PTC Converter Dyno Run Question

[nightrain]

I need an opinion on the attached dyno graph and the performance of the PTC 9.5” converter I’m using. The graph compares one of last years dyno runs using a West Coast Converters 2800 stall L/U (locked up) with my current PTC 9.5” 3000 non-L/U. The top light blue line represents last year’s torque curve (locked up). The upper light red line represents this year’s torque curve with the PTC. The numbers inside the graph are meaningless as they are just where the reference bar happens to park on the printout.

One thing I see is that I’ve given up a huge amount of time where over 400ft/lbs of torque is being applied to the pavement. The PTC doesn’t catch up to the locked up WCC until about 4700 rpm. Then, when the PTC does “couple” it really drags down the rpm as indicated by the curly-Q. I then continue to apply some decent torque, but only to about 5150 rpm where it drops below last year’s curve again. Although, HP stays somewhat stable, but still lower than last year.

The AFR is quite different than before and at 14.4AFR, I would assume I’m loosing quite a bit of power, thus making the comparison suspect overall. The dyno O2 didn't agree with my PL AFR readings, but the trends were parallel (his showed lean, so did mine). But, comparatively, the AFR is pretty close in the 3700 rpm range where the WCC outperforms the PTC by a mile.

I’m headed to the track tomorrow to see what the car does in real world conditions, but my main question here is why does the PTC couple so hard that it drags the rpm way down. Can the converter be reconfigured to avoid that or is that normal? I can actually count the time that it takes for the rpm to flash, then stop rising (the curly-Q), then start climbing again. I suppose if I’m anywhere near that rpm after the shifts, I guess I’m making decent torque, but it sure doesn’t seem like it will outperform the WCC given the narrow band of time it’s above the WCC numbers.

Thanks!

 

[Dusty Bradford]

With the 14.4 AFR I'd spend more time tuning it and get it to a track. An unlocked converter on the dyno will never look like a stick shift car which is basically what a locked up converter will look like.

Get the AFR situation fixed and then see what it does at the track. If the car is down on power where it couples, the converter will bend the engine over more than usual. If it drops to much on the gear change once you have the engine making good power, we can loosen it up.

 

[norbs]

Just remember a locked torque converter produces 0 torque multiplication,

 

[bison]

I need an opinion on the attached dyno graph and the performance of the PTC 9.5” converter I’m using. The graph compares one of last years dyno runs using a West Coast Converters 2800 stall L/U (locked up) with my current PTC 9.5” 3000 non-L/U. The top light blue line represents last year’s torque curve (locked up). The upper light red line represents this year’s torque curve with the PTC. The numbers inside the graph are meaningless as they are just where the reference bar happens to park on the printout.

One thing I see is that I’ve given up a huge amount of time where over 400ft/lbs of torque is being applied to the pavement. The PTC doesn’t catch up to the locked up WCC until about 4700 rpm. Then, when the PTC does “couple” it really drags down the rpm as indicated by the curly-Q. I then continue to apply some decent torque, but only to about 5150 rpm where it drops below last year’s curve again. Although, HP stays somewhat stable, but still lower than last year.

The AFR is quite different than before and at 14.4AFR, I would assume I’m loosing quite a bit of power, thus making the comparison suspect overall. The dyno O2 didn't agree with my PL AFR readings, but the trends were parallel (his showed lean, so did mine). But, comparatively, the AFR is pretty close in the 3700 rpm range where the WCC outperforms the PTC by a mile.

I’m headed to the track tomorrow to see what the car does in real world conditions, but my main question here is why does the PTC couple so hard that it drags the rpm way down. Can the converter be reconfigured to avoid that or is that normal? I can actually count the time that it takes for the rpm to flash, then stop rising (the curly-Q), then start climbing again. I suppose if I’m anywhere near that rpm after the shifts, I guess I’m making decent torque, but it sure doesn’t seem like it will outperform the WCC given the narrow band of time it’s above the WCC numbers.

Thanks!

I see several problems here. Dynos are not good for comparing converter performance. Im assuming you have an S trim turbo based on the stall Dusty gave you. Like Dusty pointed out you have to get the a/f consistent. If on 93 i myself target 10.6. Another problem i see is that Dusty will spec a converter based on the fact that you are going to be throwing some power at the converter. With your combo you DO NOT want the engine rpm below 5000. Preferably you want it between 5100 and 5600 with those parts. Its almost the same as what i have and i have a stock block and stock manifolds. Below 5000 rpm and my combo slows down. I shift at 5800 at 28.5psi and guess what? The converter flashes to 5100 at that boost. So once my engine goes over 5100 rpm in 1st which is within about 1 second it never goes below 5100 till i let off at the end. The highest average power is right in that window i gave and the engine spends almost the entire pass in that range. The dynojet probably cant load the converter like the pavement will in 3rd gear thats why you get that curly q on the graph. My slip at 134mph was 3%. If the PTC didnt couple as well as it does you will never be able to make a quarter pass without running out of rpm. Mine pulled all the way to 5750 in 3rd. When the car is at 28.5+psi and between 5100-5600 its like the car was shot out of a cannon. If i turn the boost down to 22-23 the converter will only flash to 4500-4600. No good. Way to low to get that sling shot effect where the engine power band is. If your engine wont pull to 5700 with that combo id look at valve springs or cam timing. I doubt that Jack would make an error on cam timing and or valve springs so my advice to you would be fix the lean problem and turn the boost up. Add octane if you need to. You should not be below 5000 rpm with those parts.

 

[quickt]

Just remember a locked torque converter produces 0 torque multiplication,

also no slippage

 

[Dusty Bradford]

The tune just looks to be way off from the other runs. I'd find out the reason it went 14.4 and go from there.

I don't put much faith at all in dynoing converter cars and never care about hp #'s on them. Alot of it comes down to the dyno operator. I've spent a day on the dyno tryng to help a local guy. His converter showed 47% slip before I got there......it showed 14% when I left and then 7% at the track.

The loaded dyno's aggrivate the issue if the operator doesn't know what he's doing. Most of them want to treat it like a stick car. Put it in drive and floor it at 3k rpm. You can't do that with a converter car unless it's a lock-up where you can lock it. The problem is the converter will flash and never recover before the pull is over. When dynoing a converter car, you have to slowly roll into it so the car isn't at full boost until 5k or so. This keeps the converter from flashing so high from all the low end torque.

 

[charlief1]

Good info Dusty.

 

[WSLN 6]

I concur on the info given. I went from a locked to a 9.5 PTC nd they are very different animals. The converter will pull the engine back down if you are not pushing it hard enough. Last season at 24psi my car would shift at 5800 rpm, then go back to 5100 or so and repeat. I am tuning my new XFI at only 14psi, and the car has a tough time even revving past 5200.
Time to crank it up!!

 

[nightrain]

...Im assuming you have an S trim turbo based on the stall Dusty gave you...

Actually, I have a P trim turbo. Not sure how that applies to stall, but that's what I gave Dusty when I ordered the converter.

...at 28.5psi and guess what? The converter flashes to 5100 at that boost. So once my engine goes over 5100 rpm in 1st which is within about 1 second it never goes below 5100 till i let off at the end. ...If i turn the boost down to 22-23 the converter will only flash to 4500-4600. No good. ..

Yeah, I kept the boost controller and wastegate actuator as it was from the last track runs where it ran 25lbs on the track. I didn't know that would have that effect on the converter, so that explains some of it. I could only push 21-22lbs on the dyno and was using C16.

Of course, I have to get the AFR in line. Not sure what happened there, but I was getting really funny readings on the PL (look liked an earthquake on a seismometer between 3500-4500rpm, then leveled out). Changed the WBO2, but then had that lean spike.

Here's a PL shot of the dyno run:

After reading all the responses, I don't think I want to be tuning on the dyno anyway. I didn't get to the track last Friday as it looked like rain. We'll see this Friday.

Thank you all for the responses! Very informative.

 

[bison]

Actually, I have a P trim turbo. Not sure how that applies to stall, but that's what I gave Dusty when I ordered the converter.



Yeah, I kept the boost controller and wastegate actuator as it was from the last track runs where it ran 25lbs on the track. I didn't know that would have that effect on the converter, so that explains some of it. I could only push 21-22lbs on the dyno and was using C16.

Of course, I have to get the AFR in line. Not sure what happened there, but I was getting really funny readings on the PL (look liked an earthquake on a seismometer between 3500-4500rpm, then leveled out). Changed the WBO2, but then had that lean spike.

Here's a PL shot of the dyno run:

After reading all the responses, I don't think I want to be tuning on the dyno anyway. I didn't get to the track last Friday as it looked like rain. We'll see this Friday.

Thank you all for the responses! Very informative.

With the p-trim it will spool faster and will give up some at over 5600 rpm. It will still go faster if you keep it over 5000 with that turbo and cam. You will need to run extra tension on the actuator to get more boost as rpm increases since the back pressure will over power the actuator spring even faster with the p-trim. I lost about .5psi from 5500-5750 with the S trim. I had an HD actuator with about 3 turns past a slip on the swing valve. When you run it again post the data logs.

 

[bison]

Looking at the injector DC on your Powerlogger file it looks like you are having a fuel delivery issue. Your DC shouldnt be that high with those injectors for that hp.

 

[Ed Valvo]

You were richer on the PTC pass. Leaner is meaner.... I'd say the HP would be about the same if the AFR was identical. Hard to do an apples to apples comparison with locked vs nonlock converter. Dynos are for bragging rights. Do your real tuning at the track. The dyno loads are much different than at the track. I found this out the hard way. I lifted a head. You need more fuel at the track cause the loads are greater.

 

[JDSfastGN]

do you have a sideband tracking chip? sorry if this has already been answered. If it is, then you may not be letting the sensor adjust long enough. When I went to the dyno I had an issue with it running fat because i wasn't letting it warm up and it defaulted to rich. Maybe your sensor is doing something similar but defaulting lean?

 

[nightrain]

do you have a sideband tracking chip? sorry if this has already been answered. If it is, then you may not be letting the sensor adjust long enough. When I went to the dyno I had an issue with it running fat because i wasn't letting it warm up and it defaulted to rich. Maybe your sensor is doing something similar but defaulting lean?

Yes, I have a wideband chip (6.0) from Eric Marshall. I think I have the mid-boost level setting too lean (12.0). That lean spike occurs early in the boost rise and mid boost AFR is set for 11.9. That's too lean, but I forgot I was trying to tune out a rich initial stumble. I have an SD chip on the way, but I'll try one more night at the track with the 6.0 before installing it.

 

[nightrain]

With the p-trim it will spool faster and will give up some at over 5600 rpm. It will still go faster if you keep it over 5000 with that turbo and cam. You will need to run extra tension on the actuator to get more boost as rpm increases since the back pressure will over power the actuator spring even faster with the p-trim. I lost about .5psi from 5500-5750 with the S trim. I had an HD actuator with about 3 turns past a slip on the swing valve. When you run it again post the data logs.

Okay, so I have a few data logs of the runs. Best 60's were low 1.7's, so I need some tire.

Log 4 is an 8lb launch and log 5 is about an 18lb launch. You can definitely see the wheel spin on log 5. Notice the rpm drag at 4500 rpm that matches the dyno runs. The trans has a manual brake and shifts itself, of course, into 2nd. But, it's shifting about 1000rpm too early. I would assume that's dragging me down at the beginning. Boost is not as high as you recommend, but I have boost fear issues from lifting heads in the past, so I'm creeping up on it. Unfortunately I ran sub-11.49's for most of the 8 runs on Friday and they tell me I need a bar. Perhaps I will never know the potential of the car or what it would have been with a 1.5 60' and a 1/2 shift at 5800 rpm. If you see anything on the logs that jumps out at you, please let me know.

Thanks!

 

[bison]

Okay, so I have a few data logs of the runs. Best 60's were low 1.7's, so I need some tire.

Log 4 is an 8lb launch and log 5 is about an 18lb launch. You can definitely see the wheel spin on log 5. Notice the rpm drag at 4500 rpm that matches the dyno runs. The trans has a manual brake and shifts itself, of course, into 2nd. But, it's shifting about 1000rpm too early. I would assume that's dragging me down at the beginning. Boost is not as high as you recommend, but I have boost fear issues from lifting heads in the past, so I'm creeping up on it. Unfortunately I ran sub-11.49's for most of the 8 runs on Friday and they tell me I need a bar. Perhaps I will never know the potential of the car or what it would have been with a 1.5 60' and a 1/2 shift at 5800 rpm. If you see anything on the logs that jumps out at you, please let me know.

Thanks!

Ok. Ill take a look at the logs later. If you want a later 1-2 you should consider a different valve body. CZ or KC. That will take care of the early 1-2. If you are not going to turn it up which i would if i were you then id loosen the converter about 300-400rpm. Go with some c16 and turn it up to 28-30psi if you have enough pump. If you lifted heads in the past then it probably had some detonation. Whenever i hear of heads lifting of detonation the #1 reason that comes to mind is that there was not enough octane. Better to be safe than sorry on octane. If yo insist on 92 octane id look into multiple nozzles (like 2 or 3) and have a good grip on the a/f throughout the run. I target 10.5-10.6 on 93 with 22 degrees in 3rd. Going leaner while spraying in a lot of alky is asking for trouble. Getting greedy with pump gas will get you every time. :biggrin:

 

[aminga]

Your WOT fuel correction is pretty high. You may want to add base fuel. It's almost against the high limit

 

[nightrain]

Ok. Ill take a look at the logs later. If you want a later 1-2 you should consider a different valve body. CZ or KC. That will take care of the early 1-2. If you are not going to turn it up which i would if i were you then id loosen the converter about 300-400rpm. Go with some c16 and turn it up to 28-30psi if you have enough pump. If you lifted heads in the past then it probably had some detonation. Whenever i hear of heads lifting of detonation the #1 reason that comes to mind is that there was not enough octane. Better to be safe than sorry on octane. If yo insist on 92 octane id look into multiple nozzles (like 2 or 3) and have a good grip on the a/f throughout the run. I target 10.5-10.6 on 93 with 22 degrees in 3rd. Going leaner while spraying in a lot of alky is asking for trouble. Getting greedy with pump gas will get you every time. :biggrin:

You are correct. I lifted the heads when I tried running 92 octane/alky right off the dyno tuning last year. Gained 3-4lbs of boost at the track and the knock alarm yelled at me about 75 feet to the traps. I thought "the finish line is right there!" By the time I thought twice, it was too late.

So, fast forward to this season and I'm running straight C16 with at least 8 gals in the tank. I neglected to mention that and forgot about my sig. still showing alky session on the dyno.

As to base fuel, it seems if I chase the BLM's (adding fuel correction when BLM's are reading way high), it runs too rich. Drops in the 10's AFR. Appreciate if you can look at the files and advise. I don't see any appreciable KR, so I think I have room to gain some boost. I just don't like that boost spike in the beginning, so if I raise boost I'll spike higher as well.

 

[aminga]

As to base fuel, it seems if I chase the BLM's (adding fuel correction when BLM's are reading way high), it runs too rich. Drops in the 10's AFR. Appreciate if you can look at the files and advise. I don't see any appreciable KR, so I think I have room to gain some boost. I just don't like that boost spike in the beginning, so if I raise boost I'll spike higher as well.

So if you are running one of Eric's 6.0 chips then at WOT BLM isn't really BLM it's the WB02 correction factor. It's how much fuel the chip is adding to maintain the target A/F. In your case it starts out OK but keeps rising to 147 by the end of the run. The limit is 155 (I think). So the chip is adding WOT fuel to keep the Wideband at 11.5.

It looks like you are running one and your Chip is set to

11.5 WOT A/F 1&2nd
11.5 WOT A/F 3&4nd
10.9 Mid Boost A/F
And your base fuel is 120.


I'd raise it to say 138 or so and try to get the BLM cell at the top of the data screen as close to 128 as possible