Dual Plug vs. Four Plug Engine. Horsepower vs Gas Milage?
hi there guys!!
first let me thank enintho.. for helping me decide to sell my zx2 and keep the mustang.
I'm no stranger to the 2.3 turbo, I have an 85 merk right now with all the goodies I need. and I know that motor isn't very friendly on gas milage. it has the pe pcu, big vam, front mount IC and a full three inch exhaust. and the milage well.. SUCKS!!! I also have a LA2 or 3 pcu as well.
my question is will a dual plug motor re-built with forged pistons be the best for milage and performance?? I'm not lookin for mega hp 250 maybe 300hp would be nice, But I just like the sound of the whistle as I cruise by other cars!!!!
Your motor should be fairly easy on fuel if tuned properly. Most turbo guys are reporting anywhere from 20-27 mpg commuting.
I don't think you'll get what you're looking for out of the dual plug setup. One, the ECUs won't work. You won't get a PE or an LA to work with the DIS ignition and there's no way to TwEEC, tune, or otherwise alter the parameters in a DIS ECU.
Work on the tune. Not plugs, plugwires, etc. But the real tune, timing, fuel, sensor conditions, etc. You've apparently got some issues to sort out. Once you get a handle on it, you're mileage, and possibly even overall performance will be more to your liking.
actually on the rebuild you can use hypereutectic pistons, allowing for tighter piston to ring seal. by using the high silicon piston the engine will keep its compression longer allowing for a longer life. This means the motor will stay stronger longer than if you used the forged piston.
possibly having a more efficiant motor that is better on gas. Then you can use a colder range of plugs to burn the fuel more evenly..
What B--chandler said a good tune will be the first thing you do when you get the motor running.
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actually on the rebuild you can use hypereutectic pistons, allowing for tighter piston to ring seal. by using the high silicon piston the engine will keep its compression longer allowing for a longer life. This means the motor will stay stronger longer than if you used the forged piston.
possibly having a more efficiant motor that is better on gas. Then you can use a colder range of plugs to burn the fuel more evenly...
I wouldn't put hypereutectic pistons in anything I planned on running with high cylinder pressures/temps. Yeah, they're supposed to be the happy medium between cheap cast pistons and expensive yet durable forged pistons, but if you roach one of these pistons doing something that forged pistons would have survived, what money did you save? My favorite is finding a set of hypereutectic pistons pinned to a set of H-beam rods.
The tighter clearance on "hyper-euts" is piston-to-wall, it has nothing to do with engine longevity or durability. Hyper-euts just don't expand as much as they're forged counterparts and therefore need less cylinder wall clearance to compensate for thermal expansion of the piston. If both engines are built right, piston-to-wall clearances will be about the same at operating temperature.
Anyway, that's not really what he's here for. He's here because he's getting crappy fuel mileage. Changing from the dist. fired 4-plug arrangement to the 8-plug DIS system is like buying a different set of tires because yours are low on air.
nah.. I've got a 92 fox body, with the dual plug. I also have the merk, fun car to drive, but no ac. I want more than the 105 hp from the dual plug, hell if I could get 150 to 190 from it(the dual plug) I'd be happy with it. I'd probabally come out cheaper in the long run, but 105 hp???? what was ford thinking?? the 2.3 focus has more power than the mustang... it's a sad ,sad world...
my intintions are to drop the car 1/2 inch, which is why I thinking coil over', and the gt style turbine rims, header from the ranger and anything else that might get me close to 150 to 190 hp, or I go turbo a full 3 inch exhaust, front mount IC with the LA3 pc.. the PE is nice, but it also can only run with 92 plus gas... I like the thought of the cheap stuff!!!
You could sacrifice the Merk for the greater good of the Mustang or go find a similar powertrain and dump it in the Stang. Quite frankly, 150-190hp from a naturally aspirated 2.3 is going to take more than some intake and exhaust work and you won't get off much cheaper.
Something to think about if you're dead set on keeping the dual plug slug in the Mustang... The later 2.5L variant of the 2.3 that was put in Rangers had a slightly different head. In stock form, flow bench results are quite impressive compared to other 2.3 castings including the beloved 4-plug turbo head. It outflows just about all of them at lower lifts. I'd bet it'd be a nice improvement over the horrible 1st gen dual plug casting. I don't know and can't say how much of an improvement, but at this point, anything is a plus. I did a bowl blend on a '91 casting and improved bottom and midrange power a little. I don't think I got it to flow anything like the 2.5 head, but it does show that it will respond to improvements there.
Take a look over at the RangerStation to see hp specs and misc, crap on the 2.5L BTW: The crank is a direct drop-in.
the 2.5 head and crank??? but if I did that how would it gain?? would you have to use the pc from the truck?? and wouldn't the milage suck from the truck?
You wouldn't need to use the truck computer. There's no reason for it. The head will flow more air in and out, therefore it has the potential to make more power. The computer is irrelevant here.
The crank is a pretty big job. If I were rebuilding the entire motor, I'd be all over it, but if you're just looking to throw stuff at it, try the head first, then go for the typical cold air crap and header.
Read up on EEC-IV (Ford's engine management system up to 1996) You learn what it does and doesn't see, and what it does and doesn't like. You may also discover why your Merk is getting bad fuel mileage.
huh... the bad milage is the right foot!!!! I like red light to red light races!!! and the 5.0's are the most fun to beat. they hate knowing a 4 banger just beat them.
I replaced almost everything from o2 to wires... to gaps in plugs!!
ROFL!! Why didn't you just tell me that the fuel consumption problem was caused by a loose nut behind the steering wheel? Hell I'm thinking you got tuning issues!
It's funny, no one likes getting beat by a 4-banger...including other 4-bangers.
Anyway, I was digging through some old threads on a couple of sites out of boredom last night and ran across flow bench numbers for the different 2.3 heads over the years including both generations of dual plug heads. I also found factory hp ratings for dual plug engines used beyond the Mustang years. The last 2.3L dual plug Lima engine was rated at 112hp from Ford. Other than the better flowing head and tubular exhaust there ain't much difference between that version and the first gen motors. Uncork the intake, maybe play with cam timing or a different camshaft (FMS A-234 or equivalent maybe?) and a little bump in compression and you could probably get it over the 120hp hump.
I'll go back and get those flow numbers if you want them or grab the link and post it here.
Dual Plug vs. Four Plug Engine. Horsepower vs Gas Milage? 
actually on the rebuild you can use hypereutectic pistons, allowing for tighter piston to ring seal. by using the high silicon piston the engine will keep its compression longer allowing for a longer life. This means the motor will stay stronger longer than if you used the forged piston.
