4T60-E Auto Trans - Safe HP/Torque Limit?

[pocket-rocket]

The PCM won't even engage the TC lockup until the trans reaches a certain temperature, so yes a trans can be TOO cold.

I always thought it was based on engine coolant to warm the engine faster to reduce emissions?

[IsaacHayes]

Hmm that possibly for the TC lockup, but it does other things such as shortens shift points probably for trans health.

[pocket-rocket]

I'm no auto or tuning pro. I could be wrong for all I know. I never did figure out what each wire going to my 60-e's were, so I've no solid proof/clue honestly, lol. Then again, the difference between what you are saying and what I experienced is a PCM vs an ECM. IIRC a PCM even controls line pressure- something my ECM never did being an older tranny/computer combo. I never remember seeing any trans temps in any logs that came from my car which makes me think you are talking newer tranny/computer combos than I am thinking of so we might both be right.

[robertisaar]

the 91-93 3.4 PCM never logged tranny temps because there isn't a temp sensor for the tranny. the 94-95 3.4 and 3100 PCMs however, do have tranny temp sensors.

i go by the fact that if the "ECM" controls shift solenoids, it's a PCM to me.

[3400-95-Modified]

60-e doesn't like more than ~6200RPM anyways....

Thats funny, because I have some logs of mine shifting to 2nd at 6750 and thats when I got my 13.996 N/A

Its also still in one piece after running a 13.511 with my one pass on the nitrous last year. Upgraded properly they will hold up well. I wont say you wont stretch the hell out of the drive chain if everything else holds up though... Those are just too weak and need to be replaced if you send a lot of power through it.

[Schmieder]

"3400 v6 to fit a Garrett t3/t4? Going into a 1996 Grand Prix."

Yeah, options are limited and I got a deal on that turbo. Good condition, very little play and recently rebuilt....$250.00 out the door, not bad ehh?!

I actually have a 3100 block with 3400 top end swap. The bore is 90.5mm so I'm pretty sure it was bored out/honed when it was dropped in from the Beretta donor car. It was definately well built. It is a quick 3100/3400 compared to other 3100/3400 cars.

The turbo, I know it is just a tad bit too small but that is ok. Like I said I got it cheap as dirt for a Garrett! And mostly city driving. Good points I see is a really quick spool to 5 psi. It will still drive a lot more power then n/a. And after I have my turbo system welded up and running, I can always upgrade the turbo down the road.

The trans cooler in the rad is on the cold side of the radiator, and it doesn't add much heat to the transmission system (except when cold in the winter, or if your engine is overheating). Plus, a liquid cooled system like the one in the rad is much more effective at reducing temperature then an air cooled system is. That's why such a small cooler in the rad can cool a transmission effectively.

A much better option is to have the output of the rad cooler flow into a grille mounted air cooler, so you get a "double cooling" effect on the transmission fluid. The hot trans fluid enters the rad system, and gets cooled very quickly to equal the rad cold side temperature. Then it goes to the air cooler and gets cooled even more (albeit slower), resulting in nice low transmission temperatures.

This I had considered. Knowing how the Rad water heating/cooling worked on the tranny fluid, I will line the Supercooler after the rad cooling. The B&M Supercooler I am installing has a by-pass feature when tranny fluid is cold, allowing it to warm to proper operating temps. The by-pass action is gradual and more is feed through the cooling lines the hotter it gets.


I do have a question about where to install the TRANS TEMP gauge sender?? Read the cooler fluid entering the tranny or read the hotter fluid exiting the tranny??

I read somewhere it was better to read the cooler side as so one could see the cooling capacity and what temp is being pumped in to the tranny. But my logic also thinks it may be wise to read the max temp exiting fluid so as to know what the true heat conditions are.

Any advice on where to mount the tran temp sender? In-line only, as I am not going to tap the trans itself. Unless there is an effective, reliable and safe method of doing so.

[mfewtrail]

For simplicity's sake, most people install their temp sending unit in the pressure test port on top of the transaxle. It's around/under the top mounting bracket. Plug size is 1/8 - 27 NPTF for what it's worth.

[Schmieder]

For simplicity's sake, most people install their temp sending unit in the pressure test port on top of the transaxle. It's around/under the top mounting bracket. Plug size is 1/8 - 27 NPTF for what it's worth.

Hey, that is great! Thanks for that. Now i don't have to purchase a fitting with a 1/8 NPT port. And it seems I would get a true temp reading from inside the tranny housing.

Really glad you pointed this out. This is why I really like this web forum.

[Schmieder]

A turbo mounting question.

Must I mount/draw the exhaust from the cross-over pipe or can I rig the turbo on either manifold (all the while still sealing the downpipe exit)?

Would it create a balance issue in psi or would that be a non-issue?

There is probably enough comfortable space for a turbo to sit between the block and the radiator. With the advantage of airflow and not having to put the battery in the trunk. It would make welding the exhaust out easier too.

Can this be done w/o issues?

EDIT:
The only issue I can see is airflow. PSI across the manifolds/crossover should be equal through out. And tapping that pressure should have an equal effect across the manifolds. So it seems it would work just fine that way. However, there may be an issue I am unaware of. Lord knows it's happened more then twice, lol.

[pocket-rocket]

I imagine ideal is to have the turbo in the center of the crossover pipe so exhaust from the longer side bank in your idea wouldn't have time to cool down as much which would make it lose velocity.

[IsaacHayes]

I can't recall where the stock temp sender is in my 4t60-e. It may even be internal..

[Schmieder]

I imagine ideal is to have the turbo in the center of the crossover pipe so exhaust from the longer side bank in your idea wouldn't have time to cool down as much which would make it lose velocity.

Right. Even though the manifolds are getting heat wrapped.

I decided to fashion the turbo as close as possible to the cross-over. This way the exiting exhaust is as straight as possible and the intake aims towards the front left where the IC intake will be.

I can't recall where the stock temp sender is in my 4t60-e. It may even be internal..

Ehh, I decided just to mount the temp sender right at the fluid exit. So I will have the readings from the hottest fluids. Essentially, I believe that will best reflect the hottest parts in the tranny.


Now, I see two possible locations for the MAF. Before the turbo to measure uncompressed air at atmospheric temps, but the BOV will release measured air. OR, just before the TB, after the BOV so the BOV releases air that hasn't been measured yet. But that air is compressed and hotter. Wouldn't the compressed air give a false reading on the MAF since it measures by the cooling effect the air has on the hot wires?

Advice please, thanks.

[IsaacHayes]

MAF reads difference the air cools the heated element in it. Doesn't matter if it's hot or not, the IAT will adjust for that.

You want to measure actual air going into the engine. So BOV before the MAF. You might max it out though, so an upgrade might be needed and then re scale the MAF tables. But only 5psi might get by.

[Schmieder]

MAF reads difference the air cools the heated element in it. Doesn't matter if it's hot or not, the IAT will adjust for that.

You want to measure actual air going into the engine. So BOV before the MAF. You might max it out though, so an upgrade might be needed and then re scale the MAF tables. But only 5psi might get by.

Even if the air is at 5psi? Won't more air get by then what the pcm was designed to measure due to increased compression, regardless of cooling ability? Or will the compressed air cool the MAF lines faster since it is denser?

Basically, can the MAF see the difference in atmospheric presssures over 5psi boost pressures?

Now, if I max out the MAF, will the symptoms be a leaning condition? Or just an over all loss of high RPM power?

Ok, so I will place the MAF after the BOV. The IAT is obvious where it goes.

Assuming I DO max out the MAF, can I do this...?

Port it out for more airflow (probably a 7%-10% cfm increase). This would lean out the A/F mix since the engine is getting a little more air then it was tuned for. Then increase the fuel mix by pumping up the Fuel Pressure slightly to bring the lean mix back to stoich.

Since I plan on using 21# fuel inj. from stock 19#, I would have to reduce the fuel pressure to compensate for larger injectors. So there would be a counter acting balancing effect.

I know it seems like a lot of fuel pressure adjusting, but not too much. I am avoiding tuning the pcm like the plague and the 2 dyno tuners in the area have not returned my emails, 96 OBDII sucks ballz! I feel with a good fuel pressure gauge, wideband O2, Adjustable FPR and a 12:1 FMU with valve bleeder I can get great results w/o pcm tune. I may even utilize a spring loaded check valve that closes at around 3psi, in-line with this check valve will be a valve bleeder. This way I can lean out an over rich mix at mid-boost, a common issue w/ FMU use.

Or just buy the Vortech Super FMU, but they are near $400.00!!! I guess good fuel management is gonna cost $$$ one way or another.

Thanks for the MAF advice!

[robertisaar]

when the MAF maxes out, i believe the PCM will freak out and refuse to deliver fuel based on the MAF reading, and instead run off of hard-coded default tables...