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Discussion Starter #1 (Edited)
I've been contemplating a 5.0 DOHC project. Is it REALLY worth the cost to bore it over and get custom pistons? A friend of mine, who's more familiar with imports (he has a WICKED Supra and an Eclipse that'll be Vortech blown when it goes back together), didn't think that boring it out would be a good idea. Anyone had reliability issues with their bored Tecksid block?

Or should I get better rods and pistons, and use the money that would've been spent boring it over on headwork?

Does anything need to be done to the heads (combustion chambers), or do you need special head gaskets when you bore over to 3.7"?
 

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Cougar281,

You don't just bore out the Teksid aluminum block, it has to be fitted with larger diameter sleeves to get the 3.70" bore. You do not have to modify the heads, but different head gaskets are required.

Forged pistons and rods are always a good idea if you intend to build more power in a Ford modular motor. The 2V engines respond well to head porting; I'm not sure about the benefit with 4Vs.

I really like my Big Bore and would go the same way if I was building it again. It has been reliable so far, but I only have about 1400 miles on the motor (it's a "summer weekend only" car). Others on this Forum have put lots more miles on Big bores with no issues.
 

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Discussion Starter #4
Cougar281,

You don't just bore out the Teksid aluminum block, it has to be fitted with larger diameter sleeves to get the 3.70" bore. You do not have to modify the heads, but different head gaskets are required.
I realise that... What I'm wondering is is it really worth the extra cost to do?
 

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Cougar281,

Depends on who you ask. Extra displacement always adds power and torque (assuming no huge restriction on intake flow). Increasing bore size on the 4.6L engine is not cheap, but is believed by some of us to be more reliable than increasing stroke. Piston speed stays the same on the Big Bore, increases with a stroker.

With extra displacement you can make the same power as a smaller engine with (for example) a wilder cam, but at a lower rpm. That is a better compromise for street driving, if that is how you will use the car. Forced induction will get you the same gains, of course. I combined larger displacement with a roots type blower because I wanted lots and lots of torque.
 
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