1/8th Mile Woes: 2008 Gt

[Townson]

Alright, I'm gonna try to stay on topic here and get straight to the point. My car is pissing me off lol. Last year I ran a best of 8.47. So far this year I can't get anything better than an 8.58 out of it.

Last year's setup: 3.31 gears, Airaid cai, Pypes off-road x, BMR lca's and relocation brackets, 2013 variant Cobra Jet springs, Bama 93 v2 race tune, 15x8 and 15x3.75 Racestars with 275/50/15 Mickey Thompson et street radials, 5 speed.

Over the winter I added FRPP 4.10's, Bbk tuned length shorties and a wotbox.

All in all, even though we all know that I should be running a bias ply tire instead of a drag radial, my car should still be running close to the 7.90-8.0 mark.

It's been running like shit lately. I pulled the plugs without breaking any (luck) and discovered that they were all about shot. Black as hell, smelled like straight gasoline and 2 of them had really bad carbon build up. I replaced them with the one piece Champion 7989's. It's running a lot better. No more problems while idling or driving so far.

Also, my 60' dropped from a 1.99 on last year's 8.47 run to a 1.82 and 8.58 this year. So basically, I dropped nearly two tenths off my 60' but lost time on the rest of the track. I just don't see how that's possible especially with the no lift shift feature the wotbox has. Gear changes are alot faster and smoother.

Test and tune got rained out last Thursday so I haven't had a chance to try it out with the new plugs. Hopefully it will help some.

I have a few questions also:

How drastically could worn out plugs effect your et?

What rpm should I set my 2-step at to leave with 4.10's and a drag radial? 4k bogs, 4500 chirps and I haven't found out what 5k will do yet. I'm hoping a nice burnout and a little slipping of the clutch will work well with a 5k launch.

 

[stkjock]

are you doing your burnout in 2nd gear and seeing 55-60 MPH while you do so?

I found 4700-5000 RPM clutch drop worked with 265/40/18 DRs w/ my 06, 4.10s and a blower.

are you making the same number of shifts with the 4.10s?

 

[808muscle]

What's your tire psi? What was the DA? DA was shit for me Sat night and all us mustang guys were down 2 tenths. Mph was down 2. Were you running at temp with the car warmed up or full cold? If I run cold or cool it will be 2-3 tenths faster than fully warmed up. But warmed up its way more consistent. What was your mph compared to previous runs. Mph determines HP. ET is about traction.

 

[lindertw]

you should still be going through the traps in the 1/8th mile in 3rd gear with the 4.10's

rpm=(mph x final gear ratio x 336)/tire diameter (final gear ratio = 4.10*1.32 for 3rd gear with manual trans)

you didn't post MPH, but I'll guess 86-87 mph, so you should be at 5900(ish) rpm at the stripe. If you're shifting to 4th gear, don't - ride it out in 3rd through the 1/8th.

DA could be a factor, and I don't know what to say about the plugs... picking up ET on the 60' should net you a gain in the 1/8th. Something could be off with the plugs/tune, etc.

Keep experimenting with launch RPM - the higher you can get the car to hook the better.

 

[Townson]

are you doing your burnout in 2nd gear and seeing 55-60 MPH while you do so?

I found 4700-5000 RPM clutch drop worked with 265/40/18 DRs w/ my 06, 4.10s and a blower.

are you making the same number of shifts with the 4.10s?

I tried doing a 2nd gear burnout, but found it really difficult. (no line lock) so I just held it in first for longer than I did last year. 4,000 dead hooked every time and caused me to bog. 4,500 just chirped a little bit and didn't yield better results.

And yes, I'm still shifting the same amount. I'm crossing the line in 3rd gear at around 6,000 rpm as compared to about 4,500 last year with the 3.31s.

What's your tire psi? What was the DA? DA was shit for me Sat night and all us mustang guys were down 2 tenths. Mph was down 2. Were you running at temp with the car warmed up or full cold? If I run cold or cool it will be 2-3 tenths faster than fully warmed up. But warmed up its way more consistent. What was your mph compared to previous runs. Mph determines HP. ET is about traction.

Not sure on the DA. I made sure that the car was up to temperature because I heard it's bad to hit the 2-step on a cold engine, which I'm not sure is true or not.

Mph this year - 86.00 Et - 8.582
Mph last year - 83.81 Et - 8.478

I always run 17 psi hot in my tires.

you should still be going through the traps in the 1/8th mile in 3rd gear with the 4.10's

rpm=(mph x final gear ratio x 336)/tire diameter (final gear ratio = 4.10*1.32 for 3rd gear with manual trans)

you didn't post MPH, but I'll guess 86-87 mph, so you should be at 5900(ish) rpm at the stripe. If you're shifting to 4th gear, don't - ride it out in 3rd through the 1/8th.

DA could be a factor, and I don't know what to say about the plugs... picking up ET on the 60' should net you a gain in the 1/8th. Something could be off with the plugs/tune, etc.

Keep experimenting with launch RPM - the higher you can get the car to hook the better.

I think I'm going to try to get it to hook at 5k. The tune is the same as last year since shorty headers don't require any changes (that I know of)

And yeah, I'm keeping it in 3rd across the line lol.

 

[stkjock]

brain fart on my end - didn't keep the 1/8th mile in mind.

if you race often, get a line lock, burnouts are easier, better for your rear breaks as well.

2nd gear and more MPH is better to heat the tires

I'd guess DA is part of it, you should be .2-.3 faster than last year based on the MPH pick up and reduced 60' time all things equal. .25 in ET is about a 3% delta, so you're well within a DA difference possibility.

If you have the time slips for each - you can get an idea of conditions between the two dates

http://www.dragtimes.com/da-density-altitude-calculator.php

https://www.wunderground.com/history/

 

[Townson]

brain fart on my end - didn't keep the 1/8th mile in mind.

if you race often, get a line lock, burnouts are easier, better for your rear breaks as well.

2nd gear and more MPH is better to heat the tires

I'd guess DA is part of it, you should be .2-.3 faster than last year based on the MPH pick up and reduced 60' time all things equal. .25 in ET is about a 3% delta, so you're well within a DA difference possibility.

If you have the time slips for each - you can get an idea of conditions between the two dates

http://www.dragtimes.com/da-density-altitude-calculator.php

https://www.wunderground.com/history/

I plan on getting a Hurst line lock in the future. It was probably a combination of worse DA and bad plugs if I had to figure. Maybe it won't rain this Thursday and I can find out lol.

 

[NickD87]

I'm similarly set up, stick radials no line lock etc
I give them a quick spin in the water in first then drop the clutch in secoind too start the burnout vs shifting (prob hard on parts but works fine) I've experimented and found I got better results this way vs doing a longer burnout in first. (I stop as I see smoke approach my windows in second)

It's possible the tune needs to be looked at again if the plugs are smelling like fuel and lots of carbon.
I agree DA plays a huge influence but so does a cold car (I again was surprised by my tests even on a bolt on NA car)

One other possibility that I've seen in person is my friend installed a wot box and the box was cutting spark during the run, it had great 60' then almost fell on its face, maybe not the same but could be related. I think it ended up being a bad ground.

 

[46Tbird]

You gained three mph, and dropped nearly two full tenths in the 60'... yet ended up a tenth slower in ET?

Does not compute. You should have dropped six tenths.

If I'm being asked to guess, I'm thinking that WOTBOX is killing your shifting. I always thought they were for very-high horsepower cars and allowed smoother shifts at high RPM. Maybe you should make a few passes without it to see if there's a difference.

The only other thing I can think of is you might be making the 1-2 and 2-3 shifts at too low RPM. Running third gear out the back door could be picking the MPH back up but you'll never regain lost ET.

 

[Townson]

I'm similarly set up, stick radials no line lock etc
I give them a quick spin in the water in first then drop the clutch in secoind too start the burnout vs shifting (prob hard on parts but works fine) I've experimented and found I got better results this way vs doing a longer burnout in first. (I stop as I see smoke approach my windows in second)

It's possible the tune needs to be looked at again if the plugs are smelling like fuel and lots of carbon.
I agree DA plays a huge influence but so does a cold car (I again was surprised by my tests even on a bolt on NA car)

One other possibility that I've seen in person is my friend installed a wot box and the box was cutting spark during the run, it had great 60' then almost fell on its face, maybe not the same but could be related. I think it ended up being a bad ground.

I contacted Jon from N2MB right after I installed the wotbox. It was having a problem with surging idle. He looked over all the voltages from pictures I sent him of the interface. He said everything looked good, but you never know. I put the car through the idle relearn procedure and it was fine after that, apart from the stuttering and occasional falling idle I would experience while coming to a stop.

The plugs that were in it were Autolite ht0's which I understand to be sort of a colder plug. (Alot of nitrous and turbo guys use them I hear) I was thinking that could have been the cause of the carbon build up. Maybe not a hot enough spark.

You gained three mph, and dropped nearly two full tenths in the 60'... yet ended up a tenth slower in ET?

Does not compute. You should have dropped six tenths.

If I'm being asked to guess, I'm thinking that WOTBOX is killing your shifting. I always thought they were for very-high horsepower cars and allowed smoother shifts at high RPM. Maybe you should make a few passes without it to see if there's a difference.

The only other thing I can think of is you might be making the 1-2 and 2-3 shifts at too low RPM. Running third gear out the back door could be picking the MPH back up but you'll never regain lost ET.

What do you recommend I shift at? I've been shifting at 6k. I don't know if I'm making power or losing it past that rpm since I don't have delete plates. I know the people that have the plates will stretch the gears out to 65-6700.

 

[stkjock]

I would shift more like 6300-6400

 

[Townson]

I would shift more like 6300-6400

I'll try that out. Don't you have a wotbox too or am I imagining things? I could've swore I saw you post something in another thread about it.

 

[stkjock]

I do in the Shelby. I didn't in my 3V

 

[Townson]

Any problems out of it?

 

[stkjock]

Nope

 

[Townson]

Where did you mount your ground wire? Strut tower?

 

[stkjock]

it was already installed when I bought the car, so frankly, no clue.

 

[Townson]

Well damn lol. I just contacted Lito to see if he can help me out. Everyone on here says nothing but good things about him so I'll give him a shot. Gotta be better than Bama. Gotta be.

 

[Townson]

Update: track was open last night, but I didn't get there until around 8:30 and it was semi-slick by then.

Upped the launch rpm to 4500. Spun pretty hard on all 3 runs.

All 3 were 1.8 60' with 8.44 et's at 86 mph.

If it wouldn't have spun as bad it would've went 8.10's or 8.20's I believe. Feels alot stronger with the new plugs.

 

[JeremyH]

I would get delete plates and stock heat range plugs in. And yes ditching bama for lito would be an excellent upgrade.