Art Carr vs PTC converter results

murphster

Well-Known Member
I recently switched from an older Art Carr 9.5" lockup converter (14031) to a newer PTC 9.5" nonlock converter. The Art Carr did not lockup at WOT of course and was very inefficient. With some runs at lower boost on my new setup in the white T, I had concerns that the converter slippage with the Art Carr was going to cost me mph and ET once I started turning the boost up. I never mph'd very well with this Art Carr converter in the past, although it did get out of the hole well. On my old combo, the rpms were too high at the end of the 1/4 and out of the range of the stock cam, even with 28" tires.

With the new PTC converter I noticed that the rpms at the end of the 1/4 were definitely lower and the rpms dropped more on the shift. Below is a screengrab of two Directscan runs with each converter, the Art Carr on the left and the PTC on the right. Nothing else on the car was changed.
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Art_Carr_vs_PTC.JPG

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You can tell from the screengrabs that the shifts were dropping a lot more rpm with the PTC. And for a very similar mph at the end of the run, the rpm was about 600 less with the PTC. For the 2-3 shift, on the Art Carr I dropped from 6075 to 4950 while with the PTC I dropped from 6300 to 4750. As shown in the picture, at the end of the run I was at 119mph and 5950rpm with the Art Carr and 120mph and 5375rpm with the PTC.

Using some online calculators, here are the calculated slippages for the runs above:

Art Carr 9.5" lockup 14031 (not locked at WOT)

22.3%
18.2%

PTC 9.5" nonlock

9.5%
8.7%


On other runs with the Art Carr on the older combo with less power and lower rpms, the slippage was even worse. It seemed to improve with more power and rpms. If I turned the boost up for some high 120 mph runs, it might have gotten into the lower teens, who knows. I'm guessing with the PTC that the efficiency will improve to maybe 4-5% once the boost, power, and rpms are raised.

Another factor that came into play is that since the PTC converter is more efficient, at the current boost it drops the rpms down below the power range of the cam after the shifts and all the way through third. I'm figuring that once the boost and power is raised, the stall will increase to right where I want it to be and the rpms where be right on at the end of third. Both of the runs above were in the 15-17psi boost range. Next time boost will be in the low 20's.
 

2 QK 4 U

Banned
Very nice data!

I'm having the same issue with my converter. It will not lock at WOT...

I'm going thru at 5875 at 118

I'd love to get a NLU converter in my car.

Do you have any 1/4 mi track results with the PTC?
 

murphster

Well-Known Member
The run above was recorded at the track. I just have a couple of low boost runs (ex. 11.6@119mph at 17psi with a soft 1.8 60ft). I wanted to be able to compare it to the other converter first to see if it was doing what I wanted.

By the way, my Art Carr wasn't supposed to lock at WOT. It was just a lockup for highway cruising. So there wasn't anything wrong with it, just not very efficient. That was one of the reasons I wanted to try the PTC. Supposed to be very efficient for a nonlock and should be easier on the 2004R compared to something like a locked multidisc Vigilante (one of which I had brand new and sold to get the PTC).
 

2 QK 4 U

Banned
I'm wishing I had went NLU with my setup.

Lock up is nice on the highway but it's not that much RPM without it.

You are not even pushing your setup anywhere close to it's potential. That car is gonna fly on 20-22 psi...

I'm trying to get a 10.9x pass on my setup. I think it'll do it with a NLU converter. I have to run a lot of boost 27-28, no ported heads.
Then I have a set of ported heads waiting to be put on. 10.5s should be easy with those.

Keep us updated on your progress!:)
 

V6RACER

The true 8 Second 109!
Food for thought.. With my PTC 9.5 I went through the traps at 6200 rpm and 146 mph..

PTC convertors work!
 

GNVYUS 1

Well-Known Member
Yep I think everyone is starting to see that PTC is the non lock up company to turn too.

IMO, I'd send it back to PTC to tighten up and that file would probably help them. :cool:
 

VadersV6

Active Member
It has nothing to do with the brand. The TC needs to be dialed in for your weight, gearing and power curve. If the AC was slipping too much, then it was obviously designed for less power, or less weight in mind. Theres rarely a time when you can buy a TC off the shelf and have it work exactly how you want. It takes ALOT of data to get a TC made just right for your car. Your dealing with a fluid turbine, not a clutch, so theres a million variables. You think the first jet engine worked just right? Every high end racer will get a TC thats close, make some passes, datalog the crap out of it, and have the TC worked on. Then the second time around, its alot closer, but usually still not perfect. Changing brand names, often times just gets you back to square 1. AC could have taken your datalogs and all your other info, and made a TC that performs exactly like this PTC one, if not better. If you went back to PTC with this data, they could improve on it as well. The only time brand names make a difference, is in terms of engineering practices which support strength and reliability. I know the AC's are damn strong. I traded an AC 16930 for a TCS 9-11 TC, and the AC is considered billet, although its a different execution. The 9-11 was a solid chunk machined out, and looked strong, but in reality wasnt half as strong as the AC. The guy I traded with was bitching about the AC saying he'd never throw this in his car, and it's not billet blah blah. Telling him it was rated for over 1000hp made no difference. He cared about the way it looked. I ended up paying him extra money to shut him up. I do know the AC made my car pull like a rocket sled compared to the stock one. But yeah, it did slip alot. AC's seem to slip more out of the box, but they can easily be reconfigured and usually for free the first time.
 

murphster

Well-Known Member
It has nothing to do with the brand. The TC needs to be dialed in for your weight, gearing and power curve. If the AC was slipping too much, then it was obviously designed for less power, or less weight in mind. ........................AC's seem to slip more out of the box, but they can easily be reconfigured and usually for free the first time.

Well, considering my AC was pretty old and I wanted to go with a nonlock, my choices were where to buy a new converter. Getting the AC reconfigured wasn't really on the table.

I don't think its that easy for every brand to get the same efficiencies with just one restall. I think part of what your paying for is how good the given converter people are at getting the converter dialed in, and some people are better at it than others. PTC seemed to have the nonlocks running pretty good in fast cars with similar combos to mine so I decided to try it out.

If anything, my AC seems to be the opposite of what you stated above. When I ran it on a stock turbo car with less power, it was super inefficient. As I stepped up the power it seems to be getting more efficient, but I don't think it was ever going to be as efficient as I hoped. I wanted to get the best one I could and start from there.

One thing I didn't really emphasize is that most of the data out there on PTCs are from Turbo 400s, and I'm still running a 2004R. PTC is still dialing in the converters for the 200s as can be seen from other posts here and there, but I thought I share my initial results with everyone and update them as I turn up the wick.
 

Slow91z

Turbobuick.com Helper
Staff member
Hey Murph just food for thought, you said the AC was getting more efficient woth more power, I just wanted to bring up the thought that maybe it was getting more efficient with RPM.

You have to remember that the harder you spin it the more it couples, and Stockish Buick guys shift WAY earlier than most other cars at the same power level (just look at the LS1 guys). I personally think this fact plus the fact that torque is what changes stall speed (and being boosted makes the torque curve down low pretty messed up) is why the TC setup is so hard to get right on our cars.
 

johnplogii

Senior citizen
From what I have heard the Art Carr's need to be spun to 6500-7000 to become really efficient. I went from an AC to PTC recently and was very happy. The PTC spools easier than the 'n' stall AC and is way more efficient up top (14% slip to 4% slip) It was going through the traps at 6200 and is now 5600. If I would have had the AC tightened up it would have been more efficient but would have been harder to spool.
 

VadersV6

Active Member
Its news to me that AC even made a lockup TC for our cars. Mine was nonlock, and spooled like a raped ape and pulled insane. Some idiot had put 4.56's in my car and it stalled at about 2800. When I put the stock GN rear in, with stock gears, now it didnt even start building boost till 3200. The torque curve, weight and gearing have a massive impact on the way a TC works. Increasing the fin angle (higher angle) will improve high rpm coupling but reduce low rpm coupling and torque multiplication. You lower the fin angle and the opposite will happen. Its real hard to get everything you want out of a TC, especially on a turbo motor which is prone to having people change turbos or other parts that alter the power curve constantly. You may have a trick TC that couples great at high rpm and offers great slip (quick spool) / torque multiplication at lower rpms with a TE-44, but change to a bigger turbo and suddenly it's not slipping as much at lower rpm's, because the lower end of the curve has been reduced in power, and now spoolup is slower and torque multiplication has suffered...people right away accuse the turbo of being the culprit, when its really the fact that the TC's characteristics have changed. Loosen the TC up a bit at lower rpm/load and now that turbo will jump just as quick as the TE-44.
 

wbrophy

Member
From what I have heard the Art Carr's need to be spun to 6500-7000 to become really efficient. I went from an AC to PTC recently and was very happy. The PTC spools easier than the 'n' stall AC and is way more efficient up top (14% slip to 4% slip) It was going through the traps at 6200 and is now 5600. If I would have had the AC tightened up it would have been more efficient but would have been harder to spool.
I have a 16930 AC and now a new converter, how many rpm's did the AC drop between gears and the PTC?
Thanks Bill
 

johnplogii

Senior citizen
I don't know what the rpm drop is with either, never really watched, but I can tell you the difference is definately noticeable. The ptc almost feels like a lockup converter when I shift 2-3 at 6000.
 

S2V6RACER

Banned
I'd give Dusty a call and go with the PTC. I keep reading about his customer service and happy customers. Hard to see how you can go wrong.
 

Dusty Bradford

Well-Known Member
AC could have taken your datalogs and all your other info, and made a TC that performs exactly like this PTC one, if not better. If you went back to PTC with this data, they could improve on it as well. The only time brand names make a difference, is in terms of engineering practices which support strength and reliability

I have to disagree. How do you think this PTC converter came about?? It was only after I tried everything out there from Precision and both Art Carrs in Texas and California only to find out none of them made me happy. I can tell you there isn't another converter out there that will spool as easy and lock-up in high gear like this converter. It took me at least 5 converters in different housings to get to what we offer today. I have seen inside a California Art Carr unit after it broke after 3 passes. It was sent back to them for repair which they refused due to the time we had it and it was the biggest mistake they could have made. We had them send it back in pieces so we could let PTC repair it for us and you know what we found....although the converter worked very well it's internals compare to what we would call a budget converter. Definately not what I'd call 1000hp capable. The pieces inside are what we use in a $500 converter and he's charging $1000+. At that point we were done with them.

The AC works very well in some cases but it indeed needs to spin 6300-6600 to make it efficient. There is no comparison between his unit and our 9.5.

In all the converters I've replaced the only thing that comes close to ours is ATI and Neil Chance.

From what I have heard the Art Carr's need to be spun to 6500-7000 to become really efficient. I went from an AC to PTC recently and was very happy. The PTC spools easier than the 'n' stall AC and is way more efficient up top (14% slip to 4% slip) It was going through the traps at 6200 and is now 5600. If I would have had the AC tightened up it would have been more efficient but would have been harder to spool.

This sums it up entirely. Easier spool and more efficient. This is what it was engineered to do.
 
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