07 GT automatic: 1/4 mile ET improvements after various mods...

[Five Oh Brian]

This seems like a very tech-savvy crowd here, so thought I would 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 (give or take a little).

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.

 

[08nastygt]

Nice little write up, how much power is your car putting out with the vortech? I thought you would have gained more when you put the DR's on your car.

 

[Mick Mach]

you said the converter flashes to 3800 but what rpm are you at when staged? I have been anywhere from 1200 to 2000rpm and my 60 ft is always around 1.68/1.7ish.

 

[Steedman07]

I would do the meth. It will help you trap speeds and get you into the upper 11's IMO..Im sure now its pulling lots of timing after the 1/8th cuz you have no cooling..

 

[Five Oh Brian]

Nice little write up, how much power is your car putting out with the vortech? I thought you would have gained more when you put the DR's on your car.

My Vortech is non-cooled and the tune is super conservative for daily driving duties. On a Mustang Dyno it made 364 rwhp. On a Dynojet Dyno, it would likely make closer to 400 rwhp.

The DR's help a lot. I really had to cook the factory tires to get the best times I got with them, but they were really inconsistent (13.2's were the best, but I ran a lot of 13.3's through 13.7's if I didn't melt them enough). So the DR's make it super easy to launch great every time. With the supercharger on the car now, I have never been to the track without DR's.

 

[08nastygt]

I bet it would suck without the DR's now. Youd be all over the place, get ya the aftercooler kit or whatever it is for them and run some 11's bro. Good job on teh build though.

 

[Five Oh Brian]

you said the converter flashes to 3800 but what rpm are you at when staged? I have been anywhere from 1200 to 2000rpm and my 60 ft is always around 1.68/1.7ish.

The converter flashed to 3800 rpm's N/A, but it's 4800 rpm's now with the blower on the car. The company that built the converter advised me to launch without preloading the converter (leave it at idle, then mash the gas just before the last amber). They claim the converter will "hit" harder, providing more torque multiplication.

However, I've done dozens of passes and tried preloading the converter against the brakes at lots of different rpm's and learned from experience that my car with my setup gets its best ET's by preloading about 1800 to 2000 rpm's against the brakes (much like you). I mash the gas on the last amber that way, and the converter flashes instantly to 4800 rpm's when I release the brakes. This nets R/T's in the .010 to .100 range, and I even hit my first perfect light ever in 2008 using this method. 60' times are always in the 1.79 to 1.85 range - super consistent.

 

[Five Oh Brian]

I would do the meth. It will help you trap speeds and get you into the upper 11's IMO..Im sure now its pulling lots of timing after the 1/8th cuz you have no cooling..

The guy that did my custom tuning uses meth on his race cars instead of intercoolers. He's got me convinced that it is the route to go, so it's good to hear it from you, as well. My tune only has 14 degrees of timing in it, and we've flogged it long and hard on the dyno without seeing the PCM pull any timing away from that. When we tried putting more than 15 degrees timing in the tune, the PCM pulls a ton of timing when the temps go up, so 14 is the max I'll run until the meth goes on, then I think I can get away with about 21 degress of timing. How much timing can you run with the meth in your setup?

 

[Five Oh Brian]

I bet it would suck without the DR's now. Youd be all over the place, get ya the aftercooler kit or whatever it is for them and run some 11's bro. Good job on teh build though.

Thanks! Would definitely suck w/o DR's at the track; that why I don't even dare. I recently found an awesome street tire, though, that hooks waaaay better than the factory tires, so it's a lot safer to drive on the streets now. I went with Continental's Extreme Contact DWS. 255/45/18 at all 4 corners. Better traction in the rain than the factory tires gave on dry pavement! And on dry pavement, they are almost as sticky as a DR (although not quite, and not worth risking at the track).

 

[Steedman07]

The guy that did my custom tuning uses meth on his race cars instead of intercoolers. He's got me convinced that it is the route to go, so it's good to hear it from you, as well. My tune only has 14 degrees of timing in it, and we've flogged it long and hard on the dyno without seeing the PCM pull any timing away from that. When we tried putting more than 15 degrees timing in the tune, the PCM pulls a ton of timing when the temps go up, so 14 is the max I'll run until the meth goes on, then I think I can get away with about 21 degress of timing. How much timing can you run with the meth in your setup?

I forget where I am at now with timing. But the meth really helped. Not a hint of knock or detonation..My tuner is well versed with meth for his Subaru race cars and all the Evo's and Sti's hes tuned.

 

[Five Oh Brian]

I forget where I am at now with timing. But the meth really helped. Not a hint of knock or detonation..My tuner is well versed with meth for his Subaru race cars and all the Evo's and Sti's hes tuned.

The only problem with meth that I've been warned of is that our factory intake manifold doesn't do a great job of keeping the meth distributed evenly in each of the intake runners, so some cylinders run hotter/leaner than others. Sounds like the benefits outweigh the potential downside if you don't go crazy with the timing and/or have the tune written to back off timing if IAT's get past a certain point.

 

[08nastygt]

So if you ran meth, you could potentially run more power safer? Or you just are running more power? I see that your turning up the timing so thats where you are gonna make the power correct not really from the meth itself.

 

[Five Oh Brian]

So if you ran meth, you could potentially run more power safer? Or you just are running more power? I see that your turning up the timing so thats where you are gonna make the power correct not really from the meth itself.

The meth keeps temps down, which allows for more timing to be run more safely. Plus, meth will increase the octane of the fuel in the car, so you can run even more timing as the extra octane will guard against detonation with a slower burn. It's a double-whammy for the better!

 

[Mick Mach]

The converter flashed to 3800 rpm's N/A, but it's 4800 rpm's now with the blower on the car. The company that built the converter advised me to launch without preloading the converter (leave it at idle, then mash the gas just before the last amber). They claim the converter will "hit" harder, providing more torque multiplication.

However, I've done dozens of passes and tried preloading the converter against the brakes at lots of different rpm's and learned from experience that my car with my setup gets its best ET's by preloading about 1800 to 2000 rpm's against the brakes (much like you). I mash the gas on the last amber that way, and the converter flashes instantly to 4800 rpm's when I release the brakes. This nets R/T's in the .010 to .100 range, and I even hit my first perfect light ever in 2008 using this method. 60' times are always in the 1.79 to 1.85 range - super consistent.

yeah I agree with preloading the converter...and I suck at reaction times but I leave at aorund 1200....if I up the rpm to 1800/2000 will the car leave harder/quicker helping my reaction times??????

 

[Five Oh Brian]

yeah I agree with preloading the converter...and I suck at reaction times but I leave at aorund 1200....if I up the rpm to 1800/2000 will the car leave harder/quicker helping my reaction times??????

Improving reaction times just take lots of practice. 1st, pick an rpm to launch at that gives you the best ET and stick with that every run to be consistent. Then 2nd, you can start experimenting with when to launch in relation to the last amber and green light.

I always suggest launching when the last amber light comes on to start with. Assuming that you're not deep-staging, by the time car starts to move and breaks the beam, you'll be posting R/T's under .200 and not redlighting. Then it's just a matter of adjusting slightly to whittle it down under .100, then closer and closer to .001. If you're launching at higher rpm's, then you are correct that you should launch later than if you're launching off idle.

I'd say that in bracket racing, most races are decided by the R/T (with a close second being decided by proximity to dial in's, then redlighting deciding a fair amount of races, as well). Get the R/T under control, and there's money to be made bracket racing.

 

[sixshooter798]

I leave at about 1500 with the 3000 stall converter. After comparing my 60' and ET to that of a stick shift car, I want to launch the thing around 4500. However, I need a loose enough converter to keep me in the .010-.020 range on the tree.

 

[Mick Mach]

Improving reaction times just take lots of practice. 1st, pick an rpm to launch at that gives you the best ET and stick with that every run to be consistent. Then 2nd, you can start experimenting with when to launch in relation to the last amber and green light.

I always suggest launching when the last amber light comes on to start with. Assuming that you're not deep-staging, by the time car starts to move and breaks the beam, you'll be posting R/T's under .200 and not redlighting. Then it's just a matter of adjusting slightly to whittle it down under .100, then closer and closer to .001. If you're launching at higher rpm's, then you are correct that you should launch later than if you're launching off idle.

I'd say that in bracket racing, most races are decided by the R/T (with a close second being decided by proximity to dial in's, then redlighting deciding a fair amount of races, as well). Get the R/T under control, and there's money to be made bracket racing.

ok I dont race alot...thats hurts too. I did try the deep stage..seemed to help my RT's.

 

[US-1]

I'm not seeing headers in there anywhere.

 

[Five Oh Brian]

ok I dont race alot...thats hurts too. I did try the deep stage..seemed to help my RT's.

Deep staging means that you'll break the beam sooner (quicker R/T, assuming you leave on the same light compared to someone staging shallower). However, deep staging will hurt your ET compared to the same launch from a shallow stage. Sounds like it shouldn't matter, but staging shallow allows you to get a running start before you break the beam to trip the timers.

Whatever you do, don't wait until the green light to drop the hammer. Nail the gas when the last amber comes on and you'll post some great R/T's. The 1/2 second between the last amber and the green coming on is about how long it takes your car to actually start moving and trip the beam after you bury the gas pedal.

 

[Five Oh Brian]

I'm not seeing headers in there anywhere.

Headers are part of my long-term plan. I bought SLP's catted X-pipe as it is modular construction allowing me to run it with the factory exhaust manifolds now while I save up the money for their long tube headers. I'll be paying our shop to install them, so it's gonna add up quick so I gotta keep saving up.

I believe that the factory exhaust really corks up power in a blown car (more air in = more air out), so there's probably 20-30 rwhp to be had with long tubes (which would be enough to get me into the 11.90's, IMO).