Matt D

iTrader: (49)

My car is a full bolton, stock internal LS1 Camaro. My time is 11.42 @ 116.24, with a 1.47 60ft. I have a Level 4 4l60e from FLT, a Yank PT4400 converter, 3.73 gears out back, 26x8.5x15 MT ET Drag, and I cross the traps at 116.24, turning 6300 RPMs. By using the efficiency calculator, I am seeing 12% slip. A buddy of mine has an ATI 8" converter in his TH400/LS2 combo, and he is seeing 2% slip. I am happy with how the car is running, but am wondering if this is hurting my times by seeing that much slip. Would I benefit by switching to the SS series from Yank, which has a shorter shift extension and is a tighter converter? I assume if I did that that my 60fts would hurt, but I would pick up more mph on the big end? Let me know your thoughts, thanks!

Matt

Pro Stock John

iTrader: (34)

You might be losing a little mph, but all the work is really done by the 1000 anyway. Going almost 11.3 SI on a 1.47 is real strong, and I'd leave it alone. 4.10 gears would not be a bad thing at some point though you might need to change valve springs so you don't float the valves if you start buzzing 6400-6500.

Matt D

iTrader: (49)

That's a good point John. I am very happy with the 60fts and how the car is launching. It feels really good out of the hole. I shift the car at 6450 right now, but I might be lowering that depending on how the dyno reads in two weeks.

CamaroRacing12

iTrader: (5)

yea those r nasty times.... ur raceweight is nice too

chrismorales75

To compare a 1.47 60ft on a pass I ran went low 10.90's with 120 -121 mph at LACR here in california on the motor. With a 4500 stall converter 9" art carr, that locked up tight, th400 with a transbrake.

If the car 60 fts that hard you must be losing a lot of mph and et on the top end.

ONEBADWS6

iTrader: (22)

I just called ATI about a 4L60E converter and discussed slipage and multi disk lock ups. I was told that with our lower power level cars that you can't have the best of both worlds. I see 15-17% slip with my TCI converter and was told much of this is do to the weight and gear of my car. As for multi disk lock ups, adding all those disks adds so much weight that it washes any performance gain. Every person I have seen with a good 60ft LS based 4L60 car has 15-20% slip with Matt being the lowest. So I guess were stuck with what we have.

Matt D

iTrader: (49)

Thanks for the info Bill. I was going to call them today as well, so you saved me the time. I guess I will keep what I have until I decide to spray it, and then go with a SS4000.

jimmyblue

iTrader: (11)

You can't judge converter efficiency by slip RPM alone. That high
a stall speed means there is possibly some torque multiplication
still happening all the way out. Your power efficiency is
(torque_out*rpm_out)/(torque_in*rpm_in), motor and input
shaft speeds you can log but torque_out you can't. Not directly.
You can only see it by acceleration.

My 3500/2.0 converter is still multiplying torque past 5000RPM
(going by locked vs unlocked, acceleration vs RPM curves).
So I expect a 4400-range stall would push this even further out
though a higher STR would pull it back / sharpen up the coupling
slope.

I think a converter that big wants all the RPM you can safely
give it.

Matt D

iTrader: (49)

I launch off a 3500-4000 foot brake depending on track conditions, and I shift the stock internal motor to 6450. I cross the traps at 6300 in 3rd.

JL ws-6

iTrader: (50)

I can't even hold my car at 4000 with the footbrake LOL.

MY th400 converter goes to 5400 on the brake, and it calculated to 8.5% slippage going by the mph thru the traps and the rpm on the tach.

That being said, you're a little loose, but the chances are at your power level if you try to tighten it up the car will slow down.

Pro Stock John

iTrader: (34)

If it works on the 1/st half of the track, some excess slippage is something to tolerate on the back half. Plus Matt is running a 3.73, a car like his would slip less with a 4.10. My car needs 4.30's or 4.56's with the current setup to find the missing 2-3mph, but I'll do the converter first and see what happens.

Matt D

iTrader: (49)

If I do 4.10s with the 26x8.5" ET Drags, then I will be shifting into 4th. I am seeing 6300 when I hit the 1320 mark, and I shift at 6450. I guess I could do the 4.10s with a 28x9 (actual 27.3" tall); that would be about a 250rpm jump, give or take a little bit or 3.90s, and keep the same tire. Those would both be the same.

I will be taking the car to get dyno tuned as well with the new 85mm MAF & lid from FT. I would like to see where my shift extension is at. I might be bumping the shift points up to 6500-6600 if the peak power is where I think it will be.

BAIN

iTrader: (5)

SI and shifting at 6450? Wow that seems really high. When I was SI I shifted around 6100.

chrismorales75

My converter stalled to 4500 on the TB, foot braking I would be lucky to stall it up to 3200-3400 foot braking without pushing through the brakes.

chrs1313

iTrader: (24)

yeah i think mine is set to shift at 6300, when it is not hitting the limiter...i dunno matt if i was at your weight 200lbs lighter so around 2mph higher i would be clipping the traps at 118.6mph from my best run on sunday and close to a 11.37 et...assuming 2 tenths drop...and this with an ss3600...maybe around a 1.53-1.54 60ft...if i had the ss4000 i think i would at least be a tenth lower than my 3600 so my et should be somewhere around 11.27 at about 118mph...matches pretty close with the top stock internal guys...i think it would be worth it...

I am wishing i had gotten a ss4000 from the start...

Matt D

iTrader: (49)

When my car was on the dyno a few months back when we first did the ported LS2 intake & 90mm TB swap and corresponding tune, it made peak power at 6150. If I shifted at 6100, I would be losing a lot and be running slower than what I shift at now. The rule of thumb we have been using is shift it around 400 rpms after peak power, due to the shift extension on this converter. But like I said, the car will be going back on the dyno on December 3rd to see where we are at with the new gears & 85mm MAF & lid, so maybe we will change the shift points again after seeing the new peak power levels.

The stock valvetrain has been holding up rather well... (knock on wood)

Pro Stock John

iTrader: (34)

I doubt stock springs will like 6500.

NHRAFORMULA00

iTrader: (2)

Matt you are right in shifting 400 higher past peak HP.Im thinking you need to do the gear change (4.10)and taller slicks.Like others have said,Dont worry about Effeciency,it has too slip too be a converter,its more about its usefull range or shift extension.I know of two people that are pro's that have gone threw 6-8 converters untill the have found the right combo,and i mean sending it in to have somthing done to it,loosened ,tightened,this and that.Im thinkig that your car and Chris car would benefit from the ss4200 series,more than the pt series.Its just my guess!!

BAIN

iTrader: (5)

On the efficientcy topic. I went from a 4l60e with a YPT 4600, 4.30 gear, 28" slicks that had a shift extension of 6000-6100
and crossing the traps at 6800 rpm to a more efficient setup and lost ET and MPH. The new tranny is a gm/aod with a transbrake that stalls to 4700 on the TB, but leaves sluggish compared to the 4l60e and has a shift extension of 5200 which is way out of my powerband of 6100-7000 rpm. It crosses the 1/4 now at 5400 with 4.10 and 28" slicks I have lost .5 ET and 4-5mph. Be very carefull about trying to get a more efficient converter it will have an effect on the shift extension. I just ordered a Protorque 8" superstock converter that is supposed to be setup just like the 5500 ATI's most of the faster Cam Only guys have run. Hopefully this will solve the problems I'm having.

Good luck with the SI setup. I think you have about the best converter you can get with the PT 4400 as long as you keep the 4l60e. If you are still worried about efficientcy try locking the converter in 3rd gear and you might pick up some ET and MPH.