CAT3

iTrader: (9)

Ok, title hard to describe, but... At the track I been logging all the runs with new 347 setup. Basically, 11.62:1 347, ETP 225cc heads, EDC 231/242 .637/.622 @ 114*LSA cam, Rossler RMVB TH-350 w/ Brake, ATI 4,000 stall TC, stock 10bolt 3.23 gears ( I know they arent helping any). So, when I review my runs, it pulls through 1st strong as hell, and second, but third seems to drop off and not as strong. The rpms drop during the shifts from @ 6900rpms down to 5300 +/-. When I shift to 3rd, the rpms drop and seem to just kind of hang there, barely gaining any rpms throughout the run.

Could this be from a mismatched STR, or something within the TC? Or just having to deal with the 3.23's and 26" tires? Seems like it should be pulling a lot harder at the top, especially with the heads and cam. Although the cam was ground to maximize 300 shots of nitrous, not run NA.

Thanks.

Charlie

badass 2002 z28

iTrader: (5)

It's the 3.23's my car did the same thing...it'd 1/8th mile real strong..then fall on its face in 3rd.

Nate_Taufer

iTrader: (1)

how much mph are you picking up on the top end charge?

CAT3

iTrader: (9)

Looking at the logs, these are the averages....

Shift from 2nd to 3rd ~ 6800rpms
Rpm's drop to 5350 in 3rd @ 99pmh. RPM's climb from 5350 to 5600 across the traps @ 111mph.
Time stamp from time it hits 3rd is 08:44:499 to 08:47:523, roughly last 3 seconds are in 3rd gear with very little rpm climb, although mph shows increase.
Looks like it does it in second gear as well. Hangs around the 5300-5900rpms for a while. I guess my gearing is way off from optimal, but I need to put the juice in her to see what rpms we're looking at then. I want the combo setup for optimizing spray, but still be drivable, yes I can deal with a lot in the sacrifice department.

Nate_Taufer

iTrader: (1)

How much from 1/8th to 1/4? Seems like it's just falling on it's face after 5300 rpms. Is the tuning spot on?

Nate

FANTAZ28

iTrader: (2)

with a turbo 350 and a 323 gear thats whats killing you !!! if that car is oh hp i would say put at least a 430 in it. the car dosent have enough gear is what im tryin to say.

ati's are efficent converters meanning your not gonna have much slip up top, now i had a broken converter for a while and the thing would slip up top like crazy, like 1000 rpm or so ... which killed my mph. i would say put alot of gear in the car

calculate it on line with tire size and all and see what fits you best

CAT3

iTrader: (9)

Gears....I think I actually wanted to hear something like, your TC is shot, or thats normal etc. if only to avoid the headache of needing to do gear install, which brings about the arguement I need a 9". Guess I'll spray and start looking for a gear solution.

6secNaLs1

iTrader: (5)

i ran 4.56's in my stock 10 bolt with a th 350...26 inch tall slick t rex cam and my rpms went up very very quick....even in third...the car would 330 i think 74 75 mph and et 6.70's and trap 101 mph 1/8 mile....i had a 8 inch 4600 turbo action converter

badass 2002 z28

iTrader: (5)

If you're going to spray the car..I'd just keep the 3.23's

CAT3

iTrader: (9)

Thats my direction for now, spray it and find out the differences b/w the NA and Spray. My goal was to set my car up similar to how Big Mike used to, its built for juice, run it that way, what it does NA....Who cares. But, gears will eventually become necessity I am sure. Blow the rear, get new taller tires and the reasons go on.

6SecNaLs1-- I am sure my 8th ET and MPH will change once I put some tires on her again. Looking at the logs, it takes me ~4sec before I can get to 100% Throttle, which is totally killing the short times. Couple that with the 2.xx 60' and yeah, the times WILL improve. But, regardless, will see what it does off the transbrake w/ sticky tires next w/e, then add the juice the following w/e.

Thanks guys.

Charlie

FANTAZ28

iTrader: (2)

even on spray 3.23 is way to small
you'll propibly have to go to a 28 on nitrous for traction, so depending on your mph on spray i would say 4.10 or so with a 28

chpmnsws6

iTrader: (70)

with an auto wouldn't 4.10's still almost be to much gear? time to talk to the company who built the convertor about what gear to run (they can tell you convertor slip and whatnot)

FANTAZ28

iTrader: (2)

this is not a 4l60 this is a th350 big diffrence, all converter companys will tell you they have minumal silp, but do they? only running it will tell

and you have to factor in a 28 inch tire, if he sticks with the 26 than i would say 3.73

chpmnsws6

iTrader: (70)

more then likely they know more about there convertor then we do and would like to see the car run as good as possible with there product in it. correct?

CAT3

iTrader: (9)

Well, I emailed ATI a couple times, and no reply. So, I just might try calling them for ***** and giggles. I am sure they will say 8% (since most calculators say 10% ). Anyway, looking into 3.73 and 4.10's just cant justify paying the install when I'll probably blow them first trans brake launch on the bottle. Ugh..

Nate_Taufer

iTrader: (1)

Bite the bullet and get 3.90's or 4.10's and a locker with a 9"

Nate

FANTAZ28

iTrader: (2)

yeah if your tryin to have the rearend live i WOULD NOT launch off the break and a 10 bolt. instead what you want to do IF you have to use the 10 bolt is to creep up to the line at let say 1300 rpm or so jsut a little above idle and step on the brake while keeping your foot on the gas , this way it takes all the play between the ring and pinion out. and do not release the throttle , meaning keep the car at 1300 rpm till lights go green than flash it, and when i say brake i mean the actually brake pedal . i dont think you should be using the t-break at all with a 10 bolt.

SlickVert

iTrader: (5)

What does your timing look like?

CAT3

iTrader: (9)

Its pretty flat, about 20*. I had a slight curve from launch rpm, 3600, to 7200. It starts around 17* and slowly ramps up from pk TQ to pk HP, but reduced it all for the additional compression.

koolrayz

iTrader: (26)

your shift extension is 1600rpm thats way to much. the converter will loosen up on the spray but may still be to tight. i shift at 6700. on motor it falls back to 5300 and just hangs, same as your describing. on the juice it falls back to 5800. im still at an 900 extension on the juice. I am going to have it loosened up a little while i have it out. If you want to trap 140 with 26" tires at 6900 you'll want a 3.50 gear IMHO Im trapping 136mph with 28" tire at 6500rpm with a 3.70 gear. go here and run some calculations. http://www.f-body.org/gears/ dont forget to calculate for the converter slip