Everybody thinks that the bigger the number (on both the liters, and the cylenders, not to mention the horsepower) means the faster the engine. In this case, we would obviously think that a stock 2.8 v6 in a fiero would be faster than the stock 2.5 I4 in the fiero.

more than once, however, i've heard the opposite. i've heard more than once, actually, that the 2.5 can outrun the 2.8. I was just wondering if this was true.

being a proud duke fan, i was kinda hoping it was.

thanks in advance!

I've driven/owned both...unless something is VERY wrong with the 2.8, the 2.5 has no chance.

Look at the specs. 90HP vs 140HP tells the story. The Duke is a great reliable and economical engine but it wasn't built for performance nor is it a good platform for it.
The 2.8L is far better but still has limited potential. If you want more horsepower look into swapping in a 3800SC, 3400TDC or V8 engine. The question that needs to be asked is the one that V8 Archie penned several years back "How fast do you want to go?"

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 04-08-2009).]

I don't think you can just compare the motor, you need to look at the tranny it's mated to as well.

My old duke behind a 5 speed stick was pretty lively but my current one behind an automatic is pretty pathetic.
In either case my 2.8 behind a 4 speed stick beats them both but not by much when compared to the 5 speed although it leaves the auto in the dust.

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Dave

www.ltlfrari.com

Now to hijack...
How would you compare 2.8 4spd manual to 2.8 5spd getrag or 5spd isuzu?

Michael

quote Originally posted by Fierology: Now to hijack... How would you compare 2.8 4spd manual to 2.8 5spd getrag or 5spd isuzu? Michael

All better than a 3 spd auto...

Are we comparing 1/4 mile times, 0 - 60 times, or top speed?

My old 2.5 with a 5 speed Isuzu (85 car with 88 engine and 86 trans) was able to keep up with a stock 88, 2.8 auto when it came down to top speed.

1/4 mile times and 0 - 60 times? No Way...

acceleration : 4 speeds M17
top speed: usuzu 5 speeds
in between:Getrag 5 speeds

The M17 and Getrag are stronger design... for V6 and better... I know some put usuzu 5sp on there V6 without problems...

If you think gaz is expensive, dont go with 4 speeds tr.

[This message has been edited by martin_gsxr (edited 04-08-2009).]

quote Originally posted by IFLYR22: Are we comparing 1/4 mile times, 0 - 60 times, or top speed? My old 2.5 with a 5 speed Isuzu (85 car with 88 engine and 86 trans) was able to keep up with a stock 88, 2.8 auto when it came down to top speed. 1/4 mile times and 0 - 60 times? No Way...

Nah, I don't think so. I have an auto. I've also heard that for some reason my car was quick for an auto, but all that aside, it's still a 2.8/automatic. Top speed is determined by how well you can overcome air resistance (assuming you don't run out of gear.) If you can't put down the power, you can't go fast. If both cars are at 1:1 it doesn't matter what kind of trans it's going through. I know someone is going to bring up the whole issue of the auto being a hp hog, but it's not enough of a difference to give the duke the advantage. At the end of the day the 2.8 wins, with 140hp of fury. Not trying to pick a fight here, but the 2.8 is faster.

I have both - 88 w/V6 and 5 spd, 88 with Duke and auto. In this case there is no comparison. I had an 86 V6 w/4 spd. It was by far the fastest - just not the top end as the 5 spd. But top end did not matter unless you were going to race down the hiway for several miles cause the 4 spd car would literally run off and hide from the 5 spd car. Someone alos posted that 4 spd's were bad on gas. My 86 would get 24 in town and 28-29 on the highway @ 65 MPH - closer to 24-25 @ 75 and up. My 5 spd gets 26 in town and 30 on the highway. Not sure what the auto duke gets for mpg but it aint no hot rod! Torque yes. Fast - no.

Pat

I have a 4 speed 2.8 and compared to my old 5 speed 2.8, there is a big difference in town. Mileage is alot better with the getrag, but the 4 speed is more fun!

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86 SE 4 Speed 2.8 "The Short Bus"



88 Coupe 4.9 "Hibernating"

quote Originally posted by Mr_jacob7: more than once, however, i've heard the opposite. i've heard more than once, actually, that the 2.5 can outrun the 2.8. I was just wondering if this was true.

If we are talking speed? Seriously doubt it. If we are filling the tank setting the 2 cars on a strip of pavement and running them until the tank is dry the 2.5 is going to go further, so in a sense it will outrun the 2.8, but only in distance traveled on the same amount of fuel.

hehe... guess they were wrong, then.

what i meant was, in fact, speed, so you all answered the question.

it's wierd that i had heard that, twice, from different people. i know weight plays a part, but i didn't think that much. maybe the person had some mods... idk.

My personal favorites are the 3.65 4 speed with a 2.8 and anything with the Isuzu.

Most people don't like the Isuzu but I like it a lot, I have an 88 5speed duke and an 87 5speed (izzie) GT. I like both very much for overall driving probably the GT with the Isuzu, however for interstate driving you can't beat the dukes mileage!

The 2.8 will run circles around the 2.5 all day long, regardless of transmissions. Even with some 'mods' the most you're going to get out of the 2.5 is about 130HP. Unless maybe the guy with the 2.8 Fiero has never driven a manual transmission car before...

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1984 Fiero SE

I believe up to about 25 mph the duke will outrun the v6.

quote Everybody thinks that the bigger the number (on both the liters, and the cylenders, not to mention the horsepower) means the faster the engine

this statement doesn't make sense to me.. If the horsepower (and torque) is higher, it will win.. a 95hp car isn't gunna outrun a 140hp car... Now, perhaps a 2.5 with the 4.10 4spd could outrun a 2.8 with the auto trans, but not for very long.

This is a pretty useless thread. Its a no brainer, the 2.8 is always ALWAYS going to beat a 2.5. I drive a 2.5 and I know how slow it is. Doesn't matter how much you wish the 2.5 was faster, it barely has enough HP to get on the freeway. it has 50 fewer HP and 2 less cylinders than the 2.8. Why are we still talking about this??

Want power?

1. Turbo a 2.8 if you want to go through the trouble.
2. Swap an engine that your budget allows, 3800, N*, 350 SBC, 3.4, etc etc.
3. Get a different car altogether.
4. Spray a 2.5 and have fun for a week end.

quote Originally posted by kawana: this statement doesn't make sense to me.. If the horsepower (and torque) is higher, it will win.. a 95hp car isn't gunna outrun a 140hp car... Now, perhaps a 2.5 with the 4.10 4spd could outrun a 2.8 with the auto trans, but not for very long.

Yes, perhaps for the first 15 feets... I had the 4.10(M19) on my Gt last summer and you have to always be in the redline to be fast.... the tires burned at every start... a top speed of 110mph being at the redline(5500rpm).... not good with those old tech engines.
It's like driving a 5sp with the 5th gear missing.... but sometimes fun to drive in the city.

[This message has been edited by martin_gsxr (edited 04-09-2009).]

quote Originally posted by Mr_jacob7: Everybody thinks that the bigger the number (on both the liters, and the cylenders, not to mention the horsepower) means the faster the engine. In this case, we would obviously think that a stock 2.8 v6 in a fiero would be faster than the stock 2.5 I4 in the fiero. more than once, however, i've heard the opposite. i've heard more than once, actually, that the 2.5 can outrun the 2.8. I was just wondering if this was true. being a proud duke fan, i was kinda hoping it was. thanks in advance!

Seriously, WHO told you a 2.5 is faster than a 2.8? I can't even fathom anyone making that claim with a straight face. LOL

quote Originally posted by FieroFanatic13: Seriously, WHO told you a 2.5 is faster than a 2.8? I can't even fathom anyone making that claim with a straight face. LOL

Yes, that is a nonstarter. The Iron Puke is reliable within its limits, but the engine has no top end at all - it lacks spirit. I was amazed to see the difference between driving a 4 cylinder Indy and a V6 GT, and God knows the V6 with cast iron heads is no top end monster either, but it is like night and day.

There is simply no way the Duke comes anywhere near the V6 and anyone that told you that is dreaming.

Pull a couple spark plug wires off the 2.8, and a Duke might outrun it.

quote Originally posted by Blacktree: Pull a couple spark plug wires off the 2.8, and a Duke might outrun it.

LOL!!

quote Originally posted by HC: This is a pretty useless thread. Its a no brainer, the 2.8 is always ALWAYS going to beat a 2.5. I drive a 2.5 and I know how slow it is. Doesn't matter how much you wish the 2.5 was faster, it barely has enough HP to get on the freeway. it has 50 fewer HP and 2 less cylinders than the 2.8. Why are we still talking about this??

I agree. I drove a 2.5 for a year before driving the 2.8 and there is no contest. The 2.8 is WAY faster in the 1/4, top speed and acceleration. End of Story.

i raced my 88 2.5 pontiac 6000 thm125c against my brothers 88 Z24 2.8 thm125c. he stomped my ass hands down. that duke never had a chance. i thought that .3 litres and 2 more cylinders wont really matter that much. it did.

oh yea, this was like 10 years ago when we both first got our licenses

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First LX9 Fiero GT, 1987 | My Fiero Fuel Economy | MPG Display for OBD I
Youtube Videos of My GT | 87 GT Inside Test Run | 3500 Fiero GT Test Run 01
3500 Fiero GT Test Run 02 | 3500 Fiero GT Test Run 03 | 3500 Fiero GT Test Run 04
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.....

quote Originally posted by jscott1: Even this isn't true... my 2.5 auto never got over 26 mpg and my 2.8 5 speed routinely gets over 30 mpg on the highway.

That's comparing apples to oranges.

My 2.5 5 speed gets about 35 highway, and I've hit over 40 a couple of times.

My son has a nice running 2.5 and he's never seen 30 MPG.

quote Originally posted by 86fierofun: That's comparing apples to oranges.

Why is it apples to oranges? The 2.5 came from the factory with the Th125 3 speed. That's how I bought it and that's how I drove it. The mileage is what it is...crappy.

If you want to argue only compare manuals then I will tell you that my Duke with the 4 speed Muncie with the 4:10 gears also gets crappy mileage. I doubt that it could break into the 30s either.

he only comparison I can make is this. I agree you must consider the tranny as it's the gearing that decides how fast the wheels turn.

I had a 2.5 with an isuzu. I pulled out the 2.5 and dropped in a 2.8. Using the same tranny, the 2.8 is definitely the winner here.

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Jay Brintnell
Southern Ontario Fiero Association
Yellow 85 Notchback(A.K.A. GodFearN)

quote Originally posted by Eclipse: I had a 2.5 with an isuzu. I pulled out the 2.5 and dropped in a 2.8. Using the same tranny, the 2.8 is definitely the winner here.

In fairness to the duke...i've heard many that ran with the Isuzu and 2.8 complain about the RPM drop off in 2nd gear and that the duke has more torque on the bottom end. Still it's dog slow after about 20 mph.

For mileage, the trans is everything. Compare an auto duke to an auto six, or compare manuals of the same gear ratios.

I wasn;t even going to bother, but since it has gone to silly mode, the answer is so obvious that even suggesting that duke with ANY trany type is faster is ludicrous.
hp/weight. no gearing is ever going to fix that.
IF the duke was 125hp and the v6 was 130, then the arguement could have some merit. but that is not the case. same weight car and 40 less hp, the answer is obvious.
and as for mileage, on an all highway trip my fully loaded 88gt v6 getrag will get 34 mpg. porbably do better if I wasn;t doing 75-80 on the trip.

Here's some figures to put this to rest.

Road & Track Sept 1983
Fiero SE 2.5L 4 spd (410:1 Final Drive)
0-100 ft = 3.4 sec
0-500 ft = 9.6 sec
0-1320 (1/4 mi) = 18.2 sec
0-30 mph = 3.2 sec
0-50 mph = 8.0 sec
0-60 mph = 11.6 sec
0-80 mph 23.2 sec
Top Speed = 103 mph

Road & Track Nov 1984
Fiero GT 2.8L 4 speed (3.65:1 FD)
0-100 ft = 3.2 sec
0-500 ft = 8.9 sec
0-1320 (1/4 mi) = 16.5 sec
0-30 mph = 2.5 sec
0-50 mph = 5.8 sec
0-60 mph = 8.4 sec
0-80 mph 14.7 sec
Top Speed = 125 mph

Road & Track Oct 87
Fiero Formula 2.8L 5 speed (3.61:1 FD)
0-100 ft = 2.9 sec
0-500 ft = 8.5 sec
0-1320 (1/4 mi) = 16.0 sec
0-30 mph = 2.3 sec
0-50 mph = 5.5 sec
0-60 mph = 8.0 sec
0-80 mph 13.7 sec
Top speed = 125 mph

[This message has been edited by Bloozberry (edited 04-12-2009).]

quote Originally posted by tjm4fun: I wasn;t even going to bother, but since it has gone to silly mode, the answer is so obvious that even suggesting that duke with ANY trany type is faster is ludicrous.

There used to be a forum member who claimed that his dukes were faster than any V6, mainly because they weighed a pound less or some silliness like that.

There have been quite a few 2.5's pulled for the 2.8's and very few 2.8's pulled for the 2.8's.

The only 2 benefits of the 2.5 in my book are lower weight and better hwy mileage with the Isuzu/3.32 trannies... still not enough for me to keep a 2.5 car a 2.5 car.

quote Originally posted by Mr_jacob7: i've heard more than once, actually, that the 2.5 can outrun the 2.8. I was just wondering if this was true.

I'd say that what you'd heard is true, Mr_jacob7, that "the 2.5 can outrun the 2.8."

In a straight-line contest, a 2.5 always will beat a 2.8 in terms of acceleration --- as well as in top speed and in mileage --- provided that unlike the 2.8, the 2.5 is going in a vertical straight line (rather than in a horizontal straight line) after it's been pushed off a sufficiently high cliff with its engine turned off.

quote Originally posted by RWDPLZ: The 2.8 will run circles around the 2.5 all day long, regardless of transmissions.

quote Originally posted by tjm4fun:I wasn;t even going to bother, but since it has gone to silly mode, the answer is so obvious that even suggesting that duke with ANY trany type is faster is ludicrous.

RWDPLZ and tjm4fun, have either of you any hard numbers to back up those assertions? Have either of you ever actually timed the top speed of a Duke plummeting to the ground after it's been pushed off a sufficiently high cliff? Have either of you ever actually recorded the mileage a Duke would get while it's plummeting to the ground from said cliff with its engine turned off?

Aha! I didn't think so.

***
All joking aside, and also perhaps partly because I now very seldom see any Fieros other than my own locally, I very much enjoy seeing our little cars whenever I have that opportunity, no matter what powers them.

I hope that everyone has had a good Easter.

"2.8 vs 2.5 Which is faster?"

Duuh, you should swap in a Geo Metro 3 cylinder with that logic.

quote Originally posted by project34: RWDPLZ and tjm4fun, have either of you any hard numbers to back up those assertions? Have either of you ever actually timed the top speed of a Duke plummeting to the ground after it's been pushed off a sufficiently high cliff? Have either of you ever actually recorded the mileage a Duke would get while it's plummeting to the ground from said cliff with its engine turned off? Aha! I didn't think so. *** All joking aside, and also perhaps partly because I now very seldom see any Fieros other than my own locally, I very much enjoy seeing our little cars whenever I have that opportunity, no matter what powers them. I hope that everyone has had a good Easter.

Man, that gave me a great laugh...I needed that.....
have a happy Easter also, you and your family.. don't eat too many bunnies....


hmmm never thought about vertical acceleration... 9.8/f/s/s maybe the 2.5 could win in a free fall....

quote Originally posted by project34: RWDPLZ and tjm4fun, have either of you any hard numbers to back up those assertions? Have either of you ever actually timed the top speed of a Duke plummeting to the ground after it's been pushed off a sufficiently high cliff? Have either of you ever actually recorded the mileage a Duke would get while it's plummeting to the ground from said cliff with its engine turned off?

Well. I, um, err that is, um.... Blast!