I just picked up a really low mileage 04 Cobra shortblock at a hell of a deal. I currently am running an 01 GT with a Procharger D1SC. From my research it seems that I will have to have a hole drilled in the block for the timing components. Is this something that a machine shop will need to do? I do not trust any local shops with modular engines. I also am aware that I gotta change to a 8 bolt crankshaft and I guess a new clutch. Is there anything else that I should know before putting my 2v heads on the 04 Cobra shortblock? I appreciate everyones input. I sure would like to go 4v all the way but that just isnt in the budget right now...Thanks
04 Cobra SHortblock...2V Heads ?????
- Thread starter 2001BlownGT
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SaleenGT2001
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trinity_gt
10 Year Member
You'll need the 8-bolt flywheel as the Terminator already had the 8-bolt crank (I suspect that's what you meant but just making sure...)
One thing you'll need to worry about is compression ratio. The 4V motor had pistons with a relatively small dish, just 3cc whereas the 2V piston in a PI setup, for example, had a 17cc dish. When used with a 42cc chamber volume 2V head, a 3cc dish is going to return a high, boost-unfriendly compression ratio of ~12:1 (zero order estimate...).
You really should look at getting forged pistons with a 17cc dish (or so) to bring that ratio down to something reasonable for boost. At least the shortblock has the rods and crank you want...
ronaldriske
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- Mar 25, 2004
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trinity_gt
10 Year Member
You sure? Hyland's book indicates that "4V engines have used a 3-cc dish in all applications since 1993."
ronaldriske
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- Mar 25, 2004
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yep, I'm sure.
n/a 4v's had the small dish pistons.
03/04 supercharged cobras had forged 16cc dish pistons.
now, what I'm not sure about is the op's question about the need to drill a hole.
n/a 4v's had the small dish pistons.
03/04 supercharged cobras had forged 16cc dish pistons.
now, what I'm not sure about is the op's question about the need to drill a hole.
trinity_gt
10 Year Member
Ah yes, you're correct, my apologies. The book I'm referencing appears to have been published before the Terminator debuted.
Car & Driver mentions the revised piston dish here to reduce the compression:
2003 Ford SVT Mustang Cobra - Road Test/American Performance/High Performance/Hot Lists/Reviews/Car and Driver - Car And Driver
Using your numbers, I get a rough ratio of 8.63:1 which is pretty close to the figure they quote:
"Revised aluminum heads and dished-top pistons drop the compression ratio to 8.5:1..."
So, knowing this then, the compression ratio with 16cc pistons and a 42cc 2V head (including rough estimates for the gasket thickness and deck clearance...) would be ~9.8:1
The OP will need to assess whether or not this is workable with the amount of boost he wants to run and the grade of fuel: 2V heads are not as detonation-resistant as the 4Vs are.
Thanks for keeping me on my toes!
CobraRed_96_GT
Active Member
yes the 4V's heads are large CC (52 i think) so that made the compression lower, so that means it'll be higher with 2V heads, but Termi's had 8.5:1 so high is better. Should still be low though.
As far as "drilling" the engine. I remember that in order to run PI heads on an aluminum 4V block, you need to drill for a coolant passage on the drivers side of the block at the front. Perhaps this is what your reasearch has led you to believe? I'm uncertain if the later 4V iron blocks need to be drilled or not?
Here is the area in question....
As far as the actual timing front section of the block where the timing cover goes, I'm not sure. I have heard of different alignment issues between 2V and 4V and Windsor and Romeo blocks, but without seeing a pic of said problem area, I'm as lost as the rest of you.
Here is the area in question....
As far as the actual timing front section of the block where the timing cover goes, I'm not sure. I have heard of different alignment issues between 2V and 4V and Windsor and Romeo blocks, but without seeing a pic of said problem area, I'm as lost as the rest of you.
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