Horrible Dyno Numbers!! Why?

[BAD 2TB]

Just bought a 2006 a couple of months ago, 3600 miles on it. I want to do some HP mods so I went down today to run a baseline dyno so I would know what I was starting with. Three pulls, HP ranged from 401 thru 410, torque from 439 thru 447. Temp 66 humity 48%.
Air/Fuel @ 2000 rpm was 14.5 but @ 4000 rpm it was 12.0 and @ 5000 rpm it was 10.5 . What could cause the low HP reading??? Any help will be appreciated. The dyno was a Dynojet.

 

[Shandon]

Something is out of wack. Thats to low for even a stock car on the lighter side. Does the car seem to run ok?

 

[Wicked]

Must be a mustang dyno, which they typically read real low. My Viper pulled 599rwhp on a Mustang Dyno and 666rwhp on a dynojet.

Jason

 

[BAD 2TB]

Car runs fine, no hint of any problem,. The dyno was a Dynojet. The fuel/air ratio is rich but I don't know if it is enough to cause that much of a power loss.

 

[Flyntgr]

Upper rpm's seem to be rich; what you want is about 13 to one, whereas my '05 got down to a rich 11 to 1. Maybe a Dan Cragin reflash is what you need; that's what I'd do if I were you. Been there; done that. Good luck getting the correct air/fuel ratio. By leaning it out some, but not too much, you'll make more h.p. A 10.5 ratio is WAY off, hence a loss of power. Dan can fix you up. Just tell him what your baseline is, and the mods you've made, if any.

 

[MikeR]

That seems too low. My A/F readings before DC Performance tune was about 10.5 at 5k rpms. Real rich. But I was still dyno'ing 466 rwhp with corsa and Hi flow cats.

Maybe try another shop to compare.

 

[BAD 2TB]

What else could it be?

 

[Twister]

try another shop first...

When my 03 SRT had KN filters and roller rockers I took it to a shop and dynoed 430 rwhp SAE on a dynojet..Figuered I had the lowest dynoing SRT10 viper in the country since 430 rwhp would be low for a bone stock one..

Then the shop owner told me that my numbers were good because a Gt500 had just dynoed 395 rwhp. When I heard that i knew somthing was wrong and went to another shop a week later and put down 459 rwhp SAE on their dynojet.

 

[dave6666]

What else could it be?

Neighbors cat stuck in the throttle body?

 

[t i t o]

The '03 I had bone stock made 468hp/493.5tq. The air fuel only went rich on mine around 5600rpm to 11:1, and stayed there till 6000rpm where each run was ended.

Take it to a different shop using the same type of dynojet. Could have been the dyno.

 

[Hamrhead]

Screw the Dyno. If you're from the Mid-south, you must still have some decent weather - Take it to the Strip and see what it'll do!!!!



Weather ***** up our way...

 

[Paul Hawker]

Plug wires on tight. Maybe pull couple plugs and see how they look.

Any soot in exhaust pipes. Maybe running rich.

 

[BAD 2TB]

I looked at a couple of other dyno pulls from 05/06 vipers, all my power was lost between 4500 and 5700 rpm. If the only problem with my car is that it is running rich could that cause a loss of 40 HP?

 

[Schulmann]

I have a 06 coupe. I haven't done any dyno on the car but I ran it on drag strip several times. A good way to check the health of your Viper is to have a drag run.

MY 06 COUPE IS LAZY.

Other guys on this forum have complained about the fact that they can't run their 06 coupe below 12.5 on the 1/4. I have the impression that some "hidden" features were added to the 06 PCM to reduce pollution. Vipers are very simple cars. There are only a few sensors for input and Fuel/ignition for output. The equation is very simple. If our 06 Vipers are weak it is due to factory settings.

My computer is going to DC this week for a reprogramming. Unfortunately, I wont be able to test the result before April ....


NB: If you want some serious diagnostic post your Dyno charts ! Otherwize we are juste chatting for nothing ...

 

[Roysviper]

I had a bone stock 97 GTS that dynoed 423 h.p.and 469 lbs of torque to the rear wheels.Something is definately wrong there with your numbers. I now have a 2006 SRI TWIN TURBO SRT-10 coupe that dynoed 810 h.p and 800 lbs of torque. My wife has a stock 96 GTS. Good luck...its gotta be in the tune up....

 

[Viper X]

BadTB,

Not enough info to help.

Some ideas,

1 - Get a second opinion as stated above on another dyno.

2 - 10.5:1 is rich but Vipers can and do make good power running a bit rich. DC can send you a computer with a tune in it and you can do comparison runs. 13:1 seems ideal normally aspirated.

3 - How hot was the car when you dynoed it? Could it have been heat soaked? Were your tires properly inflated?

4 - Check your spark plugs and wires.

5 - Check your idle air control motor.

6 - Have your injectors cleaned and balanced.

7 - Does your throttle open completely at WOT?

8 - Are your cats clear or could there be some blockage? Exhaust flow is critical to making hp up high.

9 - Are your air filters clean and clear or dirty?

Good luck,

Dan

 

[Fast Too]

BadTB - I have an 06 too and had very similar numbers on my baseline dyno before my mods. 413RWHP. That dyno was performed on a very hot and humid day last August on a dynojet. I had to dyno after the mods on a Mustang dyno since the original dyno jet crapped out due to bad bearings on the rollers. The Mustang dyno was the closest by, and my numbers on that Dyno after the mods was 651RWHP. I would expect that number to be much higher than that had I dynoed on a reliable dynojet post mods. I'm not sure if the low baseline numbers were due to heat and humidity, or the dynojet on its last legs before the bearings went out on it. I'd try another dyno before your mods if you are that concerned over it.

 

[VIPER R]

Are there any fellow viper owners nearby, maybe you can try their car and they can try yours to see if there is a noticeable difference.

 

[Fast Too]

Are there any fellow viper owners nearby, maybe you can try their car and they can try yours to see if there is a noticeable difference.

Key swapping, and now there is an interesting diagnostic approach

 

[BAD 2TB]

Talked to Mark at Woodhouse today, he is going to pickup my car next week and install a Paxton SC. He will do a before dyno and see what he gets. It will be interesting to see what figure he gets. I hope better than 410hp. After Paxton I hope better than 600hp.

 

[Canyon707]

Call DC Performance My viper with Corsa, Air and DC computer tune pulled 450 RWHP and 480 RWT The rest is all stock. Good plugs and wires make a big difference. I kind of blew that off from Jon B. but, he was right. Not bad not great but, it is what it is. Talk to Dan he will get you going in the right direction.

 

[Thums Up]

Are you sure the car doesn't have a rear-end gear from the previous owner? A gear will throw off your dyno numbers.

 

[BAD 2TB]

Can a lower gear change your HP?

 

[mangle]

Can a lower gear change your HP?

At the crank, obviously no. Since a dynojet is an inertia dyno (it has a big drum of known inertia), the torque curve is determined by the rate the car is able to accelerate the drum. This gives a fairly accurate reading of torque at the tires. Change the gear ratio to something lower (numerically higher), and you'll see more torque at the wheels at a lower rpm (just like driving in a lower gear). This will lower horsepower numbers dramatically. That's why changing the gear ratio will mess with dyno readings (usually they're done with approximately a 1:1 ratio between the crank and the axles).

Also, because the dynojet uses inertia as a load, changing to lighter wheels/tires (with less moment of inertia) will show apparent horsepower increases.

But since your curve looks right until higher rpm, this is more than likely not your problem.

 

[Twister]

Like I said ..wait till you redyno....

when my car dynoed 430 rwhp I was running 11.9-12.1 at 119-122 mph....My previous rt10 with 445 rwhp was running 12.2-12.4 at 118-121 mph at the same location.

SO I KNEW THAT WITH 1 INCH BIGGER TIRES ON THE SRT10 AND RUNNING FASTER THAT THEIR WAS NO WAY THE CAR REALLY ONLY HAD 430 RWHP..

Dynoed again at the same spot were the rt10 hit 445 rwhp with 4-5 mods and hit 459 rwhp with only 2 mods on the SRT10

 

[Coloviper]

Point is your car is running fine, but the dyno numbers came back low. Doesn't really matter because you want to add mods. A baseline pull is a baseline pull even on a dyno not showing you the numbers you want to see. It is there to prove to you your new mods are going to be adding power.

So if you add 150 HP from the base or 150 hp from the number you really wanted, the point is you are still adding 150 hp with your mods.

Want to deflate your *** ***, come dyno here in the Rockys. Its all relative to so many different conditions and factors. Baseline is just the starting point. If it seems to be running fine to you but the baseline is low, it is low. A good tuner will use the equipment he has to make the "gain" on the dyno.

People like to throw around these wildly different numbers that range 150 HP difference. Most of it is bs. A good tuner can listen and feell the difference. The dyno helps a lot but is not the full answer when it comes to mods depending on your region and time of year, etc.

 

[BAD 2TB]

Car was picked up today by Woodhouse. Mark is going to run another dyno for me and see if he can find anything wrong with the car. I added Corsa 3" track exhaust with Randon Tech cats, X-Metal thottle body and undersized crank pulley, after I did my baseline. I'll post the results in a couple of days.Hoping for around 460 to 470 rwhp. Woodhouse is installing Paxton SC and upgraded PCS. Hoping for 630 to 650 rwhp.

 

[2002_Viper_GTS_ACR]

You'll get 640 rwhp easily, you have more mods then I do, and I got that number with a crappy off the shelf paxton tune. Now I have an SCT/Dan Craig tune on it, and I'd love to see what she pulls for power.

Jon

 

[Alexarz]

Sell the runt.

 

[BAD 2TB]

Just got my baseline back from Mark @ Woodhouse. Mustang dyno: 429.8 rwhp and max torque 446. Which should work out to 537 crank hp and 557 crank torque. First dyno must have been a low reading machine. Looking forward to the numbers after the Paxton install.