hey was wondering you guys running superchargers did you have your pistons coated? and if so are ther any benifits?thanks

 

Just had pistons, Combustion chambers & valves coated. It's a big help keeping cylinder temps down to avoid detonation.

 

Haha, I just posted in Adv. Tech bout whether or not the coatings help with reducing detonation. I had orginally planned on this but after reading Maximum Boost, I am questioning my thoughts before.

Corky Bell (author of Maximum Boost) states that keeping all that heat in the combustion chamber, instead of it being absorbed by pistons, valves and the heads, will increase detonation.

I would think that a good intercooler will fix this, but is his thinking right?

Hunter

 

About coatings, be careful. If there is any inconsistancy in the application or if the coating "fatigues" in certain areas, you will get hot spots. These hot spots will provide localized heat which can affect the expansion of metals as well as other characteristics.

The guys in the NHRA funny cars and top fuel coat their pistons but they tear down between runs. I'm not sold on the idea of coating in a street car.

My opinion...

 

Piston and combustion chamber coatings will keep more heat in the cylinder making it more thermally efficient.

It's like how you have to run approx 1 point more compression with aluminum heads than an otherwise equal cast iron head to make the same horsepower. More heat is lost to the cooling system with an alum head, so there is less heat to push down the piston.

I think that if your current engine setup is on the brink of preignition, than the extra heat contained in the combustion chamber through coatings would push it over the edge.

 

Hey, teamsleep13 if you read the posts after yours in Adavnced Tech most of them agree with mine. I tend to agree with RSKrause on this one and I believe he has been using the coating for a while with no ill effects.

 

The only drawback with coating is the care and application. Who applied the coating? I'd be interested myself. If Jet Hot flakes on headers, how consistant will the valve faces and piston heads be after 80,000 miles? I agree that the coatings should be beneficial, if applied correctly.

 

It’s close. The thing is that aluminum heads are somewhat more tolerant of crappy conditions because they conduct heat quicker so that the overall temp will be more even with less of a chance of preignition. Coating a set of chambers will have a similar effect because the head (iron or aluminum) will not be able to absorb as much heat so it will not have to be conducted away as fast to prevent hot spots. Coating the piston tops prevents the same condition with the pistons (and heat transfer to the oil). Many more serious engines use oil squirters to cover the bottom of the piston with oil to cool them…

OTOH, if you’ve got detonation as the result of excessive combustion heat and pressure, coatings will give you more since more heat will stay in that mixture (I thought about this after typing it and I’m not sure that this is really a valid concern, but I left it).

In the long run, anything that you do to keep as much of the combustion heat in the charge and out of the coolant the more power you’ll make. To control detonation (again, if retaining the heat leads down that road) you really need to add some control of dynamic events (valve timing…), efficient chamber design and good quench so that you get a complete ‘fast burn’ before detonation happen. There is a delay once the correct conditions happen before the A/F charge actually ignites, if the normal flame front can finish burning things during that time period, or if you can reduce the pressure (say by the piston moving downward) then it becomes irrelevant.

 

If the heat is kept in the combustion chamber, that would raise NOx smog levels. Interesting point if it is to be street/smog legal. To a lesser scale, O2 and HC will also rise in a high temp condition.