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engine.jpg (78132 bytes)My car is currently powered by a mighty Naturally Aspirated 2.5 liter engine.  Rated at 100 hp @ 4800 rpm and 135 ft.lbs of  torque @ 2800.  It isn't no hot rod, but is faster than 90% of the average naturally aspirated 4 bangers you find on the road.   Things like Neons and GM quad 4's are more powerful, but only when equipped with a 5 speed transmission.  Those 2.3 liter Mudstains don't stand a chance.  30 MPG isn't a problem for everyday driving.  I managed to get 39 mpg average on short road trip I recently made with the windows down, 2 people in the car, and my toolbox in back.  The big 40 isn't out of the question.

 

engine2.jpg (80409 bytes)Well, here's my engine compartment.  Most of everything is stock. Only things that are different here are the strut brace, dixie horn and a Forward Motion underdrive pulley.  I have advanced the timing slightly, and removed the warm air inlet valve for some improved airflow.  The FM underdrive pulley gave more power and better mileage at the expense of having headlamps that dim slightly at idle.   More ore less depending on how many accessoies are running.  I also bypassed the coolant hose which goes through the intake manifold to warm up the intake charge.  More power, yes...if you can put up with the low-rpm hesitation it creates.   And when its cold like 50 degrees or less, its a SERIOUS hesitation.

 

 

There is a number of performance mods you can do to a fuel injected naturally aspirated 2.5.  Some simple mods include:
Warm air inlet valve removal  1-2 HP
K&N Air Filter                       1-2 HP
A/C belt removal                    .5-1 HP
Timing advanced                     2-3 HP
Opening up the exhaust           3-5 HP   *an open exhaust only allows more power if the intake is more open.
Underdrive Pulleys                  7-10 HP
Intake & Exhaust porting        5 HP
Removal of Balance Shafts     13 HP

This gives you at least 30 more horsepower.for a total of 130 HP

If you've got money to spend, you can increase the compression, port the head, port the hole where the oil pump mates to the block, get a baffled oil pan (keeps oil from getting whipped up by the crank), get bigger valves, and try a hotter cam.  The thing that really restricts these engines is the puny throttle body.  I'm trying to find if it can be bored larger.  I also thought up a dual-TBI setup using the dual carb intake from Mopar Perfornance.  I think this might actually work, but it is my understanding that the dual carb intake was discontinued.