4500 here....

 

Depends on the tires and the altitude among other things. I had Pirellis on that I couldn't spin no matter what, in Denver.

 

my stock toyo tires would spin easy at 3500

 

round 3000, 4000 works best

 

Yeah, tires are most of the equation. When I put sticky Dunlop 9000s on my (na) FC I let my dumbass friend drive it around the block - the first thing he did was try a burnout but instead he filled the car with clutch smoke.

My old '85 GS could break the tires loose anywhere in the first 3 gears - ridin' on General Cheapies (hardcore 300 treadwear rating!).

What tires are you trying to spin, thorin?

 

Dunlop 9000's also...2500 rpm, but I don't like to do that often with the new stock-style clutch in there...

 

Like purple82 said it depends on the tires. This includes type/compound, size, pressure, temperature and condition. Also you have to take account of the engine characeristics. What is the road surface like, smooth, hot, damp? How long is a piece of string?

But a practical reponse is, for a street set up on a slightly modified 12a with good quality slightly sticky tires such as the Yokohama A539s or Dunlop w10s you will be breaking at around 4000-4500rpm. on a typical road surface. The optimal launch will depend on the torque and power curve of the engine plus the tire characteristics. The secret to good launch is to get the right amount of wheel spin to maximise the grip, plus using the clutch characteristics. For a full drag launch with race tires and 500rwhp the launch can be 7,000rpm with controlled spin.

 

i dont even know what kind of tires, im running... i could go outside and look but... meh.

the thing is, im trying to figure out a way to benchmark the performance of my car when i have
-no track access
-no money for dyno

 

2500 on stock rims and all sesons

 

shitty kelly tires don't take much to break loose, they chirp everywhere too.

 

I couldn't say, however, on the salty roads this winter, it takes much less than it does in the summer.

 

This is actually easier than you think...find a place or parking lot that is long and basically flat....mark a "start" line that you will always begin at...mark another spot a 1/4 mile or so, 1/8th if you don't have that much room, with a line or stick standing out clearly to mark your "end"...

it's the mph you're concerned with, not the elapsed time, of traversing this "course" that will show if your changes are creating any HP for you. Strange but true, elapsed times can be all over the place with inconsistent 60 ft.s, but the top speed at the end is pretty much consistent regardless for a given HP of your combo...and HP sets top speed, not torque...

 

it also depends if your car has LSD or not

I can launch mine up to 5300rpms without losing traction. But that's with sticky toyo ra1s.

 

Open diff, 3.91 gears, stock transmission, '83 engine internals/stock '83 flywheel, stock type clutch, 2200lb with most of weight removed from rear, Goodyear Club radials 185/70-13 @20psi, decent burnout - 5500rpm floored. (Floor throttle from lower RPM and dump clutch as needle swings past)

Note all of the variables I listed. Each one is important. I even neglected a few like road surface, road temp, air temp, engine power...

 

3500 for me on 205 hancok rubers

 

Thorin- mar 3 has good advice on how to measure the performance, but get a passenger to do the timings while you cocentrate on the driving. They should be able to get both 1/4 timings and top speed at the same time with a simple stopwatch. With the 1/4 times its possible to work out your approximate rwhp- its cheaper than a dyno!

 

I saw a good tech tidbits in Road and Track once that had a cool little formula for estimating horsepower from quarter mile time and speed. I'll try to find it again and post it.

 

Ok, here ya go:

Stock wheels, new Toyo Spectrum tires with 15,000 miles on them (80,000 mile tires), running at full street pressure, 83 GSL with LSD, 5 speed, Centerforce stage 1, full Racing Beat exhaust, all the mods in my sig, car weighs 2200 pounds, new pavement (as in less than a month old), I need at least 2K from a dead stop to break traction, but the roads were semi wet cause it was 9 am and it had been raining all night up until about 3 am.

I have also found that generally on dry roads, my optimum launch comes around 4K. 3K-3.5K I just get too much bogging. Anything over 4.5K I get too much wheel spin. I just hold the throttle at 4K, drop the clutch, and floor it. It spins just for a split second and then takes off.

~T.J.

 

Something interesting to note...

My engine had good low end. I had timed it on several occasions of a 30-50 (50-80 for you metric folks) time of about 6 to 7 seconds. In 5th gear.

However, on the street, with normal air pressure in the tires, if I floored it in first gear, the tires would break loose when the port really came alive at 5500. In the rain it would do that in third, never had the ***** to try that in fourth because getting sideways in the rain at ~90mph is kinda scary.