Anyone have any experience with the lighter Th350 vs. a Th400?

We all hear how the heavy internal parts of a Th400 make them sap more power, but how does this really compare to a Th350?

I'm asking because I have a Th400 in my truck and people keep telling me how it's holding me back and I need to swap in a Th350.

BUT that would require modifying my driveshaft and getting rid of my fresh, built turbo 400.


What do the "drivetrain" experts say?

Ben T.

 

I have no data on this. But my gut feeling is that it's not a huge difference.

Rich Krause

 

What Rich said.

A few % at the most. IMO, THM 400 was a better design than the 350. Clutch-on-clutch shifts and stronger parts.

Spend the money it would cost to swap in the 350 on hp. I'll bet you'll be happier.

 

First the weight diff is not really that much..forget how much but not much..not significant.Second power loss is also not much more.

All I know is was running like mid 14 with turbo 350 and put in turbo 400 and stall and right away went down 3 tenths and sure could get more out of it as 60ft was still like 2.24 .This was on worn out old street tires.Not drag type tires.Now guess the car might be a tenth faster mabye with the turbo 350 but who cares that 400 is very strong tranny.

 

The main difference that would effect et's is the gear ratios. 1st and 2nd gear on the TH350 is steeper than the 400.

 

If I recall correctly, they are pretty close:

400 2.482:1(1st) 1.482:1(2nd)

350 2.52:1(1st) 1.52:1(2nd)

350 has 1.5% and 2.5% steeper gearing. Many folks would have a tough time feeling or measuring that difference based just on ratios.

My $.02

 

Yep, those are the numbers that Iremember also.

Rich Krause