was just wondering what type of performance add on part or hop ups for the 2.5 if any.This is my first fiero and at the momment I dont have the extra cash to get another engine to put in place of this one.Any ideas are helpful

Biggest bang for the buck is a hooker header and high flow cat. I did this back in 84 and it was like a different car.

whats the cost on the header???

Chris

header-$135 on ebay

i saw one this afternoon

pil

edit: keep in mind thats for 84-86, the 87-88 heads are different

[This message has been edited by Pilrulz (edited 10-29-2002).]

Holly makes a TBI with more flow(84-86 only, the 87-88 were an improved design that appartently didn't need upgrading): http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSFI/500-1.html

In order for this to really be effective though, you would need the bored out intake that they used to make but now discontinued.

[This message has been edited by Tweek (edited 10-29-2002).]

Preformance from a Duke? Good luck. Save your money by getting good gas mileage with the engine you have no, And eventually do a v-8 swap. Those are my plans. May not convert my 85 SE 4cyl, May save it for daily driver, and find a GT to make my fast car. Some people may disagree about the 4cyl not being capable of high hp, but think about it. 151 CI can only go so far. 350 CI is double Hp stock, and most v-8's make more power easier. Good luck on whatever you choose.........Erockrocket

I saw that header on ebay too. Do a search under "Fiero"

Performance from a Duke can only be gauged by what the finalexpectation is to the owner. If you want to smoke vettes you will be disappointed. However, if you want a bit more "get up and go" a upgraded ignition, headers, hollowed out CAT and a bored out throttle body may give the 2M4 far better performance. Add a low boost 5 psi turbo and you'll be about on par wih the 2.8L. I'm going to have to turbo a Duke one of these days to determine the full impact.

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87GT 3.4 Turbo Best 0-60 5.2 seconds
http://turbofiero.fierojoe.com/turbo.htm

I am still looking for someone that has put the Mercruiser 3.0L crank, rods, pistons into an 86 duke block to see how it is done. Just wondering if the extra 0.5L and stronger crank would do anything for the bottom end of this motor. If it does, this would be a good candidate for a mild turbo and some good light HP.

quote Originally posted by mshill: I am still looking for someone that has put the Mercruiser 3.0L crank, rods, pistons into an 86 duke block to see how it is done. Just wondering if the extra 0.5L and stronger crank would do anything for the bottom end of this motor. If it does, this would be a good candidate for a mild turbo and some good light HP.

Are you certain that the Mercruiser crank rods, and pistons will just drop into the Duke block?. If the bore on the Merc is the same, then the total displacement gain is achieved by a longer stroke- not that good a change for an engine with an already low redline. Without question, the increase in displacement will result in additional bottom end torque.

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87GT 3.4 Turbo Best 0-60 5.2 seconds
http://turbofiero.fierojoe.com/turbo.htm

the 3l merc is a 2.5 just the head is different and the crank rods and ???pistons??? not sure if they are different tho but im sure they just fall right in im not 100% but my dad thinks the .5l is made up in the head has a biger combustion camber

because a few well about 6 yrs ago we replace a 3.0 merc with a 2.5 crate engine from GMX works fine and is still kickin

Chris

quote Originally posted by 4BanGinFun: the 3l merc is a 2.5 just the head is different and the crank rods and ???pistons??? not sure if they are different tho but im sure they just fall right in im not 100% but my dad thinks the .5l is made up in the head has a biger combustion camber because a few well about 6 yrs ago we replace a 3.0 merc with a 2.5 crate engine from GMX works fine and is still kickin Chris

3.0 crank, rods and pistons, as a set, will not drop right in. back of crank has different bolt pattern for flywheel and uses 2 piece rear main seal, instead of 1 piece seal that block uses. i have an early nova 153 crank in my duke, and we are guessing about 180 hp. haven't fixed the fuel delivery problem yet, so can't take it to the dyno shop. will post hp numbers and performance data when fuel problem fixed.

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86 econo coupe-ground stompin' stroker 4 cyl, koni's with coil overs, lowered 3 inches, mr2 spoiler on back.

Get a new cam. For less then about $200.00 in parts you can get a cam that improves performance. Change it yourself and save more. Add the other suggestions and a modest but fun 2 seater will be your reward. BUT, remember each time you add a performance part to any engine the reliability of that engine goes down!
I have a hooker header, Holley TBI, Holley intake, K&N filter, high flow cat, roller tip rockers and MSD ignition. My '84 SE can crews all day to 80 -85 mph(clocked with a GPS) but still stinks from 0 to 60.

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The Mercruiser 3.0L is a Duke, and in the books it was rated at 140HP at the crank. Later years (after 1986) they were rated at 130HP at the prop (two 90 degree drive angles). The 3.0L Merc crank is a 0.25" stroke over the 2.5L. The piston bore is the same as the duke, although wristpin placement may need to be different to adjust for proper compression ratio.

In general, marine engine internal parts are beefier than in cars. Boats engines are designed to operate at a slightly lower redline than automobiles, but they will operate at that level for hours on end. I would expect the crank to be stronger than that of the Duke.
BTW, here is a 3.0L crank on ebay right now. Search for Mercruiser.

[This message has been edited by mshill (edited 11-01-2002).]

Here's a picture of the Merc 3.0L crank. It is similar to the super duty crank in the sense that it has the eight counter balance weights where the Duke 2.5L crank doesn't have the counter balance. With this crank and rotating assembly balanced properly and a full roller valvetrain the 3.0L engine should rev reliably higher than the 2.5L stock duke.

Don't forget the Duke when subjected to higher rpm can and sometimes does collapse stock pistons.

Look here http://www.mantapart.com Crank, rods, pistons, supercharger etc.

Oops... Quad 4, 2.8/3.1/3.4 but no 2.5 Duke parts...

[This message has been edited by fierosound (edited 11-12-2002).]