Zepher

iTrader: (1)

My car weighs 3520lbs with me in it.
I've gotten the car up to nearly 160mph when it ran out of gears and RPM.
Need an HP estimate and tranny and gear combo.
I want to get up to 200 as fast as possible to avoid driving 100+ for a long stretch trying to gain speed.
It took forever to get from 130 to 160 with my 305 5 speed.

Oh, and btw, I don't plan to do 200mph on the street.
I am trying to get a few friends to go up to Virginia International Raceway this summer and try my hand at road racing my Trans Am.

GreenProStreet

Aerodynamically, you cant pull out to many stops. Lowering, airdams, removing wing and side mirrors, wheel wells, thin tires...

I have a calculation that I'll look up for you. But look up the cd of your vehicle stock, so you can punch in the numbers when I get the equation.

BTW- Weight couldn't have less to do with top speed. Top speed racer add weight to the rear to keep traction.

GreenProStreet

Had to go through my stash to find you this. My rather large large magazine stash.

Bear with me:

Aero Horsepower= N x Frontal Area x Air Density x Cd x Speed^3

If you can find the frontal area and cd of your TA Then I'll reread the article and help you plug it in. There im-possible to measure at home, so look 'em up.

I am glad to help!

Vader

Zephyr,

You'll likely need around 600HP to break 200 in a stock bodied car. Lowering the car will help immensely.

The frontal area of your vehicle includes teh tires, mirrors, air dam, etc. The drag coefficient is a significant factor, and is added to by the relatively "unclean" underside of the vehicle. To rectify this you'll need side air skirts to keep air from entering the sides and getting under the car. There really should be no ground effects at the rear of the car, since the desired state is to create a slight vacuum under the car. The front air dam and side skirts with an open rear can help. I'm not sure what year your car is, but the earlier T/As have a functional rear spoiler - one that actually helps. Subsequent years, like '89 and up have largely cosmetic spoilers which actually detract from the aerodynamics of the car. Exterior mirrors will cost a couple MPH even if they are "aerodynamic".

Your front air dam should not look like this:



While being low enough, it is too far to the rear to prevent some high pressure from building under the nose. One that is similar but all the way forward would be much more effective at this, like this one:



If you don't want to make your own, check out Stillen.com. They'll make about anything (if they bother to make parts for ricers, they'll make about anything). This one is a little tough on the street, and you have to watch slopes and driveway aprons pretty closely, but if you take the ramps at an angle you can usually make them without scrubbing. This tub does about 162 with a fairly full tank of fuel, or about 4,380 lbs. As GPS stated, weight is less of a factor for top speed and more for accelleration.

8Mike9

I recall reading about the Indy cars, and they say that at 195+MPH's, that there's enough vacuum created under the car and enough downforce applied to actually make it run upside down.

Pretty cool, huh?

silverstreakII

to add to the indy cars, the race producers have to make sure that on road courses the manhole covers are welded down, because at speed they create enough suction under the car to pull the covers right off the ground and shoot them 10-20 feet high.

Zepher

iTrader: (1)

Well, the car is an 86 Trans Am.
I think some body mods are in order, but I'll wait until I get the HP required.

DM91RS

Check out the pro cars that test there such as the Dyson racing team which runs 6 litre Riley and Scott prototypes and you'll see what they run.

200 at VIR? But it will be killer fun if you only get to 120 mph.

By the way I hope that you plan to upgrade at least those front brakes. I'd rather show up with good brakes and an engine and trans that will not overheat than have killer power!!

Zepher

iTrader: (1)

Ya, brakes are up on the agenda, not sure which ones to get.
My friend has Baer brakes on his 82 T/A and they seem pretty darn good.

GreenProStreet

Yo? Do you want my help or not? Get the drag coificient and frontal area from somebody the we can calculate the exact ammout of HP needed. It took me 20 minutes to get that formula; take it or leave it.

PS- You better get a new transmission if your going anywhere. The t-5 wount handle the torque, and the Th-700 R4 is so thinnly geared you would never get there.

Zepher

iTrader: (1)

the cd of the car is between .29 and .32.

I'll have to figure out how to get the frontal area of the car.
Not sure what is used to measure it. Do I measure the width of the car and the height up to the top of the roof?

I've got some large tires on it now, 275/40/17, that gives more drag.

I'll try and find out the info so you can figure out the power required and tranny/gear combo.

Vader

An '86 T/A should have about 18 ft² of square frontal area if the fascia air dam is extended right down to the deck and the ride height is lowered about 1½" (3-3/4" to the floor pan crimped edge rails). Your cD should be about .31 with the stock aerodynamics and hood, headlights closed. Those later model aero mouldings may be ruining the drag, since they were more aesthetic than functional on '90 and later cars. You'll want the sides a clean, flat, and low as possible, and those won't help your cause.

Zepher

iTrader: (1)

I was thinking about that, but they look so cool on the car.

GreenProStreet

I'll get on plugging in the numbers. Maybe I'll have a figure tonight.

GreenProStreet

Plugged in the numbers and got a firgure of 305 hp at 200 mph, with a cd of .31 and a frontal area of 18 ft^2. But this is the tip of the iceberg. I have heard that the T-5 wont hold a lot of torque, and you will have to build a motor with a top-end hp of 350 hp. You will also have to plug in the gear ratios.

I am no engine builder, but I would think a 350 or 377, would be you best bet, leaning towards the extra cubes of the 377. Also a big cam, duration wise, mated to a miniram. The stroke of these engines will make it slitely easier to accelerate at top speed. But all these decisions are up to you, but go naturally aspirated, for sure. Also, cowl or ram air would obviously be a big help.

Keep us updated!

Zepher

iTrader: (1)

Thanks,
I do plan on adding twin turbo as well as a six speed to the car.
Turbos will give me the power and the 6 speed will give me the double overdrive.

I did have my car up to max speed a few times, 5000rpm in 5th gear, don't know if I had enough HP to pull 6th gear if I had it.
It was a slow process from 130mph to about 160.

a73camaro

From this equation a ratio can set up...

HP1 / (speed1^3) = HP2 / (speed2^3)

HP1 = ?
speed1 = 160
HP2 = ?
speed2 = 200

algebraic rearrangement

HP2 / HP1 = (speed2^3) / (speed1^3)

HP2 / HP1 = (200^3) / (160^3)

HP2 / HP1 = 1.95

so, if 300 RWHP got you to 160 MPH, you'll need 585 RWHP to get you to 200MPH.

Zepher

iTrader: (1)

Well, 200RWHP got me 160mph. I am not too good at math, at the moment.
So how much would I need now?

CODY BEHNKE

Um where did you pull 160mph from?

Vader

Like I stated in the first reply to this topic, about 600HP peak should do it. I've already been down that road, but apparently it didn't have adequate emphasis to sink in. You can substantiate this by the fact that most NASCAR teams are running cars at 750-780HP over large ovals, constantly decellerating slightly then accellerating, and running an average of almost 200MPH on these relatively small courses. Straighten this course out, or remove a lot of the traffic, and a little less power over a sustained accelleration should get you past 200MPH in an 'F' car, since the bodies can be made a little cleaner and smaller at the front.

I've done the math on my older 'B' car and determined that the current 420HP is about right for the 162 that it does.

By the same token, it takes almost 1,400HP to break 300MPH in an 'F' car with a relatively clean exterior and a LOT of rear end weight to keep the car from flying. It's been doen at least once...

Zepher

iTrader: (1)

From my tach, speedo only reads 140mph.

Zepher

iTrader: (1)

Well, I guess I am going to aim for 180 first then 200 later.
thanks for all the great info guys.

As of right now, my car won't even do 5mph, well it might do 5mph if I can get a few buddy's to help me push.

L98IROCZ89

Carbon Fiber driveshaft in perfect balance... not only will that allow the motor to spool up a little easier when it is running out of power at top speeds, but the stock driveshaft (I believe) is technically only good (balanced) up to 130mph. Going significantly faster than that, you will be running a risk of that goin on you.

Correct me if I am wrong.... ?

GreenProStreet

I think that his gear ran out more than his horsepower did. But that is quite the math equation (not taking math till next semester )

But I would bet on 600 ponies because those competitions use the average, so you will have to go up and back, and do it again back. More you have better it is!

Research your transmission. The only 6 speeds I have only have 1 overdrive gear, 1:1 being 5th. There is the 4L80-E which is a 4 speed running the overdrive between gears to make 6 speeds. I wouldn't let your rear end gear push you to 200, not the overdrive. Plus the less the RPM drops, more in the power you'll stay, and not so much wait. Plus there is the push truck to get you started!

It would be nice if they made a CVT Transmission for us, but I guess we'll have to wait a while!!!

85transamtpi

You'll also need ***** of steel

silentneko

not to offend you or anything but I don't really think you were going 160mph. from what I read in an article a while back the aero gta with a 350 ran 158mph, and it had more power then your motor and was on a 3 mile high banked track. but what was interesting was the speedometer stopped being accurate after 115mph. it was 15-20 miles an hour faster then the car was traveling when it pegged the needle. so maybe I'm wrong but did you have someone with a radar gun, or did the track have a trap sensor or something? if not you may have been only going about 140mph.

un4givin89

Strap on Rocket Engine, nice and simple.

Zepher

iTrader: (1)

The only way I estimated my speed was with the gear ratio of teh 5 speed and rear end and the RPM that I was running.
I just know I was going really really fast.

RMK

I wasn't going to bring it up on the boards until nearer the time but I've also been thinking about trying to crack 200mph in my 87 IROC. However, it's a long way off.

Vader, do you know what the frontal area for my car would be? I presume roughly the same as Zephers?

Also, overcoming aerodynamic drag at 150mph requires 3.38 times as much power as it does at 100mph. Therefore, whereas acceleration at 2 digit speeds is primarily determined by a vehicles power to weight ratio, acceleration above 120mph is limited more by the power to aerodynamic drad ratio-the factor that also limits your top speed.

It's also worth noting that braking from 150,ph to a standstill requires the brakes to dissipate 2.25 times as much energy as from 100mph. I would not attempt to do this on stock brakes.

As for gearing I'm just working on getting th power there and sort that out at the end. I'm attempting it on a 305 and will be running a D1sc for my power adder. I'm just going to be so pissed if I only reach 190 or 195. How pathetic would that be?

Keep us updated on how it progresses. And when I'm doing my runs I'll video them and post.


Robert

Craig84Z

iTrader: (2)

I'd have to agree with silentneko.
"Well, 200RWHP got me 160mph. I am not too good at math, at the moment. So how much would I need now?"

I have 200rwhp and there's no way I could go 160. I think you're tach and math is off.

Before reading all the posts I was guessing 600hp to go 200mph.

good luck with your project,
Craig

Zepher

iTrader: (1)

When I get the car dyno'd, I am going to see what the top speed of the car is onn the DynoJet. I don't know if the DynoJet has settings for cD and air resistance though.

Preak

go to this link at http://www.supersportwagen.net/ and look for the eriksson camaro z-28

all the cars on there are 200 mph or faster

LottaBallsCamaro

I'd like to see you find a CVT that will take 600hp, they are still about 2 years off from that...

You could use a 7speed F1 trans with 150millisecond padal shifts

That ericsson camaro is a tube frame car that only weighs 2,600's I cant figure out why he couldny get into the 10's even with that deep *** rearend ratio his weight advangtage should get him there...

RMK

*scratches head* I think I have one from Ferraris 2001 championship winning car lying around my yard somewhere. I'll have to have a rummage.

89 CamaroIROCZ

I'm just wondering what the track rules are for going that fast. Aren't you going to have to get a roll cage and address saftey concerns before they let you out there with a 600 hp engine and a basically stock car?


What other mods are you planning to do I'm pretty intrested.

Matt

200 mph is no joke...

dimented24x7

iTrader: (2)

Wow.... that'll be tough

dimented24x7

iTrader: (2)

As a soon to graduate student in the mechanical and erospace program, i can tell you that if you want to figure this out right, you should see if you can find someone with access to a work station with a computer modeler. Formulas only offer very, very rough aproximations and dont account for effects such as openings int teh front of the car that can induce turbulence that break up the laminar air flow.
If you are serious about going this fast, have a costom made front end that is very smooth and has all teh openings for the head lights and blinkers covered w/ clear plastic or plexiglass. Try to eliminate any thing that can cathc air or upset the flow. The more laminar the air flow, the less the frictional losses. Lowering the car and getting narrow hard composit slicks will help a grat deal too.

CODY BEHNKE

Why???? This topic is going nowhere you aren't going to hit 200mph nor will you hit 180mph so give up. My 1994 Trans Am with the LT1/Auto combo had a hard time pulling 160 and stock it had 275hp. I like 305's but you will not be pulling 160mph out of your set up, maybe 145mph but no way are you touching 160mph. Even my 1994 T/A had a speedo error of about 9mph above 145mph (by radar). 200mph is only 50mph faster than 150mph but it takes alot to make that 50mph. There is just a point all cars reach where it can't be pushed any faster without major horsepower increases. Your 305 won't cut it unless you plan on forced induction and many, many more mods. And in stock trim no way you'll never hold the road. My other hobby is motorcycles and I ride with quite a few people with a big variety of bikes, couple of F4i's like mine and even a couple ZX-12's and Hayabussa's. all are about equal 0-60 and streetlight to streetlight. 0-100 is pretty close but above that the 1100's, 1200's pull after that. Most high end 600cc's usually top out at around 165mph stock where as the 1100's and 1200's top out around 190mph. Thats only 25mph difference BUT it take's twice the engine to do so. Basically like I said before no way were you pulling 160mph with only 200rwhp. I am sure with all the motorcycle references this will flame but come on.

JAY87GTA

Hey Cody, take your crappy attitude somewhere else. He's asking what it would take, not that he's going to do it with a 305. Anything is possible with money and knowledge. There are lots of land speed guys running f-body's over 200 mph.

By the way, you got some major cojones to do 200 +, go for it. I would think a T-56 with some Viper goodies, like the input and output shafts, maybe some other things internal could handle the power. They have a Viper running 931 rwhp on the viper club boards. Hennesey built it, not sure what they did to the tranny though. Good luck

RMK

The tranny is a stock Viper T56. The only thing that stops it grenading is the wheel spin.

PimpRod92RS

Yo, you might be able to keep the stock transmissions in there, just switch to a better ratio rear say 2.73:1 or lower, that helps a little

Zepher

iTrader: (1)

I don't plan on getting 200mph with my 305, it would be nice though.
My plan is putting twin turbo on the 305 while building my 350.
When the 350 is done, I'll swap the motors and have a twin turbo 350.
Car will have a roll cage in it and subframe connectors.
I also plan on doing a Targa Top conversion.

This is going to take a couple of years at least. I've been averaging about $450/month in parts and mods for the past 2 years. If I keep going at the same rate, I can probably have the car done in 26 months with a twin turbo 350 with a 6 speed and Targa top.

NASA Langley out in Hampton, VA has a couple of large Wind Tunnels, I am going to find out if I can put my car in there to get an actual cD for my car.
All I need is time and money, and I have lots of time. Money on the other hand.................................

CODY BEHNKE

Ok, Fine I was just stating that a 305 wasn't going to pull 200mph with some bolt ons. 200mph is a major goal to reach and anyone who has reached it gains very quick respect for it. Reaching it isn't a "math formula here math formula there" feat. It takes alot of trial and error and $$$$$$. Not just a=b+2 situation.
If you think my attitude is crap oh well. Most of the goal needs to be reached with driver skill too. Someone who thinks 150mph is fast will get a serious wake up call at 200mph.

Zepher

iTrader: (1)

Just meet me up at Bonneville in a couple of years.

silentneko

I have driven almost 180 mph in a modified viper gts. you stop paying attension to anything but they yellow line in front of you. I was on the sawgrass expressway at about 4:15 in the morning, that was the first and last time I'm doing that. I'd like to build my car to do it, I have the right rear end, but I doubt my car will ever see 160mph. just consider after you make your car into a 200mph monster its not good for much else. the viper was awsome at speed but sucked as a street car, and only got about 8mpg on the street maybe 1mpg on the highway. good luck

CODY BEHNKE

Thats kinda what I was saying. A car that goes 200mph is usually a pupose built machine. Meet you at Bonniville, Why

Zepher

iTrader: (1)

Cuz that is the safest place to run 200+mph. It is nice and straight from horizon to horizon.

JAY87GTA

I'm thinking a twin turbo setup if done right might not be too bad on the street. Maybe not daily driver, but it would be funny to see the expression on the guys face next to you! Good luck and let us know how it comes out.

silentneko

the engine would have to be designed from the ground up to stay at high rpm for most of the run. if you let the car idle alot or drove it at low speeds it would just burn up the engine and its components wouldn't it.

George

$$$$$$$$$$$$$$$$$$$ and a slick paint job.