Mr_president

iTrader: (38)

I have heard people don't like dynoing or tuning turbo th400 cars on a dyno. what is the problem? how inaccurate can it be?? what about a dyno dynamics dyno?

EPP

iTrader: (22)

They can be, we do them. I am not sure exactly why shops wouldn't want to dyno a turbo 400 equipped car, unless it is because the car wouldn't have a lock up torque converter, and the dyno numbers will be lower due to the slippage. This is not a reason to not dyno a car though. Bob

kp

iTrader: (34)

If you dont dyno a rmvb TH400 correctly its pretty easy to explode a transmission. If the dyno you use doesnt want to do it then dont let them. But there is no reason you 'cant' do it, I still dyno mine when I make a make a major change just to make sure the a/f is in line before I go to the track.

Yes the numbers will be lower and yes the power and torque curve may look a little funny depending on the dyno but rwhp is rwhp..

ty_ty13

iTrader: (42)

Bob will be dynoing my th350 tomorrow .... but im actually leaving in like 45min.... wahooo, cant wait

kp

iTrader: (34)

Cool, make sure and post up the results - been a while so I'm sure you are excited.

Fire67

iTrader: (3)

What should not be done? Im really close to being ready for dyno tuning my car, and I would be pissed if my th400 exploded.

Its RMVB equipped with a Hipsters Pro Brake and Vig 4000 converter.

onfire

iTrader: (17)

Don't shift to 2nd out of 3rd at the end of the dyno run. Leave it in 3rd until the dyno drums slow way down.

Drop it into 2nd with the drums flying = boom!

SSilverSSurfer

iTrader: (8)

i saw a vido of a civic step on the brakes on the dyno....you imagine what happened next

kp

iTrader: (34)

Or dont wind it up in second and let off, that applies even driving the car. Always put it in 3rd after accelerating in 2nd, otherwise the direct drum will overun and could explode. TH400s are the main reason trans blankets were started

That doesnt apply to a manual valve body or stock valve body that keeps the front band. Also an aluminum direct drum will lessen the chance of that happening but its like a 600.00 option and not really street friendly.

vanillagorilla

iTrader: (1)

Interesting to note, thanks for the info kp. Does that apply if you have engine braking in 2nd gear?

I've also heard that you can't downshift a TH400 from 3rd to 2nd unless you're on the throttle for the same reason.

Fire67

iTrader: (3)

Ok. got ya. Thanks for the heads up. I never knew that and never had a th400 before either...

So the same rules would apply for driving the car. Dont downshift hard, just wait till Im slowed to the desired speed then shift to the correct gear

leftme4dead

I had my th400 dynoed. The numbers were sucky haha. I have around 450ish @ the motor, and I was able to see 300rwhp on paper. Mike Norris said ofcourse, that its because of the th400 and the loose converter. He said he has seen cars with 550hp @ the motor dyno around 350rwhp.

XpEdItIoUs

iTrader: (44)

Now im scared that i will blow mine up, What if im crusing in 3rd and some one wants to race? Should i downshift to 2nd?

Fire67

iTrader: (3)

From what I gather that would depend on your cruising mph... If its too high, no. If its a low mph for 2nd, go for it.

Fire67

iTrader: (3)

Ive personally down shifted mine from 3rd to 2nd and 2nd to 1st without my foot on the gas pedal. It just doesnt feel like a downshift. It feels like nothing happened untill you push the gas and the rpms climb higher than they did in the previous gear.

andereck

I think it just may be due to confusion regarding different shifters and valve bodies. Why its still necessary to build a valve body as a reverse with today's shifters boggles me. I for one would not want to leave the engine in gear on decel and always shift into neutral or the overrunning 2nd on my old TCI braked 400.

kp

iTrader: (34)

Downshifting and flooring it is OK, some valve bodies will 'nuetralize' in 2nd and its ok to stick it in 2nd at speed. Pretty much accelerating and letting off in 2nd is the worst thng to do. Also do your burnouts 2-3, not 1-2-3. I would not put the car in 2nd from 3rd unless I was applying some throttle though, its nothing new really and most can get away with doing it hundreds of times but all it takes is once when everything is just right.

No reason to be scared, just get in the habit of putting it in high gear after blasting in 2nd and try to avoid 140mph downshifts into 2nd..

kp

iTrader: (34)

You can go either way these days, they have forward manual, reverse manual and forward with the front band. I believe the TCI valve body I have says NOT to put in nuetral after a run, but use 2nd. But I just leave it in 3rd, if it was an aluminum rodded engine I would nuetral it.

The shifter I have I could blast it into neutral easy from high on a reverse pattern if I wanted to but I'm a two hands on the wheel guy once it goes in high..

Zombie

iTrader: (2)

I got my TH400 from Rossler and had him set it up so that I still have engine braking in 2nd gear (does not freewheel) even though I have a RMVB. I did this because my car is primarily street driven. It's less of a worry for me, but I try to always shift into 3rd after making a pull on the highway or on the dyno. When I do a burnout at the drag strip I do a 1-2-3 burnout because of my gearing. I don't really see any issue with this but I have been told to NOT come out of the burnout box in 2nd gear. It's possible to mess up the sprag if you have high wheelspeed and it suddenly hooks up. I usually come out of the burnout box with a wheelspeed around 130-150 mph (MPH is high because of my 2.75 rear gear) and ease off the throttle so it doesn't bite as hard. When cruising on the highway I don't just downshift from 3-2, I make sure that I'm accellerating a little for the downshift because it reduces the harshness.

As for the dyno, it hates my car. I made 470RWHP uncorrected at 14psi on a mustang dyno. Don't know what it would do on a dynojet, don't really care either.

Pro Stock John

iTrader: (34)

Jim @ Speed Inc. seems pretty adept at dynoing T400 cars. I have not personally watched him dyno a T400 in a while, but I think he's very careful to load the drivetrain before flooring it. That being said, many dyno operators would point out that a T400 car will dyno 100rwhp less than a similar M6 car.