• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

331 Motor Build questions...

  • Thread starter Thread starter caseywan
  • Start date Start date Nov 30, 2006
C

caseywan

Member
Apr 7, 2006
157
0
17
Chicago, IL
Nov 30, 2006
#1
  • Nov 30, 2006
  • #1
Wasn't sure if this should go in Tech or Talk, so move it if needs be...

Anyway, I started a thread a little while back about adding a Kenne Bell 2.2, porting my X-heads, and getting a water/methanol injection kit and having 450+ rwhp on my GT40 block in the sig below, and I decided to take everyone's advice and not split nearly new block in half and go with stronger block. So here is what I'm thinking.

I found a local deal on a 331 shortblock R302 block bored .40 over with 4340 Eagle rods forged JE pistons and a Scat 4340 crank.

So here are my questions. I was thinking about getting that shortblock and getting my X-heads ported by thumper, and my compression would be 9.0:1 with those heads. First off, would I choke a 331 with a Kenne Bell using ported X-heads, and second would that compression ratio be optimal for 14-16 psi with the KB? If I keep the X-heads, a couple years down the road I would probably get some AFR 205's or something better when I can afford them.

Also, how would the E-303 cam do with this setup? I am thinking I would want to go custom or get a Comp cam.

Last questions, what size injectors would I want? I will be going with either 14 or 16 psi, I was thinking 42# injectors, but that might be too small.

Any input would be awesome, Thanks!
 
8

86bluecobra

Advanced Member
Dec 20, 2004
4,265
12
69
B.C. Canada
Nov 30, 2006
#2
  • Nov 30, 2006
  • #2
I think 9 to 1 maybe a little high for 14lbs of boost. maybe try a 8 to 1 or 8.5 to 1
 

FastDriver

I was uncomfortably high & wearing a helmet
SN Certified Technician
Sep 5, 2001
6,076
2,679
224
Vass, NC
Nov 30, 2006
#3
  • Nov 30, 2006
  • #3
Dude, if you're going to spend the coin to get the R302 and a 2.2KB, don't skimp on the cam.... It is probably the most important decision you'll make. That said, go for a custom and tell you cam guy to get the cam that will work with your planned combo so that future upgrades won't take you away from the cam that you get.

Chris
 

FastDriver

I was uncomfortably high & wearing a helmet
SN Certified Technician
Sep 5, 2001
6,076
2,679
224
Vass, NC
Nov 30, 2006
#4
  • Nov 30, 2006
  • #4
Oh yeah.... don't go over 8.5:1 if you're going to push more than 12 psi... I'd say you'll probably be ok at 15 psi, but don't skimp on the tune... The last thing you want to do is save $500 on a dyno tune just to trash a few grand worth of parts.

Chris
 
C

caseywan

Member
Apr 7, 2006
157
0
17
Chicago, IL
Nov 30, 2006
#5
  • Nov 30, 2006
  • #5
Yeah, I was pretty much planning on getting a custom cam, just wanted to know what the general consensus would be, although I could have guessed.


FastDriver said:
Oh yeah.... don't go over 8.5:1 if you're going to push more than 12 psi... I'd say you'll probably be ok at 15 psi, but don't skimp on the tune... The last thing you want to do is save $500 on a dyno tune just to trash a few grand worth of parts.

Chris
Click to expand...

So you think I would be ok 9.0:1 pushing 15psi? I don plan on getting a good tune.
 
C

caseywan

Member
Apr 7, 2006
157
0
17
Chicago, IL
Dec 1, 2006
#6
  • Dec 1, 2006
  • #6
Any other input would be awesome...

I actually just found out the shortblock I am looking at buying is a 333, not 331. Not that it really makes much difference.
 
You must log in or register to reply here.

Similar threads

Engine Suggestions on an engine rebuild. Stock cam/GT40Ps or aftermarket on both for a fun weekend driver?
  • MadSquirrelTech
  • Apr 28, 2026
  • Fox 5.0 Mustang Tech
  • 2
Replies
23
Views
702
Fox 5.0 Mustang Tech May 7, 2026
MadSquirrelTech
Progress Thread Progress Thread- From6to8's 95 GT/Saleen Supercharged 331 install
  • from6to8
  • Mar 22, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
24
Views
798
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- May 6, 2026
from6to8
9
Forced Induction Prepping for supercharger on non-stock build
  • 91fox427
  • Nov 25, 2025
  • Fox 5.0 Mustang Tech
Replies
7
Views
392
Fox 5.0 Mustang Tech Jan 5, 2026
Qtrhrse23
Q
S
Block questions
  • s_vargas54
  • Jan 25, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
21
Views
687
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Feb 8, 2026
Trogdor
Engine An engine building combo with stock Speed Density (SD) system
  • Mcmahst
  • Jan 14, 2025
  • Fox 5.0 Mustang Tech
Replies
11
Views
919
Fox 5.0 Mustang Tech Jan 15, 2025
Mcmahst
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?