Rebuilding my 98 cobra 4v, need help please

Atrix

New Member
Joined
May 5, 2022
Messages
2
Location
United States
Hey guys just bought a 98 cobra and the guy ripped me off because it had 2 spun bearings on cylinders 2&6. I had to get block bored .20 over because it was pitted, also had to get Crank welded on journals 2&6. so i bought some new rods and pistons. well the pistons i had bought are below. I was wondering will i be at 10,6:1 ratio? and if so is that gonna be pretty safe? thank you

ModMax OEM Hypereutectic Piston Set 4.6 5.4 0cc Flat Top
  • Bore Sizes: Standard (3.552"), .020" over, .030" over
  • Compression Distance: 1.209"
  • Dish Volume: 0cc (Flat Top) no valve reliefs
  • Pin Size: OEM .866" Piston Pins - Standard Wall
  • Pin Retention: Full Floating with lock rings
  • Ring Sizes: 1.5mm-1.5mm-3mm
FOR YOUR COMPRESSION RATIO WITH THESE PISTONS PLEASE SEE THE CHART BELOW
COMPRESSION RATIOS​
2V NON PI​
2V PI​
4.6- 4V ALL​
5.4- 3V or 4V
0cc Dished with 4.6 Engine​
10.4:1​
12.4:1​
10.6:1​
0cc Dished with 5.4 Engine​
9.6:1​
10.8:1​
9.8:1​

clear1x1.gif

DBox_Border_Left_Bottom.gif
 

freebird50

Active Member
Established Member
Joined
Apr 8, 2017
Messages
140
How is your build going?
Will be totally safe with that compression even with boost.
Hey guys just bought a 98 cobra and the guy ripped me off because it had 2 spun bearings on cylinders 2&6. I had to get block bored .20 over because it was pitted, also had to get Crank welded on journals 2&6. so i bought some new rods and pistons. well the pistons i had bought are below. I was wondering will i be at 10,6:1 ratio? and if so is that gonna be pretty safe? thank you

ModMax OEM Hypereutectic Piston Set 4.6 5.4 0cc Flat Top
  • Bore Sizes: Standard (3.552"), .020" over, .030" over
  • Compression Distance: 1.209"
  • Dish Volume: 0cc (Flat Top) no valve reliefs
  • Pin Size: OEM .866" Piston Pins - Standard Wall
  • Pin Retention: Full Floating with lock rings
  • Ring Sizes: 1.5mm-1.5mm-3mm
FOR YOUR COMPRESSION RATIO WITH THESE PISTONS PLEASE SEE THE CHART BELOW
COMPRESSION RATIOS​
2V NON PI​
2V PI​
4.6- 4V ALL​
5.4- 3V or 4V
0cc Dished with 4.6 Engine​
10.4:1​
12.4:1​
10.6:1​
0cc Dished with 5.4 Engine​
9.6:1​
10.8:1​
9.8:1​

clear1x1.gif

DBox_Border_Left_Bottom.gif
Will be fine with that compression but if you are boosting I would recommend a forged piston instead. If your going through all the trouble get forged so down the line you can add more boost. Also recommend forged steel connecting rods. My motor has survived with 10:5:1 compression for years with 20+ pounds of boost. It is a fully built motor however and a good tune.
 

Users who are viewing this thread



Top