FLYNLOW92rs

iTrader: (53)

I have installed a 3-pt Strut Tower Brace, Spohn SFC's and a set of lowering springs.....

I only ask because i'm getting an LS1 that appearantly rated to have a top speed of 167mph, so i'm wondering if my suspension will be capable to handle the high speeds, I know i won't achieve the top rated speed though......

I don't have to worry about loosing traction out back.........

Zepher

iTrader: (1)

Max speed is 307mph.

"The key to keeping the car on the ground at those kind of speeds is its weight," explained Jeff Kugel. "Downforce works up until a certain speed, but then the car starts going so fast through the air that the aerodynamics have it almost flying. What keeps it on the ground is its weight. You’re okay until about 280 or 290 mph, but when you hit 300 mph the wind tunnel tests on this car say it should be air borne. But the car is heavy enough that it stays glued to the surface. Even at 307 mph, the Firebird was showing absolutely no signs of getting light on the front."


"You’ll be watching the tachometer, feeling the engine at about 6000 rpm, and all of a sudden it shoots to 8000 and you think the engine is just going to explode."
"We also run the stock rear spoiler from a 1990 Pontiac Firebird on our 1992 car because we feel that is the best spoiler that Pontiac has. It’s not an aftermarket spoiler, it’s an actual stock rear spoiler and it’s the one that starts on the glass itself and goes all the way around the deck lid."

In addition to the C(368 cubic-inch engine)/Blown Gas Altered record they now hold, the Kugel & LeFevers team holds the C(368 cubic-inch engine)/Blown Gas Coupe category record which is also a production class. The speed record in that category is 295.859 mph.

"If you’re going to go 300 mph in a stock-bodied production car at Bonneville, the car of choice is a Pontiac Firebird," said Joe Kugel. "Out of all the production cars, it probably has the lowest drag as far as aerodynamics are concerned, and at 300 mph, this Firebird has to be the most stable vehicle that’s ever been built.

Here is the entire article

fireturd350

iTrader: (8)

I did 155 mph in my 90 formula with little mods. I think car craft or hot rod said that the 3rd gens are more aerodynamic than the 4th gens that's why there more 3rd gens at the salt flats.

ebmiller88

iTrader: (7)

The late John Lingenfelter took one to 220+ on the salt flats. That's haulin ***.


Ed

ShiftyCapone

iTrader: (7)

With your suspension mods you will hit those speeds in a safe area with ease. Just make sure your tires are up to par and have the appropriate speed rating. Anything less can cost you more than a blowout. Stock LS1's (without the limiter) can hit those speeds with ease. You will be fine.

semiller26

167mph Ohhhhh now that sounds like fun. Unfortunatly I can only vouch for 120mph. The car (when it was stock) was still going strong at 120 the only thing that slowed me down was traffic.

FruityOne

I remember reading those articles about how the thirdgen Firebird was aerodynamically stable to 200mph no problem. Though I'd be worred about the windows being sucked out at that speed.

The 1987 Iroc with the 350 was tested to 149mph on a 7.5 mile oval track. Its in the Magazine Articles section of this site. With a bird being slightly more aerodynamic it my go slightly faster.

Heck if you cleaned up the bottom of the car with a body pan it might be possible to squeeze more mph out of the car, and increase downforce.

25THRSS

I have a video of a mclaren doing over 200 mph continuously and the tires started to blister. Scary stuff.

fireturd350

iTrader: (8)

Anyone got a pic of the spoiler they used that goes all the way down to the glass? I was just kind of interested in seeing it. The pics on their website aren't all that great of the spoiler.

Bandit5

150 so far with a **** ton of mods... nothing is stock anymore save for body panels. I will be getting about 200 more HP (total 550) in a while, plus some taller wheels/tires and gearing a LITTLE bit more suited to the highway. Then I will see what this baby can really do. I didn't go any further than that for a few reasons... the speedo doesn't go any higher, the engine was almost redlining, and I was pretty sure eventually a cop was gonna see what I was doing.

MrDude_1

160ish is the fastest ive ever been in a fbody.... 4thgen TA..

130ish is the fastest ive driven a 3rdgen..


the main saftey points are the tires.... you dont want to exceed the speed rating.

now heres somthing intresting... with the coupes, the rear end gets lighter with speed.... im assuming its the back glass...
with the verts, the rear end actually stays down at high speed.... and the tiny spoiler does help....

if that rear wing is angled right, i doubt you will have the rear end getting lighter at speed, but if its crooked or wrong, its going to make the car handle a bit scary.... it may not seem scary at first, until you have to turn a lil bit or somthing.... then the speed adds up quick..

even with Z rated tires, i wouldnt maintain a high speed over 130.... id want Ws or better before i even THINK of trying to top out that car...

TKOPerformance

Another problem with stock cars maintaining insane speeds for any length of time on a road course or oval is the suspension bushings. At super high speeds the rubber will start to cook and move around making for scary handling. Spherical bearings are the only way to go for an application like this.

fireturd350

iTrader: (8)

Yeah I see a lot of magazines covering tire issues on dyno articles. Most recommend drag slicks for the dyno that way you know the tread won't fly at a buck fifty (150 mph). When I had my car dyno'd it reached around 135+ mph in 3rd gear (1:1) with a 3.27 rear gear.

Another cool thing I just thought of was I was watching speedvision acouple years back and they were talking about the old motorcyclists on the salt flats that built concept type bikes to try to break the speed records... well the interesting part was how the speeds changed the way they actually turn like, 0-200 mph was normal turn left it goes left... 200-300 turn left it goes right... 300+ back to normal again turn left it goes left. I thought that was kind of cool at time.

25THRSS

care to explain this?

Zepher

iTrader: (1)

It's just the stock wraparound spoiler on the 85-90 Birds

Bandit5

There has been confusion about this for sometime... allow me to explain. Early on, Z-rated tires were rated at 150MPH. No one ever thought they would need tires better than that for normal cars, non-exotic. Now, there are several tire classes that handle over 150MPH, and the actual Z rating has moved higher. However, the tires rated for 150 and over are all in the class called" Z-rated."

The Z classes are as follows:

V - 149 MPH
W - 168 MPH
Y - 186 MPH
Z - 149+ MPH

This represents the maximum speed capabilities of the tire. Although misleading with the Z has a "149+" designation, it should be correctly labeled as "186+" for it is the only tire that should be used if a speed over 186 will ever be maintained. These speeds are not magical numbers, so if you go over the limit, the tire will not instantly explode, it is the speed at which they have been tested and are proven safe at those speeds. At the time I did my 150MPH or so run, I was using Y rated tires, so I was safe as far as tires are concerned.

TheGreatJ

Z is not the highest tire speed rating. Back in the day, tire manufacturers thought "149mph+" was as high a speed rating as they'd ever need. But thanks to technological advances and new rubber compounds, they can now make tires that are stable at even higher speeds. Since Z was already taken, they designated these W- and Y-rated tires. W=168mph and Y=186mph.

W- and Y-rated tires often still have a "Z" in the size description (i.e. the 245/50ZR 16's on my car) but have the higher W or Y rating indicated in the load description (i.e. 97W like my Kuhmo 712's.)



edit: Bah....I paused for the bathroom and Bandit beat me to it.

25THRSS

This is what I have always been know to be true as well, so what he said makes no sense. Z is what you want for absolute crazy speeds

Bandit5

He confused Z for 150MPH rated tires, but they have advanced to 186+, so I know where he was coming from.

gen3z

my late '88iroc 5.7,5-spd.,3.27s on 17x9.5 eagles,top speed in the top of 4th i got pulled over at 163,hr even showed me the radar,got a ticket for 99 so he did not have to take me to jail,but the car was impounded,total cost was 560.00,what a rush that was.He did ask me why it took me 1.5 miles to stop,i told him i did not want to warp my rotors for this!!!!!!!he laughed!

MrDude_1

since when are they 186? my understanding always was, they should be able to sustain 150, but they arnt guaranteed for anything after that... unless the tire maker specificly says otherwise.

then they came with the W and Y ratings for sustained 168 and 186 speeds...


Z tire still means only 150+ unless its also rated otherwise... like the Kumho 712 it has a W rating.. its higher then a Z so it could be mentioned... but its also higher then a P,Q,S,T,U,H,V... and noone calls them that...




then again, like TheGreatJ said, they do put Z in the sidewall, so i can see the confusion.... but Z rating does not mean ultra high speed.. and it def does not mean 186+

paul_huryk

Actually that is wrong - he piloted his twin turbo TA to something like 295mph, close but not 300mph.

The quote about weight keeping a car on the ground is a load of poop - at 300mph, even the strongest race tires need the minimum weight possible on them to keep from destroying themselves. Weight is the cheap & easy way of adding downforce. You will note the Maclaren is only 2600lbs for a reason - to keep 200+ speeds sustainable.

With the headlights down, the TA is slightly better in aerodynamics - no difference if a Camaro has light covers. You lose a lot if you have the headlights up in a TA.

I have a 15 year old hotrod that had a 1989 TA with a 650hp motor and basic aerodynamic mods (stock bodywork) and it ran 238mph, 12mph faster than the 50hp more Lingenfelter TT C5. The 300mph TA had about 1400-1500hp I'm guessing.

fireturd350

iTrader: (8)

Ahh Thanks Zepher... I was thinking it was customized aerowing that had the front extend'd so it touched the glass all the way around making it an actual spoiler (no wind going underneath it so it would make more downforce).

Zepher

iTrader: (1)

I don't plan on debating the weight issue, but that quote was from the team that has been running at Bonneville for quite some time and I believe still hold the Speed Record for Stock Bodied Production Car.

The McLaren is a different class of car, when compared to a land speed car. That Firebird can't get moving on it's own power due to the gears, it needs to be towed to 80-100mph before it can run on it's own.
The McLaren is light so that it is quick from 0-100.

ShiftyCapone

iTrader: (7)

The heavier the car the more downforce their is. For the same reason why larger aircraft need longer wings. They need to generate more lift. Cars are kept light for all of the performance factors that we all are accustomed to. That is why they add wings and spoilers to create more weight (in the form of downforce) to keep the car from flying. A car is very much shaped like a wing and if there weren't any spoilers and or wings, enough lift would be generated at 100+ speeds to make the car lose traction with the road. It will never fly of course because as soon as it starts to leave the ground it stops accelerting and comes back down and would become a cyclic process.

25THRSS

Directly from Kumho tires website:

Tire Speed Rating Symbols:

S 180km/h or 112mph
T 190km/h or 118mph
U 200km/h or 125mph
H 210km/h or 130mph
V 240km/h or 149mph
W(ZR) 270km/h or 168mph
Y(ZR) 300km/h or 186mph
ZR Above 300km/h or 186mph

laiky

The mclaren is light because it must turn and stop. Weight provides stability (inertia) and requires more lift before the car will become light due to lifting forces. Weight, when properly distributed will make a land speed car more resistant to turning as well, this is a good thing at 300 mph.

MYBLUZ

I hit 145+ in my Z stock, I did it with one window down which I wouldnt suggest. But the situation didnt allow for time to roll it up. Anyway I did this after the tire shop pulled a nail out of the tire and patched it. Rumor has it if they patch a tire, it looses its speed rating, kind of scares me to think about it.

MrDude_1

not a rumor. its true.





btw, does anyone knwo the speed that the front winshield will start failing at?

Zepher

iTrader: (1)

Yep, patched tires lose thier max speed rating.
Try doing 155mph with the windows down and t-tops off.
Then watch the speedo drop really fast when you let off of the gas.

We did this in my brothers 96 T/A to test out the speed with 4.10 gears, since some people on cz28.com (so many misinformed people over there) said you can't go that fast with 4.10's.
Top of 5th and we hit 155mph. With stock 3.42 gears, we'd hit 155 at the top of 4th.

Zepher

iTrader: (1)

795mph. Ask me how I know.

MrDude_1

lol how do you know?



seriously though, that used to be a big thing, but we dont even think about it anymore (atleast i dont...) but i was talking with some of my dads friends lastnight, and he had a winshield fall in while him and my dad were in the car going only 120-130ish... this was back in the late 70s though.. *shrug*

Zepher

iTrader: (1)

Well, this one time, on the highway, I had this rocket on my roof and at 795mph the windshield started to crack, so I slowed to 794mph and all was good.

Actually, I have no idea what the max speed is, but I am thinking it's over 300mph since the Kugel/LeFevers car looks like it has the stock glass in there and there was no mention of windshield being replaced. Doesn't mean it wasn't, just that they never mentioned that it was or wasn't replaced.

ShiftyCapone

iTrader: (7)

That depends on a lot of factors including the internal pressure of the car and the density of the air. Both change based on temp and internal HVAC condictions of the car. Also depends on the grade and quality of the glass. I would say that the wek point is the frame to which it is attached and not the glass itself.

Kandied91z

iTrader: (7)

i hit radar at 179 with no problems going a constant 170 for a bit, although i don't know if i'll do that with a fiberglass hood.

Dante93GTZ

iTrader: (5)

I instantly wanted to hit you when I read that post... lucky b@astard.... an LS1...... I'm just jealous

Barry85Iroc

Fastest I evr had my car was a little over 140....when it was stock. (no cat) Since new motor has been in, only had it up to 100. Not another drink like it!!!!!!!!!! What a rush!

Berlinetta

lingenfelter took a firebird to 298 mph with a 1400 hp twin-turbo 355. Not bad...

CALIROCZ28

iTrader: (3)

I could see the state line from about 10 miles away There were no tail lights in sight so I decided I was going to see how fast my car could go, so I slam her down to the floor and my 150 mph speedo needle quickly passed 150. ! I was approaching my destination sooner than I expected when I catch a glance of the reflective letterring distintively displayed by the CHP. I see a pair of headlights lightup in my rear view mirror which now was approximately 3 miles back and then I started to slow down not because of the cop but because of my exit was about 1 mile away. I hit the offramp at about 70 and brought it down to the speed limit and calmly pulled into the Buffalo Bills parking lot. about 4 or 5 minutes later I see a Black and White Mustang coming off the same ramp. He turned left instead of right, stopping, then going then backing up, looking left, right and all around. I went inside to check in. Later I asked a security guard what the cops were looking for earlier? He said they clocked some body in a unknown type of car and unknown color with Sonar at 158 mph and they think they saw his tailights exit at the state line but were not sure.

bigals87z28

May he RIP.

CrazyHawaiian

Fastest I've gone is around 140. I got passed like I was standing still so I gave up. I'm gonna beat that guy one day ...

acescarrsRS

Fastest for me was 135 in my old IROC on our lovely stretch of freeway called H-3. Probably the same stretch Crazy Hawaiian was on. Only reason I slowed down was because those damn louvers bolted on the hood weren't secure & actually started to bend upwards a couple inches off the hood!!!

f-crazy

iTrader: (-1)

hey guys how do you figure the top speed of a car.....i hit 145 in my 5 speed LB9, and it was at 4,400 rpms in 5th gear....
with the stock gearing of 3.42 and the stock "taller 5th gear" .71 i think....what speed could i hit at the 6000 rpm limit i have set?

ShiftyCapone

iTrader: (7)

What is your tire size and I can tell you your exact mph. There is a very simple mathmatical relationship. In fact you can go to the calculations section of this site and type it in and it will tell you right off the bat.

f-crazy

iTrader: (-1)

i found the calculator but i dunno if the radius is right...
its the stock tire...16x8 255/50/16....

i got 179...seems about right...and i have the .63 5th

LS1Formula

FWIW, I hit the 162mph fuel cut in my old 98 Formula pretty rapidly. The condition of your suspension and tires should dictate your top speed more than the engine. I had minor suspension work and fresh BFG g-Force TA KDW in 245/50-16 all around.

TKOPerformance

Try this for tire diameter:

2*((section width*aspect ratio)/2540)+rim size

The result gives you tire diameter in inches. Divide by two to get the radius.

f-crazy

iTrader: (-1)

ok...IIRC from math 101 you use PEMDAS to work this out...

so that would be
245x50=12250..divide that by 2540=4.822...multiply that by 2=9.65..then add 16=25.65 thats the diameter...then half that is 12.82 which is the radius correct...if i add this radius into the top speed calculator its now 180.1....that seems about right....just like my first number lol...hell well just call it 179.5 lol

ShiftyCapone

iTrader: (7)

You should really take all of that an mutiply it by .98. There is a 2% loss in theoretical diameter since your tire has a flat spot on it at all times of contact. That is how the auto world calculates such stuff to get as accurate as possible. It really makes a differnce when you are down to calculating every sinlge last mph.

f-crazy

iTrader: (-1)

ohhh ok i see what you mean...my speedo goes to 140 so i was wondering at what rpm the speed would be....