Just wanted to share the progression of my 07 GT automatic coupe after various mods, and how those mods helped at the drag strip....

I never ran my car at the track bone stock, but most 05-09 GT automatic coupes tend to average 13.9's @ 99 mph in the 1/4 mile.

My first mod was 4.10 gears, which required a handheld tuner to correct the speedometer. So, I set that tuner (DiabloSport Predator) to their canned 92 octane tune and ran 13.4's @ 102+ on the factory tires.

The next mod was a bigger stall converter (from Fuddle Racing). It flashed to 3,800 rpm's so the launch was much better, but tough on the stock tires (I really cooked the stock tires before lining up to melt them into submission). Car was running 13.2's @ 103+ when I could get traction. 60' times improved dramatically with the converter (1.8's vs 2.1's with the factory converter).

Drag radials made staging and launching easier and the runs got very consistent: 13.1's @ 103+.

Vortech V2 S-trim supercharger (non-intercooled) took some learning and tuning, and the stall converter now flashes to 4,800 rpm's with the extra power, but conservatively dyno tuned (daily driver) it intially ran 12.6's @ 110+

Swapped spark plugs for colder/copper FRPP 3V0 spark plugs, plus I added an oil seperator and PCV valve to keep oil vapor out of the intake tract. Had more dyno tuning done to adjust shift points & firmness, converter lock-up, etc. Car ran 12.3's @ 111+

Replaced the factory catalytic converters and H-pipe with an SLP X-pipe with high flow cats. Car now runs 12.1's @ 113+.

Always looking for that next mod, and am now very close to the 11's. I don't want to add a roll cage (required when you run 11.49 or quicker), so once I'm in the mid to high 11's, I'm done modding this car. This is a daily driver, so it has to stay streetable. Water-methanol injection is likely my next & final mod, or perhaps a set of SLP long-tube headers to match their X-pipe. Either should get me into the high 11's.

 

Good to know, planning on doing these mods as well to my auto.

 

I have the ceramic SLP long tubes, they'll definitely push that setup into the 11's, if you have the fuel to back it up. They made much more power then my hi-flow X did. If a canned tune for the LT's won't do it, then a dyno tune will be exactly what you're looking for! Nice setup btw!

 

Brian that is awesome work, congrats!

Edit: What suspension mods?

 

Our automatics are so much better with an aftermarket stall converter (faster, better driveability, etc.). Definitely make that one of your mods and you'll love your GT more than ever.

 

Thanks for the feedback. The car was custom dyno tuned after the blower went on, and has been dyno tuned several times since for various small changes I've requested (converter lock-up, shift points, redline, shift firmness, etc.). I'm really leaning toward those SLP long tubes like you have, as I know I'm really corking up all that boost through the stock exhaust.

 

Yeh once I save my money back up that is my next purchase.

 

Thanks! It's so cool to just stick the car in drive at the track and run super consistent with the automatic. I can only take credit for choosing the right combo of parts and heating the drag radials properly with each run.

The suspension is 100% factory stock. I see lots of guys with LCA's to control hop at the track, but I've never had that issue. Maybe the automatic transmission helps smooth the power delivery so it doesn't hop??? My 60' times aren't that great for a car that's so close to running 11's (best of 1.797 with most in the 1.80 to 1.85 range), so maybe some suspension goodies could help?

 

Add a 'cooler and a lil smaller pulley and run that 11.7 and call it a day.

 

Yea with that meth injec or cooler I could def see it being in the 11's easy. Good luck and keep it up!

 

Suspension, longtubes, cams. Whichever order you please, but i'm a suspension fan. Some people tend to say the car "felt" okay before it went into a wall or something.

 

I'd love to do cams. Something with a good lope at idle, while maximizing my powerband (4800-6800 rpm's). However, I have to pass emission inspections, so which cams to consider? And, what suspension pieces really work on our cars best for launching at the dragstrip?

 

On my 06 I just used Steeda LCAs, Steeda rear sport springs (stocks up front) and CHE relocation brackets. With those three things and M&H 325s on 17x9 wheel, I could dump the clutch at 4500rpm and straight hook. This was with 450/450 at the tires and 11.7s slips.

 

Congrats and good to hear you are so close to 11's. I just ordered the V3 non cooled package from brenspeed and have LT's and O/R H, I will let you know how my times turn out. Maybe it will help your desision.

 

You'll love the V3. Even non-cooled they make great power for the money. And you can't go wrong with Brenspeed (although I bought my V2 from Stillen Motorsports). And, yes, I'd love to hear how fast yours goes after the V3 goes on. I really think LT's will work wonders by reducing boost, but increasing efficiency.

After talking more with my wife about the pro's and cons (plus the cost) of LT's vs water-methanol injection, we're leaning more toward the water-methanol injection. In a perfect world, I'd do both, but I've got other financial obligations (i.e. kids in college, mortgage, vacations, etc.) to juggle with mod money.

 

Maybe a coast drive shaft along with lca's/springs

 

I just wish the 1-pc driveshafts out there didn't cost so much. I've wanted one for a long time, but they are a lot of money per rwhp that is set free.

 

Or at least lca's and springs.. LCA's were great when I was blown!

 

Before you added the supercharger, what worked best for your launch with the stall converter and drag radials? Another words what rpm etc etc. Thx

 

The converter companies typically advise launching from idle to get the hardest hit, but that didn't provide my best ET's. I found that loading the converter a bit with around 2500 rpm's against the brake worked best before the blower (I load about 1500-2000 rpm's now with the blower).

On a side note, I you launch from idle, I suggest that you hammer it on the second to last amber of the christmas tree. If you load some rpm's against the brakes, I suggest leaving on the last amber light. These should get you close to a perfect reaction time that you can adjust slightly depending on your car's on characteristics, roll out, staging techniques, etc.