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  • SN95 4.6L Mustang Tech

Is there any performance difference between romeo blocks?

  • Thread starter Thread starter 53BigDog
  • Start date Start date Aug 4, 2008

53BigDog

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May 22, 2001
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Aug 4, 2008
#1
  • Aug 4, 2008
  • #1
I just cracked my 97GT romeo block and am looking at new/used ones. I understand that all romeo blocks are interchangable but my question is specifically is there any major performance differences when swapping out a 96-98 romeo block as compared to a 2003 Cobra Romeo block?

I understand there are main bolt differences (2bolt-4bolt) but other then that are there difference in cylinder size, etc.

Which block would yeild the best performance on my 97GT with PI heads and 9cc forged pistons and forged rods. I am looking to stay N/A and gain about 10.5:1-11:1 compression.
 

mogs01gt

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Jul 22, 2002
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#2
  • Aug 4, 2008
  • #2
Any 4v headed block will not have the 2v head coolant passage on the driver side of the block. You will need to drill out that coolant passage.There arent any differences between the blocks, they can all handle the same amount of power. Also, all 2v cast blocks are a 4 bolt designed, the 4v blocks are a 6 bolt.

No mod engine is a 2 bolt design.
 

53BigDog

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#3
  • Aug 4, 2008
  • #3
However when ordering ARP main Studs you must designate between 2 botl mains and 4 bolt mains. That signifies the amount of bolts that lock down the main caps from the bottom of the engine (not including the side bolts that screw through the block.
 

mogs01gt

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#4
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the main caps are the same except for the side bolts.
 

53BigDog

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#5
  • Aug 5, 2008
  • #5
How do the side bolts differ?
 

mogs01gt

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Jul 22, 2002
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Aug 5, 2008
#6
  • Aug 5, 2008
  • #6
53BigDog said:
How do the side bolts differ?
Click to expand...
Nothing, I was having a brain fart!

This is a good link regarding the mod engines.
Rebuilding the Ford 4.6L SOHC Engine, Doug Anderson, Engine Builder, April 2002
 
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