Here's the deal, I have a 8sec Tube Chassis Chevy Luv w/ a 540BBC. But I'm looking to build a 2nd ride.




Here's what I got....

I have a mint 87 Iroc-Z...and I bought a Alky Injected 540ci BBC (1200+hp)....

Trying to decide whether I can mini-tub or need to fully backhalf the car. I love the small tire cars. And have seen 3rd gen's in the 7sec. club with a small tire. So, it can be done! I see there's a bunch of fast 3rd gen's on here...What's your guys opinion?

Any info. will definately help in making my decision before I start cutting.

 

I say sell the IROC to someone who'll take care of it and cut up a SC or RS.

 

Nothing to "cut up". Bolt-in suspension pieces readily available from any of the big manufacturers(wolfe, spohn, bmr, etc) plus some weld-in subframes and a cage, a little messaging of the inner wheels wells and viola! - Do a search on here, there's a thread about fitting 295/60/15's. Not much work. The factory type suspension will reliably handle sub 1.3 60fts, many guys going bottom 1.2's at every outlaw race around here on the radials.

 

Are you building the car for any type of local class to race or just Outlaw race?

 

You can run a small tire if you want but traction will always be limited unless there's really good track prep. I doubt you'll see that on a regular basis unless you're always attending big events.

The factory torque arm system is fine for most people. With good aftermarket components, it's easy to run low numbers.

Back halving the car gives a lot more traction and a lot more suspension adjustability for different track conditions.

If you want a small tire 7 second car, buy a turn key car from someone. It will be a lot cheaper than building one.

 

The suspension tune is a major key. One of the radial cars I've been helping with will hike the skinnies at will, even on the street. In fact, there are a few guys that run at our local "non-sanctioned events"(cough, cough) that run the same tune-up that I've seen them run 5.8x(1/8) or better on at the track.

There are many consistent small tire cars, but not nearly as many as there are big-tire/back-half cars. No matter which you decide, the tune is key.

 

Once you get into big HP numbers, 800+, most people, if they're allowed to or can afford to, will go to a big tire. Sometimes class restrictions prevent you from putting a big tire on the car or many people after spending $20,000 on a high HP engine can't afford the $8-10,000 to back half the car.

Look in classes like SuperGas or SuperStock. It's unlikely you'll see a small tire car. One may pop up from time to time. They don't have to run big tires but they all do for a reason.

On the other end of the scale, Stock Eliminator is restricted to a maximum of 30 x 9 slicks and the quickest cars, AA/SA, are running high 9's on a 9" slick.

Many Stock and Superstock racers have switched over to radial slicks allowing them to run higher pressures which reduces the rolling resistance.

Cars that race in the 10.5 class and run 10.5W tires are trying to use a bigger tire that what's allowed. If they can run that fast on a smaller tire, why are they trying to stuff a bigger tire under the fenders? Some of the sanctioning bodies now say that the 10.5 class is restricted to a measured 10.5" tread regardless of what's on the sidewall. If the tire is rated as a 10.5W and is almost 12" wide, it fails.

 

I used to agree with that 100%. Now I'd say maybe 70%. - Far too many cars consistently running in the 5's at our local 1/8 mile w/o even being mini-tubbed. These are the same cars I see at cruise nights and out on some of the back-road events still pulling the skinnies.

Like I said, the suspension tune is a major key, but technology has come a long way.

It is much easier to get those type of results from big tires, but it is also far from impossible to do so on small tires. As is the case with most builds, to each his own.

 

Alky injection means lots of torque. Not a lot of "street cars" are running injected alcohol or even carbed alcohol. Many, such as the Mustangs, are using turbos to make big HP. A turbo car is a lot softer off the launch meaning it's less likely to lose traction off the line. As the turbo spools up, building up the HP, the car is already moving. NOS can be the same way. Using a progressive controller, it can have a soft, low HP launch the ramp up the shot as the vehicle starts to move. Turbo and NOS cars then make low ET numbers as the power builds while they go down the track.

800+ HP made without a power adder will have more traction problems with a small tire than a big tire. I launch at 4500 rpm right where my engine makes maximum torque. I estimate my current engine combination is making around 750 pounds of torque at that rpm and launching with a 1.76 powerglide makes the launch a little bit softer than using a TH400.

 

A properly built turbo combination does not leave "soft" unless tuned to do so. I know plenty of turbo guys sitting at or just under full spool when on the t-brake at the line. Whether or not they use/can use full boost to get moving is another story.

A 1.2x 60' is a 1.2x 60ft. Doesn't matter how you hit it, "x" tire height takes "y" rotations to cover 60'. So, it takes "z" tire speed to account for that distance plus the slip rate(no tire in the world is w/o a slip rate, no matter tire size or suspension set-up). The slip rates do vary per compounding and set-up, but it still takes the same amount of power to move the same amount of weight 60' in the same amount of time.

Carb'd methanol responds the same as carb'd gas, given proper tuning/engine combination for each. Injection definitely "hits" harder, but again, methanol is no different than gas. - Overdriven roots blowers "hit" harder than any other combination, be it PA or NA.