How much HP do you really need for Autocross?

[rohrt]

I was taking notes on some of the top 1st Gen F body cars that compete in autocross racing and one happened to mention that there comes a point of diminished returns when it come to the HP you need to compete. Then I read were Kyle Tucker is competing with a simple 383 crate motor with a hot cam. I realize its a subjective question but wanted to hear what others feel that point is.

[rchaskin]

In the Second Gen, He runs a Mast 427" LS7 at around 675hp if I remember correctly.

There was a thread on this a while back.....

[GEARBOXGARAGE]

If I remember correctly, the DSE '65 Chevelle has the Hot Cammed 383. I believe there was a time when Stacey's First Gen had that motor, but upraded to LS power, and the 383 went to the '65.

HP is secondary to everything else. If you are to the point of running maximum consistent lap times, but the car is able to take more, then upgrade from there. Most guys these days run in the 500-700 HP range, depending on what level you want to compete at. a Hot Cammed 383 with good heads will easily be in the 450+ range, but I've seen Mustangs with HO 289's run strong lap times as well.

[Project92rs]

If you're just starting out, the question should be "how much horsepower can I handle". If you've been doing it long enough for the power of the car to be the limiting factor, then the question becomes how much power do you need to shave time off the runs. Never underestimate the driver experience factor when looking at the times the top cars are running.

[rohrt]

I'm looking at that from the opposite end. What is the least amount of power can a person get away with so the car can still be a jump in and drive anywhere and at the same time still keep the fun factor.

I was impressed that Kyle had a 383. (May have been an old article) but he wanted to put in a power plant that was a common swap that many of his customer would have and show how his parts worked over how much was done to the motor.

[GEARBOXGARAGE]

If you are looking at it from a budgetary "best bang for the buck" standpoint, never underestimate a mild 350. It'll will go a long way in getting satisfaction. You could always build a Hot Cammed 350, use quality heads and valvetrain components, and have plenty of fun with 400 HP. That's what I'm running now in my C10 with the Terminator EFI. I've been spending this summer getting geared up for next year's season. Granted the truck is a lot heavier than a First Gen F-body, but still plenty of power to move it along quickly.
Plus you'll already have a solid foundation, err, top-end, for putting in a stroker rotating assembly in the future if you and when you need more torque and you're ready to expand your budget.
Look into a driving class or two. (next on my to-do list). For the cost of a stroker kit, you could take a driving class and gain more for your lap times than what higher HP will get you.

[Project92rs]

I'm looking at that from the opposite end. What is the least amount of power can a person get away with so the car can still be a jump in and drive anywhere and at the same time still keep the fun factor.

In that case, we've had good times with a bone stock 1990 IROC convertible making a blistering 195rwhp at some events. Even came in second with it at a Super Chevy Autocross against a field full of V8 5th gens. Had some good times with the 88 GTA when it was still near stock with mid 200's hp and took home a few trophies in that trim. Since then we've modified the GTA to about double the power and done a lot of suspension work to keep up with driver improvements and expectations. Those lessons will get applied to the next project to start it at a higher level of preparation from day 1 and improve from there over time.

Fun at a lot of events isn't all about winning. Trophies gather dust. It's about who you get to hang out with between runs and when the runs are over. Those memories last forever.

You will have more fun with less power starting out than you will with a car that makes enough power to scare you. Engines aren't cheap but it's far easier to redo the engine after a few years to make more power than it is to repair or replace the car if the first build is more than the driver can safely handle.

[WallaceMFG]

My Chevelle has a relatively stock 350 in it and it is plenty of power for me to start off with. Even with the "low" hp my motor has, it is still enough to make the rear end slide out and is plenty of power to go have fun with. I'd rather have low HP than have a car the smokes the tires if you sneeze on the accelerator pedal haha

[hotrodalex]

My 350 is somewhere in the low-to-mid 300 horse range and it isn't a dog at events. Not a whole lot of time to take advantage of 700 hp on a tight course, so I think having a usable powerband + appropriate gearing is more important.

Not that I'd ever say no to a Mast 427...

[mike@sim-seats]

My 350 is somewhere in the low-to-mid 300 horse range and it isn't a dog at events. Not a whole lot of time to take advantage of 700 hp on a tight course, so I think having a usable powerband + appropriate gearing is more important.

Not that I'd ever say no to a Mast 427...

Appropriate gearing is key. I auto-x'd a 2002 camaro on a short course that I was able to do entirely in first gear. It kept the car "on the pipe" and felt great. Running the same course in 2nd gear was terrible and I wanted more power.

Also, lots and lots and lots of tire + quick steering.

[Nicks67GTO]

Assuming a capable driver I think its somewhat subjective to weight like any racing. I rode in Ryan Bucks 63 Chevy II and he's at around 500hp/500tq at the flywheel and that was like getting shot out of a cannon....but those cars weigh just about nothing and hes got it dialed in. He got 3rd in DSM at Good guys and won the Hotchkis cup over a C7ZO6 at Street Machine Nationals StPaul. With that said my 455 is a worn out turd that is dead at 4800 rpm and it did ok at both above events this summer. Both times I'm pretty sure the driver was the limiting factor....both times were really fun too. Are you wanting to auto x that firebird?

[dirty rick]

Someone said

"if you have enough power to leave black marks from one corner to the next,

you have enough power."

[nokones]

If anyone needs a perfect motor for autocrossing, I have a 89 Corvette L98 for sale with 363 Horsepower/392 pounds of torque at the wheels and the motor is cammed for autocrossing. The engine comes complete with AFR Alum heads, Comp Cam with rev kit, fuel injection (Lingenfelter Super Ram Box), DFI ECM Computer, Distributor, starter, and alum flywheel. The only thing that you will need is the water pump and the pullies. I'll let everything go for $4,000 and the motor only has 2,000 miles on it.

Let me know at [email protected] if you are interested.

[rohrt]

Assuming a capable driver I think its somewhat subjective to weight like any racing. I rode in Ryan Bucks 63 Chevy II and he's at around 500hp/500tq at the flywheel and that was like getting shot out of a cannon....but those cars weigh just about nothing and hes got it dialed in. He got 3rd in DSM at Good guys and won the Hotchkis cup over a C7ZO6 at Street Machine Nationals StPaul. With that said my 455 is a worn out turd that is dead at 4800 rpm and it did ok at both above events this summer. Both times I'm pretty sure the driver was the limiting factor....both times were really fun too. Are you wanting to auto x that firebird?

That is exactly what I'm talking about. That is a HP number that is easy to achieve and he obviously has a very well setup car.

I have a HT 68 Firebird that I was mostly thinking on for this. It could very well be the last car I ever build. In thinking what I want to do with it, just has me going in circles, I want to be able to travel the country and yet do some fun events. For most any event you build a purpose driven car but the whole point of pro-touring is do everything well is it not? The HT FB car has no motor and is mostly in pieces but has a very solid shell from southern california. It was a parts car for the convertible. If I put all the left over pieces together now it would be red front clip, white shell and blue 400 hood. I kind of like the idea of a Joe Dirt/Road kill Red white and blue car.

Here is circular thinking at work:
I'm having the inner turmoil of stay Pontiac or go LS? Do I go automatic or manual? Do manuals slow you down in a autocross? Would I get sick of shifting all the time? I would love a LS3 crate motor but do you go with the 525HP motor or better to stay with the baseline motor since it would be a 85% road touring car. It would take years to save up for LS swap or do I lower my wants and go with a 5.3? But then I'm back to an iron block. But I'm a Pontiac guy. I have a bunch or parts to throw together a 428. Put the FITechh carb on top and maybe add a TKO to the back. Still would be as light as a LS nor would I get the same MPG. Look a squirl!




I might auto x the convertible if I get some SFC on it, and if another event comes around. The stock seats and belts give me a little concern. They don't hold me in at all.

Its all your fault Nick, talking about how much fun the Des Moines Good guy show was;).

[nokones]

For autocrossing, you want low to mid-range torque. 380-480 pounds at the wheels is very adequate. This is accomplished with the right engine, cam, and fuel injection. Then you need to decide automatic or manual tranny. They both have pluses and minuses. The gearing is very important. If you go with an automatic, you will need the right torque converter that is designed for autocrossing, not drag racing. The torque converter needs to be designed with your CAM profile and the rear diff gear ratio in mind. Speaking of rear diff, you will need to select the right gear ratio. The right gear ratio will depend on your vehicle weight, tranny gear ratio, and the CAM profile. Essentially, you want to be able to get in the torque band immediately when you come off a turn at lower speeds and the torque needs to be manageable with your right foot. Too much torque will cause you to have a hand full of car or too little will make you doggie off the turns which will result in slower times.

Most autocross courses are designed with running in second gear for most of the course. Very seldom you will need to downshift to first and some faster courses may require you to shift into third. This will be true for both an automatic or manual tranny.

[parsonsj]

Fixed:

If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

[hotrodalex]

Manual shouldn't slow you down any, unless you find an autox course that has a big long straight followed by tight 1st gear corners. But that's just cruel. I usually start in 1st and go to 2nd if needed (many Goodguys courses don't require it), then leave it 2nd for the rest of the course. Guys with 450+ HP can start in 2nd and get off the line just as quick.

[rohrt]

For autocrossing, you want low to mid-range torque. 380-480 pounds at the wheels is very adequate. This is accomplished with the right engine, cam, and fuel injection. Then you need to decide automatic or manual tranny. They both have pluses and minuses. The gearing is very important. If you go with an automatic, you will need the right torque converter that is designed for autocrossing, not drag racing. The torque converter needs to be designed with your CAM profile and the rear diff gear ratio in mind. Speaking of rear diff, you will need to select the right gear ratio. The right gear ratio will depend on your vehicle weight, tranny gear ratio, and the CAM profile. Essentially, you want to be able to get in the torque band immediately when you come off a turn at lower speeds and the torque needs to be manageable with your right foot. Too much torque will cause you to have a hand full of car or too little will make you doggie off the turns which will result in slower times.

Most autocross courses are designed with running in second gear for most of the course. Very seldom you will need to downshift to first and some faster courses may require you to shift into third. This will be true for both an automatic or manual tranny.

Good info that answered several questions.

I assume there are different classes of auto crossing event? And different classes means different speeds? And different speeds means different rules and safety equipment needed?

[nokones]

In most organizations like SCCA, there are several levels of preparation that you can compete in. In each preparation category, there are several classes and depending on the modifications done to your car that will dictate which level you fit in and depending on the year make and model that will depend on which class in that category you will compete in.

For an example, the stock class now called Street, you are allowed a few modifications. The next category up is called Street Prepared and you are allowed a few more mods. The next level up is Prepared and you are allowed a lot more mods. The next level up is Modified and you are allowed a bunch more.

However, if you have a Pro-Touring Muscle Car, like a primo 69 Camaro with a killer LS motor you will not fit in any of the aforementioned categories. SCCA just came out with a new category called Classic American Muscle (CAM) and there are currently three classes within CAM. Essentially, the basic rules are the car must be an American production car, licensed and insured for the street. You are allowed to do any performance modification you want. You can even put a Chevrolet engine in a Mustang of you want. If you want a 1,000 horsepower motor, you can have one.

[IndyDave]

Good info that answered several questions.

I assume there are different classes of auto crossing event? And different classes means different speeds? And different speeds means different rules and safety equipment needed?

The short answer is yes, yes, and maybe. The best way to approach autocrossing is to get out and do it for a while before doing too much to the car. The biggest mistake people make is thinking they can't run until their car has X, Y, & Z parts. All you need is a car in good working order that can pass the most basic of tech inspections. Most clubs tech only focus on safety items in tech. Things checked usually include checking for loose wheels and bearings, tires not showing cords or other defects, missing lugs, a good brake pedal, acceptable steering, securely held down battery, positive return of the gas pedal, and no loose items in the car that could fly about and brain you. They should also look at your seat belt and make sure you have an approved helmet (if one is required).

Classing is up to you, again most clubs classing rules are policed by the competitors so ask for help with classing. Your best bet is to check the clubs classing rules to see where your car fits. In the case of SCCA, given what I can gather has been done, CAM is the best class but you might also fit in STX, or ESP. Do a little research. Starting out, worry less about where you fit and concentrate on getting as much seat time as possible. You'll learn what you and your car needs and wants instead of throwing a bunch of cash a go-goodies that won't help you a bit.

On how much hp? All the top autocrossers I know all do the same thing when developing a car. They start out good running basic engine and work on suspension, brakes, and chassis first. Then comes more power, as well as driveline improvements. In autocross you can have too much hp. Say you're running a class that requires street tires, you're only going to be to put so much power to the ground before the tires are overcome. While 700hp may be impressive, it's harder to handle in an autocross than the same car with 3-400 hp.