Interesting "stock" dyno results

[RobZ]

Interesting \"stock\" dyno results

Just picked up my dream car last weekend, a '97 GTS, red. So I strapped my supposedly stock Viper to our shop's dyno yesterday and got some very surprising numbers. The car has K&N's, smooth tubes, and rear muffler delete. That's all as far as I know...


Here are the numbers.

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I am the third owner of the car. The second owner just cruised around in the car, only drove it 5K miles in 6 years. I'm wondering if the origional owner did anything special to the car like a head/cam package or something.


This was done on a Mustang AWD dyno (setup for 2WD mode, checked twice) and the RPM scale was calculated at 4000rpm in 4th gear. Three pulls were made, the rpm scale was recalibrated between the first and second pull. The whole dyno was recalibrated after the second run because the numbers were still way too high. The rpm scale was recalculated yet again at 4000rpm in 4th gear. We made a full pull (see graph) and the numbers were still out of whack. We decided to give up for the day.

Note that two cars were dynoed before mine and one after, all put down proper numbers.

Anyone hear of crazy results on a Mustang dyno before? They're supposed to read a few % lower than a dynojet.

Gonna do a compression check and see if that gives me any clues, what is the factory spec?





Glad to be a part of the group,

Robert

 

[plumcrazy]

Re: Interesting \"stock\" dyno results

thats not a stock viper

 

[valentine_viper]

Re: Interesting \"stock\" dyno results

Those numbers would produce a low 10 sec to high 9 sec car with sticky tires. To get that much power out of a N/A car, it would have to have been heavily worked; big cam, lots of head work, fuel system and management, etc. If it's making that kind of power, it should feel (and sound) freaky fast to you.

Does it?

 

[RobZ]

Re: Interesting \"stock\" dyno results

Not really, that's why I think the dyno is having an issue. It's strange that the other three cars put down proper numbers and the fact that we calibrated it between runs.... something's not right. It definately does not feel like a 10 sec car.



Robert

 

[plumcrazy]

Re: Interesting \"stock\" dyno results

id take it to a different dyno

 

[Casey]

Re: Interesting \"stock\" dyno results

LOL

 

[KepRght]

Re: Interesting \"stock\" dyno results

1st off, WELCOME TO THE CLUB

you should see 400-450 rwhp with those mods depending on how well the engine is holding up.

to give you an idea, $8,000 or so in heads and cam and your looking at 525hp add a computer and fuel system and your looking at 600ish

check the computer, see if it says AEM

 

[jcaspar1]

Re: Interesting \"stock\" dyno results

If I'm reading that right, I think the -267 HP at 24 mph is a clue that something is amiss.

 

[RobZ]

Re: Interesting \"stock\" dyno results

The negative HP/TQ is from decelerating. I left the car in 6th while the dyno was slowing to maintain oil pressure and coolant flow. The readings are negative due to engine braking, we didn't pull all the way to the designated MAX rpm set on the dyno.


That said I still do not agree with these numbers, the car feels like a slightly modded Viper not a 885tq/705hp NA beast that the chart suggests.

 

[Go Fast For Life]

Re: Interesting \"stock\" dyno results

6th You should have been in 4th for the dyno. 6th gear at high rpm will overspeed the dyno.

 

[Tom F&L GoR]

Re: Interesting \"stock\" dyno results

Even decel shouldn't be -267HP. Level road power requirements, the typical load used during the highway portion of fuel economy measurements, is 12HP-15HP.

Depending on where the dyno measures load, this could be dyno braking rather than engine braking. I hope anyway - that's a whole lotta friction goin' on.

 

[RobZ]

Re: Interesting \"stock\" dyno results

OK let me clarify...

The pulls were all done in 4th gear. I shifted into 5th then 6th while the dyno was slowing to help maintain higher oil pressure for the cooldown.

The dyno brakes were applied to slow the rollers so that is most likely where the negative numbers came from.

Time to get on a different dyno and see what she's really putting down. The funny thing is that i'm not really concerned with the power output as it is enough for me right now. With these crazy numbers though I want to get down to the bottom of this.

Anyone in the Tucson, AZ area want to strap down to our dyno and see if your numbers are accurate?




Thanks for the help guys,

Robert

 

[TheMeat]

Re: Interesting \"stock\" dyno results

Hey Rob, I live in Tucson and would like to take you up on your offer of a free dyno pull!!!

I have just added Belanger headers, custom exhaust, AB wires, and VEC1 to my 94 GEN1.

Do you by any chance go to LA Fitness?

Ray.

 

[RobZ]

Re: Interesting \"stock\" dyno results

OK guys, we figured it out. The AWD dyno we have was set to 2WD mode mechanically but somehow the software was still in AWD. This caused the funky readings. I will be dynoing again next week to get the real numbers.