Who has hard data, E.T,MPH,RPM, Converter slippage and combo? I need real world info

[Amelio]

There has been lots of discussion on converters.....which one for my combo? Is my converter slipping too much? Difference between LU and NLU....etc.......

I like many other members on here am starting to get lost and I am trying to clear this stuff up for my own education. I have talked to a handful of well known and respected members and I keep getting different answers on what to expect out of a given converter and combo.

So I am starting this thread in hopes that members will post real numbers to help educate me and any other person in the same boat trying to pic a converter or figure out if they currently have a converter issue. I am interested to here from the people running a 10" NLU because thats what I am using but I would like to also hear from a variety of others.

I am currently running a 10"3000 stall nlu.....the converter however only stalls 2600@0 psi and it has 14% slippage up top. I am currently working with Dusty to get this resolved. However the more I research and talk to different people I get different expectations. On one hand I am being told a 10" nlu will not stall high enough for my needs (3000rpm) and lock hard enough up top......on the other hand I am being told it can and there are converters out there doing it.

So I am hoping to get real numbers to see for myself instead of being told.

Please post your combo...just cam heads,turbo gear,converter and tire size also your e.t,mph,rpm and converter slippage.

If you dont know your slip% you can go to Wallaceracing.com they have some great calculators select converter slip it will ask your trap rpm,mph,tire diameter and give you a %

 

[pacecarta]

my 86 last wed night

ptc 9.5 19 blade for th400 - trans brake (dusty worked the specs )

spool stall on brake .. time is time from first touch of throttle after engaging brake
0psi @ 2900 (.6 sec)
3psi @ 3400 (1.6 sec)
5psi @ 3600 (1.95)
8psi @ 4100 (2.39)
thats enough time to rollin at idle set bulbs engage brake achieve 8psi and leave with a perfect RT
after release of brake
8-23 psi .7sec and now its at 5000 and converter starts grabbing hard
shifting 1-2 at 6250 (2.3 sec)
drops to 5200
shift 2-3 at 6050 ( 5 sec)
drops to 5200
cross traps at 134 @ 5800

though it leaves hard 60' was only a 1.55 (have to discuss this with dusty after the season )
1/8 6.48 @ 108.13
1/2 10.12 134.27

stock rear gears 3.42
28" MT drag radials

rest of combo is in sig
turbo is bigger than most would expect for a this converter to spool
71 Gtq with the old .70 AR S cover 2.5 outlet 4" inlet, exh housing is a precision .63 three bolt
intake has egr tower removed and closed but not ported
8445 heads set up for roller (guides cut) and T+D rockers (stands grinded for clearance) , have cleanup behind valve to guide protrusions but no chamber or runner work

on comparison i was spooling an old vigilante 10" that had 2650 at opsi , trapped same mph at same et (but with a 1.42-1.46 60') would trap at 6150rpm . because of the raised rpm that old vig converter took about 2psi less boost to reach same et/mph

 

[pacecarta]

..

 

[turbobitt]

There has been lots of discussion on converters.....which one for my combo? Is my converter slipping too much? Difference between LU and NLU....etc.......

I like many other members on here am starting to get lost and I am trying to clear this stuff up for my own education. I have talked to a handful of well known and respected members and I keep getting different answers on what to expect out of a given converter and combo.

So I am starting this thread in hopes that members will post real numbers to help educate me and any other person in the same boat trying to pic a converter or figure out if they currently have a converter issue. I am interested to here from the people running a 10" NLU because thats what I am using but I would like to also hear from a variety of others.

I am currently running a 10"3000 stall nlu.....the converter however only stalls 2600@0 psi and it has 14% slippage up top. I am currently working with Dusty to get this resolved. However the more I research and talk to different people I get different expectations. On one hand I am being told a 10" nlu will not stall high enough for my needs (3000rpm) and lock hard enough up top......on the other hand I am being told it can and there are converters out there doing it.

So I am hoping to get real numbers to see for myself instead of being told.

Please post your combo...just cam heads,turbo gear,converter and tire size also your e.t,mph,rpm and converter slippage.

If you dont know your slip% you can go to Wallaceracing.com they have some great calculators select converter slip it will ask your trap rpm,mph,tire diameter and give you a %

I think I have some real good data. I datalog wheel speed, RPM, and calculated MPH. The only thing I can't account for is tire growth. My combo may be to far out of the box for to compare against.

Stage 2 w/stage 2 heads
88mm turbo
3.91 gears and 31" tall tire
9.5 PTC converter
TH400 transmission
3650 race weight
8.97 @ 153.25 best ET and MPH
Trap RPM = 6778
DS RPM = 6200
Calculated slip = %8.5 (6778-6200 RPM = 578 lost RPM . Check - 6778 x .085 = 576 lost RPM or close enough).
Wallace Calculator says %5.03 ?
Converter charge pressure = 40.5 PSI
Allan G.

 

[Amelio]

thanks guys looks like a couple of real good running cars.....I also see the common link of the 9.5 being used and slip being in the 8%area....hope to see more guys post with some 10" converters.

Thanks again for the info!

 

[turbobitt]

thanks guys looks like a couple of real good running cars.....I also see the common link of the 9.5 being used and slip being in the 8%area....hope to see more guys post with some 10" converters.

Thanks again for the info!

Here is a picture of a data log. Although related to your converter slip question it may hijack this thread a little, sorry....Would like to get an opinion from Dusty on this.
After I release the transbrake, the charge pressure fluctuates then nose dives down. At the same time, the RPM's are slowly climbing. When the charge flow reaches it's lowest point, the rpm's take off. (Area marked by red line)
Would like to know if this is related to charge flow or simply cam/power band.

Allan G.

 

[pacecarta]

heres a screen shot of the run data i posted and you can see where the converter grabs and seems to hang at same rpm , this is still in the 60' which for how it feels on hit should be in the 1.3s

this is where i need dusty
that flatline at coupling point is .5 seconds long (runs flat from .75 to 1.25 seconds since release of brake) holding at 5139 rpm while the boost climbed from 23.8 to 25.6

 

[turbobitt]

heres a screen shot of the run data i posted and you can see where the converter grabs and seems to hang at same rpm , this is still in the 60' which for how it feels on hit should be in the 1.3s

this is where i need dusty
that flatline at coupling point is .5 seconds long (runs flat from .75 to 1.25 seconds since release of brake) holding at 5139 rpm while the boost climbed from 23.8 to 25.6

That trend is similar to mine only mine looks a little longer than .5 seconds and more like .75 seconds. Maybe typical of these converters ??
Allan G.

 

[bison]

my 86 last wed night

ptc 9.5 19 blade for th400 - trans brake (dusty worked the specs )

spool stall on brake .. time is time from first touch of throttle after engaging brake
0psi @ 2900 (.6 sec)
3psi @ 3400 (1.6 sec)
5psi @ 3600 (1.95)
8psi @ 4100 (2.39)
thats enough time to rollin at idle set bulbs engage brake achieve 8psi and leave with a perfect RT
after release of brake
8-23 psi .7sec and now its at 5000 and converter starts grabbing hard
shifting 1-2 at 6250 (2.3 sec)
drops to 5200
shift 2-3 at 6050 ( 5 sec)
drops to 5200
cross traps at 134 @ 5800

though it leaves hard 60' was only a 1.55 (have to discuss this with dusty after the season )
1/8 6.48 @ 108.13
1/2 10.12 134.27

stock rear gears 3.42
28" MT drag radials

rest of combo is in sig
turbo is bigger than most would expect for a this converter to spool
71 Gtq with the old .70 AR S cover 2.5 outlet 4" inlet, exh housing is a precision .63 three bolt
intake has egr tower removed and closed but not ported
8445 heads set up for roller (guides cut) and T+D rockers (stands grinded for clearance) , have cleanup behind valve to guide protrusions but no chamber or runner work

on comparison i was spooling an old vigilante 10" that had 2650 at opsi , trapped same mph at same et (but with a 1.42-1.46 60') would trap at 6150rpm . because of the raised rpm that old vig converter took about 2psi less boost to reach same et/mph

The flash stall isn't high enough for that combo unless you turn it up. Also it needs another 400 as you're building boost. 5400 flash would help everywhere. The 60' would be back in the low 1.40's and the 330' would improve big time. The only reason you're dropping that much on shifts is because of the late shift.

 

[bison]

That trend is similar to mine only mine looks a little longer than .5 seconds and more like .75 seconds. Maybe typical of these converters ??
Allan G.

I've got a couple logs where you can actually see the rpm dip several frames after the shift at flash stall. Thats where the car is hauling ass. Look at the average g force/time where it's hanging there

 

[Dusty Bradford]

I can't go in detail posting from my phone but I will reply in detail middle of next week. Basically the flat spot in the rpm line is where the converter is coupling. This is where u want to pour the power to it to get this line as short as possible.

Amelio. The 10" can't couple as well as the 9.5 but can couple well enough with the right stall to run low 11's efficiently depending on the shift rpm. The more rpm, the more efficient a converter can be. I'd say your issue is the converter needs to be closer to 3100-3200 at 0 boost.

 

[Dusty Bradford]

Alan. The dip in pressure after t brake release is usually related to the valvebody used in the trans. When the charge pressure drops off it loosens the converter. Some valvebodies are worse than others.

 

[turbobitt]

I can't go in detail posting from my phone but I will reply in detail middle of next week. Basically the flat spot in the rpm line is where the converter is coupling. This is where u want to pour the power to it to get this line as short as possible.

Amelio. The 10" can't couple as well as the 9.5 but can couple well enough with the right stall to run low 11's efficiently depending on the shift rpm. The more rpm, the more efficient a converter can be. I'd say your issue is the converter needs to be closer to 3100-3200 at 0 boost.

Thanks for the support Dusty. The flat spot has me less concerned but when the RPM take off was making me wonder if it was a charge pressure issue since the RPM takes off at the lowest pressure. Maybe just a coincidence.

Allan G.

 

[kidglok]

Can the type of fluid have an effect on stall speed? (Such as tractor fluid or something?)

 

[turbobitt]

Alan. The dip in pressure after t brake release is usually related to the valvebody used in the trans. When the charge pressure drops off it loosens the converter. Some valvebodies are worse than others.

This is hard for me to visualize since the pressure source is the pump and converter is charged directly from the pump. The VB has very short passages and little chance to influence pressure due to leakage.
The return side I would think is constant resistance or orfice and wouldn't expect it to change.

Allan G.

 

[Amelio]

I can't go in detail posting from my phone but I will reply in detail middle of next week. Basically the flat spot in the rpm line is where the converter is coupling. This is where u want to pour the power to it to get this line as short as possible.

Amelio. The 10" can't couple as well as the 9.5 but can couple well enough with the right stall to run low 11's efficiently depending on the shift rpm. The more rpm, the more efficient a converter can be. I'd say your issue is the converter needs to be closer to 3100-3200 at 0 boost.

Dusty the converter should be delivered on Monday.......yeah agree you originally spec'd the converter to be 3000 stall and its only 2600 @ 0psi anoth 400-500 rpm sounds good. Now thats going to make it looser up top correct? its already slipping at 14% or are there other adjustments that can be made to increase the stall and improve the slippage up top? Also as you say more rpm helps it couple well I think my engine is done around 5600 I dont think I can turn it much higher so this is where my concern is....if my rpms are 5600 at only 107mph which is what it did last week whats gonna happen if the slip% stays where it is and I turn up the wick.....at 117-120mph my rpms are gonna be through the roof if it will even pull that high? This is what the car ran with my old converter...11.7-11.5 @116-118

 

[Dusty Bradford]

Sorry Amelio. I had your converter confused with the other with high slip. You are correct. If I loosen it to help spool, slip will possibly go up. I'll get it open and take a look at it and we'll go from there. To answer your question though. The only way to gain spool rpm and gain efficiency is the 9.5. It shouldn't be needed at your power level but I'll be able to let u know something next week.

 

[Dusty Bradford]

Alan it can be a coincidence depending on your power curve but the lower pressure will loosen the converter. This is how variable stall work. Some valvebodies will let the main line pressure drop when on the brake or after the release. We see it on the dyno often. People don't realize the transmission is a far more complicated piece of the puzzle compared to a converter. We use valvebodies from FB because of pressure issues we've found on the dyno with others. I'm not saying this is your issue with the pressure drop but it's a possibility.

 

[murphster]

The flash stall isn't high enough for that combo unless you turn it up. Also it needs another 400 as you're building boost. 5400 flash would help everywhere. The 60' would be back in the low 1.40's and the 330' would improve big time. The only reason you're dropping that much on shifts is because of the late shift.

I'm running a similar combo with the same converter at the same power level and seeing the same thing. So the solution seems to be either to raise the power level which will raise the flash stall, or get the converter tweaked. I guess we could turn up the boost more out of the hole to get it through the coupling stage and then turn it back down to current levels afterwards. Maybe this is what Dusty meant by pouring the power on? I'd hate to get the converter adjusted since I know it would work better with a little more power, but I'd like it to work better at current levels. Tried leaving with more rpm and the initial hit is hard, but the coupling still drags it down and hurts the 60ft. Running 25lbs of boost or so, similar to Paul, so it seems like I'd have to raise the boost to 30lbs or so after the hit to shorten the coupling time.

Does this sound about right?

 

[bison]

I'm running a similar combo with the same converter at the same power level and seeing the same thing. So the solution seems to be either to raise the power level which will raise the flash stall, or get the converter tweaked. I guess we could turn up the boost more out of the hole to get it through the coupling stage and then turn it back down to current levels afterwards. Maybe this is what Dusty meant by pouring the power on? I'd hate to get the converter adjusted since I know it would work better with a little more power, but I'd like it to work better at current levels. Tried leaving with more rpm and the initial hit is hard, but the coupling still drags it down and hurts the 60ft. Running 25lbs of boost or so, similar to Paul, so it seems like I'd have to raise the boost to 30lbs or so after the hit to shorten the coupling time.

Does this sound about right?

I've learned that they are better off looser than tighter if you're not going to throw power at them. It wont hurt e.t. As much being looser and driving into it harder as much as having it flash low. Keep in mind the engine will spend the most time during a pass at or near flash stall. Throwing more power at it will make it couple later relative to driveshaft speed. It only makes sense to have it flash right in the power band. That's another reason why looking at dyno runs using the mph vs hp/tq gives a lot of info about how a car will run on the strip. When I was dynoing my blue car all the time I got the combo to work so well that it went 10.61@127+ with only ever seeing a little over 500whp. If you looked at the engines peak power it occured at 5150. The converter flashed to 5100. Shift at 5500. If you looked at road hp it was within 3% of peak the whole time.