FIRST IMPRESSIONS of SRT/10

[King GTS]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Dixter:
Cajan Viper, Congrats on the new ride....

those are some pretty nice numbers on the Dyno too... I bet it
goes over 450 after you break it in a little more...

Stock to Stock it looks like the SRT will beat any of the past
vipers...

Glad to see it recieved by the public so well too....

Now if Dodge will just bring out my Coupe.....

Come on Dodge... Coupe...Coupe... Coupe....

woops.. sorry I got a little carried away ther

<HR></BLOCKQUOTE>

NO! Let's get carrired away!! COUPE!! COUPE!! COUPE!!

Maybe then we'll get what we've been waiting for. Not impressed with what I'm reading at all.

 

[Mike Brunton]

I think some folks are hearing something different than I'm saying

I don't think the car is ANYTHING less than advertised - absolutley not. It CERTAINLY makes 500HP and 525LB-FT and then some - which is a good thing. Whether this particular model put up a high or a low number is speculation since it's one data point on the chart. Hopefully this is the lowest SRT dyno number we see (I doubt it, but I hope it is as I'm sure we all do).

The first thing I'm saying is that I expected more. No, not because I don't think the car makes 500hp, but because I had heard from a bunch of people that the car could easily have been rated 525hp. I think that the actual number was something they had to reach a bit to obtain due to emissions requirements. Maybe that's why the car was delayed - they needed to be sure it made at least 500hp but also meet emissions. Who knows.

The second thing I am saying is that I don't think this car is gonna be enough to stave off the competition for the lifetime I believe DC is projecting for this car. I bet they won't upgrade the power on it for at LEAST 4 years, possibly (and probably) longer. I don't think that's gonna cut it. The GTS was far enough above the competition to hold it's lead for 7 years, and the original RT was far enough ahead to hold the lead for it's lifetime too. Again, this is purely speculation but I just don't think this extra 50HP (which I was hoping was really "50hp, wink wink" but is really just 50hp) is going to keep the Viper at the top for the lifetime of the car in it's current state.

I'm just personally disappointed. I was hoping that after 7 years of 450hp and a 300cc displacement increase, we would be looking at more than 447 to the wheels. I was disappointed (and I posted about it before) when the rated number was only 50hp above the GTS, but a bunch of people told me not to worry, that the SRT would be just as underrated as the GTS, probably a lot more... so I was expecting a fair bit more to the wheels - which is looks like didn't happen. Just expressing my own personal disappointment, and my feelings that the domainance of the Viper is probably gonna be short lived.

 

[nitro]

I think all VIPERS are **** beast! Yeah Baby, yeah!

 

[Brian Kelly]

A few years back John Henessey said before they did any modifications that the Gen I RT's typically dynoed in the 325-330 neighborhood and the Gen II were in the upper 390's. He also said the 405 rated ZR1 vettes typically only pulled in the 290-305 range. FYI.

 

[Joseph Houss]

Let's slow down a bit....

All of a sudden the naysayers are shouting 11% driveline loss ... yet for years .... 12-14% were being used for many of the numbers on our Gen2 cars? (at least that's what I thought?).

Any way you look at it.... it's going to be tough for ANY car manufacturer to muster 500 HP out of a emissions certified V-8... so let's enjoy being King of the Hill once again.... and if the competition gets close ... I betcha PVO can kick it up a notch!

 

[Fred(DrivingSchool)Kinder]

At our dyno events we have observed 402 to 422 rwhp from a stock GEN II's corrected numbers from a dynojet. To me the reported numbers for the first SRT10, customer dyno, are on target for a new motor. Those who see only the empty 1/2 cup are alive and well.

 

[Viperrick]

Mike, I am not sure who your contact is but, I know that the Comp Coupes were suppose to be in the 525 range with an opened up exhaust and minus CATS. I agree with the Dyno number posted on the old cars. I have seen Gen I's at about 360RWHP and 400 RWHP +/- 5 for Gen II's. I have rarely seen 420hp for a Gen II and then I am sceptical whether it is truely stock. Some people feel K&N's, smooth tubes and a CAT back exhaust and rear gears are stock. My complaint for years was this posting of corrected dyno numbers. Everyone had a differant factor. I guess it was a feel good to the owner to change the number so, I didn't gripe about it. How about we all stop wth the fudge factor on the new car and only post what the actual reading is. I liked that this owner stated 447RWHP.

 

[GTS Dean]

I don't care what the raw, uncorrected numbers from any dyno are. The "Corrected" numbers take dyno cell elevation, temperature, atmospheric pressure and humidity into account and correct to Standard Temperature and Pressure (STP.)

When a dyno is installed, the tech is supposed to input the elevation (+/- 20' is fine) and calibrate the atmospheric sensors. These things should be serviced and recalibrated on an approximately annual basis. My club hosted a dyno day last summer in San Antonio. We were within 1 mile of the airport which has a 720' elevation. The dyno software showed an elevation of about 3400' and all the dyno numbers were significantly down from what people had tested before. The guy who owns the dyno doesn't know doodly-squat about STP and gave me a puzzled stare when I pointed it out to him. I know the Terpstras have that much figured out.

As for the driveline losses - a 1% improvement in efficiency here is considered HUGE. I doubt there was more than a 0.5% net improvement over the last Gen2s, if any.

 

[Fred(DrivingSchool)Kinder]

Has any one contacted Dynojet for dyno accuracy and or repeatability numbers for a 400-500 rwhp run. How are dyno calibrated?

These numbers are only relative to show changes while tuning. They do not represent actual RWHP without being calibrated to a known standard, and correction factors used for standard temperature, pressure, etc.

 

[Frank 03SRT]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by GTS Dean:
I don't care what the raw, uncorrected numbers from any dyno are. The "Corrected" numbers take dyno cell elevation, temperature, atmospheric pressure and humidity into account and correct to Standard Temperature and Pressure (STP.)<HR></BLOCKQUOTE>

If humidity has much to do with the correction, then without regular calibration, I'm not sure you could trust the dynos. Humidity sensors are very unreliable and require frequent calibration, I have been told by HVAC types. If these operators don't know what they are doing, all these results we have been seeing might not mean much. After reading the above info, I'm not too sure a person could trust the results without reviewing the calibration and looking at the operation and maintenance manual, if one exists, for recommended calibration frequency of the dyno.

I wonder if anyone out there has a dyno they are sure is calibrated regularly?

 

[Viperrick]

Dean I agree with what you say when you are talking about a dyno cell. I presume you mean where you test just a motor and not a chassis Dynojet where I feel you loose the labratory type of environment. So, I guess if someone pulls their motor and runs it in a cell with no accessories, than I would accept those as HP of the motor. A chassis dyno does nothing more than give you a baseline against other cars that are being run that same day under supposedly the same conditions. If exterior conditions change than you will not get a true comparison.

 

[toddt]

Mike--

Cheer up mate! I want to be the one to remind you of something you, yourself said a while back. Remember, if someone is getting 119's consistently down the track at nashville in wet weather, you can bet that a 1/4-mile specialist will do 123. Keep your perspective--if we see 123 on the lights for this car, that's diablo 6.0 territory. That is serious, world-beating business.

Secondly, the dyno numbers proved a very positive thing--the viper is now a 500-500 car, and its torque and horsepower are still number 1, with the z06 (now and 4-year future) being WAY behind. They are going to stay with a V-8. They will NOT catch up to this performance, I will guarantee that.

Thirdly, you seem comfortable with the "fact" that the 2002 zogs are only .1 or .2 behind the gts. I would never support that statement. My WORST time was .1 ahead of a 2001's best time on a particular day. My BEST time, on the other hand, was .6 better, and all this with him having a carbon fiber intake and aftermarket exhaust, AND much more track time (my only day at the track). I would put the number closer to .4-.5, not .1-.2.

Now, .4-.5 behind (along with SEVERAL MPH (5?!)) is going to be REALLY hard to close over the next few years. And I don't care WHAT they do to the chassis and tranny, their MPH gap is insurmountable in stock trim. Honestly, the SRT is really going to increase the gap and dishearten the competition.

Furthermore, I'll repeat my prediction for the street coupe of 550 HP. It is clear that DC will HAVE to keep taking it up a notch to keep the Viper as the DC performance king ahead of the amazing mercedes supercharged v-8's (which now make more HP/Torque than the Gen2 v-10s!).

What I'm trying to say is, that although you are "underwhelmed" with the numbers (i.e., they are what the official sources claimed they would be), clearly the SRT is the performance king of America and near the top worldwide for 80 grand. It also happens to be the most exclusive 80-grand ride in the world today. (none were ever sold to the public)

When YOU (or even better, Evan Smith! LOL) get one on the track, we will see how they can sing. It's my bet that on the racetrack they have a very good chance to hang with a GT-2, or at least be within 2 seconds at the most. It wouldn't even surprise me much if it beat a GT-2.

Bottom line: The SRT is now the undisputed king of the performance world (that is, on the road course and the straight line), and Chevy needs to go back to the drawing board to figure out how to compete with it. The Z06 will not do it. Not even close.

Viper wins again!

 

[GTS Dean]

Rich,

*ANY* dyno worth having will offer built-in correction or the formulas for manually adjusting the measured data. This is NOT just limited to engine dyno cells.

Humidity measurement is as simple as wet-bulb/dry-bulb temperature readings. One of the major isses at the San Antonio dyno cell was a big industrial fan blowing hot air past a mist of evaporative cooling spray nozzles. Sure, it cooled the air (a little) but the water displaced the oxygen required to make horsepower.

 

[kenvw]

Reading this thread has been interesting! started out with a great review about the new Viper and is ending up with who thinks they know the most about dyno's and all other kinds of mechanical jargon. I think it's interesting but let's just think about this logically. I would guess that the DC group would have all these gadgets at their testing facilities and that they are perfectly calibrated(probably on a daily basis). This is their business day to day they must be on the top of their game to be able to know exactly what their cars are doing. Also I am sure that the same testing equipment and environment were created for each viper model. We see the quality they have put into this new viper, so lets give them the benefit of the doubt that their claims are accurate. I do believe they are the experts and that their claims on all their vehicles are pretty accurate from last year's viper to this new viper for 2003. So the difference in the HP from last years models to this years model is going to be close to what their claims are ( about 50hp at the flywheel or the RW). Well not to spoil the fun if their claims are not sufficient, by all means keep up the discussion.

 

[GTS Dean]

Ken,

I would guess that with all the crap Ford stirred up recently by selling overrated Mustangs, Dodge would not let that happen. However, the low numbers of vehicles and impracticality of an engine vs chassis dyno shootout for the same engine would mean it is unlikely that anyone would try verify driveline losses for the better part of a year, or more. I doubt that FWHP will be less than 494 for any production engine, and that's pretty darned close to 500 for me.

 

[Mike Brunton]

I'll say this...

Dyno's don't vary NEARLY as much as many people think they do. They are actually a very accurate way to measure horsepower. The guys who claim otherwise USUALLY don't know what they are talking about. I say this only because a friend is an engineer and one of his roles is in helping to design/improve dynomometers.

The dyno has a big drum - of a precisely known weight. Predictable-friction mounting that stays true over a long period is used on the drum. Temperature matters, but that's pretty easy to control/read. Humidity and air pressure matters too (not all THAT much though) but that's likewise pretty easy to read.

I would bet that, barring any "foul play" by the dyno operator (like falsely heating up the temp sensor or putting it right next to the computer monitor in 20 degree warmer air), that a dyno will read accurately most of the time.

Toddt, you're still buying me my SRT right? Or are you welching on me????

 

[jamie furman]

Who cares what the percentage loss is and mumbo jumbo, the bottom line is most gen 2 engines make low 400's stock on the rear wheels, this engine made 43 more rwhp average than most truly stock vipers I have seen, made on the dyno.Alot of guys claim no cats or no muffler or rockers as stock but that ain't stock, I think it is very impressive number for a brand new car, it certainly will kick a stock gts *** HARD if I am driving it and when I get my new one I will prove it!

 

[46hemi]

And it wont even spill your Grande Latte in that fancy cupholder while doing it

 

[Viperrick]

Dean, I don't want this to turn into Dyno-talk but then why have we been reading for years "What is the conversion factor because my car dyno'd 40? at the rear wheels?" What is it's real hp. number? The drive line loss computation is 12% no 11% no 18% etc.

 

[Fred(DrivingSchool)Kinder]

Dyno numbers can vary from operator to operator.

 

[George Murray]

OK OK! One of you tuners just hurry up and stick a blower on one of those SRTs already. Hell, the cars have been on the road for a week already! Add some nitrous for the hell of it. The stock dyno number has become tiresome. Oh, yeah. Paint the first SRT tuner car YELLOW.

So stick that in your dynojet and smoke it.

(Or I'll scare your wives with my 18" dynomax)

 

[Frank 03SRT]

Interesting. I have always wondered about how accurate dynos are, and since I know little about them, wanted to find out how accurate they are and how reliable they are over time. Went to the DynoJet web page and pulled this off:

"Automatic measurement of the barometric pressure and ambient air temperature together with humidity measurement ensure repeatability between tests.
----------
The unit is a durable, factory calibrated dynamometer that requires little maintenance and no calibration."

Notice they say "no calibration." Does anyone know how they have "automatic measurement of --- pressure, temperature, and humidity ---" without sensors that, in my experience, occassionally need calibration? I left a message on their tech services e-mail asking.

Maybe I am the only one that worries about accuracy, but just a small difference in calibration or operation can make up a noticable difference in 447HP --- if off only 3%, that would give 460HP and nobody would be complaining.

Like I said, I know little about dynos, just trying to learn something.

 

[GTS Dean]

Rich,

An engine dyno only needs to correct for atmospheric conditions to provide accurate Torque readings. Then you convert Torque to HP using the formula. Minor parasitic losses like water pump, alternator, oil pump, fuel pump can and have made for some questionable numbers, but the SAE includes these accessories' influence according to a prescribed standard. What the manufacturers now quote is SAE Net HP/Tq., or DIN Kw at the flywheel.

Chassis dynos measure the net torque provided by the vehicle to accelerate the drums of a known mass over a given period of time. The raw readings indicate the net power to the tires, including mechanical driveline losses through the clutch, gearbox, diff, u-joints and contact patch tread sqirm. The raw data is then corrected to STP. High temp and humidity require correction factors greater than 1.0. Good atmospheric conditions factor the baseline data by a number less than 1.0.

Recently, there is a new type of chassis dyno that measures torque directly from the wheel hub or drive flange without the wheels installed. There is a lot of inertia loss through the tire and wheel assembly, plus the tread squirm issues mentioned previously.

Frankly, I still fail to grasp exactly why cars with more aggressive gearing seem to generate questionable power levels on the Dynojet 248C. The gearing increases multiplied torque, but over a shorter period of time. I'm not a mechanical engineer, but Ben Treynor or Kyle Kent could probably offer useful commentary here.

 

[Russ Oasis]

Dean,
I don't want to jump into the fray about all of this, because I think most of it is BS, however, you stated that you dynoed your car at an altituded of 720' when the dyno was set for three thousand some odd feet (I don't want to go back and find the exact numbers because it doesn't matter). If the dyno was set to 3000 feet, the numbers that a car (any car) would be generating on that dyno would be HIGHER than the actual (or real) numbers. Higher altitudes have thinner air which creates LESS horsepower. If the dyno thought that it needed to correct for thinner air, it would have ADDED horsepower to the computation, not subtracted it.

 

[GTS Dean]

Russ,

Intuitively, you're right. I can't explain it unless what it was showing was the corrected density altitude = bad air. Serious Eric was one of the very few cars that seemed to be about where it should be (408). A brand new 1000 mile GTS only hit 360-something. Go figure.

 

[George Murray]

That rear gear ratio factor, again...

JPH mentioned two or three years back that he saw something like 2-3% LESS rear wheel HP and torque with 3.54-geared Venom cars vice 3.07-geared Venom cars.

Makes one wonder about other variables, like Dean mentioned.

Dean: what mods do you have planned in the next few months, following exhaust mods? Are the TNT folks using your car for their developmental work? Or is this all "skunk works" CSSP (can't say $hit pal) "will tell you then have to kill you" secrecy?

Also - who makes the wheel hub dynos...dynojet or another manufacturer?

TIA, George

 

[CajunViper]

George, The answer to your question is "YES"


Dean

 

[GTS Dean]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by George Murray:

Also - who makes the wheel hub dynos...dynojet or another manufacturer?

TIA, George

<HR></BLOCKQUOTE>

Try these:

rototest

or dynapack

 

[Venom Lover]

This is exciting! Too bad I couldn't join in the fray while on holiday with my family....

Bottom line: it looks to me like the SRT is only 30 rwhp above the GTS, which is around a 35 bhp increase (13% driveline loss). Sure 447 rwhp meets (and slightly exceeds) the 505 bhp claim (wasn't the final claim 505 bhp?) -- but just barely. The more unfortunate part is that the increase is nowhere near what the GTS vs. SRT rated horsepower would lead you to believe. Hence, we are left wondering how much quicker the SRT will really be. Certainly VOI and magazine numbers do little to convince us that the gain is very noticeable.

Consider this. My '97 GTS dyno'd at 425 rwhp (SAE corrected) bone stock. And I mean bone stock. Stock tubes. Stock exhaust. Stock filters. My creampuff even dyno'd at 410 rwhp (SAE) bone stock. So, 447 rwhp (assuming that's also SAE corrected) for the SRT represents only 20-35 rwhp gain over the GTS, at least based on my experience. You can argue all you want about whether driveline loss is 11% or 13%, but the bottom line is that translates to only 25-40 bhp increase, against Dodge's claim of 55 bhp increase (450 to 505). Should we be happy with that? You can be the judge.

Yeah, the SRT meets Dodge's power claim based on this one data point, but will it truly end up being a lot quicker than a GTS? I guess we'll let Jamie prove it to us....

And before we get too excited about 447 rwhp, let me just mention that my $34K Ford dyno's at 400 rwhp with just K&N filter and catback exhaust (very cheap parts for a Ford), and with another $100 for a smaller pulley, 450 rwhp happens. If it's dyno numbers that float your boat, there are much cheaper ways to get to 450+ rwhp than the SRT. (With another $1K in chip and tuning, the POS Ford achieves 500 rwhp, BTW.

)

Oh, and to the guy (Brian Kelly) who quoted a well-known tuner's ridiculously low dyno numbers of 325 rwhp for stock Gen I Vipers and upper-390 rwhp for stock Gen II Vipers -- think about that really hard....If a hypothetical tuner claims a 50 bhp increase for his "Poison 500" package, it's very convenient if your car starts at 395 rwhp (never actually measured -- just based on this bogus claim) and ends up at 437 rwhp. That's a supposed increase of 42 rwhp x 18% driveline loss (also bogus) = VOILA! 50 bhp! When in fact 437 rwhp is easily achievable with catback and K&N filter (or perhaps just K&N filter) because your car probably really started at ~415-425 rwhp....Sorry to be cynical. Oh, and of course this scenario is entirely hypothetical and any similarity to real events is purely coincidental....

P.S., to Russ M, that 425 rwhp number on my '97 GTS was achieved at R&D Dyno -- the same place you claim is 20 hp below other dyno shops. If you're right, then I would love to believe that I was really at 445 rwhp in my '97 GTS stock, but I don't think so. At the SoCal dyno day -- probably the one you're referring to -- I dyno'd at around 448 rwhp, with K&N filter, smooth tubes, exhaust mods, and 3.55 rear end (the latter robbed me of 7 rwhp based on before and after dynos at Darren's shop). Anyway, I'll contend that Darren's dyno isn't off -- we just had some weaker Vipers there that day. No offense intended.

P.P.S., since treynor decided to toot his own horn, let me point out that I forecasted 445-450 rwhp for the SRT back in July. See this thread:

http://vca1.viperclub.org/ubb/Forum21/HTML/000602.html

--Mike

<FONT COLOR="#ff0000" SIZE="1" FACE="Verdana, Arial">This message has been edited by Venom Lover on 01-01-2003 at 12:47 AM</font>

 

[Mike Brunton]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Fred(DrivingSchool)Kinder:
Dyno numbers can vary from operator to operator.

<HR></BLOCKQUOTE>

The only variables are the "correction factors" (temperature, pressure, humidity, etc) and whether the gas pedal is all the way down or not. There is nothing else.

The only way different dyno operators can screw with the numbers is if they screw with those sensors - like doing something to give a higher temp reading then is really ambient.


EDIT:

Regarding the gears showing differences in power... it makes sense that a more aggressive gear would show a greater driveline loss. The answer JPH gave in the past was that more aggressive gears reduced the time that the dyno pull lasted and this led to a lower RWHP number. I don't believe this to be true, and I asked Dynojet about it and they said it was BS also. It's clear that this is the case because the dyno doesn't know anything about your gears or your cam or your wheel height or tire wear - it only cares how quickly your car accelerates that drum and what the weather is like - nothing else.