Yea, this is actually why I posted this one being a little "ouch". Just because SRT gave us a benchmark, which we know will swag around. So this one was 40-50hp down, that could all be dyno, just sayin I'd be a little hmm on that number and I'm not a dyno guy myself, I like checking trap speed.
Viper Dyno Results
- Thread starter Jack B
- Start date
Yea, this is actually why I posted this one being a little "ouch". Just because SRT gave us a benchmark, which we know will swag around. So this one was 40-50hp down, that could all be dyno, just sayin I'd be a little hmm on that number and I'm not a dyno guy myself, I like checking trap speed.
That 557 is the same as the recent dyno on Giles car. All the customer cars have been in the 530 range. I did not like my dyno numbers, however, the input errors bring it up to the 530 level.
What I find very interesting is that the car does not seem to follow the norm. With any other car I would have identical trap speed for every run on the same day. Two things that showed up on on track day Saturday was that the car started out at 122 mph and the last runs were all 126 mph. The trap speed should not vary that much. What is good is that it settled in at 126 mph. It is almost as though the pcm was pulling hp at the start of the day.
The second item was that the 126 mph was with a density altitude of 3000. That is a 130 mph plus car next month. That number takes at least 550-570 hp. Could it be the cold air intake helps at high speed and hurts the hp on the dyno.
What I find very interesting is that the car does not seem to follow the norm. With any other car I would have identical trap speed for every run on the same day. Two things that showed up on on track day Saturday was that the car started out at 122 mph and the last runs were all 126 mph. The trap speed should not vary that much. What is good is that it settled in at 126 mph. It is almost as though the pcm was pulling hp at the start of the day.
The second item was that the 126 mph was with a density altitude of 3000. That is a 130 mph plus car next month. That number takes at least 550-570 hp. Could it be the cold air intake helps at high speed and hurts the hp on the dyno.
Newport Viper
Enthusiast
So let's say that 2 Gen V's raced each other with everything being equal one had 640hp and one had 600hp
what would the difference in trap speed/quarter mile times/0-150/top speed be?
what would the difference in trap speed/quarter mile times/0-150/top speed be?
kratedisease
Enthusiast
- Joined
- May 2, 2013
- Posts
- 936
- Reaction score
- 1
Just had my Gen 2 with ROE supercharger dynode.... 560hp at the rear wheels.... not too shabby for a 17 year old Viper... the engines are bomb proof
Voice of Reason
Enthusiast
Your observation here is interesting because I have similar questions from my dyno run a month ago. I posted about it back then when I had ~600 miles on the car (now at 3400), my first run was 506 hp and run 2 done about 2-3 minutes later was 529. It doesn't make sense to me that HP increased that much on a second run when normal logic should show heat soak taking away power. This is also part of the reason I started my thread on IATs, I'm trying to figure out what set the PCM off to pull timing on my first run, because I think that run should have been in the 535-540 range given where the second run was.
When I saw my trap speeds I thought of your post also. The next time I race I am going to log timing, throttle position and pedal position. The car's 126 mph trap speed last week when the DA was 3000 indicates almost 580 hp (with STD corection factor). That does not sound correct, but, I am only inputting the data into a common/accepted formula. It might be possible that the cold air intake is the culprit on the dyno. On the previous versions of the viper the pcm did not pull timing until the coolant and intake temps were both extremely high and it did not pull a lot of advance.
TrackAire
Enthusiast
Jack,
Throwing this out there but on the GM chassis, they always had some sort of torque management, even when you thought it was turned off. Could the issue be the stability control/traction control is really never completely off (even though you turned off all nannies) and the car is literally in a self learning mode? I've never seen a computer based system that did not have a "default" setting to drop back to when things got a little complicated, like super hard launches yet not a lot of wheel spin due to drag radials. There are so many sensors and measuring devices on the Gen 5, I really have to wonder if it starts out on the conservative side and self learns as you go. An example would be the motors timing vs knock sensors. Maybe the more runs you do down the drag strip without knock, the more timing the pcm allows at the giving load/rpms? Just a thought.
Also, in testing aftermarket cold air intakes years ago for the SUV market, the faster the air flow through the system the colder it dropped the IAT's. So at the drag strip, by the 1/8 mile the air is going into the system so fast it is dropping the temps allowing more timing and top end. It will be interesting to see the data from the IAT's on the next outing. In our testing, we found by the end of a 1/4 mile full out run, the IAT's were within 15 degrees of ambient assuming the system was pulling air from outside the car (like your Viper) and not an open element under the hood. This was on SUV's (240 hp to 270 hp) running 17 plus second ET's, so it had 5 or 6 seconds more time to cool down in a quarter mile than your Viper but I would expect something along the same lines. What I've never tested is how hot it is under a Gen 5 hood just from the fact that 640 hp produces a crap ton of heat just on its own and even with air rushing into the manifold, does it even go below a certain temp regardless of incoming volume and air speed??
Is there more than one IAT sensor on the Gen 5?
Cheers,
George
I have dozens of logs from my Gen 2. The car had a custom cold air intake and I found the same thing, the ambient and intake air were very close at the end of the 1/4. There is definitely something affecting power on a limited basis. When i autox'ed last month, the car seemed to get stronger as the day went on.
Jack,
Throwing this out there but on the GM chassis, they always had some sort of torque management, even when you thought it was turned off. Could the issue be the stability control/traction control is really never completely off (even though you turned off all nannies) and the car is literally in a self learning mode? I've never seen a computer based system that did not have a "default" setting to drop back to when things got a little complicated, like super hard launches yet not a lot of wheel spin due to drag radials. There are so many sensors and measuring devices on the Gen 5, I really have to wonder if it starts out on the conservative side and self learns as you go. An example would be the motors timing vs knock sensors. Maybe the more runs you do down the drag strip without knock, the more timing the pcm allows at the giving load/rpms? Just a thought.
Also, in testing aftermarket cold air intakes years ago for the SUV market, the faster the air flow through the system the colder it dropped the IAT's. So at the drag strip, by the 1/8 mile the air is going into the system so fast it is dropping the temps allowing more timing and top end. It will be interesting to see the data from the IAT's on the next outing. In our testing, we found by the end of a 1/4 mile full out run, the IAT's were within 15 degrees of ambient assuming the system was pulling air from outside the car (like your Viper) and not an open element under the hood. This was on SUV's (240 hp to 270 hp) running 17 plus second ET's, so it had 5 or 6 seconds more time to cool down in a quarter mile than your Viper but I would expect something along the same lines. What I've never tested is how hot it is under a Gen 5 hood just from the fact that 640 hp produces a crap ton of heat just on its own and even with air rushing into the manifold, does it even go below a certain temp regardless of incoming volume and air speed??
Is there more than one IAT sensor on the Gen 5?
Cheers,
George
kratedisease
Enthusiast
- Joined
- May 2, 2013
- Posts
- 936
- Reaction score
- 1
1997 GTS with 5 pounds of boost. with 15% driveline loss that calculates to 644 horses !! 4 more than the gen5
kratedisease
Enthusiast
- Joined
- May 2, 2013
- Posts
- 936
- Reaction score
- 1
Everything is debatable...
Newport Viper
Enthusiast
Cool Thanks. I grew up in Bainbridge, OH and my dad is still in Mentor.
Now Jack & I are the 2nd & 3rd coolest guys from NE Ohio http://www.cleveland.com/golf/index...s_pga_championship_for_first_major_title.html
MoparMan
Enthusiast
Newport Viper
Enthusiast
Dave, isn't that akin to being the tallest midget in the room?
You must be registered for see images attach
mnc2886
Enthusiast
Seems like SRT will have PCM updates in 2014 or 2015.....
Hope they do what McLaren did and mod all of the previous year vehicles. Shouldn't be a big deal to download a new flash anyhow....
Hope they do what McLaren did and mod all of the previous year vehicles. Shouldn't be a big deal to download a new flash anyhow....
Why would the final drive ratio affect the dyno result?
Tom Welch
Enthusiast
Hello All,
As I just picked up my GenV today and have not had a chance to do anything with the
car yet....I can only speak from past experiences with Gen 2 and 3 Vipers.
One thing I remember vividly about the PCM is that it is a "learning computer". You need
to unlearn it when you arrive at the dyno or track. This is done by disconnecting the battery
for 10 minutes. I typically did this after the car was secured on the dyno or after I had
warmed it up at the track. Otherwise the PCM is thinking you are leisurely driving, not
using much WOT and it requires a few bursts of WOT or drag strip passes for it to see
that your driving habits and fuel/timing requests have changed......and in my novice opinion,
that is why you are seeing a ramp up in power and MPH in your dyno pulls and 1/4 mile
passes.
Just my novice $ 0.02
Tom
As I just picked up my GenV today and have not had a chance to do anything with the
car yet....I can only speak from past experiences with Gen 2 and 3 Vipers.
One thing I remember vividly about the PCM is that it is a "learning computer". You need
to unlearn it when you arrive at the dyno or track. This is done by disconnecting the battery
for 10 minutes. I typically did this after the car was secured on the dyno or after I had
warmed it up at the track. Otherwise the PCM is thinking you are leisurely driving, not
using much WOT and it requires a few bursts of WOT or drag strip passes for it to see
that your driving habits and fuel/timing requests have changed......and in my novice opinion,
that is why you are seeing a ramp up in power and MPH in your dyno pulls and 1/4 mile
passes.
Just my novice $ 0.02
Tom
PilotaX:3206437 said:
The lower gear(higher#) will spin faster creating more heat & friction resulting in a slight diff in tq/hp. I think its only like 2-3 difference which basically gets lost in the +/- accuracy of the machine and +/- consistancy of the conditions & pulls. Not worth bringing up IMO especially considering with the hundreds of dyno days the VCA has done i dont recall anyone saying that the switch from stock 307 to the 355 made a measurable diff on the dyno. I could be wrong though. If so, someone with experiance is welcome to speak up.
slowhatch
Viper Owner
Jack,
It could be the pcm limiting timing aggression to aid break in. I know the new Shelbys pcm is programmed to be down over hp for the first x amount of miles to prevent morons wrecking them during transport/delivery.
Also, one of my friends taped your dyno run if you don't have a copy.
I am very happy with the results that day. I had two back-to-back runs of 126 mph trap speed. That was on a day where the Density Altitude was close to 3000. That is close to 130 mph trap speed on a normal day.
There is something that else that has to be explained, the car started out with a 122 mph trap speed. It makes no sense that as the Density Altitude got worst the trap speed got better??
There is something that else that has to be explained, the car started out with a 122 mph trap speed. It makes no sense that as the Density Altitude got worst the trap speed got better??
