edcmat-l1

iTrader: (10)

Just like the title says. Check out the difference in numbers, locked/unlocked. The wavey-ness (new word) is from the clutch not holding. We will probably do some diag work to determine the cause, if the customer wants us to. Could be electrical, could be fluid pressure, could be a clutch issue.
Almost a 50 hp difference. This case is extreme, but shows the drastic power absorption of a high stall speed converter. This one probably has too much stall speed for the motor its behind. Nothing like 48 HP just 'disappearing', huh?
Comments.......

lt1s10

iTrader: (2)

what was the engine build and the stall speed??

edcmat-l1

iTrader: (10)

H/C/I/LTs 346 98 Fbody with spray. Stall speed was/is 4000.

Gilbert@Ace Racing

I have been speaking with this customer via p.m. last week and as recenlty as today he provided me with the same dyno graphs. I saw this thread and thought I would chime in as well. I invited the customer to call me so we could discuss it, feel free to do so yourself.

Based on his description of driveability symptoms and now the Dyno graph's I would suspect that the Convert Clutch is failing. An easy way to determine that is to remove an inspection cover on the bellhousing and visually inspect the front cover of the converter. If it is discolored or the paint is damaged, then the clutch is definately slipping. Also, what is the fluid condition... before and after the pulls, assuming you checked it that is?

If you commanded the converter to lock and you experienced rpm flares then it only points to the converter IMHO.

But that is without a detailed discussion about the vehicle and symptoms of course.

g

edcmat-l1

iTrader: (10)

I'm very **** about the way I diagnose electrically controlled mechanical devices. In other words, any damn thing controlled by the computer.
This could be caused by nothing more than a bad connection at the trans.
The only way to eliminate the electrical system is to scope it for volts and amperage draw. If the 12 volt source is good and steady, and the ground switching circuit (driver) is steady, then the amperage should remain steady. If there is a fluctuation of either, it will be pretty easy to find. If the + and - side of the circuit is steady, and the amperage fluctuates, chances are the solenoid is going south. If everything looks fine, we're down to a fluid pressure leak, or the clutch itself.
I am more leaning towards an electrical problem, as it does this with very little load on it.
This thread wasnt about the clutch problem, but the power absorption of an unlocked stall converter.

Speedmonster185

iTrader: (1)

Wow, that makes me feel a little better getting 313/320 today with my ss3600 unlocked. an M6 SS with just the dual-dual catback, lid, and a MAF put down 314/327 right after me and I felt kinda bad about that. It's amazing how much faster the autos are (if the two cars have the same rwhp and especially with the auto is unlocked like it would while racing) even though they are actually putting down so much less power than the M6 with the same mods... That just doesn't make sense to my head... haha. I don't like dynos anymore... I like tracks... lol

12secSS

iTrader: (30)

Is that 4000 stall (please don't say) before or after (hopefully) the spray? Also what is the STR? By the looks of the dyno graph, regardless of TCC issues, the converter is not matched right for the combo. You shouldn't see that much difference in power, even with a 2.8 STR (hits hard of the line, but losses top end, pretty much a bracket/60' converter). Unless this is a track only car, just my thoughts on the subject.

edcmat-l1

iTrader: (10)

You are correct. The converter is not matched to the combo. You are also correct in that there should not be that much of a power loss. I'm not sure exactly how its rated, the car owner just told me its a 4000 rpm stall speed.
The stall speed has nothing to do with the wavyness of the graph. But it does have everything to do with the power difference.

silver-mod-o

iTrader: (15)

LOL, you could surf on the wave in my graph hahaha...

a bad solenoid or too little lockup/apply pressure could make it act the same way.

edcmat-l1

iTrader: (10)

You are correct. As well as a bad connection at the trans harness connector, inside at the solenoid. Alot of stuff besides just the 'verter bein bad.

Slowhawk

iTrader: (12)

I believe the difference. We have a 02 with a 4400 stall make 445rwhp locked and 365rwhp unlocked. Car still runs 10.8 at 3650lbs.

DannoWS6

iTrader: (5)

Yeah. my car is also about a 40hp difference locked vs unlocked.

If it's slipping when commanding lockup, I'd bet anything it's the lockup clutch at this point.

edcmat-l1

iTrader: (10)

Its very possible, but theres too many variables, too many parts that all contribute to the clutch locking up. From a professional stand point, we cant just throw a converter in it and hope thats the fix. If he wants it diagnosed, and the cause pinpointed, then thats where we come in.
As for the stall speed, and the power absorption, I think it needs a dif converter. But again, if hes happy with it, and just wants to cure the lock up problem, we can do that.

Muerte_X

iTrader: (1)

I didn't realize the difference was that much. Unlocked with a 3800 converter I dyno'd 302whp (free mods, lid, cutout), and with a 4400 converter I dyno'd 298whp (different dyno's though, and I'm not even sure that's beyond the error of the dyno). They were both 9.5" converters (3800 was yank, 2.7STR, 4400 was built by a local guy). With a lid only, I dyno'd 295whp iirc. What type of converter is it? Maybe if it's a bigger sized (physically) stall it might not be very efficient at that stall speed?

There was a 6-speed car of the same year and mods, and he put down something like 320. I figured the loss of the slipping converter would be even less, considering the rotating mass of a converter, even locked, compared to a clutch.

I'm about to put headers on, and I'm really wondering what it'll put down compared to before.


And i'm sure you guys realize this, but I don't think a converter clutch is designed to be able to hold WOT while locked up, the clutches inside are pretty small. Of course, I see the advantage if you're going for dyno numbers, but personally I'd rather see how the car puts the power down the way i drive it. In certain parts of the graph, it's putting down 40whp more than with the stock stall, that's what I like to see

slimcracka

iTrader: (7)

how much would someone loose to say a bolt on car that dynoed 323\324 unlocked with a ss3600?

98Camarod

iTrader: (43)

This is my car. I just seen this thread. My combo consists of comp xer 230/230 .591/.591, stock 241 heads with prc dual springs, chromoly pr's, cloye's timing chain, melling oil pump, lid, pacesetters, tsp duals, hp series 4000 converter with a 2.4 str, 4.10's, and a hsw wet kit that has not been used yet. I am out of town and haven't had a chance to jack the car up and inspect the converter. You can hear exactly what you see when you have a steady load applied.

RedDemonLsX

iTrader: (2)

This is almost exactly what happened to my car,my fuddle was pooping on the dyno and i only made 405/385 with mods in sig...Yank and FLT level 5 are going in this week and i expect to pick up more power

98Camarod

iTrader: (43)

Can you post your dyno graph?

RedDemonLsX

iTrader: (2)

Its still at the shop,i didnt bother with taking it yet because my trans and verter are going in and i wanted to forget those numbers...this was 2 weeks ago.When i pick up the car this week ill post up for ya..ill get both graphs,before and after..

slimcracka

iTrader: (7)

nice man i want a flt level 4 with a pt4000...cant wait to see your results..