I just got this car recently and I am amazed at how smooth it is at speed. I have not had opportunity to get it out on a desolate road and crank it up but it got me thinking anyways. I know that the cars are supposed to get light in the front at high speed but i am sure with proper aerodynamic mods and a well setup lowered suspension it would be possible to take it so some pretty respectable speeds. ( not condoning any wreckless driving here) Perhaps some have had opportunity to run on a racetrack in their street fiero? What do you guys think? peace

Pete

I had an '87 4Tech with an Isuzu, I would get the speedometer to spin around and around. It spun slowly at first and then faster and faster. I don't know how fast it would go but it was much faster than a V6 on the highway. Tri spokes everywhere.

I do not know the speedometer only goes to 120..

I don't see how it could be faster than a V6, but I can't argue since I have no experience with the 2.5.

The fastest I have ever gone in my Fiero was 110, and that was in a junky '86 GT. My land-speed record is in my Saturn SL1 though, and I went 114 before the limiter kicked in and didn't give me throttle back until it was down to 90.

90

Got there in 7 seconds LOL

Alrighty then, looks like the smartiepants guys are online tonight..... seriously, anyone? I realize that the speedo only goes to 120... peace

After calculating speed from RPM, transmission ratios, tire size, etc. I think my Fiero ChumpCar project can attain 125MPH, and my stock '86 SE will do about 121. Purely hypothetical, right?

im not sure mine only goes to 85 and ive barried that to almost 0 again and ya the front ends dont like to go strait when u hit a gust of wind at about 90

[This message has been edited by 2m4dude (edited 03-17-2010).]

Since the speedo only goes to 120, you are unable to say if you were going faster than that unless you have a GPS unit installed. My 88 GT 3.4L 4t440 auto was clocked at 142 @ 5000 rpm in third gear on a dyno run years ago. On the highway I was at 4700 rpm in third and the speedo was past 120. My 87 GT I had past 120 on a desolate highway, but ran out of room to continue. Both cars have lots more miles on them now, so I don't push them anymore.

Well over 85... My best guess is around 100-105 (automatic turning around 4k-ish, I'm not exactly sure; I don't like to look down at that kind of speed)

But I had a headwind

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Notchback GT

[This message has been edited by skuzzbomer (edited 03-17-2010).]

193 km/h.

By the way, my speedo only has graduations until 140 km/h.

You don't have to guess. For a given gear, without any clutch slip, the ratio between road speed and engine RPM is constant.

So in my case, I took note of the RPM @ 140 km/h in 5th gear, reached maximum speed, and then took note of the RPM at top speed.

You can then deduce your speed.

The same is true for an automatic with its torque converter locked up.

If you have non-stock diameter tires, you would have to compensate for that. Alternatively, use the gear ratios and tire diameter, the point is that it's NOT a guessing game.

[This message has been edited by pmbrunelle (edited 03-17-2010).]

my 1st 86 auto i maxxed the speedo and was still going faster. Even got to the fuel cutoff or whatever the fiero has. my other 2 i havent had above 90

quote Originally posted by pmbrunelle: 193 km/h. By the way, my speedo only has graduations until 140 km/h. You don't have to guess. For a given gear, without any clutch slip, the ratio between road speed and engine RPM is constant. So in my case, I took note of the RPM @ 140 km/h in 5th gear, reached maximum speed, and then took note of the RPM at top speed. You can then deduce your speed. The same is true for an automatic with its torque converter locked up. If you have non-stock diameter tires, you would have to compensate for that. Alternatively, use the gear ratios and tire diameter, the point is that it's NOT a guessing game.

That's exactly how I came up with my figures. My 1986 SE only has an 85MPH speedometer, so I need to use the calculations for anything more.

had my 88 gt l67 with getrag and 17in wheels max rpm in 5th gear on 465. gps said 155

I estimate around 135ish.

165 mph "according" to the Viper that was alongside of me, that was with the my old engine !

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Car History: https://www.fiero.nl/forum/Forum1/HTML/025670.html

Maybe this is not what you intended, but the fastest I have driven it is flat out around Watkins Glen... well... in portions. The top speed I hit was 90 (or so) down the front straight. I was more concerned with the first turn than the exact speed I hit before I had to hit the brakes. The car had more in it, but going thru turn one, then up through the shecane (sp?) and bus stop at the limit was a LOT of fun.

85 mph (Man i need to upgrade my speedo...)

88mph, then the flux capacitor kicked in....

wait, wrong car..

quote Originally posted by fieroguy123: had my 88 gt l67 with getrag and 17in wheels max rpm in 5th gear on 465. gps said 155

You hit 155 on 465?? Ballsy...

As for mine (stock '86 base coupe 5 spd), I got to running with a Mercedes-Benz SL55 AMG and an Infinity G37R on SR 37 between SR 44 in Martinsville and caught the green light at 144 in Waverly with clean and clear roadway to Smith Valley road, all told it's about 20-25 miles of straight, smooth roadway and my GPS said 115 for most of the trip. I was trailing the 2 the whole way, and I think they felt sorry for me and kept their acceleration and cruising speed low so I could keep up (If I hadn't been trying to keep up, I think they would have been looooong gone), but I can honestly say that I got to run with 2 of the fastest street cars I have ever seen.

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Pennock's Official Thread Killer
Indiana Fiero Club

The Duke will NEVER DIE is DYING

100mph (all the way to FL and back) but that was simply on the highway. I haven't had it on a high speed track before.

Wow man that is impressive, 155-165 mph!! I knew that with an engine swap anything is probably possible and this is inspiring. I am getting the 3800sc in mine and I am curious as to just how fast that much power will push the car. Of course the car is pretty aerodynamic already and a little suspension lowering and tightening and perhaps some lightening of the car and it would have to be pretty fast. Mine is currently stock and runs pretty strong with a 2.8 and the four speed. When I bought the car I was thinking I could always swap out the four speed for a five speed thinking it would be less than ideal but to be honest I really like the four speed. I have owned many different cars including a bunch of 5.0 mustangs, some hondas, a beautiful 93 Ford Probe GT which until the fiero was my favorite car and all were five speeds.

Funny thing happened today on the way to work. I am barely awake at like 6:15 this morning and minding my own business on the drive in and a Dodge Stratus pulls up next to me at the light. I did not even notice it at all but I hear the engine revving up so I look over to see what it was. The guy driving it is staring at me and I am wondering If I accidentally cut him off or something. Then the light turns green and he squeals away burning the tires and I am like what the hell? Like my grandmas car is probably faster than that thing.... SO I let him go and he races down the road only to catch the next light. I roll up next to him again and he is still staring at me. I am not sure what to do so I just ignored him as I am barely awake as it is. Sure enough he tears away and I noticed it had some exhaust mods and some different badging on the back of the car. Then he goes like a mile or so and catches the next light again. Since we are like the only two cars on the road I get the same light alongside him again. Sure enough I look over and he is still staring daggers at me and revving the engine. I am thinking what a moron but then I thought the road ahead is void of lights and it is mostly wooded for about two miles at least so I snick the shifter into first gear and get ready to launch my car at the green. I see the green glow and feather the clutch at like 2500 or so and the car just takes off without even a chirp. I could hear his tires squealing and I showed him the top of first and second gears and before I knew it I was at least four car lengths ahead of him. Once I got near redline in second I backed off so I do not attract any unwanted police attention on the way to work. This guy just then blows by me continuing to accellerate to what had to be like 80 or 90...... What a wierd guy I was thinking but I was smiling because my fiero just spanked it's first opponent. For sure that is no fast car but he wanted it I suppose or he would not have done all that weird crap. Felt good!! I was thinking what will it be like when I get the l67 in there.... gonna be fun that is for sure..... peace

quote Originally posted by rourke_87_T-Top: I had an '87 4Tech with an Isuzu, I would get the speedometer to spin around and around. It spun slowly at first and then faster and faster. I don't know how fast it would go but it was much faster than a V6 on the highway. Tri spokes everywhere.

The Isuzu has the tallest gearing, it takes a long time to get the rpm's up in 5th gear but on the highway the isuzu will leave a 2.8 V6 behind. I had the speedometer spinning many many times.

6 cyl., 5 speed. i did 100 mph. without trying the other night. trying to run some injector cleaner thru, it's running better.

90 mph 86 iron duke 5 speed coupe

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Cliff's 610th Positive Feedback Giver.

88 Formula - Was last year coming back from the Round Up somewhere between Del Rio and Sanderson - as fast I cared to go was 127.3 per the GPS - I have some video of it somewhere - I'll post it if I can find it.

Pat

my fastest on PA roads was 247 MPH. the speedo stopped at 220 mph but i had another 4000 rpm's left on the tack. after putting both needles to the bottom i gave it a little more. needless to say but as i went on the off ramp she was a knocking oh wait that was my super bike :P as for my fiero i think i had it 100 mph. not happy at all with it. found the 2.8 to be completly worthless as 99% of all GM V6s ( and yes i ment every word of that!). but the handeling is what i like

I have only had my 86 5 spd GT up to 101 (indicated). Had plenty of road left in Nevada, but the wife factor kicked in. The year before, could only get my 88 Honda Civic station wagon (with the CRX engine) up to 97 (indicated) before I ran out of road. I was very disappointed, as I wanted to see the headlight doors come up, I had heard that was about 120.

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Scott

A 2.5 will NOT be faster than a 2.8 on the highway all things being equal... There is a huge horsepower difference.

And the tallest gearing is not necessarily the best.

For maximum speed, the gearing should be arranged such that the engine is operating at its peak power at the maximum speed.

quote Originally posted by pmbrunelle: A 2.5 will NOT be faster than a 2.8 on the highway all things being equal... There is a huge horsepower difference. And the tallest gearing is not necessarily the best. For maximum speed, the gearing should be arranged such that the engine is operating at its peak power at the maximum speed.

Don't believe me then. peak power, horsepower, what difference does that make for top speed. A 4 Tech can turn as many rpm's as a 2.8

[This message has been edited by rourke_87_T-Top (edited 03-17-2010).]

Here's a pretty decent article related to HP - Torque - Speed - RPM - Coefficient of Drag:

What Is Torque, What is HP?

[CT] Torque is basically the rotational equivalent of a force. In that sense, torque can be thought of as the potential to
do work.

But just as a force can only do work by being applied through some distance, torque can only do work by being applied through some angle. The rpm is simply the rate at which that angle changes (i.e., the rate of rotation).

Power is the rate at which the torque is doing work. Technically, power = torque * rotation rate, but usually some constant is included to correct for a convenient choice of units.

For example, if power is expressed in units of "hp", torque is in "lb-ft", and rotation rate is in "rpm", then power = torque * rotation rate / 5252. That constant (5252) will change depending on which units are chosen for power, torque and rotation rate.

[AWN] Torque is the product of a force and its moment arm. That is, Torque = FR, where F is the force in pounds and R is the length of the moment arm in feet.

Work is, for our purposes, the product of a force and the magnitude of its displacement. That is, Work = FS, where F is the force in pounds and S is the displacement in feet.

Power is the rate at which work is performed: Power = Work/Time. We'll measure time in minutes.

Dynamometers can measure torque, in foot-pounds; they can NOT directly measure horsepower. To calculate horsepower, we have to combine the torque measurement with a time measurement. Here's how:

A long time ago, before any of us (except maybe Harry Somerfield and Don Jewett) were born, James Watt performed some experiments and determined that a horse could lift 550 pounds at a rate of 1 foot per second. This unit of power, 550 foot-pounds per second, became known as the "Horsepower."

Since I already said that we'd be dealing with time in MINUTES, not seconds, we can multiply by 60 seconds/minute to get: 1 Horsepower = 33000 foot-pounds/minute, which implies that a horse can list 33000 pounds a distance of one foot in a minute, or launch a one-pound weight to a height of 33000 feet in the same time. No mean feat. But I digress.

To calculate an engine's horsepower at some given speed, you do the following: Rev the engine to the desired speed. Measure the torque at that speed. Multiply the torque by 2 * PI * the engine speed in revolutions per minute. This gives you:

X foot-pounds * 2 * PI * REVOLUTIONS
-------------------------------------------------------
MINUTE

Which, if you look closely, is a FORCE (in pounds) times a DISTANCE ("one foot * 2 * PI * revolutions" is the distance the tip of our one-foot moment arm travels, in feet) divided by TIME (in minutes).

As we know, FORCE times DISTANCE divided by TIME = POWER.

We now have power expressed in foot-pounds per minute. To convert to horsepower (33000 foot-pounds per minute, remember), we simply divide by 33000. So Horsepower =

Torque * 2 * PI * RPM
-----------------------------
33000

Torque * RPM
= ----------------------
33000/(2*PI)

Torque * RPM
= ----------------------
5252

Which, incidentally, implies that an engine's torque and horsepower curves cross at 5252 RPM.

1 hp (Metric) = 0.986320406 hp (550 lbf.ft/s)
1 hp (550 lbf.ft/s) = 0.745699872 kW

There are two forms of drag on a car; rolling resistance and aerodynamic drag. Rolling resistance (tyres and drive train losses) increases slowly, but constantly with speed. Aerodynamic drag increases as the square of the speed (V in km/h) and power required to overcome that drag increases as the cube of the speed.

Power (Kw) = rolling resistance + V^3 Cd A / 76716 + rolling resistance

The number 76716 is a conversion factor accounting for air density at sea level and converting from m/s to Km/h. The frontal area A of the CRX is about 1.7 square meters. With a drag coefficient (Cd ) of 0.31 and estimating rolling resistance would absorb about 6 Kw at speed, lets have a look at the power required to achieve at 240 kph.

Power (Kw) = 240 * 240 * 240 * 0.31 * 1.7 / 76716 + 6 = 101 Kw

You can calculate the frontal area by parking the car against a concrete wall at night and using a spotlight and someone to help trace the outline of the car. The shadow can then be measured to give the frontal area. Simple things like removing the wing mirrors reduces the frontal area by 1% which increases the top speed by 1%. Lowering the car by 2 cm reduces the frontal area by 1 % and reduces the drag because the body covers more of the wheels. These two procedures alone add about 5 km/h to the top speed.

Increasing the power of the car by 30 % would only add about 10% to the top speed of the car, as would reducing the drag by 10 %.


Have HP Calculations Changed?

This is how horsepower is calculated now, and it's how horsepower has ALWAYS been calculated. Now there ARE a couple of different ways to set up a dynamometer. Specifically, the SAE and DIN organizations have different rules about which engine accessories must be running while dyno testing is performed. However, these differences have NO effect on the actual torque-to-horsepower conversion.


What Factors Affect Top Speed?

[AWN] Many factors affect top speed. Weight (except very indirectly) is not one of them. Think about WHY there's a top-speed limit at all (i.e. How come you can't just put a really tall 5th gear in a car and accelerate all the way up to 600 MPH or beyond?)

The reason is friction, of which there are three main sources: Aerodynamic drag, losses through the transmission, and tire friction. The loss from each of these sources increases geometrically with increased speed. Eventually, you reach a point where all the engine's power is being used to overcome these losses, so none is left over for acceleration.

Weight affects none of these drag sources except tire friction, and even then, its effect is almost COMPLETELY overwhelmed by aerodynamic losses. If you loaded up an NSX with a couple tons of lead, it'd only drop the top speed by maybe 10 MPH or so.
Just how big were those horses anyway?
by Dennis Simanitis

The power of horses came up recently in a chat with longtime reader Bob Michaud (kin by marriage to R&T's late Nat Michaud, by the way). In particular, he'd heard recent tub-thumping about today's 300-bhp sedans harking back to the glorious days of the Fifties.

"But aren't today's engines even more impressive?" he asked, "because now it's net horsepower and back then it was gross."

Yep, was it ever.

We both did some research on this technicality in the pages of our favorite enthusiasts' magazine, and here's what we learned.

By background, and worth repeating periodically for new readers, an engine's output is measured on a brake dynamometer, hence the term "brake horsepower." As its name suggests, this gizmo is essentially a giant brake that resists the rotation of the engine's crankshaft, this twist measured in our English system in lb.-ft. of torque (think of a 1-lb. weight suspended from the end of a 1-ft. ruler).

Horsepower and torque are related by the formula:

bhp = torque x rpm/5252

Lurking here is the fact that 1 horsepower is defined as 550 ft.-lb. of work expended in 1 second; engine revs are ordinarily measured per minute; and pi, approximately 3.1416, crops up through angular velocity relating ft.-lb. of work and lb.-ft. of torque (conceptually two different things with similar names). Succinctly, 5252 = (550 x 60)/2pi.

So, for instance, suppose an engine produces 450 lb.-ft. of torque on the dyno at 3,500 rpm. This equates to:

(450 x 3500)/5252 = 300 bhp

A nice round figure, 300 bhp.

And this brings us to Bob Michaud's observation, because the real question is, "Under what conditions was the engine operating when it produced that torque?"

Equivalently, "Just how big were those horses, anyway?"

There were, and continue to be, relevant standards for horsepower measurement, originally J245, now J1349 and J1995, promulgated by my old employer, the SAE. In fact, they list two different measurements, net and gross. (I warned you.)

Succinctly, gross measurements are taken with a stripped engine running only its internal ancillaries such as fuel pump, oil pump and water pump. By contrast, net measurements require a fully equipped engine fitted with all of its accessories, generator/alternator, starter, emissions controls and a full exhaust system.

Obviously, each of these components robs a tad of power. Engines evidently differ, but generally, gross bhp ratings may be as much as 40 percent greater than net.

And, indeed, let's harken back to the glory days of the Fifties. Ford certainly learned that safety didn't sell diddly in 1956; Chevy's new V-8 ruled. Until the Chrysler Hemi came along. And the Ford V-8s.

The Horsepower Race was on, gross figures were the norm, and competitors should be excused if these ratings got a trifle exaggerated. As some suggested, bhp meant "horsepower at the brochure."

This continued into the Seventies, which somehow or other turned Socially Conscious. (Don't look at me; I was fooling around in the Virgin Islands.)

The automotive upshot came in 1972 -- and, wouldn't you know, first in California. In R&T, February 1972, my Engineering Editor predecessor, Ron Wakefield, cited a new state law requiring that all automakers henceforth use net ratings in any advertising, brochures or manuals of their motor vehicles.

As usual in such things, California led the nation, we all became less gross, and the rest is history. Until, of course, today's 300-bhp sedans that Bob Michaud and I were discussing.

Let's celebrate a real 300 bhp!

Note: not signed by author, copy write expired 2008

Fast enough that my headlight doors came open....

160mph is my top. GPS said so and jane(maryjane's wife) said yeah that was very fast, with a huge grin on her face.!!

Some reason she is always the one with me on the two of the three high speed runs I have done.

oh 3800sc w 5 sp getrag

177 mph with GPS, 200 speedo and Sheriff friends radar. not stock.....

I hit 145mph (once) indicated on my digital dash when my headlight covers flew up!!! and that is with a vented hood......thought the headlight covers would be ripped off so I backed off....even though the car had more in her.....back in the day I had an 86 SE w/ 2.8, 4sp Muncie and an 85mph speedo that I removed the peg in it so that it would wrap back around.....it was funny to watch but had no idea how fast it was going after 85mph....probably 110ish?

well, with my 4.10 4-speed - 120 is about it.
which kinda sucks with the 140 kph speedo modified to read in mph

65 mph. Roads are too rough around here. Went 135 at the track, got there in 10.20 seconds

How fast do you think mine will go now, X?

Got to about 125 in the 85SE V6 (scary floaty!). About 110 in the 84SE auto (maxed weakling). And have yet to get the 4.9 getrag above 90. I suspect with the larger diameter tires and higher redline I'll be able to reach 150+. Time will tell.

[This message has been edited by Fieroseverywhere (edited 03-18-2010).]