I'm just wondering what sort of top speeds people have had their autos upto and what gears/power/rpm etc they were at. Reason I'm asking is I'm serriously thinking about changin my 2.73 one wheel go nowhere crap with a 3.23 and SLP posi but I'm not wanting to be left limited with top speed potential.

I'm in the UK and a trip to the Autobhan may be inorder this year with some others and I wouldn't want to fall behind.

Thanks

Robert

 

With 3.23's you wouldn't even be close to topping your car out. To find out your theoretical top speed simply do the normal calculations and factor in about an 8% slippage factor.

 

Check that your trans will hold OD at WOT. Some do, some don't. If not will need either a different 3-4 upshift valve or a different/modified TV valve.

RBob.

 

i didnt think any 700r4's could shift into 4th at WOT in stock form. i believe you have to be at 2/3 throttle or less.

 

The B4C cars do.

 

Early 80s chevy vans maintain OD at high speed at wot. That is with a 700r4. Mine upshifts a 4,400 to 4th then starts slowing down due to aerodynamic drag and the fact that the engine will not pull it @ 2,800 rpm.

 

my 85 trans am does the 3-4 wot upshift. The only had a thermotech chip , but otherwise its stock and it does a 3-4 upshift at wot.

 

been up to 123mph with 85 berlinetta , stock lg4 cept for little bit of cammage , headers, and exh. 3.08 rear not sure exact rpm, dash was unplugged....was testing out new speedo.woulda pulled more, most likely. got paranoid. have enough points on my license

 

forgot..planning on adding a 3.23 posi i have soon.........dont see it affecting top end very much at all

 

The 3.23 grears will lower your top speed from the 2.73

 

My 90 Formula 350 has 3.23's and the modified boost valve in the trans to hit 4th at WOT.....I've had her up over 140mph, no markings on my speedo after that but it looked like i was at about 150mph.....and still pullin!!!

 

I had my car up to 5500 in OD with 3.23's and 255/50/16's on the back, I don't know how fast that is cause my speedo doesn't work. I slowed down soon after that for fear of going to jail or something bad happening.

 

Well... I don;t want to rain on your parade, but it isn;t the best idea to maintain speeds over 120mph for long periods of time if the car is equipped with the steel driveshaft. That thing will vibrate so much above 120 it is a saftey hazard! Just friendly concern. Pick up an aluminum driveshaft and speed away

 

umm...... no.




its a hazard if you have a unbalanced driveshaft, but the material its made out of has nothing to do with that.
you would have to be a idiot to have a driveshaft vibrating that much at 120 and say, "hey, lets go even faster!"..



a better hazard to mention is the fact that alot of the people here dont have tires that are safe for thoes speeds.
the brakes are inadquate for a 60-0 stop, nevermind a 130+ to 0 stop.
most people here have old suspension components.
most people here have old steering components.


and im sure theres more.

 

100% wrong in 99% of the cases.

 

The factory only rates the steel driveshaft as safe up to 119 mph. The factory aluminum is rated for 200 mph IIRC. (Just updated)

My 700R4 doesn't upshift to 4th gear at full throttle currently, but it will hold 4th gear if I ease into it. Using a calculation based on rpm, I have had my car over 150 with 3.42 gears. This was before I upgraded the heads (pocket-ported, upgraded the valves to 2.02/1.60, backcut stems) added headers, and recalibrated the chip.

Currently, my transmission doesn’t hold anything above 2nd gear........ I’m anxiously awaiting the arrival of my ProBuilt 700R4 and the 9.5” Edge converter!!!!!!!!!

 

i think thats 100% right in 99% of the cases

 

Most of our cars are limited by drag and power, not gearing. Replacing 2.73's with 3.23's will only help your top speed in this instance. Do all the theoretical calculations you want, but when they say something like180, it will never even come close to those speeds. In most cases more gear will actually increase the top speed by putting you in a better spot in your power band and putting more tq to the ground.

 

Having higher RPMs at the same speed then another car with lower gears(lower number like 2.73) means that you will run out of RPM range faster therefore losing top speed.

 

yes, but you don't understand that no stock third gen will come even close to running out of gear with 3.23's. It'll run out of power before it ever will gear. What third gen do you know that can hit 175+ stock?

EDIT: It will lower your theoretical top speed, but not your actual top speed.

 

With 2.73's you'll top out in 3rd gear, you won't have the power to go any faster in 4th. With 3.23's you'll either be at the top of 3rd or well into 4th depending on your engine.

I got pulled over at a police radar verified 148mph (he showed it to me ) in my '83 TA 27" tall back tires, 3.23's and some mild mods…

 

I've hit 140 with mine embarassing and newer Mustang GT. I can only do about 75/80% throttle in 4th before it tries to downshift to third. It just won't climb past 4200-4300 RPM with that much throttle. Kinda strange really, it doesn't actually downshift. It tries, but the engine just spins freely almost. Too much throttle for 4th, but too much RPM for third with not enough throttle opening and its like revving in neutral.

If I could lock the trans in 4th at WOT I should be able to hit 160 or so with the 3.42s.

 

My car feels like it is going to blow up at about 105-110 and I don't even try to go faster. My motor has the power easy, but maybe it's cause I have a steel drive shaft. My 700 wouln't even hold 3rd gear at WOT the engine would just start reving slowly after 4000 in 3rd but I would not be going any faster. I guess it was slipping. Haven't tried to max it out with the 5 speed yet but the car still feels like the chassis will blow up if I try anything faster than 110. Maybe it's time for some new suspension. and maybe a tire balance. (209,000 miles on stock suspension)

 

My '83 had the stock steel DS at the time. My '87 has a big, Denny's 3.5" Metal Matrix DS in it, but I've never had it over about 125mph. My '97 wouldn't go over about 75 (4.10 gears) without a killer vibration, but at about 95 would smooth out again. Would start the same crap at about 140, but I fixed that eventually

 

>

 

you know that's not a good idea on a cold engine dont you
I wish I woulda got a 200mph gauge for my cluster, coulda posted a buried pic and wowed everybody gear swap, smaller tire, ice patch, etc...If that's legit, you got *****

 

not cold… ever since I reprogrammed the fan temp, with the HPP+ that's where it sat once it warmed up. (also how I got rid of the rev limiter and moved the top speed fuel cutout).

No ice, it was a sunny, 50* afternoon. If I remember right the tach in that car is about 100 or 150rpm "happy." That was in 5th gear with 3.73's, and the speedo needle is pegged. I'm not sure I'd call it *****, more like insanity… at least the part that I decided to take a freaking picture while doing it

 

I have a 92 Z w/700r4 and as far as I know it dosnt have any special TV valve to make it hold 4th, I just go onto the throttle smooth and it will stay in 4, I have 2.73s w/ posi and I was at 140 and still pulling, third gear it would only do about 120. stock motor w/150k. just to let you guys know.

 

my speedo only goes up to 120 and i had it on the peg and also my tach was tached out...lets just say i don't plan on doing that again........state trooper flaged me at 170.....luckly for me he was a good friend of mine...i told him i wanted to find out what i could do top end and he said sure..just don't make it a habit........besides........it scared the bejeebus outta me and the guy riding with me

 

What turned out to be the cause of the vibration?

 

Driveshaft harmonics... it just didn't like a steel shaft. I tried another steel one that I had sitting in the garage that I knew worked in another car and it did the same thing. Finally just got a big, Denny's 3.5" MMC shaft that fixed it.

 

I've topped out the speedo in the '89 so 145+ maybe 150. 3.27 r9bolt/ modded 700R4/ balanced steel shaft. I don't remember the RPM's. I was walked like I was standing still by a early '80's capri style stang @ the same time!

 

Reason for this thread was I was thinking of my Pro-Built that I'm about to order and....


.....3.08's, about 500bhp at 5650rpm and an Autobhan to have a realistic attempt of 200mph. I believe that's about it. Just need to setup for that.

 

where would I be able to find an aluminum driveshaft and for how much? Pm back

 

Theoretically you should be able to achieve almost 204 mph in overdrive with stock size tires.

 

Main thing im wondering is what would be the difference in top speed of lets say...

3 speed auto ( th 350 )
4 speed auto ( th 700 )
5 speed manual
6 speed manual

?????

In the 1/4 it makes no difference in speed, but were talking top speed. I would think the higher gears will give more, but the lower gears in the others just keep you in the same gear longer. So what does it come down to? Final drive gear maybe?

Just wondering.

 

OK, to start with, you're not going to put down any real power to the ground in overdrive in most trannys. they just aren't designed to do it.

 

lol.

well everyone else is saying what they have done i have been to 132mph in my 89 and it definitely was werid seeing how if a cop ever saw that in a 65mph zone bye bye license. i only did that 1 time and my 84 trans am seemed like i got that up there in speed but it only had the 85mph speedo.. but i let the gas off and it just stayed burried (the speedometer) but now i am switching my 89 from 2.73's to 3.42's but i also have many many mods to my motor so now i think my speedometer will be off alot.

also had a chance to snap this on a back road.. that was scary because it's about as wide as 1 lane but it's a 2 lane road.

 

oops

 

137mph here.....


3.27 rear
700r4
L98

had more in her, but the road was closing fast

 

You think trying for 200mph with a 700R4 is shooting for an unobtainable goal?

 

Unattainable? No, but you won't push enough hp to go 200 trough OD. You could do it if you're geared to hit 200 in 3rd, but then what's the point of having OD?

 

What do you think is a more realistic top speed that could be reached with 500bhp?

To hit 200mph in 3rd, I'd have to rev the engine to around 7200rpm with 2.73's, and i'm too far into my current project of 500bhp to change things now. This is most unfortunate.

 

In canada the guage on a third gen says KPH on top and MPH on the bottom, that and its about an inch lower, I went right past that sticker and i was only at 4k rpm, and plenty of power left. According to my calculations, 336 is my top speed.(theoretical) (~56 kph, per 1k rpm in 4th gear is about that) now factor in 10% slip and you get 302.4. So im guessing my top speed is 302.4 kph. Ofcorse, im not going to test this. My DS is aluminum but dont be stupid, tires can blow really easily.

PS, 89 gta, 350, heavy mods (unknown the extent, but it blows away ALL my friends cars, even a done up 350 iroc) with 700r4.

oh and 302.4kph is around 190mph (189 sometihng). And i still burn out the tires in dry weather at any more then 1/3 throttle.

Oh, and if anyone tells me that thats impossible, keep it to yourself cause like i said, its theoretical, and im not going to test it. All i know is i definitly went halfway to the peg before i backed off.

 

83' crossfire T/A isnt relating to your engine torque. Its that very unkown complex "Axle Torque" that i think he's talking about?

 

First, I'm not talking about either… at this point it's not even a question of power. It's a question of what overdrive was designed to do. 200mph will take every bit of 700hp (drag goes up by the ^4 of speed), and overdrive is not designed to hold anywhere near that power. Remember that to keep your car going 30-65mph you're probably actually using about 30-60hp trough overdrive. Double that (say something like my full size truck towing a car trailer up a hill) if you managed to get it to stay in 4th you'd find it's limit very quickly.

Second, sounds like we've got a lot of 10, 11, 12 and a few 13 second f-bodies here. Figure it would take about 300hp to put your average camaro or 4th gen into the 140-150mph range, slightly less with a firebird/ta depending on the years and options. Most stock/near stock TPI cars will top out in the 130-135mph range. If you think that you're going to go over 150mph in an f-body that's running less then 12's at the track, well…

 

I believe the stock L98s would do about 145-150mph. I would have expected a 300bhp 3rd gen to go a little higher, like 155.

 

my 91 l98 camaro is pretty much stock powerwise besides a k and n filter directly on the throttle body. it has 120k miles on it and i did install the 3-4 wot upshift sleeve. and i managed to bury that needle and kept it buried so it was going over 150. and my speedo is correct

 

better add another 150hp and hope all the stars align to over come the wind resistance to achieve speeds near what your dreaming..WOW

 

whats the top speed you can get to with the t-tops off? How much of a difference does it make when there off or on?