3rdBird

iTrader: (1)

Just like it says, Low ET & high MPH. the best so far is 11.3 @ 125 mph.
I run a 406ci w/a TPIS mini ram, TH400, 5500 stall, Moser 12 w/ 373's.
I leave off the tbrake @ 4500, shift at 7 grand & I go thru the traps in 3rd gear at about 6000 rpms.
I run a 28 10.50 15 MT ET Drag @ 14 psi
My engine is built for the bottle so I'm hoping the bottle will compensate for the lack of gears.

????

brandoz28

iTrader: (1)

is the converter set up for nitrous too? what does your 60ft look like?

ZONES89RS

iTrader: (2)

That happens when the 60 foot is poor usually.

3rdBird

iTrader: (1)

The converter is an 8" w/ a Billet front section.

The 60' averages 1.65

Fast 383

iTrader: (2)

Sounds like your not 60 ft'ing or the lack of gear is leaving you at a low RPM when crossing the traps. My first pass out with my car was good for a 11.33 @ 122 with a horrible launch. I was able to chisle at it and ended up with 11.0's at 125 with no chages at all. Just a harder launch and better 60ft. I then changed out the carb and went with a more agressive tune and the results are in signature.

If you're running 125 it's a 10 seconed car no doubt.

Fast 383

iTrader: (2)

That 60'ft belongs to a 12 seconed car. Who's converter? Have you tried checking the stall against the trans brake with no chip in place? It's probably comming up short is my guess.

drperformance

iTrader: (5)

I would be looking at my rear tires. If you are shifting at 7000 you should be trapping at about 7300 to get everything out of the car (you are barely using 3rd). Take some tire out of the rear or change the grearing to get the desired rpm at the traps. The larger then needed OD or wrong gearing is also scrubbing torque off the line lowering your 60'.

This is assuming that the car is hooking.

brandoz28

iTrader: (1)

if its built for the bottle spray it and see where it goes. there are some guys who will go from low 11's to high 8's on 150-200 shot of spray because their car is totally designed to run on the spray

Orr89RocZ

iTrader: (20)

Thats a turbo car 60 foot leaving off the footbrake and no boost

That car needs more gear to go better on motor alone but with spray, even a 150 shot can expect another 10-15mph trap speed which makes those gears much more optimal for the top end. At 125mph and those tires, you should cross the line at 5600 with no converter slip. You naturally want to be closer to peak power which I'm guessing is in the 6500 rpm range?

With a 150 hit, say you trap 138 now. That makes rpm at the finish around 6200..much closer to optimal.

I would expect a nitrous motor setup to not run the ET's it should run when its on motor. Nitrous setups just arent geared for ET

i still would expect a much better 60 foot on that car however. 1.65 is almost where my bolt on L98 ran. My 383 with less converter and motor than you ran mid high 11's and easily hopped off the line with 1.55's not trying to hard, 26" tire 3.42 gear on a setup that peaked near 6300. I would have expected a better 60 foot.

Fast 383

iTrader: (2)

which still = 12 second 60'ft



Check your converter stall.

drperformance

iTrader: (5)

Do what ever you want and take peoples suggestion with a grain a salt. With that being said until you get your gearing/rear tire set up optimal you are pissing in the wind.

Fast 383

iTrader: (2)

You should start with taking this suggestion with a grain of salt. 1/4 mile runs need to be diagnosed from the beginning. Starting with the 60FT. Gears/Tires are a tool to fine tune your trap RPM's. There is no way changing gears and tires are going to drop this cars 60FT to a high 1.4 or low 1.5.

Something is wrong. I would guess that the converter is not what he thinks or the suspension isn't loading/unloading properly.

That is not a suggestion. It is a professional opinion.

Orr89RocZ

iTrader: (20)

Especially if he's leaving off the Tbrake at 4500, this car should go much faster than 1.65 60 foots. Converter may be too soft?

drperformance

iTrader: (5)

Hmm, lets sit back and think about this!

Things that can kill 60' times: (just to name a few)
-tires spinning (never stated)
-wrong stall (never stated)
-not enough torque caused by wrong gearing, tire diameter (ding, ding, ding)

Not only is he crossing the line not a peak power but the wrong gearing is killing his short time.

torque=force x lever arm

ex. tq=300 foot pounds x 14" (radius of rear tires)
tq=4200

tq=300 foot pounds x 13"
tq=3900

This is why people always wonder why their stuff does not perform. You must match all parts for optimum performance. This includes the torques converters stall speed mentioned above but I would get you gearing correct first and cross the line slightly above your shift point. It will help your ET and short times.

Make up your own mind!

Orr89RocZ

iTrader: (20)

I agree, but still...... 3.73 on a 28" tire on a trans brake at 4500 rpm should go quicker than 1.65.

If he goes thru the traps at 6000, his converter is slipping 7% which isnt that bad. It may not be hitting the tires all that hard however.

With 4.30 gears he'd be spot on naer 7000 rpm crossing the tape but the nitrous shot would over rev him. I dont know how low the 60 would drop with 4.3's compared to 3.73's. It may be a tenth, hard to say.

If you have a power band upwards of 7000 rpm shift, i'm willing to bet the peak torque is near 5000 rpm or so. you may want to try setting the brake to 5000 rpm and see what the car does. I see the car has a 5500 stall which is alot but should fit that setup. Car may want more rpm on launch.

Shadow Z

iTrader: (2)

This is a simple one to solve. You see, your gas turbine engine is so powerful that you do not hook up until you're past the 1/8th mile mark. Then, you take off like a rocket ship.

Fast 383

iTrader: (2)

WTF, lol ...What does all that mean?

This car is missing 1.5 in the 60'. Theres no way that 3.73's could kill off that much time. Especially if the car calls for 4.10's or 4.30's.

How do you know that this car doesn't make peak power at 6000-6500
making 6000 rpm's a conservitive but decent place to cross? Have you listened to the cam specs? Looked at the dyno sheet? There's no way you can attribute the problem to gearing without those extra facts. Gearing is a top end tunning tool. It is not a factor in lowereing 60 ft times.

This question being asked is one that I answer sometimes 10 times a day. probably 50 times a week. The answer is always the same. Start at the begining....Check your launch tactics and stall speed. Once your 60Ft is right than move on.

3rdBird

iTrader: (1)

Lots of good input, until the end haha. heres my last 3 runs

#1 Transbrake @4500, the shift cable was mis-adjusted & I never shifter shifted into 3rd. i buzzed the rev limiter & coasted thru the beams.
60' 1.606
I2 4.806
I3 7.387
MPH 96.968 (I3)
I4 9.582
ET 11.598 @ 108.750

#2 I adjusted the shift cable so I could shift into #rd gear & hear is what happened.
60' 1.652
I2 4.871
I3 7.471
MPH 96.807 (I3)
I4 9.676
ET 11.538
MPH 123.976

I understand why the MPH increased, because I was able to shift into 3rd gear, but shouldnt it have got a lower ET?

This entire car was build with new parts and built to run nitrous, I have a dyno session to in april to start introducing nitrous to the motor, but thats not on the track time. ?????????

Fast 383

iTrader: (2)

You can start here.

Fast 383

iTrader: (2)

How many times have you been down the track before? How many times with this car? I ask because your runs are all over the place. I think if you practice with this car you'll get close to where you should be. Take it back to the track and I'll bet it goes 1.5's in the 60ft and 10.9 -11.1 with better driving and more seat time.

3rdBird

iTrader: (1)

The runs are the similar. I've been bracket racing this car off & on for the past 3 years, almost every time I go out. there is something new, Just like the Tbrake that is 6 passes new.

I've foot braked this car w/a 150 shot on the launch off/on for the past 2 yrs. It was deadly consistant 12.2 @ 110mph.
Heres the prev set up,
L98 TPI, 150 shot N02 off the line, TH400 3500 stall, stock 10 bolt-373 gears, 26 10.50 15, the prev 60' was 1.5-ish all day long.

The only thing that has changed is a high dollar 406 small block, w/ Brodix Track 1's.

A new Moser 12 bolt, and a new 8" 5500 stall converter.

WTF? keep it coming.

brandoz28

iTrader: (1)

the 2nd run there is slower everywhere. did the weather change at all? was it in the same lane as the first?

cp87GTA

You need some video of this car leaving. I agree it is very soft on the 60. It's either spinning the tires or slipping in the converter or trans. Even with the 373s it should be 60 ftn at least mid 1.40s or so. If it's flashing the converter after you leave it could be spinning there too. I'll bet it would run faster foot breaking it, leaving at 2000 rpm.

3rdBird

iTrader: (1)

Well, I talked to the engine builder/converter builder/tuner/dyno tuner, and everyone seems to think the combo needs to leave closer to 5-5500 rpms.

so next time out, I guess I'm gonna be leaving at 5000 & possibly 5500rpms!

I'll keep ya posted.

cp87GTA

You do what you want. My little 406 with a carb will blow those little tires you have right off. My car weighs 2840 and I leave at 4200, with a 1.27 60 fter. I can foot brake it and it'll 60 ft 1.32, on the motor. If you have enough cam to shift it at 7000, it ought to 60 a heck of a lot better than it is. I'll stick by my first comment. It's already spinning.

Fastbird

iTrader: (5)

What cam are you using?

I have a 406 with AFR heads and miniram in a 91 Formula. With the 700r4 I just took out, 4.56 gears and 3800 stall convert, leaving off idle, it would pull mid 1.5's in the 60 foot.