Percentage power loss through auto

[apkole]

Just had my early '91 dyno'd at a Cummins shop. The truck has the 727 TF transmission, no OD. No intercooler. Stock hp for the engine is 160 hp. Dyno says 139 at rear wheels. I was surprised it didn't read lower, but wasn't sure what to expect. Is this about right for a stock setup?



Andy

 

[sparks57]

Yeah, I think autos loose like 10-15% because of the torque converter slipping... I'm not very knowledgable about autos though...



Standards read about 145.

 

[bgilbert]

Yep, from what I've read it is, 145 for stick 140 for auto. Another thing I've heard some of the engines left the factory pushing 500ft-lb of torque dont know bout the hp. My stocker 89 before any mods, beside air in air out- kn air filter in box, and 5" stacks, I layed down 177hp, 417 ft-lbs on Dyno-Jet 240 I think they call it. Bill

 

[sparks57]

WOW! I was right!

 

[dpuckett]

I thought it was 10-15% for manuals, 30-35 for autos. Seems like i remember reading an article about someone's 95 putting 105 to the wheels, and the dyno tech sayin it was about right. The stock 91. 5 250 I had a few years ago put 140 to the wheels- 16psi boost with 21cm housing (which was soon changed to about 21). 160 engine hp; 140 RWHP = 12. 5% loss.



I had a 93 that was stock, putting 616tq to the wheels; I think the dyno was off a little. IF that one was putting 616 to the wheels, my 91 is topping 800.



-DP

 

[apkole]

Great, thanks for the reply guys. I have a buyer for the truck and he wanted the performance checked out. I'm going to miss this truck. I was really looking forward to having all three generations settin' in my shop, but pockets aren't deep enough.



I really am impressed that from this basic design, that hp is more than double from this '91 to the 2004. 5 model.



Andy

 

[bgilbert]

[I really am impressed that from this basic design, that hp is more than double from this '91 to the 2004. 5 model. ]



Yep but you can easily make the 91 160hp engine put down alot more than the 04. 5 will do and alot cheaper... Bill

 

[apkole]

Yeah, bill, that is one of my dreams when I get my 2nd million made (I've given up on the 1st). Take an "undervalved" truck and make gobs of hp. The best feature of this truck is that it is PAID FOR. Hmm, no truck payments, what a concept! andy

 

[dpuckett]

yup, and you can take a couple month's of payments on the new one, and BOMB the holy cr@p out of the first Gen. $2500 (what's that, 4 payments, maybe?) in BOMBs will getcha gobs of power and torque, may not be the maz that some are shooting for, but still outrun a majority of the V8s out there, in cars and pickups. Oo. Go all out for 6 mo of payments.



Daniel

 

[sparks57]

Originally posted by dpuckett

I thought it was 10-15% for manuals, 30-35 for autos. Seems like i remember reading an article about someone's 95 putting 105 to the wheels, and the dyno tech sayin it was about right. The stock 91. 5 250 I had a few years ago put 140 to the wheels- 16psi boost with 21cm housing (which was soon changed to about 21). 160 engine hp; 140 RWHP = 12. 5% loss.



I had a 93 that was stock, putting 616tq to the wheels; I think the dyno was off a little. IF that one was putting 616 to the wheels, my 91 is topping 800.



-DP

I don't know about that power loss theory... . maybe from FLYWHEEL HP. In direct (4th) there is supposed to me no power loss.



Correct me if I'm wrong...

 

[JLEONARD]

Just for comparison, my early 91 5spd did 165 hp (at 2600 rpm) and 375 ft-lb (at 2200) in stock form except for a K&N filter and 16 cm housing.

That was in 5th gear.

There is a power loss from flywheel hp to rwhp. I was always lead to believe it is close to 15-20% in a manual trans.

Jay

 

[Greenleaf]

Boy, I'd simply love to dyno my truck... ... but I can't locate it ... ..... not to mention the engine will eat the transmission for lunch



Has anyone seen my truck around the Dover/New Philly area???



GL

 

[MidwestMotorman]

There are a few factors with hp loss. 4WD will take more hp to turn the transfer case. If you run synthetic, you will see less hp lost. (If you run synthetic in the trans, t-case, and rear end, you will definitely see a difference. )

 

[sparks57]

Why do synthetic lubes rob HP?

 

[y-knot]

They will loose a % like anything else, but they are not what completes the total parasitic loses. You have a alternator, vacuum pump (some do), AC pump, Fan drag, power steering pump, Transfer Case if equipped. They all add a certain amount to the total loss, and yes the manual has a loss also. What most forget to mention, is the automatic transmission through it fluid coupling (TC), makes approximately 40% more torque. Just one of the reasons autos leave so hard, and why they are popular in the drag racing community.

 

[Greenleaf]

My brother said when he needs extra power in the hills, he turns off the locking TC to gain torque 'cause then it's multiplying.



Whatever. I don't worry about it 'cause I ain't got a locking TC



I rode with him once down into the hills of TN and when he would turn the TC clutch to lock mode the engine rpm's drop a good bit and vice versa.



I enjoying setting him back into his "chair" when I get the 5. 9 wound out in "D" and hit "OD" Oo.



He's a gasser V8 hunk-o-#@!!#$ fan.



-S

 

[1stgen4evr]

Hmm, no truck payments, what a concept! andy

My kind of thinking. Got the 89 to try some upgrades. Got the 93 to pay for it.



1stgen4evr

James

 

[dpuckett]

Originally posted by CB_Parker

Why do synthetic lubes rob HP?

I hink he meant that with synthetics, you lose less power than with conventionals; i. e. the synthetics arent as parasitic as dino oils.



-DP

 

[jlast]

dpuckett



i have also heard that the TC is only about 70% eff in 1st gens.

 

[BushWakr - RIP]

"... ... arent as parasitic as dino ... . " DARN !!!! I think I went out with her... .



Pb.