Scott(382-$T$)

iTrader: (2)

Well guys I took the car to the track yesterday and the results was not good. I made 3 runs (8lbs boost) and she did almost the same on each run. Some of my problems I believe are as follows: #1 Headers, converter, trans shift points. My Vigilante converter is the same as I had in my car when she was just a head and cam car. Terrible 60' times; 1st 1.789.....2nd 1.831....3rd 1.89. The track was very good and no wheel spin..on the street with wheel spin she pulls harder. The very 1st time at the track a few years ago when she was a 382 with the little GT67 on her and 17' wheels(wheel spin) she did a better time. With the wheel spin it actually helped her spool. I think maybe a braked glide or TH400 with a looser converter and regular iron manifolds might be the ticket. Any thoughts would greatly be appreciated

1st run:
R/T .465
60' .1.789
330 .5.081
1/8 .7.617
MPH 98.66
1000 9.774
1/4 11.583
MPH 125.66

2nd run:
R/T .380
60' 1.83
330 5.111
1/8 7.610
MPH 100.04
1000 9.709
1/4 11.484
MPH 127.22

3rd run:
R/T .316
60' 1.890
330 5,227
1/8 7.751
MPH 99.32
1000 9.861
1/4 11.638
MPH 127.22

Disturbed Bird

iTrader: (9)

up the boost!!!!! or get a procharger! lol

jmill96Z

iTrader: (3)

A 2 step will help you build boost. What was your tire pressure? Did you try playing with it a little to maybe promote spin?

Slowhawk

iTrader: (12)

You need to get the correct converter first.

98transguy

iTrader: (7)

are u running a stock 4l60?how much power did it make on the dyno?did it make any more boost when u had the car tuned?

Photochop

iTrader: (74)

Were you able to build any boost on the brakes on launch? What RPM were you launching at? Did you happen to see where the converter flashed? What converter is in the car?

Your 1/8 mile ET looks like it could improve alot - I'd think you'd be in the low 7s, better 60s will help...the 1/8 mph looks good though. 27 mph from the 1/8 to the 1/4 isn't too bad with only 8 lbs, figured you'd see a 30 mph increase though with the 408. Maybe boost more on it? I'm not as familiar with rear-mounts...do you think that 76 is on the small side for a 408 and maybe chokin it down some? How did it dyno?

Hopefully Zombie will have some answers for us...

Schantin

iTrader: (6)

Improving the 60' times will help a lot. Cross between sizing the right converter + traction.

See you have headers. That's not helping you build boost. At the very least you need to wrap the exhaust Y-pipe back. Cast manifolds will also aid in lowering the lag, resulting in better times.

What kind of tuning/operating system are you using. 2-bar SD or MAF. If you're still using MAF that will slow the car down off the line and 1/2 way to the eigth mile....as the fueling requirements are more when the engine is under load in higher gears (ie the car would run richer than you want in 1st-2nd in MAF mode to give the correct fueling in 3rd and 4th). That will decrease the ET's significantly. If you're running SD, is the AFR staying constant through all the gears and making a full 8PSI in all gears?

Finally, if it's a forged 408....why only 8PSI. Kick that puppy up to 12 and roll w/ it

Good luck sorting things out...... you'll get it.

Scott(382-$T$)

iTrader: (2)

Tranny is a fully built from RPM, and I know my Vigilante 3200(put on when she was a head and cam car) isnt nearly suited for my apllication. Tires had 20lbs in them. Practically no boost off the line at all. With wheel spin she runs so much better. She is running a SD tune and the exhaust is wrapped from the headers back. Bottom line....longtubes and poorly matched converter= miserable 60' and 1/4 mile times. Cranking up the boost with the issues I was having wouldnt have made much of a difference with the poor off the line start. Maybe better MPH at the end.

MY99TAWS6

iTrader: (3)

You are almost in the 10s at 8 psi. I wouldn't be complaining much.

You could try that lingenfelter two step and it also has antilag function it seems on the newer ones.I bought one but have not played with it since my engine and turbos are not installed still.
So what stall should he have? A higher stall? What gears do you have in the rear end?
And why are you running only 8psi. Crank that sucker up.

Photochop

iTrader: (74)

Almost in the 10s at 8 psi with a 408??? I'd be just as irritated as he is! If I go out and run exactly what I ran with 100 or so more rwhp than my H/C setup I'm gonna be pissed myself.

127 traps are good for solid 10s, I'm sure you'll get it worked out and where it needs to be after tinkering with converter etc

It's going to be hard to get that car to 60' much better without a transbrake, you have to find the perfect converter that will allow you to build boost on the footbrake, and I'd leave that up to the pros. Call up Yank or PI and have them spec you a converter to what you have.

Zombie

iTrader: (2)

Before you change any parts on the car, get rid of the headers and put stock manifolds on and wrap the exhaust the entire way. Then and only then make the decision to change your converter.

I'm beginning to sound like a broken record on the header/manifold deal for rear mounts.

https://ls1tech.com/forums/forced-induction/822122-zombie-rear-mount-turbo-saga.html

quicksilverado

iTrader: (8)

What stall do you have and what rear gear? A 2-step will make a huge difference off the line. I've pulled a 1.65 short time in a 4500 lb truck. 2800 stall, 2-step set at 2800 rpm, 3.42 gear and LT headers at the time.. This was with a t67 sts setup.

Pro Stock John

iTrader: (34)

Post the whole combo, and best dyno numbers.

ninetres

iTrader: (35)

I think your car did VERY well all things considered.

Jake@EPP

Its a PTE76GTS rear mount with a .96ex housing i belive.

We had done i think 708rwhp on 11psi on the dyno, but didnt want to do higher due to a 4l60e.

He has slp long tubes with a 3in Y pipe. We talked about doing it with manifolds before but didnt get that far. Wrapping the exhaust helped a TON though.

In the end, its the rear mount demons, a smaller EX housing (.81) would help out as well as a trans brake and a correctly stalled converter.

It definatly has the potential to run bottom 10s or high 9s, no cage though.

Great to see you running it Scott, even if she doesnt run too great at first.

Cchris1109

iTrader: (11)

something doesnt sound right, i trapped 123 mph with a stock 347 and a GT67, and I didn't even accelerate until the 330' mark, although I was at 10 lbs but your 408 @ 8 lbs should beat a 347 @ 10 lbs.

Zombie

iTrader: (2)

Those SLPs and Y pipe really kill spool, that same setup is what I use to have on my car. If you think wrapping helped out, just wait until you put manifolds on, it's HUGE difference. You'll probably need to go to a larger exhaust housing just to keep it drivable (and make more power) because boost will come on much much harder. The .96 a/r T76 on my 370 spooled too fast for the street which made the car scary to drive. I was going to go to a 1.14 a/r housing to tame it some but went to the ST80 since the turbo died.

I believe the primaries on the SLPs are about 36" and are 1.75" OD. That means you have 1584 sq inches of surface area, that is the equivelant surface area of 14 FEET of 3" od piping

1.75 * 3.14 = 5.5 sq inches surface area
36" per primary in the header = 5.5 * 36 = 198 sq in per primary
198 * 8 primaries = 1584 sq in of surface area on a long tube header with 36" primaries.

3" OD pipe = 9.4 sq in surface area
1584 / 9.4 = equivelant to 168 inches of 3" OD piping
168" / 12 = 14'

I think it would be best to get the turbo spooling the way it should before trying to change any parts to compensate.

Scott(382-$T$)

iTrader: (2)

Thanks Zombie....I do think that is what I will do 1st.

Zombie

iTrader: (2)

what size is your intake piping from the turbo to the i/c? I think that is the bottleneck in my setup since it's 2.5" at the largest and 2.25" at the smallest which makes the air speed way too high for the amount I need to flow.

Jake@EPP

Give us a ring Scott, i think i might have some factory exhaust here.