Alright here' the deal, back in April my car made 517/340@17psi on a dyno jet with pump gas. Yesterday I had the car retuned to max pump gas out and to add c16 to the mix. The car made 400is on 19psi on the pump 93. This concerned me as 100whp was missing while 2 more lbs of boost was added and a litle more agression with the timing.

A leakdown test was done and it came back 9% across the board. The car isn't smoking, knocking, nothing. The shop owner where the car is at is an instructor for EFI College so I trust his word not to mention he and his dad are very well known in NHRA drag racing (look up Chuck Wright). He says the tq curve is amazing and that the car is holding power all the way to 9500rpms. He also states that a "1200hp" Mustang came to his dyno day last year and only put down 1024.

The dyno I originally used was a Dyno Jet, the one we are using now is a Dyno Dynamics. Doing the math it appears that there is around 14% difference in power numbers between the 2. Now I am wondering if maybe the Dyno Jet reads high, the Dyno Dynamics reads low or maybe a combination of both. Also the tuner feels that pump gas has been maxxed out and thats why no additional power is showing up when psi is added or timing is changed.

So have any of you ever seen this big of difference between 2 dynos. I know numbers are just for bragging rights and that a dyno is just a tuning tool, I get that. However the big jump in loss has my mind going 1000 different ways trying to figure out if its a bad turbo, motors hurt (although it doesnt appear to be), ect...

PS....don't use H rated tires on a dyno, they will destroy themselves. Ask me how I now know

 

sounds about right

 

depends on what inertia and correction factors are used on the dyno dynamics but normally, dyno dynamics will read lower.

your 517 was on dynojet std or sae? go on another jet and make a pull and pull up std or sae numbers again.

 

I had an interesting experience with a dyno dynamics dyno the first time I used one. The car I had on the dyno had previously made 683whp on a dynojet at 36psi. This go around we were running 25 psi and looking to clean some things up with the tune and we used a dyno dynamics dyno we made 314whp first pull at 13psi and then at 25psi we made 250 something whp. Needless to say I was kinda confused until I decided to pull the car off and saw a pile of rubber several inches thick sitting between the rollers. After talking with chris harris on the phone about my issue I took the front wheels (had drag radials) and switched them with the back wheels (street tires) put the car back on and made 541 first pull. For me lesson learned don't used a soft tire on dyno dynamics dynos. Its funny though to tell people that our 250whp car runs 10's

 

That sounds about right a good friend of mine had a dd and he always told me it was 13% difference. So sound right. O and traps tell the story.

 

Haha you mean like this:







The car has trapped as high as 129.4 which isn't bad considering the weight of the car (guessing close to 3k lbs with me in it).

 

well we didnt have such large chunks but yes we had a very large pile of rubber

 

Apparently Kumho AST's don't like high MPH over and over again

 

so true, I saw 80whp increase going from DR to small street tires

 

i run the exact same tire on my crx man and they have **** 150 dyno pases on them with no rubber like that falling off.

and have been over 150mph on the dyno

 

I made 510whp/330ft on a Dynamics. 560whp/405ft on a Dyno Jet.

Ive always heard that the Dyno Jet is the accurate one.

 

We have a dyno dynamic and it reads low. Also, with the two small rollers it is really common to get tire spin on the dyno. This requires heavy strapping that also kills power. One example was a high compression all motor ITR reid was doing. It picked up 15hp just loosening the straps. Crank them back down and power was down.

Also, it seems that the higher power cars have a larger reading diifference. A 300hp dynojet car will make 270hp on a Dyno dynamic, but a 800hp dynojet car will make 600hp on a dyno dynamic. I dont know for sure, but its probably a result of the resistance of the DD and the heavy strapping required for such a car. The other difference is boost levels and spool between the two dynos. The dyno dynamic is load based and will only let the car accelerate at a given rate (also the reason for tire spin on big turbo cars) where the dynojet just spins as fast as the car can spin it. This difference in time and load will play a role in boost numbers, spool, duty cycles, etc.

A stock S2000 on our dyno with no correction will make 180hp.
Our FWD outlaw car will only make 9XXhp and it does 176mph :p

Just food for thought.

 

We've never has tire issues except you should NOT run slicks on a dyno dynamic. We dyno with nitto 555r drag radials.

 

Thanks Andy, I was hoping to hear more information from tuners. I have terrible luck so the tires blowing apart doesnt suprise me at all haha. Hell so far on the dyno we've had battery voltage issues, ignitor go out and no the tires blowing off. I am goin to get some tires up to the dyno and have them do the race gas tune. From there we will be track tuning to get the car dialed in for the remained of the year. I just wanna see mid 10s this year and then over winter maybe go bigger who knows

 

Had the same experience day before yesterday... Beter than H ratedbut same result. Took off M&Hs to save them... TOYO Tire exploded and took out fender, bumper, lip. sideskirt, corner lamp, sub harness... ****.

At only 600-620 wheel (Were tuning pump 92 and meth). Tires were in good shape and all. Lesson learned.

My tire actually threw semi style strips of tire 4 " wide and 2 feet long a ll over the place, flung pieces up to the ceiling of the shop and broke windows out of the garage door that was up and if anyone had been standing next to it, would have SERIOUSLY ****ed them up. THis was at about 140 MPH (on the way down from 160+) they came apart. Blew the fender outwards, severed the Fender harness, blasted the mint bumper, pulled the hood latch cable out... cut the front lip and sideskirt Never found the corner light, then the rubber cuaght fire on the car. It was ****ing great.


Mental note, I will never dyno the car with anything short of z rated tires again.

 

You must be the one Bone was telling me about last night as he was threatening to kick my *** for saying I was gonna part car out hahahahaha

 

Ya I know Chuck. Was me. 205 60 15s. Tires were in good shape. I put the pile of rubber that wass on fire out with my hand, that sucked, but it was close to fuel ****... Then, after I got that out.... The inside of the ****ing tire lit up and we hammered it with the extinguisher. I never stand next to cars on the dyno out of paranoia. Looks like for good reason.

 

Haha yeah I am the same way. Might be all the final destination movies throughout the years combined with my terrible luck.

 

I wouldn't get caught up on the numbers on a dyno. Just use it for it's purpose, a tuning tool.

Then go to the real dyno aka the dragstrip.

 

We use a Mustang Dyno and I've seen other local dyno's (Dyna Com, Dyno Jet) read anywhere from %8-25 higher then ours.

Numbers don't win races, but you know that. Dyno's are a tool.

 

Dyno jets give inflated numbers, mustang/dynomite give more accurate readings to what you would experience while racing due to them being load bearing dynos. Either way, its just a tool used for tuning.

 

Dynojets can have load control as well. The main issue is that any dyno other than a Dynojet can be manipulated by an unscrupulous owner/operator. The online java applet horsepower calculators show numbers close to a Dynojet for the most part.

Someone above said that dynos are tools and that is the thing, big numbers are nice but look dumb when the car fails to perform. Low numbers look cool when you get the car to do what it is supposed to.

 

My stock accord made 131 on a dyno jet and 124 on a superflow, both SAE correction.

My friends c6 zo6 heads/cam etc made 588 on a dyno jet, but 530 on the superflow, both SAE.

Your H rated tires are not the problem, its the dyno dynamics fault. Ive used those for plenty of dyno time.

 

correct. I now own a dynojet where as I had an AWD MD dyno. dynos that allow load control sweep rates can also play a part in how a car performs on a dyno as well, if the load percetage is set funky it can make a car seem to spool really late or really early. I like my dynojet because it is unchangeable, undebateable numbers. I have no influence on the output, it is what it is.

but like stated before, dial in the fuel and timing and hit the track. trap speeds will tell you everything you need to know if the numbers are even in the right ballpark

 

Your car was so clean...