5.0 theoretical top speed?

[Hi-Po]

Here in Norway the highway speed limit is 100 km/h (roughtly 60 mph or so), and violators are likely to get stoned to death or jailed and fined so they will be impoverished for the rest of their miserable lifes.
So, in that respect I am curious - what is the theoretical top speed for a bone stock say 1992 5.0 LX? My understanding is that a stock '92 will reach somehere like 140+ in fourth - but if this thing had enough power to top it out in fifth, what kind of speed would it reach? Surely someone must have calculated this - or tried

 

[BK_CAULEY]

about 135 is all a exhaust only aod car can get. with 2:88's

 

[Hi-Po]

about 135 is all a exhaust only aod car can get. with 2:88's

yea well ok - but in theory, with a manual and 2:73?

 

[Cobra912]

92 auto 2.73 would go to 135-138 before she would start bucking like a bronco, not that I tried

 

[302GTS]

I've heard rumors that a 95 has hit 135 - nearly bone stock 5 speed with 2.73 rear (the car ironically has the same mods as mine in my sig!). The rumor was that the car wasn't topped out, the owner just didn't want to take it any higher.

 

[5.0Droptop]

If it has an 85 mph speedo it will only do 85 max 140 max with 140 speedo. Only if u top off the blinker fluids and tq the tach cable

 

[jrichker]

Figure 40 MPH per 1000 RPM using 2.73 gears and 225-60-15 tires. Turn 5000 RPM and that is 200 MPH. Of course, the car will go faster in 4th gear than 5th because the stock engine does not develop enough power to make the RPMs top out in 5th gear.

 

[Hi-Po]

If it has an 85 mph speedo it will only do 85 max 140 max with 140 speedo. Only if u top off the blinker fluids and tq the tach cable

You can torque the tach cable? I shall definitely try that tomorrow

Apart from this good piece of advice I am not really getting any wiser

Come on

 

[Hi-Po]

Ah, jrichker - my man! So say 268 mph at 6000 rpm with stock tires? Am I right? I suppose no one has tried that for real and survived.. What kind of power would be needed to achieve that - in theory?

 

[Cobra912]

haha all in theory he says

 

[gt40_2003wes]

Ah, jrichker - my man! So say 268 mph at 6000 rpm with stock tires? Am I right? I suppose no one has tried that for real and survived.. What kind of power would be needed to achieve that - in theory?

withe the aerodynamics of these foxes prolly 1500 hp lol no freal maybe more.

 

[89lxsport50]

Years ago when the 89 was fairly new and bone stock, I burried the needle of my 140 mph speedometer a few times. I'm not sure how accurate the speedo is at higher speeds though. Of course I'm older and wiser now, and wouldn't do it again.

 

[1987LXragtop]

268 with a 300 mph tail wind.

 

[fiveohwblow]

withe the aerodynamics of these foxes prolly 1500 hp lol no freal maybe more.

Believe it or not Shaolin schooled me on the aerodynamics of the stang. It has less coefficient drag that you would suspect. I think he said like .38 or something close to that.

I can remember an article 5.0 did where they built a 500 rwhp machine to do the race in Nevada and their goal was 200+mph and they hit it. Only thing they did for aerodynamics was front chin spoiler, lowering and a functional rear wing. I have heard of someone I know that was over 160 in their fox on a closed off track that told me it was rather stable...

 

[TRWXXA]

Here's the formula if you want to have fun playing with the numbers yourself:

Tire Height × 0.002976 × Eng. RPM ÷ Trans. Gear Ratio ÷ Axle Ratio = MPH

So... A stock '92 5-speed would look like this:

25.63 × 0.002976 × 5800 RPM ÷ 0.68 ÷ 2.73 = 238.3 mph !

Now that's THEORETICAL top speed. It's highly unlikely you'd get top speed in 5th gear, so...

25.63 × 0.002976 × 5800 RPM ÷ 1.00 (4th gear) ÷ 2.73 = 162.0 mph
(Yes... I know dividing by 1 does nothing. But for the sake of keeping the formula intact, bear with me.)

Of course real-world tests have shown the stock Fox Body is drag-limited to about 139 mph (give or take an mph or two). Higher axle ratios will help you get more power out of the motor to overcome the drag. 3.08s have a theoretical top speed of 143.6 mph (in 4th gear), and you might get close to that.

 

[TRWXXA]

Ah, jrichker - my man! So say 268 mph at 6000 rpm with stock tires? Am I right? I suppose no one has tried that for real and survived.. What kind of power would be needed to achieve that - in theory?

Good question!

Drag increases by the square of speed. So double the speed creates 4 times as much drag (2^2). However, the power required to overcome that drag increases by the cube of the speed! So double the speed requires 8 times as much power (2^3)!!

Let's just say, for the sake of the argument, that the stock '92 5.0L Fox Body is drag limited to 140mph w/225 flywheel hp.

268mph ÷ 140mph = 1.914

1.914^3 = 7.015

7.015 × 225hp = 1578.38hp, or about 1380rwhp !!!

If you don't think this is accurate, try comparing a Sprint Cup car to the Mustang. Both are close in weight, but give a bit of a bit of a drag coefficient edge to the Sprint Cup car (0.28 vs 0.38). The Sprint Cup cars are capable of going 215 to 225 mph if left unrestricted. It would take about 815 to 900hp to get the Fox Body going those speeds. What does a Sprint Cup car have? About 800 to 860hp, and cleaner aerodynamics.

 

[1987LXragtop]

Now that its been established the amount of theoretical hp to reach 268. The next equation comes into play.
Newtons 2nd law of motion force=massxacceleration or written as F=ma.
but in the instance solving F looks like this...

F=3200x268mph then F in this example actually will equal F**cked when you hit that immovable wall

 

[Lawbreaker5.0]

I pushed my vert passed the 140 mph mark years back and it only had minor bolt ons like exhaust. Pretty scary having to jump 3 lanes cuz it feels like it's gonna roll over on the slightest turns.

 

[5.0Droptop]

My autometer speedo showed me doing 150 with my 347 stroker under the hood... dunno if it was accuret.

 

[94GTMustang5.0]

I had my 94 gt with bolt-ons up to 145. stock 3.08 gearing near the top of 4th