how efficient is the th400 compared to the 4l60?

 

Well the th400 has a higher mass and a higher reciprocating mass so it should be less efficient

 

put it this way...

i have no proof, no evidence, i just remember a few months ago, i guy came in here that went from an M6 to a TH400 and lost 90rwhp. granted that was from an M6 and i think he had a heads and cam package, but you'll see a significant drop in horsepower to the wheels.

 

Also you lose OD which sucks but you wont break that tranny no matter what you throw at it..

 

guys that go with 3 speeds arent too worried about gas milage and efficiency on the dyno

at the track i will take a th400 over a 6 speed in nearly every case. booth et and mph

 

It took me 15psi of boost from a T76 to make 470 RWHP on the dyno, but the car goes mid 10's at 130 mph and is 3800lbs.

Dyno's number bragging is for people with slow cars.

 

In my opinion its the power path and inertia that make the TH400 less effecient.
I can not see how an overdrive transmission can weigh less than a 3 speed, even a TH400.
The ODs case is longer, and there are more parts inside it with the overdrive so the "TH400 weighs more" is not a valid arguement IMO.

 

i never noticed that, a th400 will not only yield better ets(thats a given) but a higher mph as well? any direct gains from a 4l60 to a th400?

 

True, but not convinced about the higher trap. Lower ET but I'm trapping about 4 mph less with the A3 all else unchanged.

FWIW.... I only "lost" 20 rwhp/24rwtq going from an M6 to TH400 w/a steel DS, 4.56's in a 12 bolt on 28" slicks. Not too bad afaik. Granted, this is a LU trans/verter, but still. I can't imagine losing 90 rwhp going from the M6 to A3, but I guess anything's possible under the right conditions-

 

if you dyno it unlocked it would change your numbers alot

 

Unlocked my 4L80E/Vortech-blown 383 combo made 462rwhp, locked it made 501rwhp. 40HP loss when relying on fluid drive as opposed to a straight mechanical link.

Jim

 

The reason the TH400 wieghs more has to do with the beefier components used to keep it together, vs. the flimsly light weight components in the 4L60E that help it with fuel efficiency. Nothing to do really with how many components one has over the other.

 

The th400is the heavier unit I know I have shipped and handled them , heavier equals more mass to turn equals loss , Though that may not reflect on a dyno because of the way it measures power

 

I understand completely..... so I guess a 40-60 rw loss could be considered the norm as Delta's results showed, but 90 rwhp?

Again, I haven't yet dyno'd unlocked, but "thought" it was a valid comparison as the M6 was also a 1 to 1 mechanical link. Trying to compare apples to oranges the most logical way possible to see how the A3 compared to the M6 as far as actual rw power efficiency. I guess my logic was AWOL-

 

That makes sense, you probably had a fairly loose coverter to compliment the blower right. So your converter is about 92% which seems somewhat reasonable.

A 90rwhp loss seems a bit much for just a H/C car. If it were making over 700rwhp I could see that but not for something in the 400rwhp range. I'm willing to bet it had a loose inefficient converter...been there done that.

 

how can i unlock my Th400?

 

Your TH400 already is unlocked.

And I still think the 60E is heavier than a TH400.
Someone PLEASE weigh them on an accurate scale dry with no TC so we can find out once and for all the truth.
I would do this myself but even though I have access to the scales I don't have both transmissions side by side to get the answer.
All I have seen is Fedex freight said this or ABF said that or "it just feels heavier"
I have pulled a 60E twice and installed the TH400 in my car and in my opinion the TH400 "felt" lighter.
I have no problem saying I am wrong if I am wrong but so far no one has any concrete evidence.
Even if the TH400 is heavier I would be very curious to see exactly how much.

Sorry for the rant and no I don't know why this bugs me so much.

 

I wouldnt doubt it.My 400 felt as heavy as my T56

 

i knew we can lock the 4l60e (or any OD trany)....but i got confused when ls1408cp said "
if you dyno it unlocked it would change your numbers alot".....

thx