid forged bottom end upgrade.

If we’re talking about a Challenger with the 5.7 engine, you are maxed at the real horsepower it can make to begin with.  The heads on this car cannot breathe enough to handle more than about 550WHP reliably, without being modified to do so, although we have built a few that are at about 600WHP.  At this level, it is strongly advised to change driveshaft and axles as well, and likely the clutch.  Anything planned for above 550WHP should get at least a forged bottom end done with the heads being re-worked as well, among others items.  If the car is a Hellcat, much more can be had, as that engine will breathe and handle far more power.  The drivetrain components can also handle more power and don’t really need to be changed until you breach around 900WHP as well.

If you want to talk about the Camaro, it’s not much different either.  The Ford engine will breathe better than all of them and handle more power adder horsepower in the end with less modifications, which is why they are so popular to build.  It takes larger engines and more build work to make the Camaro and Challenger make the same power as the Ford.  That doesn’t mean we want everyone doing 5.0 swaps, but it is something to think about and remember when buying one of the other cars when considering your build and budget.


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