Auto Trans and Rear Wheel HP

[Texasdeere]

I have seen many Dyno results showing a loss in hp at the rear

wheels on auto equiped trucks as compared to manual ones.



The question is, once the converter locks up, shouldn't all things be equal? Or is there too much resistance still found inside the auto transmission eating up some hp.



Also, I am not at all familiar with how a dyno run is performed, or with respect to gear selection during a test run...

 

[HOSS]

Auto vs manual

Your automatic transmission is basicly a hydrolic pump and it robs power from your engine to run it. Therefor a rear wheel power loss that a manual does not have.

:--)

 

[Cummins4Life]

"lock up" in an stock auto is a mis-nomer, it locks up but it still slips alot more than a manual will.

 

[Strick-9]

Torque converters don't slip in lockup unless there is a problem.



The torque converter hub drives a pump to maintain line pressure in lockup. We are talking only a few HP here.



The highest dynoing trucks are autos. Unless I'm forgetting someone.



-Chris

 

[Texasdeere]

I just remember seeing Dyno results on mostly stock trucks where lets say they both had 235hp engines. The 5spd would have around 220hp at the rear wheels. The auto would have around 185hp at the rear wheels.



Thanks for the info. . MH

 

[Jim Fulmer]

Manuals are fine on the dyno but take that same setup out and drag down the street, the auto is always the winner in a drag race (power the same and a good auto) Running on the dyno in lockup is fine as long as you have pump speed..... engine RPM... . my . 02



Jim

 

[otis]

I recently had my stock 2001 auto on the dyno at the BD day. It put out 225hp . My dads ETC six speed did 217 hp which is also stock. We both figured the manual would be higher.

 

[rspinks]

My dyno numbers

Well I got a whopping 176hp on a mustang dyno with my stock 2001 ETH/DEE, only 6000km however. I think (hope) there's some variation between dyno's and programs for them? I showed 520ftlb so that made me happy. A stock PSD got 175hp and Dmax got 230 the same day. My truck feels strong so I'm not too concerned. It's chewed up a good portion of my MTR's in 10,000 km anyways.

 

[Chipstien]

Otis, do you mean ETH. The six speed is only offered with the high output ETH. Very interesting that the ETC dynoed higher than the ETH. Seems that something must be wrong somewhere for that to be the case.

 

[KatDiesel]

Originally posted by Chipstien

Otis, do you mean ETH. The six speed is only offered with the high output ETH.

For a very short time you could get the 6 speed with an ETC motor... before the ETH motor was introduced. THey are pretty rare tho, the only person I know for sure that has one is Mike R.

 

[otis]

Chipstein, my dads truck is a 2000 which was a very short production year. The 2001 came out with the ETH, he was a little disappointed that he just missed out on the HO and trailer towing mirrors. Probably would have seen it coming if we were TDR members back then. I ordered a ETH and at the next BD day in April I am going to run it on the dyno to compare it with my dads 2000 ETC.

 

[Chipstien]

Thanks for the replies guys.

Learn something new everyday