Manual Lockup Switch

[BMF_Racing]

Ok, still being new to buicks, I was dynoing the car yesterday and we were discussing %'s of loss through drivetrain when a thought popped into my head from when I bought the car. I remembered the previous owner told me that he had installed a manual lockup switch intalled under the dash, which I had totally forgot about till then so we did a pull with it locked.

not locked --> 279 whp / 361 wtq
locked up --> 311 whp / 467 wtq

-Boost was spiking 21 and then fell back to 18psi. This was with stock turbo and intercooler with 93 and alky.

the questions:

-- is this normal for it to gain this much power and tq with it locked?

-- is it extra hard of the trans, outside of the extra temp ?

-- if I was to lock it at the track do i do it in high gear only or is it safe to turn on in 2nd and 3rd?

-- is it normal for boost to fall back to 18 or is that because of the mbc ?

sorry if these are basic questions, I just havn't had any experience with lockup transmissions.:frown:


thanks, in advance,

Brad

 

[KevinB]

Hey Brad!

Some chips will scale boost back in 3rd and 4th gears. Maybe this is what's happening?

Some people gain up to .2 at the track with the tcc locked. So there is a gain of around 20 hp or so according to my crude math. My car liked the tc lockup...until it started going 11's. It is hard on the tranny in a faster car. I don't see any problem until you get that car in the 11's or so. Especially with your stock transmission and tc. I eventually went with a non-lockup due to tc problems from locking it up when I was in the 11's. Give me a call if you got any questions. See ya at BG

 

[77 cruiser]

Here's the difference with mine locked.

 

[bison]

The numbers on the dyno change quite a bit for the better locked but real world performance gains are at most .2 and 3-4mph. Having the converter locked actually reduces trans temps when its locked. It is hard on the internals if there is a ratio change while locked. But not much of a worry in your application assuming your shifts are accumulated. Otherwise it just wears the converter clutch over time. Ive locked up a stock type converter over 150 times at WOT at a higher performance level than yours before it wouldnt lock up anymore. Fwiw the numbers in my sig are a with a fairly loose unlocked converter.

 

[BMF_Racing]

ok, I can follow what is said above, so thank you for the help. I read somewhere that it will only lockup in 2nd 3rd and 4th only, so if thats true could i lock the convertor when i stage and make a pass that way ? or is this something that needs to be switched on mid-pass?

 

[bison]

ok, I can follow what is said above, so thank you for the help. I read somewhere that it will only lockup in 2nd 3rd and 4th only, so if thats true could i lock the convertor when i stage and make a pass that way ? or is this something that needs to be switched on mid-pass?

This is something you will have to experiment with. Ive seen cars go quicker and faster using both techniques. You can flip the switch before launching if you want it to lock asap. If you have a tall tire i would lock it later. If you have a short 26" tire then you usually have better results locking in 2nd. Its hard on trans internals shifing while locked though.

 

[BMF_Racing]

This is something you will have to experiment with. Ive seen cars go quicker and faster using both techniques. You can flip the switch before launching if you want it to lock asap. If you have a tall tire i would lock it later. If you have a short 26" tire then you usually have better results locking in 2nd. Its hard on trans internals shifing while locked though.

ok, i did notice it changing the shifts to be much more violent when i was at like 1/4 throttle running through the gears, up to 3rd on the dyno. it has 235/60/15 bfg dr's now. ~ 26" tall i think. best it ran so far was 13.30 at 103.5mph but this was with 2.00 60ft, launching at about 1500 rpm (0 psi) and boost hits about 10 to 15ft. just starting and dont want to break anything right away , just want to learn as much as i can before i go to hard lauches(car has max-boost launch kit).

so is it true it will not lock until second gear on?

 

[MeanBuicks]

so is it true it will not lock until second gear on?

Yes, that is true. The fluid signal to the TCC valve/solenoid comes from the 1-2 shift valve after it strokes.

 

[GNVYUS 1]

That is a huge jump in torque!!!

What converter are you running??
Stock tranny, rebuilt, billet internals??

You definitely need a much bigger DOT like 275/60.

If you have a solid lock up converter ( Precision, PTS etc ) and billet internals then try the 2nd gear lock up ( might not gain any MPH over 3rd lock up ), but IMO stick with only 3rd for now.

Jim P, your A/F ratio is a bit to lean even for a N/A motor.

 

[BMF_Racing]

That is a huge jump in torque!!!

What converter are you running??
Stock tranny, rebuilt, billet internals??

You definitely need a much bigger DOT like 275/60.

If you have a solid lock up converter ( Precision, PTS etc ) and billet internals then try the 2nd gear lock up ( might not gain any MPH over 3rd lock up ), but IMO stick with only 3rd for now.

Jim P, your A/F ratio is a bit to lean even for a N/A motor.

- stock converter/trans
-tire can on the car and just using then till we need new one, hello 275's

- all stock trans parts

 

[BMF_Racing]

HERE'S THE DYNO CHART PIX: LOCKED VS: UNLOCKED

there was an issue with the way I had the boost setup, it spiked 21 psi and then held 17 psi steady, but that was my fault. It was pig rich also, 10.4 falling to 10.0.

Is it normal to gain this much?

 

[BMF_Racing]

Mod List:

**all stock if not specified**

Stock unopen 3.8L w/ Moroso valve springs
Akly Injection kit w/ 375ml/min nozzel
t-bolt intercooler clamps
36lb injectors
Buschur MBC (spike 21psi & hold 17psi)
3 1/2" flex CAI
Red Armstrong fuel pump w/ hot wire kit
Red Armstrong voltage booster
Red Armstrong 93 chip
3" THDP w/ adjustable wga
Cat-delete cutout w/ e-cutout
dual 2 1/2" exhaust
torque converter lockup switch
36,000 gvw trans-cooler
adj fuel pressure reg. set @ 43 psi

 

[bison]

You probably have another 25hp with a leaner a/f. I picked up over 35hp going from 10.3 to 11.3.