Dyno'd the Viper

[DadsFinalEdition]

Dyno\'d the Viper

Ran it on Sat. Bone stock 02Final Edition
400rwhp
440rwtq
The car is running very lean, I will get the dyno graph up shortly, but don't know what the problem is. it hits about 15-16 at 5700rmps. not good any help would be great
-Austin

 

[KenH]

Re: Dyno\'d the Viper

The HP/TQ numbers sound about right, but the A/F sounds way off. Most stock Vipers seem to run a little lean at lower RPMs and rich at around 11.5 at the upper RPMs. Anything above about 13.5 sounds like potential trouble to me. Any chance they didn't have the WB sensor inserted very far into the exhaust causing a false reading?

If you can get a dyno posted with the A/F, I am sure some of the more knowledgable around here can help sort things out.

 

[DadsFinalEdition]

Re: Dyno\'d the Viper

The HP/TQ numbers sound about right, but the A/F sounds way off. Most stock Vipers seem to run a little lean at lower RPMs and rich at around 11.5 at the upper RPMs. Anything above about 13.5 sounds like potential trouble to me. Any chance they didn't have the WB sensor inserted very far into the exhaust causing a false reading?

If you can get a dyno posted with the A/F, I am sure some of the more knowledgable around here can help sort things out.

well both times the A/F was shot out of the exhaust, second time it didn't even get a reading.

 

[KenH]

Re: Dyno\'d the Viper

If your graph shows the AFR going rich (11.0 to 12.0 or so)at around 4000 - 4500 RPM and then going back lean near the end of the run about the time the sensor was being ejected, I think you probably just got an incorrect reading. I am pretty sure that if the sensor is near the end of the exhaust pipe, the exhaust air mixes with the (very lean) outside air resulting in an incorrect lean reading.

 

[Joseph Dell]

Re: Dyno\'d the Viper

Keep in mind that you are suppose to pull A/F from before the cats... if you are pulling it at the tailpipe, then you are going to be on average 1 to 1.5 points off on the scale.

Where did they stick the A/F ****?

JD

 

[DadsFinalEdition]

Re: Dyno\'d the Viper

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[DadsFinalEdition]

Re: Dyno\'d the Viper

Keep in mind that you are suppose to pull A/F from before the cats... if you are pulling it at the tailpipe, then you are going to be on average 1 to 1.5 points off on the scale.

Where did they stick the A/F ****?

JD

They stuck it in the tail pipes...I am not sure the reasoning behind it, but I know the viper club was at this place last month so who knows...

 

[CMilViper]

Re: Dyno\'d the Viper

That A/F ratio does not look accurate.

Your peak numbers are on par with most other stock creampuffs (00-02).

 

[CMilViper]

Re: Dyno\'d the Viper

Here is another FE dyno graph I found....He put down:

Max Power: 400.7 HP
Max Torque: 442.6 ft-lbs


http://www.feviper.com/dyno.html

 

[J DAWG]

Re: Dyno\'d the Viper

I wouldn't put much stock in that a/f. Needs to be precat to get the best reading.


If we are wrong....well the car is still under warranty.

 

[GR8_ASP]

Re: Dyno\'d the Viper

Another concurrence that any reading post cat is only indicating the efficiency of the cat and nothing about the pre-treated a/f ratio. 15:1 is almost stoich so it sounds like the cats were working well.

 

[KenH]

Re: Dyno\'d the Viper

Virtually all dynos take the A/F measurement in the tail pipe from what I have seen as most cars do not have an extra **** welded in. I have seen it reiterated a number of times including by tuners like Sean Roe that tailpipe readings still gives a reasonably accurate A/F, but that it will be delayed slightly in relation to the RPM scale. I do not believe that all the tuners are welding in O2 bungs everytime they dyno tune a car, but there is a slim chance that I may be wrong .

 

[BadVenm]

Re: Dyno\'d the Viper

I dyno'd my 99 RT-10 today to get a baseline. The car has smooth tubes, filters and a 3" Corsa cat back. It pulled 432.5 RWHP and 467.4 Tq.

I didn't see any A/F numbers, nor did they put anything in my tail pipe. Should I go back and ask them to redo it with the A/F readings? How critical are the A/F numbers during a dyno run?

I'd post a graph, but I don't know how.

 

[DadsFinalEdition]

Re: Dyno\'d the Viper

thanks guys, i am headed up to the IL cruise meeting tomorrow, so i will ask those guys too!

 

[C O D Y]

Re: Dyno\'d the Viper

I pulled 435 and 426 on two different dyno's (dynojets) and on two different days. At the time the car had tubes, filters, and a cat back.

 

[BadVenm]

Re: Dyno\'d the Viper

Cody,

The shop that dyno'd my car today, had dyno'd this car back in May of 2001 for the previous owner. I knew it before I went there, they didn't know it was the same car. I asked them to pull up the dyno from 2001 after they dyno'd it for me today. I was amazed back in May of 2001 it pulled 432.5 RWHP and 467.6 or 7 Tq. The guy said it must have been the same kind of day, temp and humidity back when to orig owner did it.

Do you know the significance of the A/F stuff they are talking about above? Do I need to re-dyno the car and get that info?

Thanks.

 

[DadsFinalEdition]

Re: Dyno\'d the Viper

I pulled 435 and 426 on two different dyno's (dynojets) and on two different days. At the time the car had tubes, filters, and a cat back.

Cody- did you have your dyno'd before those mods? and are those hp numbers above?

 

[KenH]

Re: Dyno\'d the Viper

For comparison, my '01 with smooth tubes, filters and Corsa catback pulled 432rwhp and 469rwtq SAE corrected and smoothed.

My stock baseline was unfortunately done on a Mustang dyno which gives a lower reading than a dynojet, so can't really compare the two. Those numbers were 394rwhp and 404rwtq if I remember correctly. That had me worried until I learned of the difference in the two dyno systems.

I don't think it is all that important to get an air/fuel reading on a mostly stock motor. Unless there is something wrong with the motor you are going to get pretty much the same readings as everyone else. If you start doing more serious mods and you have a way to control the air/ful ratio, then it is more important. You generally pay extra to have the air/fuel reading taken, so you can't automatically assume you will get one.

My guess is that the air/fuel reading in the dyno above is flawed somehow and probably not an actual reading. To put your mind at rest, I'd take it back and ask them to rerun it. If it is a valid reading then I would suspect a weak fuel delivery system (weak fuel pump, clogged injectors or something like that).

--- Ken

 

[DadsFinalEdition]

Re: Dyno\'d the Viper

thanks for the reply, I will prob have the fuel system checked out, wouldn't think there would be a problem at 800 miles, but you never know, it does sit a lot

 

[PRVT JET]

Re: Dyno\'d the Viper

We dynoed at street stuff also, Some cars did shoot the reader out the tail pipe. My car dynoed 442 and 485, with full exhaust, k&n, 1.7 rockers. My a/f at top was 11.2-11.5, On a stock car you should be around 13.

 

[RobHook]

Re: Dyno\'d the Viper

Wait, 800 miles??? Eight HUNDRED? That car's barely broken in. Is it even a good idea to dyno a car with miles that low? Unless you're trying to establish a baseline of some kind, I wouldn't dyno a car with miles that low. Factory break-in calls for no more than 1/2 throttle until 500-700 miles, right? Doesn't explain the A/F problem but might explain low HP or TQ numbers, not that you have them.

--Rob

 

[DadsFinalEdition]

Re: Dyno\'d the Viper

Wait, 800 miles??? Eight HUNDRED? That car's barely broken in. Is it even a good idea to dyno a car with miles that low? Unless you're trying to establish a baseline of some kind, I wouldn't dyno a car with miles that low. Factory break-in calls for no more than 1/2 throttle until 500-700 miles, right? Doesn't explain the A/F problem but might explain low HP or TQ numbers, not that you have them.

--Rob

We were told 500 is the break-in. So we didn't bring it above 3000 till 500 miles. Then we let her loose. Whether or not it is bad, I guess it is too late now. Geeze we have even had it to the track. I guess when you never drive it, that's what you get. Oh well

 

[BWoodbury]

Re: Dyno\'d the Viper

HP and TQ look about right for a stock creampuff. And your 1/4 mile ET and MPH match the power readings pretty well.

Put some miles on that thing!

 

[VIPER006]

Re: Dyno\'d the Viper

Hey Guys I dyno'd my 2001 GTS yesterday and I was please with the numbers but the torque seems off. It is also the second time at a different dynojet and the numbers are consistent. The Viper is stock, just the drop in K&N's. Not even smooth tubes.

At a run temp. of 100.35 F, it put down 407.77 Rwhp and 423.68 Rwtq. I don't know but the torque seems low. What do you guys think??

 

[VIPER006]

Re: Dyno\'d the Viper

BTW, this info might be of interest to DadsFinalEdition: Yesterday when I went to the dyno it was with two more friends. On the very first run my friends car showed scary lean, it was around 18 for the A/F. The shop owner replaced the filter for the A/F reader because of the reading. He said the last car on the dyno was running av gas and it possibly damaged the filter. After that everything was normal as far as A/F ratios including my passes. Good luck with the problem.

 

[Jack B]

Re: Dyno\'d the Viper

Viper006 is probably right, the air/fuel sensor had to be bad. Are you sure that it was even a wide-band sensor. Contrary to what others during this post are telling you the cats are not going to change the a/f reading drastically. You can easily verify this by putting the dyno's a/f sensor into your forward oem O2 well.

Something is wrong, hopefully it is on the dyno end. You can always look at your plugs under high magnification and look for splatter which you would have with the a/f ratio you are displaying.

 

[2002_Viper_GTS_ACR]

Re: Dyno\'d the Viper

Hey Guys I dyno'd my 2001 GTS yesterday and I was please with the numbers but the torque seems off. It is also the second time at a different dynojet and the numbers are consistent. The Viper is stock, just the drop in K&N's. Not even smooth tubes.

At a run temp. of 100.35 F, it put down 407.77 Rwhp and 423.68 Rwtq. I don't know but the torque seems low. What do you guys think??

TQ defintely seems down. Stock my 02 ACR pulled 410rwhp and 450rwtq, being that you got close to my 410 hp, I would expect you get close to the tq. you are missing about 25 rwtq

Jon

 

[VIPER006]

Re: Dyno\'d the Viper

Jon,

Thanks for the feedback. That is exactly what I thought. Oh well, I will soon fix that deficiency. I am planning on Belanger complete exhaust system (everything with no cats). K&N cone filters with polished tubes. NX wet kit. And lastly have my computer tuned by West Coast Vipers. I can not wait.