2012 Boss 302 qualifying?

[darreng505]

Hi,

After reading the AI rules, it seems my 2012 boss 302 violates the LBS/HP ratio. @ 444hp/3600lbs (3850 with me in it),

it's well short of the 4218 (444 * 9.5) ratio needed to qualify for this class. Is that right? Even with the balast, I don't

think the boss can achieve the weight needed. Does this mean no bosses can run this class? Thanks for any tips.

 

Darren

[tacovini]

Hi Darren,

Your Boss HP is the advertised rating at the flywheel and the weight you list is how heavy the car rolls off the showroom floor. (with the full interior and other do-dads).

The reality of the racecars is that we measure HP at the rear wheels, and that HP can also be detuned/restricted. In addition, the racecars are lightened as much as possible and it isn't uncommon to see the cars down to 3300-3600 lbs with driver.

 

Hope that helps and thanks for your interest in the series!

[UBR]

Hi Darren,

it isn't uncommon to see the cars down to 3300-3600 lbs with driver.

Some of us are under 3100, although not in S197 (new body style Mustang). We overbuild our motors and restrict them down to meet the AI rules. This gives us some room to "grow" if the rules change and helps the motors last under race conditions.

There are quite a few guys running the new 5.0 motors. I think with limited mods, the HP comes out right where you want it.

 

j

[Red Tornado]

The world challenge 49mm restrict or slides in to your tb and brings it in to the perfect range so no worries

[thonczarenko]

Then take it to the local Dynojet dyno and you will know what weight you need to get it to (with you in it of course). I think we are allowed up to 300lbs of ballast now.

[marshallmosty]

300 lbs of ballast is the current rule for 2012 (up from 150 in 2011). Restricting the motor at the airbox is the easiest way. Rehagen sells a restrictor that fits in the OEM airbox that drops it down to approx 345HP/345TQ...

 

With ABS in that car, and 345HP, you would be at 3278lb minimum.

[marshallmosty]

Hi Darren,

In addition, the racecars are lightened as much as possible and it isn't uncommon to see the cars down to 3300-3600 lbs with driver.

 

Todd,

Don't know how large your "driver" is, but I've had my AI FOX down to 2760 post race with me in it (170 at the time...).

 

Weight is just a number... What counts is how good ya look!

[thonczarenko]

Hi Darren,

In addition, the racecars are lightened as much as possible and it isn't uncommon to see the cars down to 3300-3600 lbs with driver.

 

Todd,

Don't know how large your "driver" is, but I've had my AI FOX down to 2760 post race with me in it (170 at the time...).

 

Weight is just a number... What counts is how good ya look!

 

Was that with the PVC roll cage? LOL! I'm over 250 with my gear on, but I look GOOOOOD! And also important is how you feel.....

 

I used to ride motorcycles with a girl who wore a shirt that said "If you think you feel good, you should feel me". Best shirt ever!

[marshallmosty]

Suprisingly enough that was with a NASA compliant 1 3/4" 0.120 wall cage. It was "pre aero", so the car has gained some weight in wings/splitters and is now 2910 with me in it... I've also put on 30 lbs in the last 7 years...

[thonczarenko]

And that's why I can't afford to do aero just yet. I struggle to meet the HP:Weight ratio, and 150+ pounds would hurt pretty bad.

[marshallmosty]

I've also added extra roll cage to beef up the car weight. I found that a 290HP AI car, even at 2700 lbs wouldn't compete with 360HP car at 3400 lbs...

[Ted J.]

Marshal,

 

i'm new here and building an a/i car and wondering if the heavier combination (3400#) is better than going with the lightweight combinations? My thoughts are lighter is better from all aspects from reiliability to wear and tear and hopefully competitivness. What do you feel your car lacks running the lightweight combination? I'm making my decisions very soon on which direction to go so any help would be appreciated.

[marshallmosty]

Woody,

I've run really light (2760 all the way up to 3200) in the current car. Light vs. Heavy really as advantages and disadvantages for each "idea". Lightweight is easier on tires and brakes, and allows you to divebomb in the braking zone and not worry as much about brake capacity. However, it's not a good idea for slow speed corners with a long straightaway afterwards, or large tracks with a bunch of straights that put you in 5th gear. The higher HP cars just destroy you there.

 

I've found a good combo for AI is somewhere around 3000-3200lbs. This gives a bit of the best of both worlds. You have to learn to manage your tires and brakes on longer races 30+ minutes, but the big HP guys don't pull away as bad.

 

Also, now that we have ABS HP/TQ splits, that also opens up another level of thought. I run the FR ABS unit in my FOX. Partly because I was the 2nd guy in the AI community to do so (Jay Andrews was the pioneer, to my knowledge). I like to fiddle with technology and try to adapt it to older stuff. 2012 ABS in a 1989 chassis fits that bill for me...

 

That's my .02

 

I'm sure everyone will weigh in on the "best" combo... At the end, it's personal preference.

[Ted J.]

Thanks Marshall,

 

My next question is how (if possible) can engine dyno numbers be converted (roughly) to dynojet numbers? My local engine dyno numbers, compared to a mustang chasis dyno was roughly 100 hp loss from the crank to the rear wheels on two differnet cars. I have no experience with a dynojet (soon will) but as I put an engine combination together I need a ball park estimate of losses from crank hp numbers to dynojet numbers. I've heard dyno jet losses are much less. Roughly 40 hp give or take is what i've been told? I know there are many variables to this question but just looking for ball park losses. 40 hp? 60hp? I know driveline losses can be decreased but just looking for rough numbers.

 

Thanks for the help.

[Racer91m]

Woody,

 

I ran across the scales at 3600 pounds after the Saturday race. Your decision is very much track dependent. Mid Ohio favors Higher power. Miller will reward lower weight cars. Build it light with a bunch of power. Choke it down for Miller and weight it up for Mid Ohio. Lots of variables to play with, but the most important thing is to make everything work together in harmony. A well rounded nad developed car is best...

[UBR]

Woody,

 

There is no pure calculation to convert bhp (crank) to RWHP (wheels). There are vague guestimates between 15-30% reduction from BHP to RWHP. There are a lot of factors that determine how much loss you get through the drive train. Best way is to load it up and get it to the dyno.

 

We suscribe to the same practice as Dean. Overbuild and de-tune as needed. We have FRPP Boss blocks (4 bolt main 302 based) stroked up to 347 in both of our cars. 1 runs a carb, the other fuel injection. Both motors make 400-420 HP/ 420-450 Tq unrestricted. We use timing, fuel curves and restrictor plates to get them down to the HP range we need (348/370 for the Fox. About 20 more for our S197- it's a pig) Restricting is fairly easy when you're on the dyno. There are several plat systems our there. We have a machine shop make the plates for our FI motor. Square plate infront of the throttle body with different size holes in the middle. We get a little fancier with timing and fuel to maximize the power curves and make sure we have throttle resonse on the carb'd motor. But plates do a good job hitting a specific number.

 

j

[Ted J.]

Thank you guys. It really helps with the decision.