Dished, Domed, or Flathead Pistons??

[LEM]

Could someone take the time to explain to me the differences between and the benefits of these type pistons? I assume my '90 LX 5.0 has flathead pistons; why would I go with a dished or domed piston? Also, why forged versus hypereutectic?

Thanks much.

[351wStang]

The differences in piston style or design are self explanitory.

A flat top piston is just that, a piston that has a smooth flat surface on top. Sometimes a flat top piston will have valve releifs, cresent moon shaped cuts that allow more piston to valve clearance. Take this link for a picture.
http://store.summitracing.com/partde...1&autoview=sku

A dished piston is just as the name describes it. A piston with a "dished" top. With the top of the piston having a lower height this gives you more room, or combustion chamber volume at top dead center or TDC. Dished pistons are used to acheive a lower compression ratio for super or turbo charged applications. Here is a picture.
http://store.summitracing.com/partde...1&autoview=sku

A domed piston is simply a piston with a "domed" top. The top of the piston is above level, or higher/taller than a flat top piston. Domed pistons are used to acheive a higher compression ratio which benifits naturally aspirated motors as well as motors with nitrous oxide. Here is a picture of a domed piston.
http://store.summitracing.com/partde...1&autoview=sku


Now you also asked about forged vs hyper pistons. Basically forged pistons are much stronger than hyper pistons. For instance if I where to run hyper pistons in my turbocharged motor I would have to turn the power way down. But since I have a good set of forged pistons in my motor I can tune it a little more agressive, get more power, and not melt a piston. A forged piston will allow you to run higher cylinder pressure, more timing (hotter), more boost or nitrous, ect ect. With hyper pistons you have to be very conservative. With forged pistons you can be much mor aggressive.

If you are planning to build a motor then ask questions before you act. If you dont know the answere just ask. This is an expensive hobby and nobody wants to spend their hard earned cash on a motor just to blow it up. If you are looking for power dont just stop at the pistons. The rest of the rotating assembly may need to be upgraded as well depending on the application.

[LEM]

Thanks for the explanation. I have a '90 Mustang LX 5.0L that I am hoping to restore; it has over 200K miles and is still my everyday car and has been since I bought it in 1990. I want to keep it stock, atleast as much as possible, but would like to improve its performance just a bit. I probably won't mess with the tranny or rearend, other than to rebuild them as is.

It needs a good paint job and just a little bit of body work. I'd like to put on some headers and replace the exhaust system (one tailpipe was damaged when I backed into a low wall one day many years ago - thus the little bit of needed body work). The interior is in okay shape, some small items have wornout (pwer door locks, radio backlight, sun visor mirror lights) and I messed up the driver-side door panel when I had to replace the power lock gizmo. Oh and the driver seat lumbar won't hold pressure; it'll inflate, but then deflates right away. BTW, do you know of any sources for stock seats for the Fox body Mustangs?

Thanks again and wish me luck...

[SkylineUSA]

David,

Good explanation. Look to ebay for seats, but I would go with a good set of aftermarket seats, the stock Mustang seat just plain SUCK! I bought a set of CR1 Corbeaus for $125, a couple of small tears, but still a hell of a lot better than the stock seat they replaced.

With your engine, go with Hypers. Good for what you want.