Wild one
Senior Member
- Joined
- Jan 17, 2016
- Posts
- 14,050
- Reaction score
- 24,363
- Ram Year
- 14 Sport
- Engine
- 5.7
Darin Morgan
November 3, 2019 ·I had a customer come into the shop hauling a cylinder head off a 1.4 liter 4 cylinder engine. He is building a rally car out of a Chevy Cruze. I will port the heads and do all associated things one does to increase power. When I disassembled the engine I was treated to some nasty looking, coked valves. I have long been dismayed about the associated problems with DI engine utilizing "cam retard" EGR to increase fuel economy. The picture of the valve below was taken after I had cleaned half the valve off to see the extent of the coking. Looking at this valve you would think the engine had 100000 miles on it, but no. The odometer read 14384 miles. Your looking at a valve that has choked off the intake port by about 15-20% in just 14384 miles! Guess what these valves will look like in 30000 miles. How about 50000 miles.
This is what I call " False economy fuel savings". I coined that phrase because it describes exactly what is going on in four simple words. Does it save fuel? Yep it does that.
It also has some associated effects that in my opinion, cancel out any benefits to the consumer. You get a bit better fuel savings but you also get,
-- Increased engine wear
--Decreased engine life
--Increased Maintenance schedule
--Increased maintenance cost over the life of the vehicle
--Decreasing fuel economy and power over the life of the vehicle.
When you go buy your new Corvette with the LT1 DI engine they fail to mention that you will have to spend on average $2500.00 over the life of the vehicle. In order to get this extra 1.2 miles to the gallon you have to fork out $1200-$1500.00 every 30000 miles. You don't have to maintain it but I must mention the fact that the reason one buys a high-performance car is for the performance aspects not fuel savings. So, why would a person by a performance car that's performance degrades quickly every single time you use it. How does the dealership maintenance this issue? By pulling the intake manifold off every 25000-30000 miles, sealing off the engine and blasting the intake ports out with nut shells. That's the only way to get rid of the coking on the valves short of pulling the heads and rebuilding them.
Let’s say you save 1.2 miles to the gallon. Over the life of a 100000-mile vehicle it will save around a $1000.00 in fuel. If you look at it from a global standpoint, I can see how they think this strategy is a win. It saves millions of barrels of fuel over all. It does this by passing the cost onto the consumer.
----Maintenance cost over 100,000 miles = $2500,00
----Fuel saving over 100,000 miles = $1000.00.
If my math is right, the OEMs just saddled your ass with a carbon tax of $1500.00. A carbon tax that causes no amount of Aggravation over the fact that you have to spend money to fix an out of tune engine that the factory produced on purpose!
This is why I tune ALL my vehicles with either EFI LIve or HPTuners. I tune out all the cam retard and put the cams at 2 or so advanced in the lower rpm range and slowly retard the cam (or cams) as engine speed increases for a broad power curve. Yes, I lose 1-1.5 MPG but, I am not saddled with maintenance or the increased cost over the life of the vehicle. I also sleep better knowing the valves stay clean and engine performance is is not slowly decreasing over time.
