what i want to know is how much harder is it to swap a 3400 or 3500 compaird to the 3.4 pr iron head if it's not much more then i think i will do a 3400 or 3500 . this will just be my DD

[This message has been edited by engine man (edited 03-02-2010).]

The iron head 3.4 makes 160 HP, the 3400 makes 185 HP and the 3500 makes 210 HP per 60Degreev6.com specs.

If you go the 3500 route that’s 50 more HP than the Iron Head 3.4 bone stock.
You’d have to spend a lot of money and spend a lot of time trying to get the 3.4
To make another 50 HP

As far as the swap goes it not as easy as a 3.4 swap because all the 2.8 Fiero stuff bolts right on, but what you are bolting back on is a severally restrictive intake and exhaust system.

So it depends on what you consider to be within your means for the swap.

You will need to change the exhaust manifolds.

You will need to deal with the alternator (low mount it or notch the deck lid)

The harness and fuel control will need modification (nothing too major)

The dog bone will also need changing or modification (not too major)

I’m sure im missing a few things, but these are the major obstacles to overcome.

A good exhaust and a good tune should put you close to 250 HP on a NA 3500 motor, much more potent than if you spent thousands trying to get a 3.4 in the neighborhood of 250 HP

Hope this helps

The 3.4 swap is like a stock engine r&r with a few small issues to overcome.
3400 swap is more complicated. You have build a harness whether you go obd1 or 2. The engine mount fits it just has to trimmed to fit the oil pan. You can use the timing cover and accessories and dogbone if you want. I prefer the compact serpentine setup though. I opted to notch the decklid and make a custom dogbone.
3500 swap is much like the 3400 swap. You need an external 7x crank sensor. Wot-tech sells them. You use a 3100/3400 fuel rail and regulator. You still have to use DIS. If you go OBD2 you need a 3400 pcm and comparable sensors. I don't think the 3500 pcm has been hacked yet. It mounts the same as a 3400. I'm not sure if the 2.8 front cover will work on a 3500.

These new(er) 60 degree v6s are very well engineered engines. I would recommend the LX9 3500 and obd1 if you don't mind a little wiring. You can usually pick these engines up fairly cheap compared to the L67, northstar, sbc, or3400.

Goodluck,
Joe

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1987 SE / Fastback - 3500T / 4T60e / OBD1 / broken
Projects: 5-speed swap / retune

Here is a swap that is very similar to what you are asking about.

well see what the 3500 can do here soon....

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First LX9 Fiero GT, 1987 | My Fiero Fuel Economy | MPG Display for OBD I
Youtube Videos of My GT | modernize your fiero with technology!
If you can't fix it with a hammer, you've got an electrical problem
Fiero's are people too. We pay just as much attention to them, if not more than our loved ones
screw paying those bastards. im not going to become rich by paying for things.....