Re-read my first post, I addressed everything you said.

No, your knowledge of engines is a joke. This forum is probably one of the greatest things to happen to the Fiero and it's owners since it was released. Maybe it would be better for you to get a Camero, I hear the V6 models put out 400HP with a cam and lifter change! And could you, please oh please, enlighten us as to how you plan to make a Fiero into a TRAILER!. Good luck with that one!

Edit: Maybe you should give this a read: How to Build Horsepower

This was done with a Super Duty 4, commonly called the SD4. It was a special race only block, heads and parts specifically for "off road use" Pontiac in the mid 80's had the SD4 engines being used in IMSA Fiero race cars, Power boat racing, and even today are still being used in the ARCA class racing. The stock production is in no way near the strength and flow of the SD4 engines.
If you really want to know about the differences from your 2.5L and an SD4, Here is a good website to look at:

http://www.k12.nf.ca/gc/Staff/Teachers/Crummey/fiero/IronDuke.htm

They also did everything you mentioned in your previous post to a 2.5L. You say you should see 200hp, they dyno'd their engine and got 120hp:

http://www.k12.nf.ca/gc/Staff/Teachers/Crummey/fiero/builtduke.htm

Looks like someone is asking how the rating system works.

Well if you get a Camaro then I guess your cousin will build you a 1300hp 350 for it. Just have him remove the catalytic converter and make the entire exhaust out of 5" diameter pipes.That should get you to 1200hp, Don't for get to add the "Type R" sticker for the extra 100hp to get the 1300hp.

I purchased a showroom fresh SE in 1984. A real "first model year" automobile! The dealer got real tired of doing warranty work on my car.
This car spent most of its time running between Myrtle Beach and Philadelphia on I95 at speeds in excess of 100 MPH. (Radar Detector engaged of coarse.) Hell! I was 30 years old and indestructible! But the car was brand new, and I was "in a hurry".

The car threw a rod at 60,000 miles. Dooohhh!
I think that speaks volumes about the 2.5 internals.

Five years ago, I bought a 1986 coupe for reasons I can only call NOSTALGIC. That was followed by the purchase of another coupe a short time later, an '84. When placed side by side the 84 was quicker, but the 86 was smoother.

Well, the '86 broke a piston ring awhile back, and I'm now ready to do the V8 thing. Many obvious reasons.

In short. The Duke with the CAT and A/C removed sounds a little better, pulls just a little harder and gets great gas mileage. On a real twisty road with the right "moves" the little car with the Duke is alot of fun. But if you're looking for straight line HP, do an engine swap.

If you must keep the Duke, just do the cheapest things to help it breath. Holley throttle body, headers, porting, and free flow exhaust. You'll have a real "sports" car. A bit underpowered, but FUN. I say this because I used to restore and autocross english sports cars. Not real fast, but great in anything except a straight line.

Sorry so long, but all of us old farts think we are "entitled".

Have fun!!

Mike

My feelings, exactly. I plan to enjoy the benefits of the Duke -- better handling -- until the time comes for the V8 ...or I find a very light engine with lots of hp/torque.

With a heavier engine, I am sure I would have a hard time NOT wrapping it around my neck in some of the turns and curves I love to force the car into after it rains.

Beno

If you simply have to try to get some performance out of a duke, pick up a spare head from a junkyard. Read all you can about head porting and buy a porting kit. Normally I don't recommend that novices port heads. The 2.5 ports are so restrictive that any material removed will really help. Practice on one port and drop by a machine/racing shop to see if they can give you any pointers. You may go through several heads this way if you screw one up, but duke parts should be nearly free from junkyards. While the head is off, try decking it to increase compression. Pay someone to do a good 3 angle valve job.

After making a head that will breathe easier, other upgrades will help make even more power. You get the most gains from upgrading the most restrictive part of the engine, I'd bet that a stock duke doesn't get hardly anything from a K&N because the head has ports the size of drinking straws.

The next items on my list after a head woul be in no real order : cam, intake, exhaust.

Here is his head. I dont have anything else, and now the head is on the block.

My dad did the head on my car, and with a 120000Mile bottom end and rings, it gets roughly 100HP, I also have no cat on the stock exhaust. I still have the stock coil too.