Project_1986_TA

I just had my TA dynoed at the shop. Are some dynos way off on numbers? For what i have done to my car i think the numbers are quit low. Its a 'Mustang Dynometer'. My car has a 350 TPI with 21lb fuel injectors, Mild cam (268*), Custom Chip, Magnaflow exhaust, and a high flow cat. The guy who put the engine in says it was a 300hp engine (at the crank) without the cam. The dyno says i only put out 163hp and 275ft lbs of tourqe. Does this sound right?? Its sounds pretty low to me. It might be because my tranny is starting to go?. Any ideas? Thanks!

Project_1986_TA

Also does it matter if its an auto?

Squeeks83

well with the dam tranny slipping it aint gonna help the power numbers, plus its an 700r4, which suck because they take ALOT of power away, thats why im ether converting or finding a manual car. but once you get that tranny fixed you should put down a little better numbers, plus people were saying for my car like 384 and 391 for the numbers at the crak, also desktop dyno said the same thing, but i still threw down 213hp and 307tq.

rezinn

What cam is in the engine? Do you have headers?

Acidtalons

163hp does sound a bit low. Bear in mind however, they say assume 14% lose to the drivetrain on most automatics, and 700r4s are a bit worse from what I hear, and if its slipping thats certainly not gonna help.

300 flywheel - drive train = 252 rwhp. Could a slipping tranny cost you 89 hp? not sure

however I would consider what kind of Dyno is was, some are less accurate than others. An engine dyno is the only true way to know, chassis dynos can be off by more than you would expect.



Edit - January 2003 Hot Rod

Chassis Dynos: "Chassis dynos measure torque at the rear wheels. All vehicles will see loses through the drivetrain between the flywheel and tires. Losses through a manual trans all less than those through an auto trans. Collectively, Harold Bettes of SuperFlow says manual cars will see 50-80 hp loss through the drivetrain, with 70-120 hp the norm for most automatics. Full-race automatics will be on the high side because thier loose convertors have more slippage. Late-model vehicles with high-tech trannies and rearends with synthetic lubricants may see slightly less loss. In any event try to run the trans in a direct 1:1 gear to prevent any losses through the "extra" gears (which could be as high as another 20hp).

Even with these variables, a reasonable relationship can be established between rear-wheel output and engine output, depeding on the sophistication of the dyno and the operator skill. Old style Clayton chassis dynos use a water brake to measure torque at the dyno's rear wheels. They don't have computerized data recording or software that compensates for drivetrain losses and can't make a quick acceleration pull. Data must be manually recorded at each checkpoint, and the old-tech dyno may not be up to holding a high-powered car on the rollers without slippage. A step up is the inertial chassis dyno, which as its name implies uses pure inertia to estimate power and torque. Although usually computer controlled, they rely on a set of preprogrammed assumptions rather than direct measurement, and may underestimate torque and power during a quick acceleration pull, particulary with a heavy vehicle and / or an engine with a large internal mass. (Can you say classic big block muscle car?) At the top of the pecking order are Eddy-current chassis dynos, which use opposing electromagnets and sosphisticated computer compensation. They are much more accurate and can withstand extremely high torque levels. Most importantly, they use direct measurement to derive torque and horsepower. Some even take into account vehicle frontal area and vehicle coast-down time to home in on actual drivetrain losses"

Any errors or typos are my own.

Z28DJP1987

Average Drivetrain losses on a Dyno are:
1) Automatic trans. 20/22%
2) Manual trans. 15/18%
Also note engine builders are notorious for over estimating their products. It makes them look good until you Dyno it, and then the
excuses start to fly.

As for your low numbers, the slipping Tranny will not help your RWHP & RWTQ. Note! I said Rear Wheel numbers the Flywheel number is still a guess.

Parrydise7

iTrader: (1)

I put my Camaro on a dyno and it showed 119 horses(!). The guy running the dyno is an ex-drag racer so he spent no more than ten minutes tweaking the carb. The horsepower jumped to 150. I added a dual snorkel and the power actually dropped a little bit. The dyno operator explained that sitting on the dyno that dual snorkel wasn't getting any ram air (plus the fact that it was one of the hottest days of the year).

The place I took my Camaro to uses a chassis dyno in conjunction with a four gas analyzer to tune a car. Was it expensive? Oh, yeah.

Make sure that everything is working the way it should.

Project_1986_TA

Through this link is a picture of what kind of dyno it is. Im not framiliar with what kind of dynos are what so.... Its a 'Mustang Dyno like i said earlier. The guy did say that most other dynos would be about 10* more than thiers. It feels way more powerfull than what it shows. Go figure. Thanks for all the replys.