99 2V Dyno'd

[Krewat]

I missed this. WOW - what a difference. And all in the top-end, and NO LOSS at the bottom end. Cool

[Johnny Langton]

Originally Posted by Krewat

I missed this. WOW - what a difference. And all in the top-end, and NO LOSS at the bottom end. Cool

Better cams and compression are your friends..
JL

[Krewat]

Compression is higher on the PI heads?

[Johnny Langton]

Originally Posted by Krewat

Compression is higher on the PI heads?

The piston dish on NPI shortblocks is smaller than the PI shortblocks(10cc vs 17cc if memory serves me right).
The difference is 9:1 CR vs ~10.3:1.
JL

[Krewat]

I was always under the impression that the V10 pistons were the same from 1997 through 2004 or even up through the 3-valver.

For instance, from a Ford parts online web site:

"Piston, f250 pick-up - 6.8l - 1999-07 super duty - 6.8L - 1999-07 SUPER DUTY"

The V8's are definitely different between PI and non-PI.

[Krewat]

And from Sealed Power, for their piston # H885CP

FORD E SUPER DUTY (1997 - 2002)
FORD E-350 ECONOLINE (1997 - 2005)
FORD E-350 ECONOLINE HD CLUB WAGON (1997 - 1998)
FORD E-350 ECONOLINE SUPER (1997 - 1998)
FORD E-350 ECONOLINE SUPER WAGON (1997 - 1998)
FORD E-450 ECONOLINE (2003 - 2005)
FORD E-550 SUPER DUTY CUSTOM 2003
FORD EXCURSION (2000 - 2005)
FORD F-250 SUPER DUTY (1999 - 2004)
FORD F-350 SUPER DUTY (1999 - 2004)
FORD F-450 SUPER DUTY (1999 - 2004)
FORD F-550 SUPER DUTY (1999 - 2004)

[Johnny Langton]

Originally Posted by Krewat

I was always under the impression that the V10 pistons were the same from 1997 through 2004 or even up through the 3-valver.

For instance, from a Ford parts online web site:

"Piston, f250 pick-up - 6.8l - 1999-07 super duty - 6.8L - 1999-07 SUPER DUTY"

The V8's are definitely different between PI and non-PI.

The cylinder heads also have different size combustion chambers. The PI being approx 42cc and the NPI being 50cc.
There IS a compression difference,with PI heads on a NPI shortblock being higher. The pistons ARE different as well. Seeing the Sealer Power numbers shows me that it isn't the first time I've seen the aftermarket get something about a modular screwed up,and it won't be the last.
JL

[fordmdb]

Just to clarify, the engine in 99 truck is a complete PI engine... We did a complete engine swap from a non PI to PI... same exhaust system, S&B intake and calibration.

[Johnny Langton]

Originally Posted by fordmdb

Just to clarify, the engine in 99 truck is a complete PI engine... We did a complete engine swap from a non PI to PI... same exhaust system, S&B intake and calibration.

Now you've skewed the results......
Using a different engine can result in that engine being in better condition than the original.


JL

[Krewat]

Originally Posted by Johnny Langton

The cylinder heads also have different size combustion chambers. The PI being approx 42cc and the NPI being 50cc.
There IS a compression difference,with PI heads on a NPI shortblock being higher. The pistons ARE different as well. Seeing the Sealer Power numbers shows me that it isn't the first time I've seen the aftermarket get something about a modular screwed up,and it won't be the last.
JL

But even Ford says the V10 pistons are the same from 99 through 2007.

Are you sure this is true for the V10 and not just the 4.6/5.4 PI vs. non-PI?

[Johnny Langton]

Originally Posted by Krewat

But even Ford says the V10 pistons are the same from 99 through 2007.

Are you sure this is true for the V10 and not just the 4.6/5.4 PI vs. non-PI?

Think about this....
If they used the same pistons for ALL 6.8L's,then the non-PI engines would have less than 8.5:1 CR,and the PI engines would be right around 9:1.
They 6.8L's all use the same con rods as the 5.4L, and the crankshaft stroke is the same between all of them, so with the same head gasket, same piston and different head combustion chamber cc's,then you have a vastly different compression ratio. Over the years I've found countless errors in Ford's printed and online reference material,and their part number/cross reference interface is hideous.
JL

[fordmdb]

Originally Posted by Johnny Langton

Now you've skewed the results......
Using a different engine can result in that engine being in better condition than the original.


JL

You can look at it that way... I guess

[Krewat]

Originally Posted by Johnny Langton

The cylinder heads also have different size combustion chambers. The PI being approx 42cc and the NPI being 50cc.

My service manual CD for 2001 says combustion chamber size is 52.6-51.6 cc. For a PI head V10.

Ford service manual I downloaded from motorcraft.com back when it was still available without a subscription, also says 51.5 cc's for 2001. Not to say, of course, that there aren't errors in Ford's literature

I dunno, I know at least one person here has put PI heads onto a '99 long block and I doubt he's running over 10:1 compression on 87 octane without issues. The knock sensor logic will only pull back the timing so far - 4 degrees?

Picture of a '99 head, typical NPI.



V10 PI head:



Typical 4.6 NPI vs. PI:



Looks like you might be right - the PI V10 head does look like a smaller combustion chamber.

Oh well, there's something about "assuming"

[Johnny Langton]

Originally Posted by Krewat

My service manual CD for 2001 says combustion chamber size is 52.6-51.6 cc. For a PI head V10.

Ford service manual I downloaded from motorcraft.com back when it was still available without a subscription, also says 51.5 cc's for 2001. Not to say, of course, that there aren't errors in Ford's literature

I dunno, I know at least one person here has put PI heads onto a '99 long block and I doubt he's running over 10:1 compression on 87 octane without issues. The knock sensor logic will only pull back the timing so far - 4 degrees?


Looks like you might be right - the PI V10 head does look like a smaller combustion chamber.

Oh well, there's something about "assuming"

The PI does have a smaller chamber. You're not necessarily going to have a problem with spark knock by swapping the heads and upping the CR by that amount. It won't be optimal and the knock sensor will have a bit more of an active role in spark advance adjustment,but it's not going to just knock uncontrollably at that level of CR increase.
JL

[mwsF250]

Regarding pistons, the piston crown looked different on my '06 3V block as compared to the '99 2v block. The "ridge" around the edge was wider, so the dished part was smaller diameter.
But some rough measurements and math indicated the "volume" between the piston top and plane of the cylinder head was really close.

So while the pistons appear to have changed over the years, the changes may be so small that they are effectively interchangeable. So Ford (and others) may be offering only 1 to fit all to minimize inventory.