Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Pistons on SVT?

Anyone catch in the article in

http://www.contour.org/cgi-ubb/ultimatebb.cgi?ubb=get_topic&f=1&t=010373

In the caption showing the "pent-roof combustion chamber" that is says the SVT pistons are in fact different than reg 2.5L, is this something only I missed?

I guess so.

The SVT uses piston dome height to change compression ratio.
Be it 10:1 CR or 10.25:1 CR
Everything else is the same.

In the 98.5 the CR is still 10:1. The pistons are also hypereutectic...whatever that means.

Hypereutectic Pistons use a high silicon (Normally ~14-18%) content & are CNC machined to make a stronger casting. Plus they are lighter, have better ring seal, & less thermal expansion.

A pent roof combustion camber normally refers to the way that the roof ie the head section of the chamber looks like if you notice the top part of the combustion chamber is not flat but almost forms a triangle it really has nothing to do with the pistons.....however the svt are different from the regular 2.5 for higher cr

The SVT uses forged pistons. The regular Duratec does not.

Incorrect Big Jim, as stated above and in the linked article, all Duratech pistons are hypereutectic cast pistons. They are definately not forged.

The jury is out on the 2000 SVT's as the sell booklet and CD say Forged Alloy...

They do use different pistons to make the 10.25CR

I'm sure that I remember reading in more than one source when the SVT Contour was new that it had forged pistons. I can't find one of those articles at the moment, but I did find something interesting in the SVT Contour broucher that I got when I bought my car. It refers to the rods as forged (really?) on the same line as describing the pistons "aluminum alloy".

The brochure is quite large (10" x 12"), has a dark blue (Ford blue) cover, is labeled "Special Vehicle Team 1998 Contour", and has 14 pages inside plus a fold out double page of a beautiful cutaway drawing of the SVT Contour by David Kimble. I destroyed one copy of the broucher to take that cutaway drawing and frame it to hang in my family room.

The pages are not numbered, but on what would be page 5 it says the following:

"Forged Rods, Aluminum-Alloy Pistons"

"The connecting rods are sinter-forged alloy components. They are made from powered metal that is compacted into the rough shape of a connecting rod and then 'hot-struck' at 1,024 degrees Celsius in a 600- ton press. After forging, the rod big ends are mechanically fracture-split to create the bearing caps. Due to the irregular, interlocking surfaces along the fracture line, a Duratec bearing cap and rod can be reassembled only one way, ensuring an exact fit and making the entire bearing cap assembly especially strong."

"The SVT Contour V6's specially designed alluminum-alloy pistons deliver a compression ratio of 10.0:1. The piston pins are full floating, reducing friction. Like the main bearing inserts, the rod bearing inserts are aluminum alloy."

I can see how someone reading this quickly may have the mistaken impression that it said forged pistons. I'm sure that I did read that somewhere else though.

Back to the rods for a moment. I certainly would not equate this sintered metal with cracked caps with the strength normally associated with forged rods. It makes me wonder if the "forged rods" slated for the SVT Focus are also really the same thing as the normal Zetec rods. Maybe this is an example of "Fordspeak".

I have talked with SVE's Tom Lavender, the man in charge of SVT Duratec project (and Troy has chimed in as well). None of the SVT pistons are forged (including 2000s) but Terry has said they are pretty tough anyway. SVT pistons are all similar to regular pistons but have thicker, dommed crowns. They sound quite durable for all but high boost - which would dictate low CR pistons anyway...Also, nice full floating wrist pins.

Rods are powder-metal "sinter forged" stronger than cast but weaker than billet/forged. Still, not bad IMHO - several VTEC designs use them at 8000 RPM, Ford SOHC/DOHC modular V8 (MustangGT and 4 cam cam Lincoln, not sure but probably Cobra. Cobra R uses Cunningham billet). Saleen & Rousch both supercharge the stock block 4.6 with sinter rods.

Crank is forged billet.