Converter holding me back?
Converter holding me back? So I just came back from the track, slightly disapointed. DA was around 1000. Was pulling 12.3's@112mph and one 12.2. Only cutting 1.8 60' times (having problems with air in ABS module after putting in line lock. Front brakes still have air in there and I can only footbrake it to about 1400 rpms before it will push through the brakes).
60' is not my problem, just my mph. Mods are ms4 cam, ls6 intake, pandp tb, 3.73's, longtubes, true duals, lid, a good tune, and a midwest 3400 stall. I'm not sure of the weight of the car, but I have no weight reduction, only taken out the spare tire and jack. I've ran a best of 12.0@114mph, but that was with a -400 DA and BEFORE I added a better tune, 3.73's, subframe connectors, and DR's. I am running better ET's than before in similar weather.....but the mph hasn't changed. I was almost certain that with 3.73's my 3rd gear would be in the powerband better. But now I'm suspecting the converter.
I added the converter while I still only had a couple bolt ons. I figured it would be enough of a stall for the cam....and it is.....but I'm sure now I'm not getting the most out of my setup with the stall. It just seems like it is VERY inefficient in the top end. What do you guys think?....is it the converter "slowing" me down? Hell I've seen bolt on m6 guys trap better than 112 mph in similar weather, lol.
I'm pretty certain tax refund check is gonna supply me with a new yank pt4000 if ya'll think my converter is holding the car back.
60' is not my problem, just my mph. Mods are ms4 cam, ls6 intake, pandp tb, 3.73's, longtubes, true duals, lid, a good tune, and a midwest 3400 stall. I'm not sure of the weight of the car, but I have no weight reduction, only taken out the spare tire and jack. I've ran a best of 12.0@114mph, but that was with a -400 DA and BEFORE I added a better tune, 3.73's, subframe connectors, and DR's. I am running better ET's than before in similar weather.....but the mph hasn't changed. I was almost certain that with 3.73's my 3rd gear would be in the powerband better. But now I'm suspecting the converter.
I added the converter while I still only had a couple bolt ons. I figured it would be enough of a stall for the cam....and it is.....but I'm sure now I'm not getting the most out of my setup with the stall. It just seems like it is VERY inefficient in the top end. What do you guys think?....is it the converter "slowing" me down? Hell I've seen bolt on m6 guys trap better than 112 mph in similar weather, lol.
I'm pretty certain tax refund check is gonna supply me with a new yank pt4000 if ya'll think my converter is holding the car back.
Is a 3400 stall really enough for that cam? I think if you have the money the step up to a Yank would not hurt. I daily drove a 4400 stall with full bolt ons and a 4000 would be a walk in the park, especially if you are already used to the 3400.
Ya, I meant "enough" as is not to have idle/surging problems and pushing through the brakes like a lower/stock stall would. It works, just not the best for my setup.
Whats your 1/8mph? if your trapping 93 in the 1/8 there is something wrong with your 1/4mph. A friend of mine was having a similar problem, Car ran very strong in the 1/8 but died on the big end and he changed the converter just to find out that the tranny was pretty much dead. About 2 grand and a lot of down time later his car went from running 12.5's to 11.7's with nothing else other than his 3500 stall changed for a 4000 and trans freshly built.
By enough he means large enough to get that cam into its power band. Whats your 1/8mph? if your trapping 93 in the 1/8 there is something wrong with your 1/4mph. A friend of mine was having a similar problem, Car ran very strong in the 1/8 but died on the big end and he changed the converter just to find out that the tranny was pretty much dead. About 2 grand and a lot of down time later his car went from running 12.5's to 11.7's with nothing else other than his 3500 stall changed for a 4000 and trans freshly built.
Ya, pretty much decided that income tax check is buying me a new PT4000. What do ya'll think I can gain with that? maybe a couple tenths and a couple mph?
....or maybe a PT4400 (probably won't run nitrous....and by the time I do I'll be running a new setup anyways.)
....or maybe a PT4400 (probably won't run nitrous....and by the time I do I'll be running a new setup anyways.)
Last edited by black00ssFL; Apr 4, 2008 at 04:23 PM.
I had a 244/245/598.598/114lsa cam that i teamed with a midwest 3400 converter, it was the worst decision ever. It felt slower than stock, then i switched to a fuddle 4000 with a 2.7 str and it was a whole different ball game....
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Have any mph or e.t. differences between changing the two? Or was it seat of the pants feel? I'm getting more and more excited about getting a new stall. Shoulda did this in the first place. BTW, decided to go with the 4400 stall since I won't be using nitrous, and I've heard the rule of thumb is to get a stall approximately 500 rpms lower than your peak tq. Just looked at my graph and tq peaks about 4700-4800 rpms.
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I trap similar and am built similar (smaller cam but otherwise...). My
60' times are worse even on ET Streets. Question for the short time is,
are the DRs enough? I don't think so.
Can you see the TC slip RPM as you run through the gears? Look at
the slip RPM as fraction of engine RPM. I'd say if you slip more than
5% at 6000RPM you could gain from efficiency. My old TCI made 3%
(3000 stall) and my Fuddle (3500) is just coming down to 5% there.
But I have locked / unlocked logs showing it's still multiplying torque
past 5000RPM. The slip % is only a rough indicator of efficiency. But
if you slip without multiplying torque that is juat a waste.
I'd think with that cam you ought to have a pretty flat torque line
and could shift pretty high. Basically shift as high as the springs
and pushrods can take. The converter gets more efficient the more
RPM you run.
60' times are worse even on ET Streets. Question for the short time is,
are the DRs enough? I don't think so.
Can you see the TC slip RPM as you run through the gears? Look at
the slip RPM as fraction of engine RPM. I'd say if you slip more than
5% at 6000RPM you could gain from efficiency. My old TCI made 3%
(3000 stall) and my Fuddle (3500) is just coming down to 5% there.
But I have locked / unlocked logs showing it's still multiplying torque
past 5000RPM. The slip % is only a rough indicator of efficiency. But
if you slip without multiplying torque that is juat a waste.
I'd think with that cam you ought to have a pretty flat torque line
and could shift pretty high. Basically shift as high as the springs
and pushrods can take. The converter gets more efficient the more
RPM you run.
Right now she's shifting as high as the tranny will take. If this was a 6 speed i'd be running her right up to 7000 rpm. But, being that she's a stock auto....shifts are set at 6600 for now for the tranny's sake. I don't have tuning software to log any runs either.
I had a Midwest 3200 and it was a piece of crap. Honestly, it acted more like a stock converter. Plus, the internal seals dissolved, the converter turned into a grenade, and the resulting shrapnel took out my transmission.
You're going to be really happy with a TP4000.
You're going to be really happy with a TP4000.
