We have been making slow but steady progress towards making my wife's car (1984 base model) more reliable and enjoyable to drive. What I would like to plan ahead for is improving its performance. With about 200K miles on the clock, yes, it burns a little oil. No doubt the bearings are going to start letting go pretty soon, too. So a rebuild is in the future, whether near or more distant. But, is there anything short of an engine swap that would wake it up even more? My wife would really prefer to keep the whole car as stock as reasonable; the one concession she has made will be to lose the 4-speed transmission in favor of a 5-speed. So, are there any exhaust, ignition, valvetrain or fuel/air delivery mods that can be made to the Iron Duke that will keep it from turning into a 97-pound weakling if we decide to turn the air conditioning on while driving from Branson, MO to St. Louis or Kansas City? Or are performance improvements to the 2.5 as rare as unicorn farts? Any/all input is, well, you know the rest... Thanks in advance - Chris

I wish I could add something to what has been written on this subject....but no.

https://www.fiero.nl/forum/Forum2/HTML/136279.html

About the only thing I've seen that is low cost and gives the Duke any more pep is to block off the EGR and to advance the timing 2 or 3 degrees.

I added a larger Holley throttle body which made a difference but those are very hard to come by...
High flow cat, advance the timing a few degrees, complete tune up...

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1984 Indy Fiero

quote Originally posted by edfiero: About the only thing I've seen that is low cost and gives the Duke any more pep is to block off the EGR and to advance the timing 2 or 3 degrees.

AFAIK, EGR function allows leaner mixtures to be run, with more timing and no detonation. If you eliminate EGR, its wise to increase fueling to compensate, then safe adjustments to timing can be tried. I would be inclined to not eliminate EGR and increase timing without fueling adjustments.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
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Note that many 84 got engine replaced under recall/warranty.
See my Cave, Duke Quick Ref

EGR is not open all the time. Mostly during cruising on highway etc. At or near Idle or WOT the EGR often closes.
Car 2.5 uses Exhaust pressure and vacuum port from TBI to work. Can't remember right now if EGR's TBI port is Manifold vac or Ported vac. Difference is where port opens inside the TBI.
(Car engine because many Trunk 2.5 EGR are ECM controlled sim to Fiero V6)

Check TBI will reach WOT when pedal is floored. Many cars have problems because iffy cable and/or pedal parts.
See my Cave, Throttle Cable and https://www.fiero.nl/forum/Forum2/HTML/132523.html
The "bearing" where mounted to firewall wears out too.

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(Jurassic Park)

The Ogre's Fiero Cave

Well, if you just want to keep a four cylinder engine, there is always the Super Duty for improved performance.

Nelson

..

[This message has been edited by tshark (edited 09-08-2018).]

My 88 duke is bored .040 over, has an Accelerated Motion cam shaft, big block Chevy roller rockers, and a 91-92 head (flows better), Puts out about 120 HP. But the 84 duke is not a good candidate for those changes. The later head wouldn't fit, and the crank and rods are weaker than 88 crank and rods. And I think the 84 has flat lifters (mine has roller lifters).

See here:
http://ironduke7.tripod.com/IronDuke.htm

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