Re: 2015 Mustang Ecoboost K/SA?
 

2015 Ford Mustang Ecoboost Auto on craigslist Portland Oregon for $17,500 if interested?

Re: 2015 Mustang Ecoboost K/SA?
 

I would use the stronger half shafts regardless. Especially using slicks and shocking the rear end at the launch. With the stiffer gear and it shifting into over drive I would think the 4.09 gear should work fine.

Re: 2015 Mustang Ecoboost K/SA?
 

If you were going to switch to a C4, then the 4.09 might be needed, but if you're using the stock 6R80 transmission, I'd gear it to go through in 4th and leave it.

The 6R80 transmission has a 4.17 first gear. If you combine that with a 4.09 ring & pinion, that would give you a launch ratio equivalent to running a C4 with a 6.50 rear gear. I just don't think that's necessary for an engine that makes almost all of it's torque by about 2,500 rpm.

The calculations I ran, had the car going through in 4th gear, which is 1.14. 5th gear is .87, and 6th gear is .69. This engine makes so much torque and has such a wide powerband, with a horsepower peak at a relatively low 5,500 rpm, I don't think it would need to use that many gears to get down the quarter mile efficiently.

With a 30" tire, a 3.73 ring & pinion, and a 1.14 4th gear, the car would do just about 115 mph at 5,500 rpm through the lights.

With a 28" tire and the stock Performance Package 3.55 rear end gears, it would do 113 mph at 5,500 rpm in 4th.

With a 28" tire and the stock non Performance Package 3.31 rear end gears, it would do about 115 mph at about 5,300 rpm in 4th.

I'd be tempted to try it with a 28" tire and the stock gearing.

Re: 2015 Mustang Ecoboost K/SA?
 

Earlier in this thread, there is a video of a stock-turbo stock-engine street Mustang Ecoboost running an 11.03 at 122 mph, on the stock axles.

If you can get a K/SA four-cylinder Mustang into the 10s, then yes, the rulebook will require you to run aftermarket axles. But until that point, I think that $2,000 would be better spent elsewhere, in my humble opinion. :)

Re: 2015 Mustang Ecoboost K/SA?
 

Have you bought a Mustang Ecoboost yet or did you check on the one I posted for you on craigslist because you will not find one any cheaper?Just Saying.

Re: 2015 Mustang Ecoboost K/SA?
 

I never heard of this 15% rule before this thread, where is it published?

So would a MY2008 car get the 15% reduction? There's a certain Pontiac Solstice/Saturn Sky combo that Billy Nees likes a lot that the rule may apply to.

They did make a few Pontiacs & Saturns in 2009, but they're not in the Guide. If they were to be added to the Guide, would they get that 15% reduction?

Pontiac made a G8 GXP with a 400HP LS3 & a stick in 2009 that's not in the guide, which would be pretty cool also!

Re: 2015 Mustang Ecoboost K/SA?
 

Kyle;

The 15 % reduction on combos already listed in the guides never went into effect.

Jesse tried. He had a meeting with NHRA but Glendora did not go for the idea of re-factoring existing 1996 and later production line ( VIN )combos.

However, I do believe his meeting set the foundation for the current 85/85 deal for all new combos listing in the guide this year (and beyond)

Re: 2015 Mustang Ecoboost K/SA?
 

Thanks for the info!