build a 600 hp ls3 motor and want to know would i need a roll cage in car. also have t-tops, i would like to have only subframes on car. any input would be nice.

 

Horsepower has no bearing in whether or not you need a cage. NHRA rules specify that you need a 5 point cage if you run 11.49 or faster in the 1/4 mile. Whether a 600 horsepower LS3 powered thirdgen will run those times depends on a lot of factors, the biggest of which is driver skill.

 

All third gens need subframe connectors. Needing a cage or roll bar depends if you take it to the dragstrip and how quick it will run. As mentioned above, at 11.49 at NHRA and IHRA sanctioned tracks, a minimum of a 5 point roll bar is required. A full cage isn't required until you hit 9.99 or run faster than 135 mph in the 1/4 mile.

With only 600 hp, it's unlikely you're going to get into the 9's in a third gen in street trim. Providing you can get traction, you will probably need a roll bar as you should be in at least the 11 second range. Although a 5 point is minimum, most people put in the passenger door bar to make it a 6 point. 8 point just has the diagonals under the main hoop. It's not a cage until it gets a halo bar and a-pillar tubes. If you don't like climbing over the door bars, you can install swing out bars. The back seat however will become useless once you install a roll bar.

Driving only on the street and never taking it to a track, you can do whatever you want.

How much is too much? Most people will be happy with 350-400 hp on the street. My car isn't a street car and it's pushing around 1000 hp and I'd love a couple hundred more.

 

i will be drag racing and i don't want to put in a roll bar because, i like stock look of interor.

 

Then you better keep it 11.49 and slower or find a non sanctioned track. The roll bar is for your own safety.

If you make a pass close to the bubble, they'll warn you to slow it down. If you go deep past 11.49 without a roll bar, you'll be booted off the track and told not to come back until you put one in.

 

600hp is 3x faster than many people realize.

 

QUOTE]i will be drag racing and i don't want to put in a roll bar because, i like stock look of interor.[[/QUOTE]

It depends on how much you like being alive. A highly modified car can get out of hand in a hurry, and you never know when a suspension component will fail giving absolutely no control over the situation at 140 mph.

According to a calculator on www.measurespeed.com 3700 lbs and 600 hp should be in the ballpark of 10.7 seconds at 127.7 mph. (take this with a grain of salt.) I'd call these numbers best case scenarios. Since you are asking about the need for a cage I'm going to guess this is your first "serious" drag setup, so your times/speed won't be near this since you don't have enough experience to setup transmission/gearing/tires/suspension/etc.

The question you really need to ask yourself is do I feel lucky enough to crash into a wall sideways at 127.7 mph and roll a couple times without a roll cage. I have experienced a brake failure on an 85 corvette at 140 mph, left the course and jumped it at about 100mph afterwards. Blew all four shocks, ate the dash, and generally had a very bad day. After that I don't like to ride in anything over 500 hp that doesn't have either hellacious brakes, or a cage if not both. While something like this is not highly likely it is entirely possible. And I hope you think seriously about it.

 

I feel safer in my car at 150 mph going down the track with a full cage than I do in my truck at 60 mph going down the highway.

My car has a chute and I pull it a couple of times a year to make sure it still works. If I had a situation, it's nice to know the backup is there even if I don't need it.

If you want a high HP car without proper safety equipment, you'll never be allowed on the track. Might as well enjoy what you can on the street and hope you don't have any problems. Either that or you've built a poser show car.