parish8

iTrader: (6)

running a FLP built 4l80e and a 10.5" tripple disk PI converter. both FLP and PI say i can lock it up at WOT but i am not sure when would be the best time.

my 2nd gear takes me from about 60mph to 100mph and my rpms are only about 5300 at 120mph in 3rd when i go thru the traps. can i lock it in 2nd and would it help with my ET?

the only rule of thumb i have ever head was i can lock it up anytime i want but i dont want the converter to try and pull the motor down more than 500rpm. i think the stall is so tight that it will never drop the rpms more than that. should i lock it shortly after the 2nd gear shift as long as the rpms dont drop too much when it locks?

a theory question here. other than the launch when the converter can give you some torque multipulcation wouldn't it be better to be locked if you can be?

cablebandit

iTrader: (37)

I am wondering the same thing.i am hopefully going to get to try a run with it locked in 3rd and one without this weekend. we run about the same times....I am only wanting lockup in 3rd though. i think locking around 100-110mph might pick up a tick.

Colonel

I think you'll have to time it just right in 2nd to stand a chance of helping. You want the lock to be complete just as you're reaching the point that the HP is about to fall therefore pulling the RPMs back (or holding them) into the HP peak range. I've managed to do this well in 3rd but doing it in 2nd might be difficult since the RPMs are climbing quicker. Also, there is less to gain by doing it in 2nd since there is less slippage in 2nd (due to more gearing advantage.)

No sense locking it in third if you're crossing below the HP peak. You'll only stand to go slower.

parish8

iTrader: (6)

so Colonel, from what i hear you saying the purpose it to try and keep it at peek hp a little longer. i thought that locked would put more power to the rear than unlocked anytime but it doesn't sound like that is the case.

right now i apear to be geting spark blow out and am shifting before my peek hp. maybe i should worry about that first

JxxxOxxxE

iTrader: (1)

I have thought about trying this, but is it not bad on the converter to go from say 5500 RPM to a direct lock? I have a PT4000, but I just cant see that lasting too many times...???

parish8

iTrader: (6)

i really dont know how bad it is for them. acording to mike at yank the killer is large rpm changes so if when you lock it up at 5500 it drops to 4900 than that is bad for it. if you lock it and it goes from 5500rpm to 5200rpm he says that is ok.

he was speaking of the converter he sold me, not sure if what he told me applies to all lock up converters or just some of them. the converter i have now has a prety massive lock up, 10.5" tripple disk so i think it will be ok but the question still remains weather i should lock it up at all or not. will locking it at the top of 2nd help at all? i only get to 5300 or so in 3rd so i dont know if it would help or not.

parish8

iTrader: (6)

i just talked to PI, he told me to lock it right after i shift into 2nd. i asked if the converter can take that kind of abuse and told him i was making some prety good power and he said it is rated to 1600hp and i can lock it any time i want.

i guess i will just try it and see if it is quicker. sounds like i can't really hurt it.

James B.

iTrader: (1)

Jim, it will be slower tying to lock it. Leaving the converter unlocked will prevent it from bogging at the bottom of second or third. If it locks in second the 2-3 shift will bog it as soon as it gets into third. Unlocked the converter will allow more slip and torque multiplication at the bottom of the gear. Since the converter gets tighter as RPM increases the top end of each gear should feel the same. Leaving it unlocked will keep RPMs and boost up.

If it can be programmed I would aim for a 50mph lock-up under normal throttle in fouth gear only and no-lockup above 80% throttle.

parish8

iTrader: (6)

i have a track report.

first run 15psi open exhaust no nitrous 2.11 60' 12.01@117.18

2nd run same boost setting but saw 15.8psi, open exhaust, locked up converter from about 5000rpm in 2nd gear on. 2.164 60' 11.93@119.47


looking at my slower 60' time and the better ET it looks like i picked up about 2mph and .1-.2 ET, i dont know what my boost was for sure but my boost controler records the peak boost and that is what i listed above. one test isn't really enugh to make any conclusions from but it looks promising for locking up the converter eairly.

skinnies

iTrader: (33)

Why the weak 60fts or does the spray help spool it so your 60ft drops that much?

Ragtop 99

iTrader: (7)

There is more benefit to locking the converter with FI than with NA because of the much higher TQ levels between 4000 - 5000 rpm.

Be sure that FLP says that locking the converter in 2nd gear won't toast their tranny. I have seen it toast a stock tranny.

parish8

iTrader: (6)

i called flp and PI, prety much got the same sugestion as well as from a buick GN guy.

my last run of the night was 5th run, let it cool for a long time and bumped the boost a tiny bit and ran a 75shot out of the hole. saw 17psi. 1.76 60' 11.33@121.17, on this run i completly blew off the tires(all 4). it wasn't smooth at all. i believe the truck could pull some 1.5's with the right tires. i am only spraying for 1 sec out of the hole and it gives me that much better of a 60' time. it has some prety good lag.

Smokinstorm

iTrader: (5)

I was hoping to see you get the slight improvement in ET and MPH that you got. That's about what I expected to see. Being FI, you do get more of a benefit that NA guys do because of the monster torque but I expect to see some improvements from doing this on my NA car also. I don't plan on locking mine until Drive because of the bog associated with having the converter locked on the 2-3 shift. I'm hoping for a .1 and maybe 1 mph but we'll see. I've got a manual lockup switch installed so I can play with the lockup points to see which, if any, benefits me the most. I'll then use LS1 edit to automatically lock the converter at the optimal point so I don't have to mess with it anymore.

98ls1

i dont understand what you guys mean when you say you can lock up the converter when ever you want can you guys explain thanks

cablebandit

iTrader: (37)

Parish I locked mine tonight at around 120mph ...dunno how much it helped but got a new best of 14.45 @ 131. I feel it helped at least .1 and 1-2mph as you suggested.

Smokinstorm.....the converter slips a little to keep your engine in the higher rpm band where your power is...when the converter locks up, it doesnt slip at all and is almost like a manual transmission then as far as efficiency goes. You need big power to take advantage of it tho or it will bog your motor down

Smokinstorm

iTrader: (5)

Thanks. I'm aware of this. But also the engine is transmitting a bit more of it's available power to the rear wheels when the converter is locked. I'm not saying I'm guaranteed a significant performance increase or even a noticeable one as long as my car is NA and only making horsepower in the 400 range. However, once the blown 408 gets installed, well.....................like I said. We'll see. And obviously I'll post whatever performance increase or decrease I get from doing this. Trying new things and sharing information is what it's all about, right?