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Discussion Starter · #1 ·
A big problem with small engines is low end torque. Yes, you can make the max torque occur very low in the RPM range then have a very flat curve throughout the range, but give or take 30 lb-ft you really can't make a whole lot more torque with the standard mods. I can't remember the website, but they did a sequential buildup and dyno test of a Zetec. They started with what we all do, intake, then exhaust, then TB, then low pro cams through high pro cam, then low press trubo and high press turbo... blah blah blah, but they never got more than 160 pounds of torque out the engine.

This is a classic case of [?|] with a small cube engine. We all have the problem as compact owners. You can make gobs of horsepower but thats a BS number. I want torque, I want lots of it, and I want to make it efficiently. Horses don't kick you back in your seat when you mash the accelerator, torque does. Take note of the new 2.3L, more torque than the SVT but less HP on a much less exotic engine buildup. Far more useable. The reason, more cubes. A bigger bore almost always results in more torque per liter than any other mod.

So, I pose this question to all. Considering the age old mantra that there is no substitute for cubes, has anyone ever seen/heard of/done any overboring of the Zetec engine? I have never heard of it myself, so when my ride makes the transition from daily driver to weekend warrior, I will seriously be considering boring it over.
 

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Boring out a zetec isn't worth it and will not give you the gains your looking for.

Well your wrong on that torque issue, many turbo kits like the aerocharger which was out. Made as much if not more tq then hp. Heres an example.

One guy near me had an AC3 turbo kit and we dyno'd his car, it made 211 whp and 201 wtq on hi boost setting, on low boost it made 198 whp and 196 wtq.

Eclipsing 160 wtq with a turbo is very easy.
 

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Discussion Starter · #3 ·
I agree that you can make monstrous gains from a turbo, but at the cost of durability. you have to build the sh't out of a small engine to hold up to 1.75-2 atm pressure if you want to keep it for a while. With boring an engine doesn't reduce the durability nearly as much and it does give direct advantage. Its a matter of the physics. Even if you kept the same ignition pressures, Pressure x Area = Force, Force x Lever length = Torque, varying pressure, area, or lever length will give you additional torque. Bumping pressure is obviously forced induction. That is all well and good, but that increases the engine temp, seal fatigue, ring wear, journal wear, likelihood of valve burning and adds weight to the car. Increasing lever length is tricky, you have to increase the center to center distance on the crankshaft while decreasing the connecting rod length, this is major league territory for internal clearance issues. By increasing the borediameter, you do have a lot of surgery and cost involved, but the durability of the engine when its complete is excellent. You dont win races when you're parked on the side of the track. Now, if you've got the bucks doing all three would make for huge power gain. I doubt it would be hard to make a really reliable 300 - 350 hp out of this engine if you had the bucks and the time.
 

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They make close to 600 hp when built properly.

My friend with the turbo setup has 60k+ miles without a problem. I think the question of durability is an old wives tale.
 

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From everything that I have heard, when it comes to turbo, tuning is the key. There are a lot of cars out there running turbos on stock internals just fine.
 

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Discussion Starter · #7 ·
I really don't know. I'm in the initial reseach stages. This project would probably be two years away, when I get a new daily driver. If I remember correctly the sleeves are pretty thick. A solid 7-9 mm. That's recollection from my SPI engine factory days though. If I'm not mistaken the block of the SPI and the Zetec are the same (as well as other bits of course). I don't even know if I could get pistons that would work. I have never heard of anyone doing this so we'll see. If I were to give it a shot, I'd pull an engine out of a scrapyard and try it out. Just build it up out of the car and if it works, swap em.

Anyone have any clue how much an engine out of a wrecked car would run? I know they are something like 2500 from Ford Performance Parts, but thats stupid high when you could almost buy the whole car for that much.
 

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I'm sure it depends on the scrapyard, and the demand in your area.
 

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This has been done before, the zetec stock block doesn't have alot of room for removal of material. I think the last guy that did it just bearly got 2.1 liters of displacement. believe me, it is not worth it. I wouldn't tell you it wasn't if it truly was not.

Just beef up the stock bottom end and block.
 

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i agree with focaltech on this not worth the time and money, and as far as durability i would say boreing it out also has its disadvantages, #1 100k down the road your gonna have alot piston slop and wont be able to over bore at that time #2 if you scar the cylinder walls for any reason once again you out, My own opinion is keep it how it is if you want more displacement you could stroke it. Or just like focal said run turbo, destroke, drop comp., and run insanely high boost. OH and as far as torque on small engines try driving a honda, the focus definately has the best low end torque of any small car i've driven
 

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Discussion Starter · #11 ·
I agree about great low end torque in the Focus. The torque curve is insanely flat right from the factory. But, like Tim Allen, I say... "More power." I am coming around to agree with you on the boring. I have over the weekend done my homework and you are right, the amount of displacement gained is negligible... maybe an engine swap is in order. I wonder how hard it would be to put the upcoming Ford 500 powertrain in the Focus, complete with 200 hp(baseline) V6, 6 sp auto, and a Haldex AWD system. A man can dream cant he? OOO OOO, what about the Volvo S60R powertrain? Turboed I-5 with 300 hp, 6 sp manual and AWD. I like the sound of that much better. And I bet it would fit. The C170 and the F6 chassis share a lot of geometry, especially on the next Focus. mmmm, delightfully stupid engine swaps that I'll never do.
 

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who dont you get some bolt ons and see how you like it
 

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Discussion Starter · #13 ·
Like I said, a man can dream. I talk big, but it will be well into the year before I buy anything else for my car. Have school to pay off. Sutpid skool. No real good garage access really limits my ability to do stupid things too. I may just skip out on going crazy with my focus and build something from scratch. I've built a lot of hand fabbed project cars in school with other people and I want to do something on my own. So I may start with the Zetec and the MTX75 and build a 1200 lb mid engine road scorcher. Wouldn't that be fun? For my capstone at school we took a miata powertrain and did something similar. Tube frame, fully independent suspension, turbo, no HVAC, no top, no doors. 0-60 in 3.8 secs. Woohhoooo! But then again, thats just more big talk. We'll see if I'm singing the same tune when I'm saddled with two kids and a mortgage.
 

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The only way to swap one of these systems into a focus is to spend big money. I don't see it happening in the near future by anyone.
 
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