HP Influenced by Stagger & Tire Pressure

[dynoman14]

Got asked by someone in another thread to post info on this;
About 50% of a race vehicles energy output is consumed by friction and dissipated as heat...
Although you might never have thought about it the Cf of a race car has a large factor involved in the tires...

Back about 30 years ago I was a top level race bike builder for Bikeways of Tucker and I built some of the most expensive bikes and wheels in the country $10,000+ for bikes and $1000-$2500 for wheelsets. Jobst Brandt was one of the foremost wheel engineers in the world for a long time and his book is one of the best on how to get max HP out of a set of spoke laced wheels. My fastest and best racers ran Italian Silk tires and they were pumped up to 125-150psi. That being said...

Tire pressure in race tires can increase RWHP up to 2HP per 1# pressure increase, why do you think they have maximum tire pressure rules for CUP races??? Surely not for safety.

At Daytona and Talladega we had a couple really goo tricks for running +5-10psi and still passing tech. Learning how to use inner liners to your inner liners to your advantage you can pick up 1/2 second a lap in Qualifying.

Tire Stagger is the same deal, the more you run the more drag you put on the car up the straight. The key is to get maximum turn in the corner with less stagger as it is as much as +/-10HP per inch... on both pavement and dirt.

As to how you test it on the chassis dyno you just get an air gauge and raise the air pressure in both rear tires as to not change stagger.

As for stagger you just change the LR smaller or RR bigger and do it an inch at a time and see what happens.

I have done this testing at least 50 times for teams and customers over the past 25 years and most folks don't believe the results til they try it at the track and see the results.

Another post that relates to this is the one on the use of locking diffs on dirt. If you know what you are doing there is 25RWHP in this system.

Your chassis dyno needs to be run in uncorrected mode, with no curve smoothing and has to be accurate to less than 1% to produce credible numbers. This eliminates about 99% of the chassis dynos out there but you will still see some changes hopefully.

A lot of folks don't see the stuff I do because the repeatability and accuracy of their instrumentation, software and inertia wheel is not capable of showing A/B/A repeatability to less than 1%.

[Egoracing]

"At Daytona and Talladega we had a couple really goo tricks for running +5-10psi and still passing tech. Learning how to use inner liners to your inner liners to your advantage you can pick up 1/2 second a lap in Qualifying."

Dyno dummy Nascar mounts the tires and has for MANY years, there is NO way you were getting a secondary inner liner into the combo. Besides the fact that the inner liner has ZERO effect on the tire presssure the same way that the steel wheel has no effect and the linners are already run at a higher pressure than the tire is. Also Nascar mandates the pressure on the inner liner for safety and measures it.

[zeroracing]

Increasing air pressure in the tire would reduce drag because it will decrease contact patch area. Which will lower both longitudinal and lateral grip. This trick would only help if you already are not driving on the edge of your cars lateral capacity, and do not have enough motor to spin the tires or enough brakes to lock them up. If your not driving at the limit of the car before, then what is more HP at the rear wheels going to do, give you more potential car to waste?

I have never ran a crate car, if they dont have enough power to even spin a tire then that would make for one boring race car... better put an alarm in the car to keep the driver awake.

[Matt49]

Decreasing air pressure in the tire would reduce drag because it will decrease contact patch area. Which will lower both longitudinal and lateral grip. This trick would only help if you already are not driving on the edge of your cars lateral capacity, and do not have enough motor to spin the tires or enough brakes to lock them up. If your not driving at the limit of the car before, then what is more HP at the rear wheels going to do, give you more potential car to waste?

I have never ran a crate car, if they dont have enough power to even spin a tire then that would make for one boring race car... better put an alarm in the car to keep the driver awake.

Decreasing the air pressure in a tire INCREASES the contact patch area.
Less pounds per square inch of pressure inside the tire means more square inches in contact with the ground is needed to support the same weight.
This is of course as long as it isn't riding on the rim. Then it's the wheel holding the car up and not the air in the tire.

What dynoman seems to fail to understand is that oval track cars spend the majority of their time TURNING, accelerating, decelerating, or some combination of these.

We aren't drag racing and an extra 5 HP at the rear wheels has never won an oval track race.

[zeroracing]

That was a typo, meant to say Increasing Pressure. One of those thinking faster than typing.

[racer69]

Stagger

I can't say for other tire brands but Hoosiers never ever grow the same with x amount of pressure! Each set we buy is a roll of the dice to get what we need. At times we have to go back and swap out a tire because its so far off. Luckily Baum's takes care of us there.

[dynoman14]

Last time I checked Drag cars don't run stagger...

I was referring to working with Oval track teams on dirt and pavement...

Just a short time back most dirt folks did not have a clue about bump stops, 5th coil binders, shock cushions and all the rest of the stuff from pavement racing.

If you do have a brain and you are able to discern what I posted you might learn something about your race car and how to free up some power. As there is a certain range for tire pressure and from what I have seen on lefts it is up to +/- 5# as well as 2-3# on rights there is significant power gains to run the higher pressure. I have seen dirt cars run 2"-7" tire stagger.

Why such a large difference??? I am told it is to get the car loose enough to turn??? Wonder how them guys running 2-3" get their cars to turn???

Depending on tire size, wheel width and tire loading the tire contact patch can sometimes increase with an increase in pressure. Working with tire engineers to determine the loads tires will take can greatly increase your ability to hook up a tire, while reducing the Cd of the tire.

As a former ARCA owner I was involved in 50+ tire tests for CUP teams as they were limited on testing and would SUB out the work and pay for all testing expenses to certain teams that purchased cars and engines from them. They still do it, rules don't state you can't test and ARCA car with Goodyear rubber in a private test session.

ego,
Inner liners as well as tires usually have a range of pressure allowed +/- 5#. If you know what you are doing you can get significant advantages with how you load your tires and what you use. That is one thing that NASCAR does not have the ability to check yet, trust me I know some very smart tire specialists and have worked closely with them on what goes into their tire filling cans.

As far as inner liner pressure affecting the outer air cushion you might want to think of it in terms of variable Spring Rate of the tire. If you are such a genius you might understand how that might effect the Cf and Cd of a tire. I think some of you dirt geniuses have started copying the Pavement Late Model trend of stacking springs with different rates to achieve greater tire grip. Seems like differential loading of the tire itself might achieve a similar result if you understood what I was talking about to begin with.

You can also control the rate of growth of the tire by the gases you use to fill your tires, if nitrogen is good to stabilize pressures wonder what gas might allow you to grow a tire quick if you need it?

Since you are such an expert, what could you coat the inside of a fuel can with to jack up the O2 content of the fuel. I designed and built a coating that I use on intake manifolds, fuel cans, fuel tanks and bladders fuel lines etc. just cause you don't have a clue about it, don't mean it don't exist.

[dirty white boy]

an you already sold the preparatory rights to the special tire dyno you designed to test these theory's and is leagly bound not to discuss such information any further.....and you lernt such theory's while on mars,..setting up surdi machines for aliens to use on there U.F.O.'s,.during the time you partyed with captin kerk an elvis,.........some body call the orderly's,...tell'um straight jacket stat,..an prepare the padded cell.....

[zeroracing]

Very little of our grip is generated by actual Cf, primarily we develop grip by mechanical keying and deformation. Most surfaces are too irregular to utilize full potential of Cf only, short of a glass plate.

Since we're having a quiz, why do wider tires generate more traction than narrow?

Note: I typically use very little stagger, due to modified habits and tend to drive straighter.

Final note, bump stops and other pavement ideas have also become more common as our track surface has tended to become smoother. The recent trend for tracks has been slick and smooth, before was heavy and rough. As we see dry tracks we can try more things that require a stable platform.

[Egoracing]

A secondary spring would only work IF it were touching the first spring at some point. DO it on an inner liner and the tire will not last and the friction would raise pressure until failure or no more friction was present. #2 You said "use inner liners to your inner liners". Please explain how you got them into the tires, where the 3rd valve stem was and how you got them back out with out Nascar busting you. They mount and take back the tires, Watch the races, they take the tires off the car and back to the trailer to get the tires pulled. Watched year after year at Daytona standing in the garage.

[C10]

Hell we were running bumps on dirt in 96.

[Matt49]

Dyno I know you think you know everything here amongst us dirt boys since you had so much success as a "big time" ARCA owner. How many races did you get a car to finish again? Keep your day-trading job.
Anyway, us boys on dirt spend 60-80% of the time (not DISTANCE...but TIME) TURNING. And we figured out a long time ago that what you lose/scrub on the straights due to stagger can be more than made up for in the turns which is where everybody is searching for traction anyway.
If you're running big pavement tracks with long straights where the driver can take a nap like most those snooze-fest ARCA races you could barely qualify for, you might have something...but you're barking up the wrong tree here and you're quite frankly outsmarted. Quit making a fool of yourself.
As far as how to get a car to take tight turns with just 2" of stagger...I think the people you're pretending to be smarter than (including myself) know just how to do that with a 4-bar car but I'd prefer not share it with you or anybody else that might be paying attention. You'll be claiming you invented it next week.
And what are you talking about with this "just a short time back dirt guys didn't know about bump stops"? Guys have been running them ever since LR spring behind setups became popular (over a decade ago). Do you know what that is or do you need it explained to you?

[MM90]

The special coating that you invented. Is that the same thing that Michael Waltrip got caught with at Daytona a few years ago?

[stockcar5]

I just got done adding 50 extra lbs of air to the rear tires on my truck. went from 50 to 100. went out and test drove it...i could really feel the extra 100hp from the additional 50lbs of air! It really works!!

[ford396]

MM90, Waltrip got caught with ACES lV didn't he? At least this is what I believe it to be.

Bob