Dyno Dynamics Pulls

[turbo.pwr]

hey guys,

I dynoed my gts on friday on a Dyno Dynamics AWD Dynometer and I was realy surprised with the results. This is my first pull ever didn't do a base stock pull. I knew going in that dyno dynamics machines put out smaller numbers, but still....the car is a 97 gts with the following mods: bored '20over(495cu.in)/ported heads & intake manifold/lighter forged ross pitons/180 thermo/highflow cats/corsa 3" cat back/K&Ns with smooth tubes/6'600miles on rebuilt motor. The car traped 123mph in the 1/4mile. So you can see in the sheet max 360rw.hp and 390rw.lbft I was like Also the pulls were done in 3rd, we tried in 4th but the owner of the shop said it was too tall and was over spinning the dyno (this is a subaru specialty tunner shop) After he showed me the results he said he dynoed a C6 Z06 stock and it pulled 345rw.hp, he mentioned that +500hp cars normaly pull 350ish on his dyno. I asked him what my car had at the crank and he estimates 525hp. I was blown away with how low the dyno measured my power. I kinda worked out some math ratios and from 360 to 525 is +46% so you think the same could be reconized for the torque 390 +46% = 569. Numbers seem to make sense becuase the trap speed backs those #'s. Check out my A/F lean spikes all along the band and a steep drop to rich after 5500rpm then it rockets up at the rev limiter...weird but lots of room for improvent

 

[PhoenixGTS]

Those numbers are crazy low even for a Dyno Dynamics machine. My car has less mods than yours (listed below chart) and I still made significantly more power. BTW I have 3.55 rear gears so I did not have the overspinning problem and the runs were dne in 4th. On a funny note, the dyno dynamics 3 miles from my house is at a Subaru tuner also. Here is my 1998 with a Mopar HP PCM in red before and DC Performance software in blue afterward: 430rwhp/490rwtq

You must be registered for see images

1998 GTS: airbox modded to have 3" outlets. 3" tubes,70mm t-bodies, 1.7 roller rockers, Belanger headers, stock cats modded to have 3" inlet and 3" outlet, two straight-through mufflers on each side, 3.55 gears, short 5th & 6th gears, DC software, big radiator, under-drive pulleys, over-drive water pump

Here is a link to my thread on the dyno forum (includes A/F ratio chart):

http://forums.viperclub.org/dyno-results/621189-1998-bolt-car-dc-perf-software-before-after.html

 

[turbo.pwr]

ha! what a funny coinsidence that it was also a subaru tuner shop even crazier the shop in town is 6km (3.75miles)from my house!! The owner of the shop also mentioned that he did the pulls without "corrections" not sure what he meant by that or if it would have made a difference. I told him that guys on this forum had dynoed on a Dyno Dynamics machine with over 400rw.hp (thats what I was expecting to put down) his aswner all dyno machines are different.....I might take it down to the city on to a different machine, just to see better numbers.

 

[ViperTony]

Damn, that really does seem low. I don't know how a Dyno Dynamics dyno compares to a SuperFlow but I just dyno'd mine on the SuperFlow: http://forums.viperclub.org/new-york-connecticut/628471-just-off-dyno-mark-golinos-viper.html

 

[turbo.pwr]

wow 480rw.hp with vec3 and basic bolt ons on a mustang dyno.....Im going to give that mustang dyno a try, hopefuly Im not dissapointed again, or I'll be looking into moving 2 generations forward in the viper time line......

 

[plumcrazy]

id try a different dyno, preferably a dynojet to get an idea of how yurs comparoes. then just stick with one ofr the other for tuning

 

[1TONY1]

hey guys,

I dynoed my gts on friday on a Dyno Dynamics

Here's some more reading for you.

http://forums.viperclub.org/rt-10-g...anyone-know-anything-about-dynamics-dyno.html

 

[turbo.pwr]

Thanks alot for the replys guys, I'll post the results of the next pull and then go from there.

 

[99VPRGTS]

That guy sounds like a *****. The pull should have been done in 4TH gear because that is the 1:1 gear.

 

[crviper]

I thought pulls were suppose to be done in 3rd?

 

[PhoenixGTS]

That guy sounds like a *****. The pull should have been done in 4TH gear because that is the 1:1 gear.

True but if you have stock gearing the the Gen III+ height rear tires the redline in 4th might exceed the comfortable tire speed the dyno allows - plus operators don't like running cars that fast on the dyno as it is scary as heck (what if a strap fails). Just goes to show how ridiculously tall these cars are geared from the factory.

 

[1TONY1]

I thought pulls were suppose to be done in 3rd?

No, 4th gear.

This is from the Kenne-bell website when talking about their Dodge Challenger kits...they do lots of testing:
3. Manual trans cars make 15 more RWHP than the automatics at 500RWHP level. Manual trans makes most HP in 4th. Auto trans 3rd gear.

 

[isanti]

Hmmm... I dynoed in 3rd last time....

Brother put down 430/480 on a dyno dynamics with just a borla exhaust on his 02...

On a dynojet (in 3rd) I put down 410,412, and 415 (in order for HP) in 3rd gear on a 97 with exhaust. Suprised that it was going up but tourque went 428, 430, and 432. TQ seemed low to me.

Some cars in the 460 whp range run a 122 or so ET in the 1/4.

 

[turbo.pwr]

Thats what baffels me....car ran 123mph in the 1/4, I was expecting plus 400 for sure, like isanti says 460whp for that ET range and I put down 360 I realy hope its just the dyno or a setting thats different that makes it read low numbers compared to other dyno dynamics machines, we'll see Im goin to get on a dynojet at somepoint this week...fingers crossed

 

[99VPRGTS]

True but if you have stock gearing the the Gen III+ height rear tires the redline in 4th might exceed the comfortable tire speed the dyno allows - plus operators don't like running cars that fast on the dyno as it is scary as heck (what if a strap fails). Just goes to show how ridiculously tall these cars are geared from the factory.

It has nothing to do with any of that. It's about gear ratio's, thats it. The 1:1 gear will give the most accurate reading on a dyno.

I have no idea what you mean by comfortable tire speed on a dyno. My Gen II has the exact same tire height that a Gen III/IV has and many other Vipers do as well. Most dyno's are rated between 1000-1200 HP/TQ and dyno cars much more crazy than a close to stock Viper. A strap failing is not going to happen unless the person hooking the car up messes something up. The car is strapped 2 in the back and 2 in the front for redundency in case one fails (it is also for balance but if a strap failed the other strap would hold the car in place while the dyno was shut down) It would take a lot less than even 200 HP to cause a problem if the car is not strapped right.

 

[PhoenixGTS]

It has nothing to do with any of that. It's about gear ratio's, thats it. The 1:1 gear will give the most accurate reading on a dyno.

I have no idea what you mean by comfortable tire speed on a dyno.

1) I know why you dyno in 4th

2) back when I had stock gearing and Gen III height tires on my car my dyno operator (Dyno Dynamics which is what this thread is about) said at first he did not want to run it in 4tth as the tire speed would be too great for his own comfort zone but then when he calculated given the low redline of the Viper he went in 4th. Plus, note that the original post in this thread reported virtually the same thing. Why would two completely unrelated dyno operators in two different countries have the exact same concern/thought if there was absolutely nothing to it?

 

[-FROG-]

My trap was 122mph (11.5 sec 1/4) and I put down 461HP / 508TQ.

 

[turbo.pwr]

My trap was 122mph (11.5 sec 1/4) and I put down 461HP / 508TQ.

Frog, on what type of dyno did you put those numbers down?

 

[99VPRGTS]

1) I know why you dyno in 4th

2) back when I had stock gearing and Gen III height tires on my car my dyno operator (Dyno Dynamics which is what this thread is about) said at first he did not want to run it in 4tth as the tire speed would be too great for his own comfort zone but then when he calculated given the low redline of the Viper he went in 4th. Plus, note that the original post in this thread reported virtually the same thing. Why would two completely unrelated dyno operators in two different countries have the exact same concern/thought if there was absolutely nothing to it?

I don't have an answer to that. But I can tell you that I have been to some of the top shops in the country (Lingenfelter, Livernois, DynoTek, which tunes the NASCAR guys when they are in town) and they all pull in the gear with the closest ratio to 1:1. I have never heard of a dyno shop not doing it that way until I read this thread.

 

[PhoenixGTS]

. . . and they all pull in the gear with the closest ratio to 1:1.

I going to repeat for the third time that I know that the preferred gear is 4th due to the 1:1 ratio. No one in the World wants to use 3rd instead of 4th. That is not what we are saying here. Apparently the Dyno Dynamics units have a limit as to how fast of a road speed they can spin and the unique ridiculously tall gearing of a Viper pushes that limit. And by the way, Dyno Dynamics do not use front tie-downs - at least when running RWD vehicles.

 

[-FROG-]

Frog, on what type of dyno did you put those numbers down?

That was a Dynojet at A.R.T. a few months ago.

 

[99VPRGTS]

I going to repeat for the third time that I know that the preferred gear is 4th due to the 1:1 ratio. No one in the World wants to use 3rd instead of 4th. That is not what we are saying here. Apparently the Dyno Dynamics units have a limit as to how fast of a road speed they can spin and the unique ridiculously tall gearing of a Viper pushes that limit. And by the way, Dyno Dynamics do not use front tie-downs - at least when running RWD vehicles.

I know what you are saying. I went to a dyno day not to long ago at a guys shop that has a brand new Dyno Dynamics. He tunes all sorts of cars on there to include a few boosted and h/c/i C6ZO6's. They are all spun in 4th gear and I'm pretty sure that 4th in a Zo6 tops out the same if not higher than a Viper. On his dyno, he strapped down the front and the back. I guess all I'm saying is that I don't understand why that those guys would say that about that dyno.

 

[james11]

As Isanti said, my 02 GTS did 432/480 on a dyno dynamics with only a catback. Maybe it is an issue with using 3rd gear. My brother had wierd results when 3rd gear was used at a local shop. I don't see why the hp and torque would go up after each pull.

 

[turbo.pwr]

Just to set the record straight I didnt run the car in the 1/4mile its what the previous owner told me, I bought the car with the modds already. I recieved some pretty bad news on Friday when I took my car to a very good specialty shop. The mechanic there has been building race cars for 35years. He's built many vipers so he has experience with our cars....man did I ever get a bomb droped on me. He noted the exessive heat coming from the engine when the pulls were being done, temps were about 200degrees with a 180 thermo. Out of 3 runs on a dynojet all done in 4th gear the best was 419hp, this puts the dyno dynamics results bang on 360x1.18 =424.8. Note that on the final and best run we waited 10min for the motor to cool and gained 4hp. He used words like lazy and weak to descibe the motor. The worst was when he pointed out a little honda in his shop and straight up told me its puttin down more power than the gts From his experience he thinks that the ring gap is too tight and is causing the exessive heat which is robbing hp, if enough heat is created it = bye bye rings & scored cyl. walls! Also he said the cam timing sounded ********. The A/F higher in the rpm drops to rich and the power goes with it. I was told that when the motor was being rebuilt the rings were filed down to fit a .015" gap. Im realy because I picked this car for the rebuilt motor, thinking I would avoid engine problems! So now I have to deal with what I wanted to avoid in the first place...

 

[plumcrazy]

who built the motor ?

 

[ViperTony]

What year is your Viper? 200 degrees is not excessive, it's normal. A 180 degree t-stat is not going to keep the temp at a constant 180. You may want to get a compression and leak down test performed as well.

 

[turbo.pwr]

Nelson Competition Inc. did the motor. Its a 1997 GTS, this is my fist viper so I dont have anything to compare to but the vents on the hood, get too hot to touch just from idleing for 5-10min. temp also raises pretty quickly and hangs around 190-200 on city driving, definatly no overheating issues.

 

[plumcrazy]

nelson knows what they're doing... thats for sure

but if a bad tune or something changed after, its not their fault. maybe you should call them and get some input there ?

and unless im wrong, engine temps dont always equal coolant temps

 

[99VPRGTS]

nelson knows what they're doing... thats for sure

but if a bad tune or something changed after, its not their fault. maybe you should call them and get some input there ?

and unless im wrong, engine temps dont always equal coolant temps

X2. Nelson is a very respected shop. I would do what plumcrazy said and contact them and tell them what that mechanic said. Was the engine purpose built (like lowered compression for boost maybe?)? Also if a modded engine is untuned or has a $hitty tune, that will rob a lot of HP as well.

 

[turbo.pwr]

I dont think it was purpose built for anything specific its got the stock compression. I dont know what the previous owner had in mind. The motor is untuned and the mechanic did mention it was running far to rich and I could gain another 50hp from a proper tune...I'll give Nelson a call and see what they say about the tight rig gap, thanks guys!