Consistency
 

Hey guys I know this is the age old discussion but besides the normal tire psi, weather, log book etc what do you find that affects consistency of a car. Unfortunately I have literally tried everything and used every variable to find out what affects my car on race day with no success. I know y?all don?t wanna give away any secrets but any insight into direction would be appreciated. I?m literally down to deciding wether the air in the engine compartment is causing issues

Re: Consistency
 

With my big heavy wagon, wind is a huge factor as well as time between runs. My car is a tenth quicker on a hot lap and a change from a tail wind to a head wind can be worth as much as a tenth too.

Re: Consistency
 

Everything on car can be great, but without good seal, rings and valves and good balancing +/- 1/2 gram is my tolerance.
a good tune up is crucial too.
A good flat and wide HP and TQ(especially tq) curve make it easier
without those you will never get deadly consistency.

Re: Consistency
 

Without knowing more about your combo it is hard to tell what might be causing your issue with inconsistency. Heavy cars with small or low hp combo is much harder to make consistent. wind speed and direction for sure. Humidity and baro as well.

Re: Consistency
 

Don't forget the temperature of your fluids (oil, trans, etc.). My car is good for .04-.05 just from the oil being really hot. When you're in the later rounds, you've got to remember to account for that.

Re: Consistency
 

So I run a 402 375 horse combo in a 70 chevelle weight is usually 3810 my minimum is 3635. It?s got a Tilburg motor with a Sepanek metric 200. I try to keep all my fluids everything the same temperature before the run so on and so forth that?s why I?m trying to figure out if it?s a fueling issue through the carburetor or something that I?m not looking at correctly.

Re: Consistency
 

Sounds like you have some good equipment there. What kind of weather station and prediction software are you using to figure your dial in? I would try to get the weight down closer to your min weight. That will help some with consistency. I use an oil pan heater to keep the oil temp consistent between rounds

Re: Consistency
 

Nick, what I would do is go to a track rental and try to make 3-4 runs within 2 hours, don?t make any changes and see if the car repeats. This will take the weather factor out of the picture, but watch the wind. If the car repeats the car is good, probably a fuel or carb issue. If it?s changing run to run, see where the inconsistency is. 60? could be suspension, mph could be fuel. A good trans and carb can make all the difference. I?ve have ones that just won?t do the same thing twice. We expect incredible things out of our cars. .02 of a second is so little but so important.

Re: Consistency
 

That?s the plan and my 60? are within a thousandth. I do think I was fighting front springs which are changed. I try to be 100% consistent and deliberate with everything I do. But I?ve read a lot on the air inside the engine compartment being hotter then ambient will also play games with it. Luckily dad has the factor sealed cowl air cleaner that seals to the hood I?m gonna try that see if there is any truth to it

Re: Consistency
 

So I have pan heaters for trans and motor. I have a race air cloud with their race base software. I definitely do not cheap out on things. I try to buy the best of the best as long as I can afford it. I just put a grid in it to help slow it down because at minimum I?d do more harm then good due to the old ahfs

Re: Consistency
 

Inconsistencies can happen other than your 60's, as you probably know. I would start by looking at your split times down track.

1700/STY/781L :)

Re: Consistency
 

Some cars with oem hood scoops do not get enough air. Have you tried bare carb or air cleaner base only? What you may lose to heat is offset by more airflow.

Re: Consistency
 

Some combinations - low compression, small cubes, heads, big, heavy, etc - are just effected more by weather changes, humidity, wind, and plenty of other variables.

If it 60's consistently, and you keep up with maintenance, keeping up with the conditions and knowing how the car reacts to them, is critical.

My car - small cubes, low compression - would be killed by humidity, or helped by a lack of it, and the weather station and software wouldn't adjust for it. Some fudge factoring was needed to compensate.

Re: Consistency
 

I used to bracket race with a grid. Found car was more consistent running with the proper timing and at peak power than pulling timing and slowing car down. Now if you're using the ARC module dot to dot that's a different story.

Tom Flowers
E/SA 3860