OK - Dyno Experts .... 448.2 hp, 442.42 Torque. Thoughts?

[ROCKET62]

Thanks in advance for your thoughts and feedback on my 2005 with 4000 miles.

Mods - K&N Intake & Filters, XMetal Throttle Body, DC Performance PCM, Mopar Exhaust - Delete Second Cat.

Conditions - Drove 20 minutes to dyno, 78 degrees, 46% humidity, 720 ft elevation, Land & Sea Dyno-max 2000 Pro. Dyno operator thought that I was leaving a little on the table as he felt it was running on the very safe, but rich side. He also thought 20% driveline loss - but that seems a little high -so what's a reasonable driveline loss figure to calculate flywheel numbers?

 

[MikeR]

With similar mods, I was upwards of 480 rwhp and 520 rwtq. Your hp seems low and your torque real low. Could be the dyno or operator. But your putting down close to stock Viper hp.

 

[MTGTS]

Do you have have some heavy 20" rear wheels by chance?

 

[ROCKET62]

Do you have have some heavy 20" rear wheels by chance?

Interesting question. Stock 5 spokes, BUT I do have 1" H&R spacers as part of my Street Serpent conversion. These do add some weight, but I dont know exactly how much? I also thought it odd that they measured the wheel diameter (not very precisely) and he only said 26.5" when the stock is 27.4"

 

[MTGTS]

Your also moving the rotating mass out another inch as well. I don't think it would cause this much of a loss though.

 

[JonB]

I have seen as much as 50 HP lost entirely to aged plugs and wires. But 4-year, 4000 mi wires should be OK

 

[Viper X]

HP seems about normal for our area with those mods.

TQ is lower than normal. It should be about 475 rwtq at your rwhp level. Likely the combination of the big single blade throttle body and the Mopar exhaust or a tuning issue. In mostly stock form these engines seem to like a bit of restriction on the exhaust side to make torque.

Did DC know your mods when they supplied the tune or did you make the mods after the tune?

Would be interesting to see your air / fuel ratios.

Drive line loss should be about 15%.

Dan

 

[cyaford]

I wouldn't worry about it. Dyno's vary, some by a lot. Was the dyno itself a "DYNOmite" dyno?? Never heard of it, which may explain the low numbers. Do they have any records of other Viper pulls?

 

[Nader]

Dan the A/F ratio is on the chart. Looks rich to me. Mine leans out to low 13s on top. I currently have a DC tune.

HP seems about normal for our area with those mods.

TQ is lower than normal. It should be about 475 rwtq at your rwhp level. Likely the combination of the big single blade throttle body and the Mopar exhaust or a tuning issue. In mostly stock form these engines seem to like a bit of restriction on the exhaust side to make torque.

Did DC know your mods when they supplied the tune or did you make the mods after the tune?

Would be interesting to see your air / fuel ratios.

Drive line loss should be about 15%.

Dan

 

[adamlotus]

horsepower looks about right,maybe the torque should be higher but you got some nice #rs

 

[Jroc]

Yeah its running too rich.

 

[SnakeEye]

Rocket62, yeah it seems low on the torque for your mods but really with a Street Serpant it's a crying shame not to have that bad boy Paxtonized. Do this and you will see 675rwhp and 600rwtq. The next best 10K you'll ever spend on that beast...

 

[Newport Viper]

446 and 478 with K & N only here. Dyno at DC Performance with very similar conditions except, I drove 125 miles to get there.

Thanks again DC Performance for the fun day!




[media]http://gallery.viperclub.org/data/500/024.MOV[/media]

 

[Dan Cragin]

We can make adjustments to your air fuel from your dyno sheet, give us a call and we can take of it.

 

[Viper X]

Hey Nader,

You are right, looked right past the Air /Fuel ratio.

Yes, he's pretty rich up top. Should be closer to 13:1. That may account for the low peak torque.

DC can fix this as Dan says. They have done a marvelous job tuning cars for me.

Dan

 

[ROCKET62]

Thanks for all the replies. It is pretty obvious that it is running rich and we are leaving quite a bit on the table. The low torque number did kind of surprise me though - but I'm not sure it would necessarily be such a bad thing as these engines already generate enough torque to twist the earth.

Cyaford - The dyno type was a "Land and Sea Dyno-max 2000 Pro". The operator guessed a 20% loss - which may indicate they are seeing lower numbers than otherwise expected. There may be another dyno in the area - so maybe I'll switch next time?
MTGTS - I'm guessing that the combination of the spacers add at least 5-7 lbs per wheel.
Viper X - I think you may hitting the nail on the head regarding the torque number being caused by the throttle body and exhaust changes. I already had the DC Performance computer before realizing that there had been some exhaust changes or adding the X-Metal throttle body.
Dan Cragin - I will definitley be calling you to discuss possible changes!

And last - SnakeEye - I can definitely see some some sort of forced induction in my future. Something about the Paxton setup does not suit my eye (just a personal preference thing I guess). I hope to see the ROE system at VOI and Paolo Castellano was working on an entry level twin turbo that might be pretty cool - so we'll see. I'm having a hard enough time driving near the speed limit as it is. It sure would be a hell of a lot of fun to have more "go" with the "show"!

Any other thoughts/comments?

 

[Nader]

I doubt the torque issue is due to the throttle body since I recently made 514lb feet with a similar setup (see sig). My hp number was 482. the third run was 508 and 468.

Thanks for all the replies. It is pretty obvious that it is running rich and we are leaving quite a bit on the table. The low torque number did kind of surprise me though - but I'm not sure it would necessarily be such a bad thing as these engines already generate enough torque to twist the earth.

Cyaford - The dyno type was a "Land and Sea Dyno-max 2000 Pro". The operator guessed a 20% loss - which may indicate they are seeing lower numbers than otherwise expected. There may be another dyno in the area - so maybe I'll switch next time?
MTGTS - I'm guessing that the combination of the spacers add at least 5-7 lbs per wheel.
Viper X - I think you may hitting the nail on the head regarding the torque number being caused by the throttle body and exhaust changes. I already had the DC Performance computer before realizing that there had been some exhaust changes or adding the X-Metal throttle body.
Dan Cragin - I will definitley be calling you to discuss possible changes!

And last - SnakeEye - I can definitely see some some sort of forced induction in my future. Something about the Paxton setup does not suit my eye (just a personal preference thing I guess). I hope to see the ROE system at VOI and Paolo Castellano was working on an entry level twin turbo that might be pretty cool - so we'll see. I'm having a hard enough time driving near the speed limit as it is. It sure would be a hell of a lot of fun to have more "go" with the "show"!

Any other thoughts/comments?

 

[ROCKET62]

OK - so stupid question as I just watched the video of the dyno - would doing the pull in third gear vs 4th make a difference as it appeared the run was in 3rd gear?

 

[MikeR]

OK - so stupid question as I just watched the video of the dyno - would doing the pull in third gear vs 4th make a difference as it appeared the run was in 3rd gear?

Alot of times the guys will get it into 2nd gear and then just shift to 4th.

I dont know what affect it would have, but dyno runs are typically done in 4th gear.

 

[Guy]

Alot of times the guys will get it into 2nd gear and then just shift to 4th.

I dont know what affect it would have, but dyno runs are typically done in 4th gear.

Correct me if I'm wrong, but I believe that's usually done because the 4th gear in most cars is a 1:1 ratio, the engine rises in revs slower than in 3rd and so it takes longer to get to redline and this gives clearer readings. Also 4th usually keeps speeds on dynos reasonably sane. 5th and above and you go into crazy speeds.

 

[Nader]

All the runs i have seen are done in the gear that is 1:1 ratio. I am sure others will correct me if I am wrong but that maybe your problem.

OK - so stupid question as I just watched the video of the dyno - would doing the pull in third gear vs 4th make a difference as it appeared the run was in 3rd gear?

 

[ROCKET62]

We can make adjustments to your air fuel from your dyno sheet, give us a call and we can take of it.

Sent it out on Friday for a reflash. Should be interesting to see/feel the results.

 

[EllowViper]

Add in some timing and try again.