Opinion: Small motors more or less consistent than big motors?

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LXguy

LXguy

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Hey All:

Which do you think would be more consistent in a bracket race, index race environment?

a 318 or a 408? or do you think there's any difference?

Say ET range is the same. 11.70 - 12.00

Thanks

Steve
 
i don't think size matters here, although some places it does matter. to be consistent you have to have your motor tuned correctly. large slicks, the biggest you can run, 14x32's etc. you have to leave at the same rpm and shift at the same rpm every time. you also need plenty of seat time, did a mention plenty of seat time to do all this.
 
From personal experience and talking to others racing in the Stock class, it appears that the more HP a car has, the more consistent it is. Bigger engines tend to naturally have more HP and torque. But other factors are carb size and other performance modifications. Properly tuned and hooking, the same engine with a 4 barrel will be more consistent than a 2 barrel. Dialing from one day to different conditions during the next day is more difficult for slower cars. There does "appear" to be a few exceptions to the rule as I've seen some consistent slow combos.

In a nutshell, weather (temperatures, humidity, barameter, wind, etc.) affects lower performance combinations more than higher performance combos.

One, however, can sometimes learn the quirks and patterns a lower performance combo has and dial accordingly.
 
Are you asking about torque (408) vs. RPM (318)?

If you need to turn more RPM, youll probably need a higher stalling converter. To my feeble mind that in itself might make launch a little more tricky to get consistent.
 
Locomotion said:
From personal experience and talking to others racing in the Stock class, it appears that the more HP a car has, the more consistent it is.
Click to expand...

I can't believe I didn't think of this! It makes a lot of sense.

Please ignore the actual numbers in the following example in favor of the point I'm trying to make.

It takes, say 3-5 additional rwhp across the rpm range to run a 13.20 instead of a 13.30. Less if you're slower than that.

Of course, the weather, or a very slight change in fuel enrichment or engine temp at the starting line or a zillion other things can make a 3-5 rwhp difference, throwing your dial off by a whole tenth.

However, 3-5 rwhp only makes changes in the hundredths or thousandths column when you're running 10.30s or .20s.

Assuming you can hook the faster car consistently, the little stuff will be a lot less likely to sneak up on you.

Maybe now I understand why guys actually spend a lot of money to go faster in a bracket car. LOL.
 
I agree with Locomotion's assertation to a point. When a car starts to have gobs of HP, it can become very unpredictable sometimes. Although I have not raced or gone to the strip in a lot of years, when I did, we went EVERY SINGLE weekend for probably five or six years. I think you can pick consistant cars out more by class than by engine size. Bracket cars that run in the 14.00-12.50 range were generally the most consistant hands down. Whether this holds true anywhere else, I don't know But at Warner Robins drag strip in the late 70s and all through the 80s it was certainly true. My '71 360 dart used to run 13.65-13.70 EVERY time and all I did was a burnout and stage the car and footbrake it in drive to leave and bend the floorboard with the gas pedal. That car rarely lost a street race to cars much quicker than it was. Most street races occur within 1/8 mile and a good consistant car is TOUGH to get out in front of that early. It's been "MY" experience (yours may vary) that the engine doesn't make much difference. It's all about how the CAR is set up. Course I couldda pulled that near stock 360 out, slammed in a full tilt 440 and slowed down cause I wouldda had to re tune the CAR to the engine. But that's been my experience with it.
 
I'll comment from a Stock Eliminator viewpoint, as Locomotion did.
A good friend, who has sinced passed away, ran a 273 2bbl in U/SA. Weather changes were it's bugaboo. But, as Locomotion mentioned, he learned it's quirks, and well enough to be number 5 in national points one year. He also ran a few 440 Six Pack cars in C and D/SA. One of which was 1/2 mine. :) They were much more predictable, less affected by air changes. Our car would run within a couple hundreths on a given afternoon with fairly stable air.
I've heard that an air/fuel ratio that's a tad on the rich side, may be a touch slower, but will be more consistent.
I wonder how the computer/fuel injection cars fare? Meaning, do they compensate automatically, or is their computer modified so that dial changes are needed?
 
I know most people were disconnectin the MAF runnin at the strip years ago. Made um run faster. I don't much more than that because I've never raced with a computer. All I've ever done is computer diagnosis on vehicles regarding computers.
 
Just my .02. Suspension can play just as big a role as the motor and driver as far as consistency is concrned...
 
In my experience EFI cars are generally very consistent, especially OBDII stuff. Its constantly monitoring and correcting for air temp and pressure, as well as engine temp.

Of course, FWD can make a car very inconsistent, and drive by wire can make cutting a good light impossible. I'll bet an automatic V6 Mustang straight from the factory with a sticky tire would be murderously effective, if you had a model that was pre drive by wire (04 or earlier).

Also of course this contravenes the faster is better theory, but the modern EFI stuff definitely throws a confusion factor into it.

I'm not sure how an EFI car could even run if the MAF was disconnected? It would be running on idle fuel trims at all throttle positions.

Did you mean the MAP sensor?
 
The carb is the biggest thing that is effected by the weather.

Running the carb on the lean side will make the car more consistent.
A carb that runs on the rich side, tends to slow down the car as the air temp increases and pick up to much(faster et) as the temp decreases.
Leaner is way better.

Larger cubic inch engines make the carb work more efficiently.
 
LXguy said:
In my experience EFI cars are generally very consistent, especially OBDII stuff. Its constantly monitoring and correcting for air temp and pressure, as well as engine temp.

Of course, FWD can make a car very inconsistent, and drive by wire can make cutting a good light impossible. I'll bet an automatic V6 Mustang straight from the factory with a sticky tire would be murderously effective, if you had a model that was pre drive by wire (04 or earlier).

Also of course this contravenes the faster is better theory, but the modern EFI stuff definitely throws a confusion factor into it.

I'm not sure how an EFI car could even run if the MAF was disconnected? It would be running on idle fuel trims at all throttle positions.

Did you mean the MAP sensor?
Click to expand...

No. Mass Air flow. All the Late 80s and early 90s corvettes and camaros would disconnect them. Then ran like crap at idle but faster racing.
 
Well, by choice I'm not very conversant with GM stuff. But, I do happen to know for sure that early 90s (at the very least 91 and 92) Camaros/vettes were Speed Density and had no MAF sensor. If you disconnected the MAP sensor on one of these it was basically a vacuum leak, so I could see how that would be faster if the factory mix was rich, as it usually was back then.

I helped a couple of friends that had those cars back in the day. They were constantly getting their lunch eaten by 5.0 Mustangs and turbo buicks.

I don't know about previous to that (thank god). However, it would be just like the General to go to MAF, back to speed density and back to MAF again.

Steve
 
It stands to reason, that if ET was the same, the bigger engine would be better. To get the same distance a bigger engine has to fire fewer times; less work, less variation, more consistant.
Pretty simple if you look at it that way.
Talking to some Pro racers a few years ago, and they were telling me that, in order to make a complete 1/4 mile pass, a Top Fuel engine had to fire 853 times, from start to finish. Any more or less had to be decipher, to determine what went wrong.
 
I would go with the more cubes the better idea, the motor needs a little bit of a load on it, they aint happy just freewheeling. My 440 would run the same number from the first time trial to the final round unless they was a huge weather change comin, smart bracket racers have their own weather station to keep an eye on. I ran two cars, a 67 cuda with 440, transbrake, throttle stop, 4 stage timer/delay box and a 23T roadster with a 350 chevy, transbrake, throttle stop, 4 stage timer/delay box in it also, the wife would drive one and me the other, the smaller engine was harder to make consistant in the 1/8th but was deadly in the 1/4. Suspension is also critical for consistancy as is doing the same exact thing time after time, if one thing varys then something is gonna change and its usually the ET.

Man I love bracket racing, it gives an amature an even playing feild against a professional big money car in the other lane.......all comes down to your skills.
 
StrokerScamp said:
I agree with Locomotion's assertation to a point. When a car starts to have gobs of HP, it can become very unpredictable sometimes. Although I have not raced or gone to the strip in a lot of years, when I did, we went EVERY SINGLE weekend for probably five or six years. I think you can pick consistant cars out more by class than by engine size. Bracket cars that run in the 14.00-12.50 range were generally the most consistant hands down. Whether this holds true anywhere else, I don't know But at Warner Robins drag strip in the late 70s and all through the 80s it was certainly true. My '71 360 dart used to run 13.65-13.70 EVERY time and all I did was a burnout and stage the car and footbrake it in drive to leave and bend the floorboard with the gas pedal. That car rarely lost a street race to cars much quicker than it was. Most street races occur within 1/8 mile and a good consistant car is TOUGH to get out in front of that early. It's been "MY" experience (yours may vary) that the engine doesn't make much difference. It's all about how the CAR is set up. Course I couldda pulled that near stock 360 out, slammed in a full tilt 440 and slowed down cause I wouldda had to re tune the CAR to the engine. But that's been my experience with it.
Click to expand...
Stroker knows.He use to race a Edsel back in the 50s.Aheh aheh aheh. Sorry buddy I couldnt resist.=P~
 
Basically overbuild the motor and then detune for your class is the message Im seeing.
 
horsehead said:
Stroker knows.He use to race a Edsel back in the 50s.Aheh aheh aheh. Sorry buddy I couldnt resist.=P~
Click to expand...

LMAO. I ain't that old. besides, I can't stand Edsels.
 
needsaresto said:
Basically overbuild the motor and then detune for your class is the message Im seeing.
Click to expand...
Yes for bracket racing you want it built strong to last pass after pass after pass, speed is not the name of the game so its best to go with heavier components, rods, pistons, pushrods etc etc. Let the cubic inches work for you.
 
So many variables to consider to answer this...Being able to cut a light and drive the stripe goes a long way, but the car needs to show some signs of consistency. 3 sportsman track championships in 3 years at two different tracks later, I'd like to think that I proved that a slow car with a small motor can indeed be successful (17-second, 78 MPH).
 
Right! Good quality components will not only make the engine stronger but also give it lasting strength.
 
casey70dartreed said:
So many variables to consider to answer this...Being able to cut a light and drive the stripe goes a long way, but the car needs to show some signs of consistency. 3 sportsman track championships in 3 years at two different tracks later, I'd like to think that I proved that a slow car with a small motor can indeed be successful (17-second, 78 MPH).
Click to expand...

In a nutshell casey.Slow and steady wins the race and it is a whole lot cheaper than chasing the latest go fast goodies.Congrats on your wins.
 
i like being the faster car as the opponent has the first chance of redlighting. These are freebies.
 
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