I'm finally picking up the pace on rebuilding my 72 Skylark and have been working on trying to attain a top speed of 150mph on the open road and sustaining a 120mph for 90 miles. (Yes... I'm thinking of the Silver State Classic in Nevada) The car (in the avatar block) has 26" tall rear tire, 2:70 rear end, TH350 (1:1 top gear) and using the math it should be able to get to 157mph at the 5700 rpm I have on the rev-limiter. That's math though, and not taking into account the physics. The car has run at 5700rpm in drive with a 3:70 rear gear for 45 miles before, but the jump from a 3:70 to a 2:70 is a big jump. Any ideas? I'm thinking 140mph is doable, but will it be possible to get to that magical 150mph? -Phil
Here's a page with calculators so you can play with tire sizes, gear ratios and such. I have a great one on my computer at home, but I'm at work now. I was looking at this also and I seem to remember that with a 28" tire, a 2.73 posi rear and a 200-4R transmission, 200 mph was attainable at 5000 rpm's. Whether or not a brick of a Skylark could go that fast and still remain stable is another thing. Most older cars get very light up front at higher speeds. I would seriously look into a front air dam of some kind along with dropping the nose a bit. Then you will also need a real NASCAR style rear wing to hold the rearend down also. NOt to mention all the other safety stuff. They are very strict at their tech at those races. Good luck. http://www.speedworldmotorplex.com/calc.htm
With the 350? I'd say no way. My '65 has 2.78s, and while it may be a little down on power compared to your car...I've had it to nearly 120, but 150 is a lot faster than 120. I'd say you'll need 400 HP plus to get it going that fast...even if it's more aero friendly than my brick...
If you haven't seen this yet, go look at the Faithful Pursuit thread on the BCA forum. Smartin has been helping post images.The thread and images are great and will give you an idea of one way to set your ride up for some high speed hijinks.
Well, the car is already slammed into the weeds. I dropped it down with cut BBC coils up front, Moog offset upper control arm mounts and the front sway bar from a 74 Firebird SD Trans Am. All the bushings are polyurethane. The rear has progressive rate coils from a 79 Le Mans and the lower control arms are home made from 3"x1" rectangular steel tubing with polyurethane/graphite bushings. Upper control arms are stock with 1/16" thick washers welded on the sides to re-enforce them at the chassis mount. There's currently about 3-1/2 inches of ground clearance at the front crossmember. I can get the floor jack under it if I lift up hard on the front bumper. Tires (right now) are 235/60-15 front and 265/50-15 on the rear, mounted on Craiger Street Stars, but plans are for removing the front wheel wells and tubbing the rear wells to accept Old School 18" BBS wheels with BFG G-Force 275/40ZR17's that are 25.7 inches tall. Roll cage is going in and it's a full 10pt cage. Fuel cell as well, replacing the stock tank. The wheel/tire combination is going to be one of the last things done, as well as updating the front brakes.
The first 70 Skylark I built a 350 in had a 2.56:1 open rear, KB118 cam, TA manifold, modified q-jet, TH350 with a 2800 stall, 15x7 Rally's with 255/60-15 Eagle STs in the rear shifted from second to third at 112-118mph. At the time I got it completed, my dad had an '85 Vette with a digital dash. His vette would run about 137mph wide open. I could pull away from him, but I think the aerodynamics really start to come into play at that speed. I suspect it would go 150, but definitely liked 130 a lot better and would easily cruise at that speed. It ran a 15.68 quarter mile and I decided I could just as easily kill myself at 120mph and would rather get there quicker so I ended up putting a 3.55:1 rear in it. My dad had a C5 2 years ago that I had going 157mph. It is much quicker 0-70 than the Skylark was, but I think the Skylark would have easily pullled it between 60-140mph.
My engine is a 350, Poston 10.25:1 cr pistons .030, Poston 116 cam (.480 intake, .495 exh), T/A Performance intake, 800cfm Q-Jet, Competition Cams rockers and shafts. The exhaust exits thru a set of Hooker Super Competition headers and a pair of SuperTrapp diffusers. The trans is a TH350 from a 75 Pontiac built with a B&M Trans kit and a TCI 2800 stall. It's got a remote trans cooler and trans temp gauge in the dash. Based on your experience, our cars are similarly built so I think that cruising at 120 for 90 miles will probably be within my expectations, although I'd really like to see if it could hit 150.
I have no suggestions, though my stock '70 with a stock '73 motor has hit 120 on occaision (was having too much fun watching the Mustangs disappear in the rear-view mirror, then looked at the speedo). So I'm sure it is doable.
Those tires you mentioned, BFG G-Force tires are only rated to 149 mph. I know because I just put a pair on the front of mine after realizing that my front tires were only rated to 112, and I do that every time I go down the track. Here is a place that I have found to have excellent prices on tires online: http://www.tirerack.com/ and: Beginning in 1991, the speed symbol denoting a fixed maximum speed capability of new tires must be shown only in the speed rating portion of the tire's service description, such as 225/50R16 89S. The most common tire speed rating symbols, maximum speeds and typical applications are shown below: M 81 mph 130 km/h N 87 mph 140 km/h Temporary Spare Tires P 93 mph 150 km/h Q 99 mph 160 km/h Studless & Studdable Winter Tires R 106 mph 170 km/h H.D. Light Truck Tires S 112 mph 180 km/h Family Sedans & Vans T 118 mph 190 km/h Family Sedans & Vans U 124 mph 200 km/h H 130 mph 210 km/h Sport Sedans & Coupes V 149 mph 240 km/h Sport Sedans, Coupes & Sports Cars When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of new vehicles that have extremely high top-speed capabilities. W 168 mph 270 km/h Exotic Sports Cars Y 186 mph 300 km/h Exotic Sports Cars While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed. 225/50ZR16 in excess of 149 mph, 240 km/h 205/45ZR17 88W 168 mph, 270 km/h 285/35ZR19 99Y 186 mph, 300 km/h Most recently, when the Y-speed rating indicated in a service description is enclosed in parentheses, such as 285/35ZR19 (99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h indicated by the service description as shown below: 285/35ZR19 99Y 186 mph, 300 km/h 285/35ZR19 (99Y) in excess of 186 mph, 300 km/h As vehicles have increased their top speeds into Autobahn-only ranges, the tire speed ratings have evolved to better identify the tires capability, allowing drivers to match the speed of their tires with the top speed of their vehicle. And you should definitely get one of these, just for the "coolness" factor: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4543601490&category=80739
Phil - I would really like to see you run in the Silver State Classic in Nevada - thats a way cool race. I'd also like to see you survive the race. Running at high speeds for an hour is way different from running up to 120+ for a few minutes. Tires get hot, metal fatigues, liquids boil, etc. You need coolers on everything fluid, strong suspension and brakes, roll cage, and good wheels and tires. Everything must be balanced, vibration is a quick way to break things. A fuel cell, spoilers and wings, racing shocks, are also considerations. Doing some testing on a closed course is also a good idea. Find somebody near you that preps cars for SCCA, NASCAR, Trans Am, etc and find out what they do. Buick ran many cars in road racing and most were not stock. HP is important, but that is not the only thing you need to win, or even finish, races. No slam intended, but home made parts, unless you are a fabricator, should be replaced with tested and certified parts. My 2 cents. BTW - That Faithful Pursuit project is fantastic! Thanks Ints for the link! - Bill
Found these on the net surfing around. Buicks that were built to run at high speeds: Oh yea, here's that web site that's great for trying different tire sizes, gear ratios and transmissions: http://www.1bad69.com/calc.htm
12lives - Don't worry about the home made parts. I built the lower control arms long before Hotchkis started selling them commercially. I probably should have patented them, but oh well. As for my being a fabricator, l've got engineering experience in both the steel and home building industry, so fabricating parts for me isn't an ad-hoc thing. The car has a tranny cooler already, and I've got another cooler for the engine oil and the car already has a 4-core radiator. There's a full compliment of gauges in the dash pad (GNX style). Besdes all of that, there's several classes of the Silver State, and it's almost like a 90 mile bracket race. I'd planon running in the GT division which has 115, 120 and 125mph classes with 140mph top speed for that class. I'm thinking I should be able to run the 120mph class and the car should be able to run at that speed for 90 miles, which should be somewhere around 50-60 minutes of high speed run, but well under the 5700rpm redline. In 1991 one of the racers entered a new Chevy 454ss pickup he drove from Colorado to Nevada, raced the 120mph bracket and won, and drove home. I plan on driving from Indiana to Nevada, running the race, and driving home as well. Back in 92 or 93 my brother-in-law and I ran the car from Attica IN to Turkey Run St. Park, about 35 miles, at full throttle. That was with a 3:70 rear gear and although it was only a third of the distance of the Silver State, it was done at tach speeds ranging between 4800 and 5500rpm. I just want to take the car out, race it once and retire it officially before my daughter gets the car for her 16th birthday, which is 3 years away. -Phil
here's one. My advice. Do it on the track. Too many hidden "ditches" on the street that you can bottom out on.
Phil- Just a quick note. I'm not sure what you need, but as a suggestion, I think you really have a 2.70:1 ratio rear end. 2:70 is "two to seventy" or 1:35. Just a heads up before you call up some places for rear gears and they think you're talking about ramp angles :TU:
My tires were S rated, but I had them at 130+ many times over the 8 years I owned the car. Granted I never cruised at that speed, so I guess for 90 miles you'd better consider the tire rating. I think you'd be fine with a T or H.
