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07silvergt

What Are Some Easy Upgrades During A Rebuild?

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I have a 1984 Mazda 626LX coupe. It's the 2.0L FE carb motor. I've got 390000 KM (242000 miles) on that thing now and although it runs smoothly enough and seems to have ok power (don't know for sure since I can't compare to new) but it does leak a lot of oil. The main leak is the front crankshaft seal but it leaks from other places too I think. I figure with that much mileage, it wouldn't hurt to do a rebuild. The question is, what are some cheap upgrades if I were to do it? It doesn't need to be a racecar but something to up it from the 83 HP it came from the factory with!

 

Would a 2.2L stroker crank be an idea? What about boring it out a little? Both?

 

How about 12 valve heads? Do they fit onto that motor and can it remain otherwise the same? Is there a performance gain?

 

Port/polish existing 8 valve heads? Bigger valves?

 

cam with higher lift?

 

Bigger carb?

 

Higher compression ratio? I think it came stock with 8.6:1 compression, but the fuel injected 12 valve that came later had 10.1:1 compression. Somehow I suspect the higher horsepower had more to do with the higher compression ratio than it did with it becoming fuel injected...

 

Would I need a combination of those mods to make more power? eg: stroker crank, 12 valve heads, 10:1 compression, port the heads and put larger valves and a bigger carb to support it?

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Where are you located ? This might assist others in giving ideas where parts can be sourced locally.

 

Oil leaks - this can be made worse by excessive blow by. If I were you I would start with a compression test. This will give you an idea of the health of your current motor.

 

If the compression is good, just fix the oil leaks. The usual places are oil pan gasket, valve cover gasket & sometimes head gasket, especially on high mileage motors.

Use sealant on the oil pan, a genuine Mazda valve cover gasket & add sealant in the 90 degree corners where it goes over the arches at both ends. Then degrease the motor and see where else the leaks come from.

Some other places - the dizzy O -ring & the dizzy/camshaft gear plate seal.

 

Power up. stroker crank is alot of work for not alot of gain - don't bother IMO.

12v heads do fit with some work. Not much gain to be had there either. The fuel injection can be, but no more than getting the fuel injected manifolds for the 8v head.

Port and polish - if you have the time and doing it yourself then yes. Paying - don't bother. Bigger valves - don't bother with that, they're pretty big already for a 2.0. There are guys making ~500WHP (turbo) with not much modification on the heads.

Cam - yes. More duration is what you want. I ran a 26/66 at one stage on one of my NA motors. The improvement was worthwhile.

Higher compression - yes, but unless you have to open the motor - don't bother. If you do, F8 SOHC pistons should get you ~10:1 but you'll need higher octane fuel like 98RON.

Bigger carb. IMO Webers are too expensive, but other people have used 32/36 DD and claimed that they make a difference. If I had to spend over $500 on a carb I'd convert the motor to fuel injection.

 

Forgetting all that you could pull the motor and drop in an FET, FE DOHC or F2T.

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The FE is a nice square engine (78x78mm) that turbo's beautifully. Nice linear curve. The stroker kit will gain you displacement but at higher revs the extra travel of the pistons will be a big negative. The engine also becomes vulnerable to snapped timing belts. I've just gone with the fuel and compression option.

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http://mazda626.net/topic/3034-f-series-engines/

 

FE is square, yes, but 86x86mm. Still, they have a good rod ratio. Bolt on N/A Power will not be abundant, especially with carb. Shorten the intake, larger (2.5" max) exhaust, better plugs and wires, tweak the timing and maybe a longer duration cam, and you might hit ~100hp for less than $1000. More aggressive cam, high comp pistons, bigger carb, there's $1000 for maybe another 10-15hp. And chief is right, if you can fix the leaks w/o opening the engine, you're better off, and pistons or stroke by themselves are not worth the minor gain.

 

It is less work to swap a more viable engine in then to N/A build yours with the many things you would need to do. If you'd go to the trouble of converting to FI for a 20% gain, turbo is only another step for a 50%+ gain, and the FE/T is a "drop in" replacement*, or at least a cyl head donor if you can't find one with a good bottom end. Or, with the ECM, harness, and manifolds off an FE/T, your FE could be converted, most likely without taking it out and/or apart. F2 gives you 120hp-ish just for installing it. F2/T has even more power options and again, it's about the same amount of work to swap the head over as the entire engine.

 

Or 'ZE swap it for the win

 

 

 

 

 

 

* - It's never just a "drop in" replacement... right chief? =)

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New to the forum, was reading this my question is what about the gear box? If silvergt goes with a turbo FE will his box handle the extra power?

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From the link in my post:

 

I would recommend the following gearboxes for each application

FE Box - FE / F6 / F8 / F2
FE/T Box - FE/T / FE / F6 / F8 / F2 / F2/T (low boost)
F2 Box - FE/T (low boost) / FE / F6 / F8 / F2 / F2/T (low boost)
F2/T Box - FE/T / FE / F6 / F8 / F2 / F2/T / FE DOHC / FE DOHC TURBO

 

Any power upgrades will tax a transmission. It largely depends on the driver. As long as you're not an asshole to your car, it should hold up. Clutch dumps = bad, Burnouts = bad, 30 psi in 1st gear is also probably not a good idea either.

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