[footjoy]

Well I found my tc is slipping 14-15% at 2500 rpm part throttle I am using a 2200-2500 Stall Non lockup converter.

The manufacturer said that is normal.

I googled converter builders called one and he humbled me and said we don't care about part throttle overdrive applications.

So I am calling on the people who use torque converters. My transmission is a 200 4r non lock up with 3.73 rear gears. My first choice would be a NL converter with about 5-7% slippage if they make one.
if I can't find one i will have to convert my trans to lock up.

Any help would be appreciated.

Thanks Greg

[77 TRASHCAN]

Call Cliff

[76TA462]

Lonnie at Extreme Automatics is another good person to contact on this.

[Steve C.]

I use a non-lock up converter with a 200-4R. It was built by Continental before they went out of business. Under a steady state cruise speed on the open highway the converter has about a 200 rpm slippage, very acceptable in my opinion. With my 27.7" diameter rear tire and 3.73 gears it is about 2300 rpm at 70 mph.


.

[68lemans462]

Originally Posted by footjoy

Well I found my tc is slipping 14-15% at 2500 rpm part throttle I am using a 2200-2500 Stall Non lockup converter.

The manufacturer said that is normal.

I googled converter builders called one and he humbled me and said we don't care about part throttle overdrive applications.

So I am calling on the people who use torque converters. My transmission is a 200 4r non lock up with 3.73 rear gears. My first choice would be a NL converter with about 5-7% slippage if they make one.
if I can't find one i will have to convert my trans to lock up.

Any help would be appreciated.

Thanks Greg

I would also call Cliff, he's an expert in this area. Get your wallet ready you will need it. As Pontiac Greg (RIP) used to say "grab your wallet and cough".... Good luck

[Formulajones]

Wow Greg, for a converter company to just tell you they don't care about part throttle applications in overdrive just tells me they don't care about making a good converter.

You can absolutely have a well coupled converter in an overdrive application without lockup, and still have a workable flash stall speed when pushed. It takes someone that knows how to build a good "efficient" converter.

To have one slipping 14-15-17% and to then have Hughes tell you that's normal doesn't build any confidence in me using them for converters.

The issue for many with these overdrives that are mechanically controlled, the lockup feature becomes a nuisance behind engines that have any kind of camshaft in them with overlap. It's very difficult and sometimes impossible to tune the lockup where it's happy behind an engine like that with a little vacuum controlled switch and a TV cable. So many find that going without the lockup feature is the best route, but you really need an efficient converter to do that like Steve C has.
This is where the "E" transmissions have a huge advantage, with infinite control of the lockup at any speed, any gear, and any throttle position making tuning the lockup behind a more radical engine a piece of cake, there is no reason to not use a lockup in those type of transmissions.

In your case however, with a very mild 400, a 2800 or 2801 cam if I remember right, it probably idles baby smooth with tons of vacuum (it should) In which case you would have no problem what so ever with a mechanically controlled (vacuum switch and TV cable) lockup converter in this application. It should be smooth operation with a very smooth running engine. If it were mine, with a mild combo like that, I'd take advantage of what a lockup has to offer. In which case the stall speed, and how much slippage it has isn't as big of a player, since it locks up at cruise anyway.

However I don't think that's going to be the magic solution to your mileage dilemma. Single digits aren't going to magically improve to high teens (where I think you should be) with a lockup.

[68lemans462]

Originally Posted by Formulajones

However I don't think that's going to be the magic solution to your mileage dilemma. Single digits aren't going to magically improve to high teens (where I think you should be) with a lockup.

If the intent is to improve MPG the numbers simply dont make sense (in ANY way). If you are going for performance a good torque converter is one of the best things you can do!

[max 93]

Originally Posted by 76TA462

Lonnie at Extreme Automatics is another good person to contact on this.

I have to disagree. I bought a transmission and converter from him. I love the transmission but hated the converter. It was very loose for normal driving. Would have been fine if you are racing all the time. I replaced it with a converter from TSP. And I really like it.

[Navy Horn 16]

There isn't anything wrong with your convertor. Don't get your head wrapped around some theoretical loss of efficiency that you forget about the driveablity that you are getting.

If you fix your carburetor problem, with your gear ratio and transmission you should be getting well over 20mpg. Who cares about 15% slippage at light cruise at that point?

You are talking about taking major steps away from performance and driveablity to chase an MPG number in a GTO, and you haven't addressed your fuel system which is the cause of your poor mileage.

[68lemans462]

Originally Posted by Navy Horn 16

If you fix your carburetor problem, with your gear ratio and transmission you should be getting well over 20mpg. Who cares about 15% slippage at light cruise at that point?

"Well over 20MPG" ... LOL

Sent from my SM-G981V using Tapatalk

[pastry_chef]

A local here picked up a lockup converter from PTC - ptcrace.com at my suggestion. 10 inch 3200 stall.

When you lockup during cruise the tach RPM barely moves, more noticed in small change in engine pitch.
His 560 HP 455 logged just over 20 MPG on a highway cruise - 2004R.

He paid less than $500, I think it was 12 years ago.

[Navy Horn 16]

Originally Posted by 68lemans462

"Well over 20MPG" ... LOL

I can get 25 when I'm trying for gas mileage, which isn't often. If I keep it right at 70, my car sips gas. A .67 overdrive through 3.42s and a 28 inch tall tire...

I can cruise to the drag strip with that mileage and do this:


LoL right back at ya.

[pastry_chef]

Originally Posted by Navy Horn 16

I can get 25 when I'm trying for gas mileage, which isn't often. If I keep it right at 70, my car sips gas. A .67 overdrive through 3.42s and a 28 inch tall tire...

Watch out for those "experts". LOL.

[Formulajones]

Originally Posted by 68lemans462

If the intent is to improve MPG the numbers simply dont make sense (in ANY way). If you are going for performance a good torque converter is one of the best things you can do!

Not sure what you mean.

You can have performance and mpg. I chase both all the time with all our cars. Nothing wrong with someone wanting mpg out of their muscle car. I wouldn't be able to afford to daily drive them if the MPG was horrible. I have a bunch of examples here that are very respectable in the MPG department, better than most daily driven SUV's, yet can still run a very respectable number at the track. Some of them don't even need an overdrive to do it.

[Navy Horn 16]

Originally Posted by Formulajones

You can have performance and mpg.

This is true, but there are also trade-offs.

"Performance" can also mean different things, especially when you are talking about specific components like torque convertors. A non-lockup convertor like what he has is performing exactly like it's designed to perform. Most people who get non-lockup convertors are looking for aspects of driveablity or off-the line performance.

If he swaps to a tighter convertor to get better MPG for cruising, the whole car is going to perform differently from a stop and through the gears. Shift points and how hard the transmission shifts will probably be impacted as well. Not to mention how the car drives going up a hill or when you let off the gas.

He's got another giant thread on here where he's chasing timing because he had carbon build up, and he's never had his cruise AFR checked. His torque convertor isn't costing his his fuel economy any more than his ignition timing is. The same problem (overly rich mixture from difficult to tune tri-power) would cause the carbon build up and low fuel mileage problem.

Fixing AFR is low hanging fruit compared to swapping torque converters. Fix that first brother. A little time swapping jets over the fender will save you a lot of time laying under the car, and will get you driving with better performance a lot faster.

[Formulajones]

I feel it's going to be a combination of things for him. I don't believe it's just one overlying issue that's causing his single digit mpg. I've never really found a single big issue with a car and MPG unless it just came in here with the worst state of tune you've ever seen, and they are out there for sure, but that doesn't seem to be his issue based off what he's posted.


On the converter deal, if you have a pretty efficient converter they'll both drive and perform at the track very well.
Kris at Continental was pretty good at this. Tri-Shield is also pretty good at this. There are a couple others. Lenny at UCC comes highly recommended, and used to work with Kris at Continental.

I've had a Continental in my Chevelle for about 20 years that Kris did for me, with a 600hp 454 in front of it. I've had about 4 or 5 converters in this car that I remember over the last 35 years. This Continental has been the best by far. It couples very nicely around town and on the highway, to the point that it almost doesn't even feel like it has a stall converter in it. I can cruise at 55 mph and 2800 rpm with the 4.10's and 28" tire. The Calculator doesn't even factor in any slip percentage, yet at the track it will flash to 3400 and cut 1.5x 60 foot times. Even with this engine and gear setup, with no overdrive, it still gets 12 mpg with AFR's hovering in the high 12's to low 13's at cruise. I completely expect easy mid teens for mpg when the 4L80E goes in. I can't complain about that.

[Navy Horn 16]

Originally Posted by Formulajones

I feel it's going to be a combination of things for him. I don't believe it's just one overlying issue that's causing his single digit mpg. I've never really found a single big issue with a car and MPG unless it just came in here with the worst state of tune you've ever seen, and they are out there for sure, but that doesn't seem to be his issue based off what he's posted.

It may not be a single issue. But once you get the timing set right, fuel is next.

A chassis dyno is what, $150/hour max? Most of those guys are used to people just wanting to do high RPM pulls, but they will let you put the sniffer up the tail pipe and see what your AFR is at 2200-2500 rpm under a load...do that, and the pulls, see if you have something way out of whack before you go ripping parts out of it.

If someone tells me they have carbon build up and their fuel mileage sucks, both of those things point to being overly rich.

[pastry_chef]

Originally Posted by Formulajones

There are a couple others.

Some are pretty much blinded by this forum.
UCC / Lenny has accolades wide and far across brands and forums and is used by many elite racers and record holders. Probably top 3 IMO.
If someone looking to gain EVERY performance advantage won't use a brand.. Think to consider why not? Look at what the big dogs use.

[Cliff R]

I've been at this longer than most who will read this and have tried, used, and tested enough converters in my Ventura and other cars we drive/race out of the shop to nearly fill up the bed of a half ton pick-up truck. Yes, I tested converters for Kris and got so good at swapping them out had it down to under 40 minutes. Since he's out of business and they are NLA I woln't go into great detail about what we came up with and made available to our customers when I was selling them.

As for testing, luckily I have a car that not only runs the numbers it is deadly consistent. So much so that I see everything when changing parts like intakes, camshafts, converters, etc.

What I have found is that nearly every company out there will have no problem at all getting you all the stall speed you need. That part is easy and initially when you install a higher stall converter than what you pulled out it feels pretty good on the first couple of "hits". The fun begins after that as you take your first test drive and lose any sort of shift feel and rolling along at 35mph or so the RPM's rises quickly up past 2500 if not 3000rpm's just pushing down the throttle to climb a steep grade w/o shifting out of high gear (sound familiar) Your heart sinks at that point and you know in a day or so you'll be pulling that slipping POS out and going a different direction.

So you go ahead and make some track runs and find that at best you may pick up a little in 60' but absolutely KILLED the car on the rest of the run as your Pontiac engine doesn't have the RPM potential to even come close to locking this thing up....bummer.

What Kris at Continental was really good at was supplying a converter that had excellent flash stall with traction but very well coupled for "normal" driving on the street. That feat is not easily duplicated. Case in point. I hired Hugh's to build a 10" converter to rival the tight 10" or Jim Hand converter Kris was selling. They were given all the specs and the first prototype was loose as a goose EVERYPLACE and flashed to about 4500rpm's on a full throttle start with traction. Out it comes and back it goes with instructions to make it "as tight as possible". The "builder" said that we wouldn't like it. Remarkably his next effort wasn't really all that bad. It flashed to about 3400rpm's and pretty well couple on the run showing about 300-400 slippage on top end. It didn't even drive all that bad on the street but I could shoot it to about 2400rpm's against the brakes. A tight 10" Continental converter in comparison (I'll use the numbers from mine) will flash to 3500rpms with traction and go thru the traps about 50-100rpms slippage or basically locked nearly solid. Against the brakes the tires spin at apprx 1900rpm's. On the street for "normal" driving you'd never even know it's in there. Shifts are relatively firm, tach doesn't flare up when you back up in reverse or push down to climb a steep grade at lower speeds in high gear. It's just one really nice converter. That converter has also been good enough for a half dozen wins at Norwalk, won several pretty big street/muscle car events, and more Gambler's races at our local track than I can count. So it's a really nice part and even though I've moved on to another company there are no plans of ever removing it unless it breaks.

At about the same time we were testing a converter from Hughs we tested a 10" Coan in another car. It was an EXCELLENT race converter, flashing to 3800rpm's and good in 60' times, but it had a little more slippage on top end than I felt was acceptable (although the car ET'd well) and on the street it was poorly coupled for normal driving and the tach flashed up pretty high if you pushed hard on the throttle for any reason. Several trips back to them made really no improvement whatsoever.

Anyhow, I could fill 20-30 pages here with REAL WORLD test results. Doesn't make me an expert by any means but at least I have a Pontiac powered car that moves and don't rely on ALL of my information from Google and trying to associate myself with a few "big names" in this hobby/industry........FWIW.....

I'd also add that I talked to the OP today and recommended that before we even talk much about a custom converter get the carb leaned up some and nail the tune down. The fuel economy is WAY off the mark indicating fundamental issues in other areas so a converter thrown into that deal just muddies the water a bit and may not be what is needed here. Once things are optimized there we'll take another look at converter efficiency and see if a better one is in the cards for him........Cliff

[Formulajones]

Originally Posted by pastry_chef

Some are pretty much blinded by this forum.
UCC / Lenny has accolades wide and far across brands and forums and is used by many elite racers and record holders. Probably top 3 IMO.
If someone looking to gain EVERY performance advantage won't use a brand.. Think to consider why not? Look at what the big dogs use.

I mentioned Lenny used to work with Kris at Continental, they likely share a lot of the same knowledge on converters and could be fair to say that might have a little bit to do with UCC success. I wouldn't be afraid to try one.

I've used a bunch of different brand converters over a 35 year period. Not UCC, but I've had several Continentals, TCI and B&M, Coan, Fuddle (if anyone remembers them) Precision Industries, and even a cheap Dayco. Most recently Tri-Shield (TSP) I've tried Vega converters and even currently have an OEM L88 converter in one car.

There have only been a couple converters I've been happy with. Continental, the current one in my chevelle is absolutely wonderful, does everything Cliff mentions above. The TSP in a recent 455 Formula I built was very nice and acted much like a well done Continental. The Precision Industry I ran in a 4th gen was pretty darn good but it was a lockup on a 4L60E so cruise drivability wasn't quite as critical. The GM L88 converter isn't a bad piece. Not a really high flash stall (about 2600 or so) but it drives nice, very similar to the Continental in my Chevelle, just has less flash stall. Pretty much everything else I've tried sucked.
I'm open to trying a UCC, up in the air on the Hughes though.