Why Dyno numbers aren't gospel, and can you make ~500whp cam only?

[acammer]

Obviously, we all know the answers - yes dyno numbers aren't unfailable. And yes, of course you can make 500 cam only - we've seen plenty of examples here over the years.

So, it's not the point, but I did make 497whp here, "cam only". M6 car, and it's the GPI SS3, and all the supporting mods that go along with that for breathing and the valve-train. The curve is incredible, the car makes STRONG power from 5000rpm right on through 7200rpm. They let me operate my own car on the dyno too, which was awesome. I've never seen that happen anywhere, and it was a truly unique experience I couldn't pass up. If that's all you wanted to know, you can move on. If you wanna here about why I don't trust dyno numbers, continue reading below.

The point is about dyno results, and why they always need to be taken with a grain of salt (or maybe a whole jar of salt!). The package in my car was installed and tuned this spring at New Age Hotrods. Josh has a Dyno-mite dyno which operates with a load cell. We did a baseline pull on the car before the under-drive, intake, and cam which was 402rwhp. The car had previously been dyno'd a few years before at a competitors shop when the first round of mods went on, and did 412rwhp, on a dynojet. So, about a 2.5% difference there. After the mods the car put down 473rwhp, corrected with whatever Dyno-mite's software uses for a correction factor, probably SAE J1394. Knowing Josh's dyno has a reputation for being a heart-breaker I was plenty satisfied with that, the car had a savage curve that we know is gonna haul at the track.

Last night a local shop hosted a dyno-day with a Dynojet. I watched several other cars go, and the results were pretty much exactly what I expected, certainly nothing bogus or abnormally high. Knowing that a Dynojet usually beats Josh's dyno by at least 10whp I figured I'd see what I could lay out.

I made my pulls and made 485whp and 483whp, uncorrected. When you apply the STD (SAE J607) correction (which is the Dynojet STD correction factor) for temp, humidity and baro the corrected HP is 497whp.

Also, for what it's worth, my buddies ZL1 made 543whp on the New Age dyno, and laid out 570whp last night.

So, that's almost 5% variance between those two dynos. The variance was dead consistent between both cars - so I think it's safe to say it's the dyno's differences. Zero changes on either car between runs on each dyno. Not surprised, but more just interesting.

I figured I'd share my experience here, because it's all first hand, same cars, same geography, no trickery or weird stuff going on. If there is a point, it's that dyno numbers don't mean all that much, they are ok for general comparison. But don't get lost in a 5% difference, because it just doesn't translate 1:1 between each dyno, even with correction factors.

Oh, and video, because the sweet sweet sound of an LS3 running to 7200rpm should be enjoyed by all.

[Taylortoons]

Oh man, can she sing! I'm running the same cam and really dig the sounds it creates in the LS3.

[SquawkVFR]

All you need is a cam and a good dyno and you’ll be at 600rwhp in no time!

[GONIF]

DYNO'S are a tool that measures torque than converts to hp .The results are good to know and aid in tuning the car to GO FAST . The times the car turns at the track when the car hooks up is the real world result of rwhp. You may not need to twist it to 7200 rpms to get your fastest times in real life track conditions ,but it is nice to know exactly where to shift to get the best result.

[acammer]

Originally Posted by GONIF

DYNO'S are a tool that measures torque than converts to hp .The results are good to know and aid in tuning the car to GO FAST . The times the car turns at the track when the car hooks up is the real world result of rwhp. You may not need to twist it to 7200 rpms to get your fastest times in real life track conditions ,but it is nice to know exactly where to shift to get the best result.

She's gonna want all the twist, the falloff at the top is nowhere near what the falloff is into the next gear.

Track times have been substantially delayed this year do to me tearing apart my rear end. It's rebuilt, but I refuse to make dig hits on this one until I get the LPW cover - which is now been delayed over 6 weeks. Once that shows up, it's go time. Goals for now are <11.5 and >120mph. Doable, I think. If I can drive.

[lazerlemonta]

Originally Posted by acammer

She's gonna want all the twist, the falloff at the top is nowhere near what the falloff is into the next gear.

Track times have been substantially delayed this year do to me tearing apart my rear end. It's rebuilt, but I refuse to make dig hits on this one until I get the LPW cover - which is now been delayed over 6 weeks. Once that shows up, it's go time. Goals for now are <11.5 and >120mph. Doable, I think. If I can drive.

Thats a cake walk for you on a tire. Really you should be expecting 122-123 traps 11.2et How close are you to cecil? We have a private rental on november 4th with 35 cars going for personal bests. I'm looking for 10.3@133-134. Dyno numbers with discrepancies like that are usually one is in SAE and the higher in STD. I try to get all my numbers in both now so when some one cries i can tell them its only 453RWHP but runs mid 10s@131 lol Good luck brother and I look forward to your results at the track. All I can say is a radial slick with radial fronts is great. Dont mix a bias with a radial lol its not much fun on the big end

[Camaro Dude]

Nice peak number

Before and the after is what it’s really all about, and should be.

Shape of a curve on a dyno graph, isn’t 100% indicative of how the car will feel on a twisty, uphill, canyon road, or ...

Peak HP bragging rights may apply, if this car is to be a dedicated, straight line, 1/4 mile..1 mile run, weekend warrior, where driving feel, like a nice low end, to top end torque curve, like not being out of the power curve too early after a shift, gets tossed out the window.

Indeed, HP does win the races in a straight line, or very high speed circuit, but make no mistake, a strong torque/hp curve from 2700rpm to 6500 rpm, with say 25 less peak HP VERSUS 25-30hp peak more, and a curve from 5000-7500, the latter of which, will be in for a nice surprise, on a nice canyon like road

Choose your poison, choose your application.

[GONIF]

Originally Posted by Camaro Dude

Nice peak number

Before and the after is what it’s really all about, and should be.

Shape of a curve on a dyno graph, isn’t 100% indicative of how the car will feel on a twisty, uphill, canyon road, or ...

Peak HP bragging rights may apply, if this car is to be a dedicated, straight line, 1/4 mile..1 mile run, weekend warrior, where driving feel, like a nice low end, to top end torque curve, like not being out of the power curve too early after a shift, gets tossed out the window.

Indeed, HP does win the races in a straight line, or very high speed circuit, but make no mistake, a strong torque/hp curve from 2700rpm to 6500 rpm, with say 25 less peak HP VERSUS 25-30hp peak more, and a curve from 5000-7500, the latter of which, will be in for a nice surprise, on a nice canyon like road

Choose your poison, choose your application.

You got that right for sure ,those boy are looking for low ET's in the 1/4 not road racing or burning through canyons.
I can almost smell the clutch burning in the first 60 feet.

[zz430camaro]

Car sounds great and your dyno numbers are good too, win-win. please let us know the track results.

[Avenging Orange]

But it's not "cam only" when you have the "supporting" mods to go with it. They all contribute.

[zz430camaro]

I think "cam only" means no other internal engine modififications like ported heads.

[Camaro Dude]

Originally Posted by GONIF

You got that right for sure ,those boy are looking for low ET's in the 1/4 not road racing or burning through canyons.
I can almost smell the clutch burning in the first 60 feet.

Yes, indeed.

But once the mere 11seconds of glooooriuuuus fame, down the strip lane are ova, and then postin’ dem numbaz on tha internet, and then back out to life, and you happen to stumble into Sledge’s world, your giddyups will get frozen.

[acammer]

Originally Posted by lazerlemonta

Thats a cake walk for you on a tire. Really you should be expecting 122-123 traps 11.2et How close are you to cecil? We have a private rental on november 4th with 35 cars going for personal bests. I'm looking for 10.3@133-134. Dyno numbers with discrepancies like that are usually one is in SAE and the higher in STD. I try to get all my numbers in both now so when some one cries i can tell them its only 453RWHP but runs mid 10s@131 lol Good luck brother and I look forward to your results at the track. All I can say is a radial slick with radial fronts is great. Dont mix a bias with a radial lol its not much fun on the big end

I agree on both ET and MPH - my goals are WELL with reach, even in the summer heat. I'll keep the Cecil deal in mind - that would be doable as long as the weather up here is still behaving. Should be be fun to run in some negative DA.

Tire setup for this year won't change, it'll be an HP summer street tire up front on the 20x9 and the 305/45/18 NT05R out back. Definitely not ideal, but it what I've got for this season, and will likely be my street setup going forward. Slicks and skinnies will maybe be a 2019 thing, we'll see.

[acammer]

Originally Posted by Camaro Dude

Nice peak number

Before and the after is what it’s really all about, and should be.

Shape of a curve on a dyno graph, isn’t 100% indicative of how the car will feel on a twisty, uphill, canyon road, or ...

Peak HP bragging rights may apply, if this car is to be a dedicated, straight line, 1/4 mile..1 mile run, weekend warrior, where driving feel, like a nice low end, to top end torque curve, like not being out of the power curve too early after a shift, gets tossed out the window.

Indeed, HP does win the races in a straight line, or very high speed circuit, but make no mistake, a strong torque/hp curve from 2700rpm to 6500 rpm, with say 25 less peak HP VERSUS 25-30hp peak more, and a curve from 5000-7500, the latter of which, will be in for a nice surprise, on a nice canyon like road

Choose your poison, choose your application.

I hear you 100%. That's actually where this really shines, not only did it lay down a peak number, but it's a broad power and torque curve. It's ahead of the stock cam from 3250 on up in both HP and torque, and carries out well past the peak. I've had a couple laps on Watkins Glen with the cam, and several before, and I can tell you that, especially with 4.10s, I've always got a good gear for every corner, and the car has NO shortage of power, even in situations where I probably should have been a gear lower.

But don't take my word for it. Here is a before and after overlay, before with CAI/Headers/Exhaust, and after with the Cam, Under-drive, and modded intake manifold.

Also, here is the curve on the dynojet, where I stretch it all the way out to the limiter. Not much give up at all.