I have finally finished the nitrous system install on my '85gt, 3.4L PR, auto-transmission car.

I will be doing the first testing of it on a dyno on Saturday but I need to know if I need to engage the torque converter in the automatic transmission before using the spray?

A buddy of mine said that if I don't lock up the torque converter I run a high risk of smoking the converter! I definitely don't want that to happen. Is there any truth to this and if so does anyone know how to do it?
Thanks!

You don't need to lock up the torque converter to use nitrous. In fact the torque converter lockup is designed to be used primarily in cruise and disengages under medium-heavy acceleration. It's not really designed to take full acceleration power, especially with nitrous.

Thank you for the insight

What I heard some dyno shops do is to run the car in high gear once the TC locked to avoid the HP loss with slippage. I would just do a 1-2-3 run letting the trany do the shifting. On my car with the stock 2.8 auto and the 75hp shot it dropped the 0-60 time by 2 seconds. I never dynoed it. Also never used it with the 3.4. Should feel very nice.

Umm... my understanding of the TH125 is that it can't pull off a 1-2 shift with a lot of torque. IE, it'll smoke the intermediate band and put you down for a transmission overhaul.

Forcibly locking the converter will smoke the converter clutch, as it's only meant to handle 100 ftlbs or so. The unlocked converter will handle it just fine, but if you're doing a lot of runs for tuning, you'll need to watch your transmission fluid temperature.

You lock the TQ converter for a better RWHP number.

Are you using the dyno for tuning? or just to see what kind of numbers your putting down?

Also...don't spray thru the shifts!!!! I like to use an RPM switch and have the N20 shut off just before the shift point and come back on after the Rev's drop. It will save your tranny in the long run. Especially if it isn't built for that.

Also, you ALWAYS spray with the Verter unlocked! That's the only way to drive an Auto at WOT! It should only lock up after a certain mph for better fuel economy, driveablity, heat reduction.
What is your stall speed on your Verter?

[This message has been edited by SOMFormula (edited 03-18-2011).]

quote Originally posted by Will: Umm... my understanding of the TH125 is that it can't pull off a 1-2 shift with a lot of torque. ..

Please define "a lot". The 2.8 with a 75 shot shifted just fine. Depending on the 3.4 mods it won't be that much difference. I would like to hear from people that have actually used nitrous in their Fieros and not speculators.

I'm curious where/how you jetted.
I was about to post up a question,but this is better.

I've got an old manifold on the table getting powdercoat stripped.
I was going to shave down where the EGR port is and mount it there.
Wouldn't mind doing it without altering the intake substantially.
(or I would just drill/tap the neck).

I've got a bottle,nozzle,bunch of different size jet's,two solenoids and some feedlines just taking up space in the shop.
Might as well see what the old 2.8 can take.
Planning to start with just a 30-45 shot,she's got 160k lol.

quote Originally posted by Alex4mula: Please define "a lot". The 2.8 with a 75 shot shifted just fine. Depending on the 3.4 mods it won't be that much difference. I would like to hear from people that have actually used nitrous in their Fieros and not speculators.

Jeff, formerly of Engineered Performance (Yes, EP LSD) had a Grand Am with turbo OHC engine and TH125. The engine ran well enough, but the transmission cooked the band every time he tried a 1-2 shift at WOT. I was discussing this with him because at the time I was looking at a performance build of my Pontiac 6000 AWD which uses a variant of the TH125. The problems he was having and the problems that people on this forum have had with built 125's convinced me that trying to get that transmission to handle power just wasn't worth the effort.

Have you looked at the size of the servo piston and accumulator operating that band? Compared the drum diameter to, say, a TH700?

The TH125 lives forever with stock output from the engine, but is calibrated such that it goes quickly with more.

[This message has been edited by Will (edited 03-19-2011).]

Here are the results of my dyno run today. It went really really well!

https://www.fiero.nl/forum/Forum1/HTML/084629.html

I used a .020 fuel jet and a .036 nitrous jet and gained a 44HP gain in power.

We did the run by putting the gear selector into 2nd, and started accelerating. When the tranny shifted into 3rd I hit the nitrous. It worked really good and revved til 5,500RPM

quote Originally posted by Oslo: Here are the results of my dyno run today. It went really really well! https://www.fiero.nl/forum/Forum1/HTML/084629.html I used a .020 fuel jet and a .036 nitrous jet and gained a 44HP gain in power. We did the run by putting the gear selector into 2nd, and started accelerating. When the tranny shifted into 3rd I hit the nitrous. It worked really good and revved til 5,500RPM

You mentioned 4 speed auto in your other thread. That would have been a nice piece of info to have
The 4 speeds are much more durable than the TH125... Spray away!

quote Originally posted by Will: You mentioned 4 speed auto in your other thread. That would have been a nice piece of info to have The 4 speeds are much more durable than the TH125... Spray away!

Thanks for the insight!

[This message has been edited by Oslo (edited 03-20-2011).]

quote Originally posted by Oslo: I have finally finished the nitrous system install on my '85gt, 3.4L PR, auto-transmission car. I will be doing the first testing of it on a dyno on Saturday but I need to know if I need to engage the torque converter in the automatic transmission before using the spray? A buddy of mine said that if I don't lock up the torque converter I run a high risk of smoking the converter! I definitely don't want that to happen. Is there any truth to this and if so does anyone know how to do it? Thanks!

what nos system are you useing?

Remember the old rockers you sold me with the little hole in the corner ? Im planning to use it for what you meant it to be there for.

quote Originally posted by Chris Hodson: Remember the old rockers you sold me with the little hole in the corner ? Im planning to use it for what you meant it to be there for.

Purge?