what could be the problem with locking a stall on a dyno run?
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From: waterford MI.
what could be the problem with locking a stall on a dyno run? I see people with locked dyno runs all the time, and I cant figure out why it could be a problem, but Ive been told (or really a friend has been told) that its not good for the trans and the locked #s arent real world. this would be for a 4L60E Im wondering about.
now I have a 700r4 in my 95 (its out of a 3rd gen) and I have a manual lockup switch and plan on testing with it on and off. I use it on the freeway (seems to be good for about 250-300rpm on my 3800 stall) and at the track, but I need a shift kit cause I dont think it locks under WOT with out the shift kit.
I know the GN guys have been doin this forever and gain alot of MPH from it at the track. so why dont 4L60E guys run a lockup switch for track times?
now I have a 700r4 in my 95 (its out of a 3rd gen) and I have a manual lockup switch and plan on testing with it on and off. I use it on the freeway (seems to be good for about 250-300rpm on my 3800 stall) and at the track, but I need a shift kit cause I dont think it locks under WOT with out the shift kit.
I know the GN guys have been doin this forever and gain alot of MPH from it at the track. so why dont 4L60E guys run a lockup switch for track times?
Originally Posted by Irocss85
so why dont 4L60E guys run a lockup switch for track times?
I do. I pick up 2 extra MPH out the end when locking my converter. You have to be somewhat scientific about it though and not just lock it up when you feel like it during a run. Go to a dyno and get a dyno pull locked and then unlocked. There will be an exact MPH where the curves cross. That's where you lock the converter up for the maximum gain from doing this. Try it.
BTW on my stock longblock bolt-on motor this point was 84.4 MPH with 3.90 gears and PT4000 converter. I've yet to find out where this point is with my new head/cam combo but you can count on me getting this information.
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whats the whole idea about locking the conv. at the cross over point? cant figure out on my own what the bene of that would be. obviously, you dont want to lock it in first gear (700r4's cant physically anyways due to the port in the valve body being blocked in first gear) cause you'd lose all torque multi. from the stall, but once in sec. I cant figure out any benefit to waiting to a certain MPH. please explain.
so can anyone point to anything neg. about locking on the dyno?
Frost, just read your thread about your car build. I must say VERY SWEET. Im sure you are enjoying that car with your setup. what kind of track times you seeing now, and whats the boost up to? and what the hell happened to your oil pump oring? was it cut from someone jamming the pipe into the pump? cant figure out how that happened while assembleing the eng. on a stand. anyways cool story and thanks for all the pics and story.
chris
so can anyone point to anything neg. about locking on the dyno?
Frost, just read your thread about your car build. I must say VERY SWEET. Im sure you are enjoying that car with your setup. what kind of track times you seeing now, and whats the boost up to? and what the hell happened to your oil pump oring? was it cut from someone jamming the pipe into the pump? cant figure out how that happened while assembleing the eng. on a stand. anyways cool story and thanks for all the pics and story.
chris
Originally Posted by Irocss85
so can anyone point to anything neg. about locking on the dyno?
Frost, just read your thread about your car build. I must say VERY SWEET. Im sure you are enjoying that car with your setup. what kind of track times you seeing now, and whats the boost up to? and what the hell happened to your oil pump oring? was it cut from someone jamming the pipe into the pump? cant figure out how that happened while assembleing the eng. on a stand. anyways cool story and thanks for all the pics and story.
chris
...there wasn't an o-ring problem, either a new comp OE lifter failed and wiped a lobe, leading to eating a bearing, or the bearing went and the trash stopped a roller on the lifter. Either way, same outcome. I am running 15.5psi with methanol on the HPE shortblock with TEA heads and it feels NICE
I've been at this level for about 900ish miles. I don't know how quick it is yet, it hasn't been on the track, but I was dead even with a new C6 Z06 for 3 pulls from second gear to the top of fourth when I was at about 9psi, and it's a whole different animal at 15psi 
The turbo brings the luxury of a tall rear end gear, so the M6 is coming out for the th400 and a 3.08 gear with a hefty but tight stall. I hope to be on the track by May with it. Thanks for the intrest 
I think you guys missed what he was saying about the cross over. He is not talking about the TQ/HP cross over. He is probably looking at the TQ of both unlocked/locked runs (or HP of both, not sure), over laying them to see where the cross over is. Locking it there.
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There is nothing but advantages by locking up the converter to better anaylize just engine mod comparisons assuming that you have a TCC that will not slip and you always do your comparisons this way. Unless you do HP comparisons by MPH rather then RPM, an unlocked slipping converter's reading can be very misleading, especially trying to analyze different stalls. If you are troubleshooting your converter, TCC or complete drivetrain, then it's a different story.
As far as locking the converter during a race, using the fact that it's he who can average the most HP in each gear will be quicker all else equal, find at what RPM your engine HP peaks, then lock the converter so that your RPM drops and crosses that point again, like another gear. Another way to look at it, if we had an infinate ratio transmission and a joy stick to control it, we would hold the RPM at the peak HP RPM point throughout the entire race, this is what we are crudely trying to accomplish with the TCC lock up.
As far as locking the converter during a race, using the fact that it's he who can average the most HP in each gear will be quicker all else equal, find at what RPM your engine HP peaks, then lock the converter so that your RPM drops and crosses that point again, like another gear. Another way to look at it, if we had an infinate ratio transmission and a joy stick to control it, we would hold the RPM at the peak HP RPM point throughout the entire race, this is what we are crudely trying to accomplish with the TCC lock up.
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Originally Posted by LIL SS
I think you guys missed what he was saying about the cross over. He is not talking about the TQ/HP cross over. He is probably looking at the TQ of both unlocked/locked runs (or HP of both, not sure), over laying them to see where the cross over is. Locking it there.
Try this, it works.
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From: waterford MI.
what MPH was yours at? just curious. your talking about lettting the car automatically shift, but at the given mph, say 68mph, lock the conv. for the remainder of the run right?
Originally Posted by Irocss85
what MPH was yours at? just curious. your talking about lettting the car automatically shift, but at the given mph, say 68mph, lock the conv. for the remainder of the run right?
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what trans do you have? 60E? I wasnt aware they made a man. valve body for the 60E yet? as for me, Im using a 700r4, and manually shifting it (b&m hammer ratchet shifter) cause I like to shift it. been thinking of doin a manual valve body in the car, just havent had the nerve/money to yet. no question when I get around to working on my Iroc again that will have a manual valve body in it.
when I get my dynotune done, I'll have to have him plot it diff. so I'll be able to see at what mph that happens. and give it a back to back test at the track doin it that way, vs the way Ive always done it. which is turn the sw. on at the starting line after Im staged and back in first gear.
man I cant wait to hit the track again.
when I get my dynotune done, I'll have to have him plot it diff. so I'll be able to see at what mph that happens. and give it a back to back test at the track doin it that way, vs the way Ive always done it. which is turn the sw. on at the starting line after Im staged and back in first gear.
man I cant wait to hit the track again.
Originally Posted by Irocss85
what trans do you have? 60E? I wasnt aware they made a man. valve body for the 60E yet?
I'm using what started out as as Rock-On Stage 5 4L60e. It's been totally gone through again and the full manual option was chosen. Mine can be switched back to automatic shifting by going back into the valve body and changing a couple of things. Automatic gurus please chime in as I'm sure you can explain what I'm talking about.
Don't look for great ET gains from doing this. You're only using the extra horsepower available for 4 seconds or so of a track pass. I'd expect .05-.1 gain at the most but your trap speed will go up.
locked/unlocked We ran a BBC monte carlo yesterday, locked and unlocked (700r4). It made 472 HP unlocked, and 503 HP locked. It picked up almost exactly what I told the owner it would pick up. That being said, it is my belief that it not good for the converter clutch. My tranny builder says its not good for it. But he says that it IS good for his business!!!lol
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smokinstorm-
I see. basically full manual option in your shift kit.
far as track times, in my case, with my old iroc, I picked up .15 and 2 mph consistantly. that was with a faily tight conv. though. full size, 2800rpm stall speed on a mid 12 sec. car. seems there would be more to gain with a higher stall speed, and a car that makes more torque.
interesting though edcmat-l1.
keep them comeing. anyone else?
I see. basically full manual option in your shift kit.
far as track times, in my case, with my old iroc, I picked up .15 and 2 mph consistantly. that was with a faily tight conv. though. full size, 2800rpm stall speed on a mid 12 sec. car. seems there would be more to gain with a higher stall speed, and a car that makes more torque.
interesting though edcmat-l1.
keep them comeing. anyone else?
Originally Posted by Frost
The curves cross at 5250, so just log and look to see what MPH you are at.... although I'm not sure what gear he is locking it up in; from the MPH I'm guessing 2nd?
Originally Posted by Irocss85
whats the whole idea about locking the conv. at the cross over point? cant figure out on my own what the bene of that would be. obviously, you dont want to lock it in first gear (700r4's cant physically anyways due to the port in the valve body being blocked in first gear) cause you'd lose all torque multi. from the stall, but once in sec. I cant figure out any benefit to waiting to a certain MPH. please explain.
so can anyone point to anything neg. about locking on the dyno?
Frost, just read your thread about your car build. I must say VERY SWEET. Im sure you are enjoying that car with your setup. what kind of track times you seeing now, and whats the boost up to? and what the hell happened to your oil pump oring? was it cut from someone jamming the pipe into the pump? cant figure out how that happened while assembleing the eng. on a stand. anyways cool story and thanks for all the pics and story.
chris
so can anyone point to anything neg. about locking on the dyno?
Frost, just read your thread about your car build. I must say VERY SWEET. Im sure you are enjoying that car with your setup. what kind of track times you seeing now, and whats the boost up to? and what the hell happened to your oil pump oring? was it cut from someone jamming the pipe into the pump? cant figure out how that happened while assembleing the eng. on a stand. anyways cool story and thanks for all the pics and story.
chris
