'15 Viper RTX LE disappointment grows

[cannondale27]

Looks like 7500rpm for mine according to this chart from Excell. I wish all charts had RPM and Torque.

 

[kviper]

You can't have HP with out Torque! As long as Torque don't drop to fast it will still maintain a good HP number as RPM increases.

I guess what I'am trying to say is as long as you have a good HP number Torque can't drop off to much!

 

[cannondale27]

Now something that looks like this would be easy to clutch for.

 

[cannondale27]

You can't have HP with out Torque! As long as Torque don't drop to fast it will still maintain a good HP number as RPM increases.

I guess what I'am trying to say is as long as you have a good HP number Torque can't drop off to much!

I dont see that and definitly dont feel that. We are getting HP with rpm not with torque. That is the culprit here.

 

[sk-rx1]

Using Allen's numbers for driver circumference and a gear ratio of 1.86 for a Nytro (2011) the Viper is actually geared 1.5% higher than a Nytro. Meaning if it could pull the gear it would be slightly faster. There must be more to the story.

 

[titanrcr]

View attachment 104525
Now something that looks like this would be easy to clutch for.

It's easy to clutch this engine compared to a two stroke due to the broad torque curve. Power is power and this engine has loads of torque in reserve.

 

[kviper]

A Dyno does not read HP it reads Torque and multiplys Torque times RPM devided by 5252 to get a HP number. You can't drop to much Torque before HP starts to drop as well.

You can make MPH gain's with more RPM if power don't drop to much due to generating more Centrifugal force from RPM.

Looks like about 5 to 7 LB/ft of Torque drop from 7500 to 9000. That's not much!

 

[kviper]

I dont see that and definitly dont feel that. We are getting HP with rpm not with torque. That is the culprit here.

Yes as long as Torque holds HP numbers will increase with RPM.

 

[TD Max]

A Dyno does not read HP it reads Torque and multiplys Torque times RPM devided by 5252 to get a HP number. You can't drop to much Torque before HP starts to drop as well.

You can make MPH gain's with more RPM if power don't drop to much due to generating more Centrifugal force from RPM.

Looks like about 5 to 7 LB/ft of Torque drop from 7500 to 9000. That's not much!

Actually, Dynojet measures HP and calculates TQ. Impossible, but they do it They test w/o engine speed quite often which is necessary to do the math, but in some feat of reverse engineering they manage.

That is why I have a Superflow.

The Viper TQ curve is stll doing quite well and the HP is stil rising at a very good rate where the Excell chart stops.

 

[ApexGTman]

This LE just "continued albeit slower to 100mph" before or after Ulmer installed the turbo? The reason I ask is I just recently installed MPI trail turbo and Ulmers clutch kit but haven't had a chance to test it yet but Ulmer told me that it should get to 115mph before running out of gear. If there's a problem I am sure Ulmer will figure it out!

I just sold my '06 apex with ulmers clutching and air box mod and it pulled like a freight train to well over 100mph. I hope I am not disappointed with this '15 RTX LE.

 

[ApexGTman]

Will post how the 15' Blue/white 1.7" runs with MPI's trail Turbo and Ulmers clutch kit in the next week or so depending on snow conditions.

 

[cannondale27]

A Dyno does not read HP it reads Torque and multiplys Torque times RPM devided by 5252 to get a HP number. You can't drop to much Torque before HP starts to drop as well.

You can make MPH gain's with more RPM if power don't drop to much due to generating more Centrifugal force from RPM.

Looks like about 5 to 7 LB/ft of Torque drop from 7500 to 9000. That's not much!

So where does the HP fall off? Because until it does there will be many including me who want every bit of it. On that old YFZ chart hp and torque are close to each other and fall off together all in a usable range. I dont see anything like that on the Viper. Where the torque falls off is where the speed is killed by conditions.

Does anyone have a dyno chart of a Vector or Nytro?

 

[cannondale27]

Actually, Dynojet measures HP and calculates TQ. Impossible, but they do it They test w/o engine speed quite often which is necessary to do the math, but in some feat of reverse engineering they manage.

That is why I have a Superflow.

The Viper TQ curve is stll doing quite well and the HP is stil rising at a very good rate where the Excell chart stops.

They use MPH instead of RPM when RPM isnt available and yes I hate that also.

 

[Joey P]

How many miles did you have on your sled when you 95mph? any mods?

Had 500 miles on it at the time was in hard pack on a lake

 

[STAIN]

Not sure on the gearing theory you would think if you were geared too low you would fully shift out and overrev. On ideal conditions i have seen 95mph 85 is more common but my rpm holds at 9100. Leads me to believe its a hp/drag problem. Gearing for more speed with same power would only cause the clutches to upshift less to hold same rpm.

These clutches can't fully shift out in stock condition though.......you never get overdrive. If the secondary is spring binding then it's even worse.