Had an opportunity to get my 93 Corvette (62K on car) dyno'ed today and took it. 3 pulls on a Mustang dyno for $75, all for charity.

First off some background, only power influence mods/changes are as follows:

X-pipe in place of resonator
Muffler Eliminators
Fresh LT4 Valve springs, installed over last winter.
Fresh, clean fluids in driveline. Mobil 1 Syn 5W30+BG MOA, Redline in Trans./Diff.
Fresh plugs/wires. ALL AcDelco

Data for today:
Crappy Sheetz 92 Octane Fuel (I usually run Sunoco 93, have not been close enough to one lately to fill up, that and not concerned about MAX HP with auto-x).

Dyno cell was 1 bay enclosed shop, with door open all of the day since 9AM. TPG Tuning in Blairsville, PA.
Weather data at approx. 6:30PM 6/16/13
Humidity 83%
Tempurature 74 Degrees
Pressure 29.96 inches
1000ft above sea level

I made a HUGE mistake, I let the car sit after a 1 hour drive and auto-x ALL day to eat right before this. The IAT was heat soaking during that hour or so. Moved the car maybe 50 yards and did the pulls. Just before dyno pulls car was approx. 150 oil temp, 185 coolant. Last pull was around 200 coolant, did not see oil.
I am willing to bet the lower HP is due to the IAT being heat soaked, hood was never open ALL day. I did this at the track once, KILLED my top end by 6 or 7 MPH in the 1/4 mile. F

FYI, personal best ET is 13.38@105 with a 1.99 60'.

Long story short:
3 Pulls ALL SAE Corrected Rear Wheel numbers:
Car is VERY consistent layed down right on top of each other.

246HP and 304TQ

VERY flat torque curve from 2 to 5K.
One guy said, it was the flattest he had seen all day.

Using a 17% driveline loss, my engine is making 288HP and 355TQ at the CRANK SHAFT. Damn healthy torque numbers. Screw HP, torque wins races.

FYI, I set FTD (Fastest time of day) at my auto-x event today. Torque its whats for dinner!!!


What did I learn:
My engine is VERY healthy.
Sounds F-en mean as Hell. Everyone else plugged their ears after she cracked 2K, I didn't I just was grinning ear to ear. Sound of that car is Heaven sent. AMERICA!!!
This car never ceases to amaze me. Dave McLellan and Co. need more credit than they get.

 

 

Nice! Thanks for sharing the results. Yes, very healthy torque number.

 

Sounds like a killer weekend! Nice!

 

 

It was!!! Unfortunately, I'm paying for it now. The power steering line is leaking from the pump to the rack. I'm waiting on parts and need to get better tools to get the rack fitting loose. Sucker is tight!!! I think a crows foot flare nut is the tool I need.

Hopefully, its done for this weekends activities.

 

Sounds like you could use this, common problem on these cars.

http://dougrippie.com/products/c4-po...pressure-hose/

Great numbers and I bet you're making closer to 300 at the crank than you're giving yourself credit for. 16% driveline loss is pretty high unless you have a really loose stall, and even then it should be locked up at the high end.

 

There's actually a multiplier affect you have to account for.

A Mustang Dyno is an eddy-current dyno and loads the car to account for tire friction, actual vehicle weight, etc. The Dynojet is an inertia dyno....the car spins a drum of a known mass.

Given the above, the Mustang dyno, with Corvettes, typically reads ~10% lower than a Dynojet. Using your 246hp, that would be ~273hp on a Dynojet. Applying the driveline loss factor (15%-18% for an auto) gives you an estimated SAE Net engine hp range of 321hp - 333hp. The range may be a bit higher than normal (some claim an auto loses 12%-15% and a manual 10%), but it's certainly within a few percent.

With the hood open during dyno pulls, and coolant temps between 185 and 200, you didn't lose any power due to heat soak.

 

The car is a ZF6. IDK where I got 17% maybe I'm stupid.

Hood was closed from time it was parked for about 1.5 hours, then car moved 50 yards to dyno, hood was NEVER open during the pulls.

Even so with the 10% thing I'm at about 270HP on a Mustang Dyno and 334TQ. DynoJet would be close to 300HP and 365TQ.

AT any rate its a baseline number to have as a reference.

 

I ordered it late Monday. I got the shipping info today. Plan B is in effect.

 

Duct Tape!? Dyno's are great for baseline and comparison purposes. I put mine on the rollers to know that everything was healthy and to know where I started. The real proof is on the track! On a semi related note, I've seen in several LT1 corvettes the fuel pump being unable to keep up at the higher RPMs. If you're on the original fuel pump it might be a thing to test.

 

I always find this funny. There are more variables on a track than there are on dyno, the biggest of which is the driver...few are consistent from run-to-run. Then you have to account for tires...how sticky and the air pressure needs to be consistent..., suspension changes, track surface, etc.

They are both approaches...but neither is more "real" in terms of proof than the other.

 

, track temp. , humidity, sea level, etc.....

Although I do like to mph on the 1/4 ........very telling about a CAR's performance rather than 60' times (which are telling of a driver and tires, auto vs. stick, etc.).....

even a bad driver (usually) can at least pull the car to its fullest level (given enough passes) by just full throttling it down the track to make it run to its fullest mph in the 1/4...I always look at mph on the 1/4 more than anything else to gauge power....1/4 mile times always vary somewhat but mph usually remains somewhat consistent (within a few ticks of a fraction of a second) if the driver is pushing it hard.

 

I have always looked at 1/4 mile mph as a good gage of power.

I also have an onboard accelerometer that is easier/quicker to use than a track day. I like to do a pull from one mph to another for comparisons before and after changes.

 

That's just it though, most dyno's are being treated as art not science. Short of an engine dyno being set up to SAE's standard they're as much prone to the WAGs of the operators as a driver is down the track. Additionally you can build a car to be a dyno queen just as well as a 1/4 miler or a road course car. That's why the track is usually treated as the "actual" result because that's more indicative of what we value.

That and until they start using Avg Usable torque instead of peak horsepower as a measure of performance, the peak number is mostly just a bragging right.

 

When you dyno, you get a graph of the entire tq curve. It's not just peak. However, even if it was, it's still an objective data point and that is way, way better than what most people us; the venerable SOTP meter or the red-neck'in "peel-o-meter". Scrutinize it all you want, but it's something objective.

 

I'm aware of that, all I'm saying is it is not as objective as people think because of the heavy variability with how the dyno operator applies a correction factor. Additionally those correction factors are generally proprietary to the brand of the dyno.

The advertised horsepower that is stamped on the side of a Z06 is a result of the SAE J2723 certification. What you get on a set of rollers is the equivalent of throwing spaghetti against a wall. I'm not saying it isn't useful, I'm saying it isn't very accurate.

 

A chassis dyno is way more accurate then track data. The dyno will correct to standard conditions and give you repeatable results that you can use to determine if your changes are helping or hurting. The track is effected by the driver, the weather, track prep and other varaibles that do not allow you to make accurate comparisons from run to run or day to day. If you are hunting for data the track will be general and the dyno will be specific.