This is topic 03 heads on a 96-01 cobra motor in forum Tech Talk at Northern California Ford Owners  .


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Posted by cobraman_1994 (Member # 467) on :
 
will that work?
03 cobra heads and top end
96-98 cobra lower end. it should work right?
 

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Posted by ON N2O (Member # 2067) on :
 
yup
 

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Posted by cobraman_1994 (Member # 467) on :
 
sweet
 

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Posted by ON N2O (Member # 2067) on :
 
killer
 

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Posted by cobraman_1994 (Member # 467) on :
 
whats the compression ratio on that motor? and whats the weak part? is it the rods?
 

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Posted by Black94 5.0 (Member # 655) on :
 
I'm 99% sure they will NOT work....

They are different because of the 96-98 IMRC's...If you want them to work you will need a 99+ intake manifold..
 

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Posted by -NORCALCOBRA- (Member # 2383) on :
 
yes they will work i am looking to sell my
fully port 96 b heads and get some navi heads they will bolt right up to your block but you will need to get a new intake manifold and fuel rails i belive
 

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Posted by -NORCALCOBRA- (Member # 2383) on :
 

quote:

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Originally posted by cobraman_1994:
whats the compression ratio on that motor? and whats the weak part? is it the rods?

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well the compresion ration is 9.8:1 and yes the weak part is the rods and pistons

what is the reason you are going to the 03 heads i would recomend the fr500 heads if you are staying n/a the heads are almost identical except the exhaust ports on the 03 heads have a differnt port and will require differnt headers the fr500 have a smoother short turn radius preventing air from over shooting the short side radius and making more port velocity which is a must for n/a motors the b heads aka 96-98 (swirl port heads) flow extremly well on the intake but lack port volicty but the exhaust port dont flow that well
most of the guy running 9s and under with forced induction are using the b heads...

n/a= fr500
mild blown 4.6 cars = 8-14 of boost 03 heads
big bore mod engines + boost= navi heads
high boost apps = 96-98 heads

all the heads above flow well enough stock to make 490 hp for example you take a bone stock 96-98 b head and it flows 240 cfm @ .500 lift x .257 x number of cylinder in our case 8 = 493.33

240x.257x8=493.33 of potential hp with natural asperation..
 

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Posted by cobraman_1994 (Member # 467) on :
 
because i need it to mach the eaton im buying tommorrow

now, wich would be better...an 03 shortblock (wich im having trouble finding ) or the alluminum block with manley rods and mod max low comp pistons?
goal is 500 rwhp wiht the normal bolt ons for an 03

[ November 28, 2003, 02:33 AM: Message edited by: cobraman_1994 ]
 

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Posted by st5150 (Member # 51) on :
 
If you want to put '99+ heads on a '96-98 bottem end, you'll have to install a '99+ intake as well. The '99+ heads have a more efficient exhaust port and some other minor tweaks that are hardly worth the hassle. You're better off keeping life simple and porting/working your factory '96-98 heads.
 

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Posted by cobraman_1994 (Member # 467) on :
 
yes, but the 03 cobra heads are different right? i have them...well...i paid for them anyways. i was just wondering if the 2003 cobra top end (heads, lower intake, and blower assembly) will bolt up to the older cobra shortblocks. and now i know.
i found a blower to buy, im just waiting for his response. its all coming together now
 

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Posted by -NORCALCOBRA- (Member # 2383) on :
 
if you are buying a eaton then yes the 03 set up will work you ever be ready for fuel upgrade and alot of tuning as for a 03 block is gonna run you 4000 grand for the short block and 11,000 for the complete setup i can get you a hci built for 3200 of so let me know if you are interested in that the stock cobra block and crank are good up to about 1000 hp or so
 

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Posted by cobraracer46 (Member # 1142) on :
 
Swapping the 03 heads on to your Cobra will not work. Using 03 Cobra heads on a 2001 or earlier DOHC modular 4.6, 5.4 will result in port mismatch.
 

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Posted by -NORCALCOBRA- (Member # 2383) on :
 

quote:

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Originally posted by cobraracer46:
Swapping the 03 heads on to your Cobra will not work. Using 03 Cobra heads on a 2001 or earlier DOHC modular 4.6, 5.4 will result in port mismatch.

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quote:

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Originally posted by -NORCALCOBRA-:

quote:

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Originally posted by cobraracer46:
Swapping the 03 heads on to your Cobra will not work. Using 03 Cobra heads on a 2001 or earlier DOHC modular 4.6, 5.4 will result in port mismatch.

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wanna bet..all sohc and dohc blocks are all the same from what ia m told from cole at hci

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quote:

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Originally posted by cobraman_1994:

quote:

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Originally posted by -NORCALCOBRA-:

quote:

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Originally posted by cobraracer46:
Swapping the 03 heads on to your Cobra will not work. Using 03 Cobra heads on a 2001 or earlier DOHC modular 4.6, 5.4 will result in port mismatch.

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wanna bet..all sohc and dohc blocks are all the same from what ia m told from cole at hci

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thats what i thought too. thanks for all the info! ill keep everyone posted on my swap progress.

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quote:

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Originally posted by cobraracer46:

quote:

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Originally posted by cobraman_1994:

quote:

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Originally posted by -NORCALCOBRA-:

quote:

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Originally posted by cobraracer46:
Swapping the 03 heads on to your Cobra will not work. Using 03 Cobra heads on a 2001 or earlier DOHC modular 4.6, 5.4 will result in port mismatch.

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wanna bet..all sohc and dohc blocks are all the same from what ia m told from cole at hci

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thats what i thought too. thanks for all the info! ill keep everyone posted on my swap progress.

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The O3 Cobra heads will bolt up to any Cobra or other Modular V8 engine block, but you just can't go out and swap the heads on a 2001 or earlier Cobra with the 03 Cobra heads with out going to the 03 intake and exhaust headers because the the intake and the exhaust ports on the 03 Cobra heads have a new design that will result in a port mismatch if used on diffrent Cobras.

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this man is 100% correct.
 

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Posted by cobraman_1994 (Member # 467) on :
 
i already know you cant just swap the heads on an earlier motor and expect to have everything match correctly. i was just wondering about the block matching the heads. wich i now know it does.
 

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Posted by -NORCALCOBRA- (Member # 2383) on :
 

quote:

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Originally posted by cobraman_1994:
will that work?
03 cobra heads and top end
96-98 cobra lower end. it should work right?

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if anyone read this you would know what he is asking 03 cobra heads + top end which means blower so why whould you talk about ports misalignment
 

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Posted by cobraman_1994 (Member # 467) on :
 
yep. thats what this thread is all about. 03 cobra top end on a 96-01 cobra shortblock. lol
 

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Posted by Rev Happy (Member # 661) on :
 
Poor mismatch?

My friend ended up running high 10s with his 03 Cobra on the stock eaton with no nitrous using BBK LT headers for a 99, 01 Cobra...
 

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