DYNOJET: 723.6 RWHP / 625 RWTQ Thanks to DC Performance and Woodhouse

[2002_Viper_GTS_ACR]

fun stuff and I got off cheap with the bet...9 dollars covered Jons lunch my lunch and two cans of strawberry soda

I'll say this, he was a man of his word. Still cost me $125 bucks, but at least paid for my $5 lunch...

 

[Bobpantax]

here are the best graphs of the day for both of us.

power

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air fuel

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From 4350 to 6000 RPM the difference in A/F ratio is considerable. Jon's car is running much leaner. It's above 12 from about 4225 RPM until pedal lift. So, contrary to the original post in the other thread, the A/F is not 11.5 across the board or below 12 and the numbers are 704/622. The 704 is on the high side but the A/F explains the result. If it was me, I would change the pistons out at this level for the added margin of safety but to each his or her own. I assume that Jon fully understood and understands the risk inherent in the increased A/F and is prepared to absorb the cost of any issues, if any, created by it. After all, we all know you have to pay to play. Enjoy the car.

 

[ILLSMOQ]

here is what the dlm tensioner looked like after fixed it. It's still ugly but it works and it's out of sight anyway when installed. It wont be breaking again but it does not install as easily either.

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clocking the paxton tensioner didn't work, here is the back of it.

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there used to be a pin that prevented the tensionor from rotating where the little circle is...it popped off, don't need the pin with the dlm part anyway. One thought is to use a steel dowl pin or a bolt to hold the tensioner in place....thinking about the options right now.

 

[99 R/T 10]

From 4350 to 6000 RPM the difference in A/F ratio is considerable. Jon's car is running much leaner. It's above 12 from about 4225 RPM until pedal lift. So, contrary to the original post in the other thread, the A/F is not 11.5 across the board or below 12 and the numbers are 704/622. The 704 is on the high side but the A/F explains the result. If it was me, I would change the pistons out at this level for the added margin of safety but to each his or her own. I assume that Jon fully understood and understands the risk inherent in the increased A/F and is prepared to absorb the cost of any issues, if any, created by it. After all, we all know you have to pay to play. Enjoy the car.

In Jon's defense, Jack B had posted up a while back that if a Tailpipe sniffer was used, the A/F could be off by .5 to 1.0 on the A/F(to the lean side). So it's possible his A/F is where he thought it was. I don't know how they measured the A/F on this dyno, but a more accurate method is to have a second ********* to insert the dyno O2 sensor. Just my $.02.

 

[2002_Viper_GTS_ACR]

In Jon's defense, Jack B had posted up a while back that if a Tailpipe sniffer was used, the A/F could be off by .5 to 1.0 on the A/F(to the lean side). So it's possible his A/F is where he thought it was. I don't know how they measured the A/F on this dyno, but a more accurate method is to have a second ********* to insert the dyno O2 sensor. Just my $.02.

This was a tailpipe AFR check, certainly no where near as acurate if they had used my **** upfront.

But Dan Told me 11.5 across the board, and that doesnt change regardless of what dyno you use. So I could care less what others are ranting about, Dan says 11.5 across the board, and thats what it is. PERIOD.

I didnt ask for the tailpipe AFR Check, becuase I know how unpercise it is, but its included with the cost of the runs, so I let them do it.

 

[Bobpantax]

In Jon's defense, Jack B had posted up a while back that if a Tailpipe sniffer was used, the A/F could be off by .5 to 1.0 on the A/F(to the lean side). So it's possible his A/F is where he thought it was. I don't know how they measured the A/F on this dyno, but a more accurate method is to have a second ********* to insert the dyno O2 sensor. Just my $.02.

Interesting point but if the people who did this dyno run did not know how to properly use something as simple as "the tailpipe sniffer", then all of the data lacks credibility. I think that the data is correct. The laws of physics apply. The higher a/f explains the higher power level. Anyone who is willing to tolerate the extra risk inherent in a higher a/f can easily duplicate similar results with a Paxton equipped Gen III Viper. I don't think any of the other mods listed for Jon's car outside the Paxton kit are contributing in any significant way to the power increase. It's all in the increased a/f allowed by this particular DC tune. My car runs richer and it is producing 669.03/617.68 at the rear wheels. I have a stock Paxton kit with Corsa cat back. No other engine or exhaust mods. It has a DC blower tune uploaded from an SCT. The tune was prepared by DC based on a description of my car and faxed dyno results including an a/f chart. I am pleased with the results. The car runs well and I am still well within an a/f that I am comfortable with.

 

[ILLSMOQ]

I'd like to see bobs car dyno with a boost graph and a a/f graph..not squished graphs on the boost and a/f please

or get the winpep files if it is on a dyno jet and I can overlay the graphs

 

[sniper1]

I know its prob a matter of opinion but can someone tell me which S/C makes better HP and TQ on the manufactures rec boost levels? I personally like the looks of the Roe but does it make as much as the rest?

Sniper

 

[Camfab]

Get that thing some tire and get it to the track, it should run some serious numbers if you can get it to hook. Great results!

 

[ILLSMOQ]

My car was tuned a bout a year and a half ago at DC Performance with the original paxton pully and a slipping belt. At that time I requested a conservative tune since there were not any other S/C vipers running around my area and I wanted it to be on the safe side. It made around 640rwhp in that condition and A/F was high 10's to low 11's

I have since added the smaller pully and the dlm tensioner, left the tune alone and it has made almost 700rwhp. A/f usually reads around 11.5 but does get leaner depending on the air,it's gone over 12 in really cool air.

Measuring from the tail pipe is not going to be as accurate as measuring at the header collector. Dyno wide bands are all over the place, you don't know how old the sensor is etc... I use an Innovate LM1 and Innovate LC-1 to monitor and log A/F. It's installed right after the header. That being said....the A/F data collected by this particular dyno seems to be on par with the data I pull with my equipment.

 

[ILLSMOQ]

Are you saying that whoever tuned Kurtis' car did not tune it properly? Regardless of who tuned his car, if your A/F is wrong on the chart above, so is the A/F of Kurtis. And, if Kurtis' A/F is that rich, when he has his car properly tuned, the vehicle will produce considerably more power and most likely exceed the power level produced by your vehicle. Either way, the power levels currently being discussed are not that high when viewed in the context of the graphs posted from twin turbo applications and some of the cars with built motors and superchargers. I think that it is important to report accurate data on the VCA website. Some members base their modding decisions on that data. Enjoy your car.

When compared to those big power cars you are right, our numbers are small time....but they were built by guys who do this stuff for a living and have lots of experiance. We don't expect the guys that tune these cars for a living are going to jump on the VCA forum to answer our questions thus giving away their service for free...though sometimes they do pop in to maybe help settle the dust a bit

Some people like to pay to have their cars modded then just drive them while others actually like to work on their cars themselves (me) and learn what works and what doesn't work....maybe even the reason why something did or didn't work....so here we are having these discussions. A bunch of enthusiasts that have more than half a clue ( some more than others) but don't quite know it all.

It's obvious to me that these motors can handle some abuse, mine runs rich with more boost Jons runs leaner with less boost, both make simlar power and both will proabaly last quite a while. There will be a variance from dyno to dyno, wide band to wideband and of course the weather conditions play a roll. So to make a huge deal about half a point in the A/F ratio and expect a difinitive answer as to weather or not it is safe is pointless. Safe is leaving the engine alone...anything beyond that is less than safe. if you read through the years of threads on these forums yo will see that people have damaged their engines when they strayed from what was recomened by Paxton or Roe. Experimentation is not conducive to safe

 

[Bobpantax]

Back to the tech end of things...Bob do you have any black powder near your alternator? With out the dlm tensioner my belt slips and generates rubber dust....curious if you notice or have ever noticed anything like that.

I have not noticed any black powder. I still have the original belt installed at 19 miles on the clock when Mark installed the Paxton kit. So far so good after 14,000 miles. The amazing thing about the car is the little maintenace needed to keep it in proper running order. If it was a foreign exotic, by this time, I probably would have spent a significant percentage of the cost of a Viper on maintenace and upkeep and not been able to drive it in an equivalent "spirited manner". Assuming you have forged pistons, etc., you should bring your car back to DC and let them experiment with it a little while you are there. If the A/F above is correct, I think you might have a bit more power available with an A/F that is less than Jon's but a bit higher than the current settings. If you have not discussed it recently with Dan, you might want to do so. On the other hand, there certainly is a strong argument for being extra safe - especially when your power is already more than enough for most purposes. Enjoy your car. Any Viper is a mechanical creation to be proud of.

 

[ViperTony]

Due to numerous complaints, this thread has been closed and all posts violating posting policies have been removed.

- Tony