I got 1969 camaro with a 200r4 and 502 chevy bb crate engine and vortech blower 7 psi and all thru a carb . went to a chassis dyno and it made 569 hp and 560 torque to the wheels but with that set up the car went 131mph and i weight the car with me in it 3700lbs to me that equals 640 rwhp can anybody answer that and i dyno'd at a second dyno. roughly same results.

Lots of reading about that on this thread http://www.camaros.net/forums/showthread.php?t=61431&highlight=ssm

Just curious, what was your ET with the 131 mph

I dont know how you came to your conclusion as to what your horsepower should be. Was it an online calculator or was it one of the formulas? Either way, these references calculate FLYWHEEL horsepower required to run a particular speed....not rear wheel. I assume that you were thinking the formula is telling you that you need 640 at the rear wheels to run as fast as you are, so you were wondering why you were going so fast with a lot less power right? As you can see, its actually the other way around. What the formula/calculator is telling you is that you need roughly 640 at the flywheel to go 131 in a 3700lb car. And 640 at the flywheel will make 500 some at the back wheels, so the dyno numbers you got do make some sence.

So, just based on your dyno results, your makin 570 at the wheels and that would coincide with 650 plus at the flywheel. The key thing is flywheel, and when looking at the numbers like that, I think youd have a good bit better than 650 at the flywheel to put 570 to the back wheels.

So, unless the dyno you ran on was real "happy" on the high side, you should actually be able to go even faster yet with 570 at the wheels. If the dynos you tested on are conservative dynos(meaning they read realistic or even lower), than Id say you have a lot more than 640 flywheel horsepoewer with 570 flywheel. Once the bugs are worked out you can do better than 131. So, thats actually good news....especially since it seems to me that you started this thread thinking your car was too fast......turns out it should be faster yet!

Yes 640 flywheel hp will get you 131mph at 3700lbs.
my 502 made 625hp and goes 132.7 at 3300lbs.

Yes 640 flywheel hp will get you 131mph at 3700lbs.
my 502 made 625hp and goes 132.7 at 3300lbs.

And this does not agree with my 700hp at the flywheel and only 131.6 in the 1/4 @ 3500 lbs. Which either makes the dyno I used a liar, or my setup is a stone in comparison.

Engine dynos differ as does the actual HP in the car.

BTW...RWHP should equate exactly to the mph the car could run in the 1/4, assuming the fuel system can handle the G forces and the air getting to the carb isn't all messed up. Besides, peak HP doesn't mean all that much.

I tend to tire of chassis dyno numbers, the strip is the real dyno once you have the engine in the car.

And, 67RS502, as much as I admire your accomplishments with your car, it's the exception rather than the rule.....assuming the engine dyno you ran on was dead nuts accurate, calibrated to NBS, and you haven't changed the engine combo one bit since putting it in the car. No one here has accomplished your numbers with that HP level...have they?

Ron

:waving:

And this does not agree with my 700hp at the flywheel and only 131.6 in the 1/4 @ 3500 lbs. Which either makes the dyno I used a liar, or my setup is a stone in comparison.

Engine dynos differ as does the actual HP in the car.

BTW...RWHP should equate exactly to the mph the car could run in the 1/4, assuming the fuel system can handle the G forces and the air getting to the carb isn't all messed up. Besides, peak HP doesn't mean all that much.

I tend to tire of chassis dyno numbers, the strip is the real dyno once you have the engine in the car.

And, 67RS502, as much as I admire your accomplishments with your car, it's the exception rather than the rule.....assuming the engine dyno you ran on was dead nuts accurate, calibrated to NBS, and you haven't changed the engine combo one bit since putting it in the car. No one here has accomplished your numbers with that HP level...have they?

Ron


Ron, don't forget to account for density altitude. Rafel and I both run at Baytown, mainly when its cool and the DA can be below 0 ft. That will affect the performance greatly. Do you know the weather conditions/DA for your best pass? By my calculations you were making around 660hp on your best pass uncorrected for weather.

my calculator says you need 649 RWHP and 721 FWHP to make 3700 lbs go 131 MPH, if the chassis can generate 100% effiency it should go 10.40.




Rafel,
mine puts your car at 602RWHP, 668 FWHP and 100% effiency will go 10.27

Ron 498,

yous is 623 RWHP and 691 FWHP.

my calculator says you need 649 RWHP and 721 FWHP to make 3700 lbs go 131 MPH, if the chassis can generate 100% effiency it should go 10.40.




Rafel,
mine puts your car at 602RWHP, 668 FWHP and 100% effiency will go 10.27

Ron 498,

yous is 623 RWHP and 691 FWHP.

What calculator is this? Sounds pretty high to me.

Wonder what it would say about mine?

10.039 @ 132.4 mph, 3515 lbs w/driver.

Ron, don't forget to account for density altitude. Rafel and I both run at Baytown, mainly when its cool and the DA can be below 0 ft. That will affect the performance greatly. Do you know the weather conditions/DA for your best pass? By my calculations you were making around 660hp on your best pass uncorrected for weather.


Hey John.
I don't have an air density gauge, so no I never know the actual conditions.
We are also at sea level, but in the Pacific NW. Typical DA around here is around 1000ft. Very rare that we get below sea level air. And usually when it's nice and cool, the humidity is high. you know, dew forming on the car. We race in the evenings.
Maybe some day, I'll get lucky and get that perfect day!
BTW.....my typical numbers the last month or so have been between that 10.23 and 10.29. all at 131 and change.
Thanks!
Ron

I'd have to ask my engineering friend where he got this formula from. I just plug the #'s into it and it gives me the results, it also has a place for nitrous numbers. It displays in a spread sheet, so if you want to go faster you just look down the chart and it'll let you know how much more HP you will need to achieve that #. I'm thinking he mentioned NHRA when he first sent this to me. I believe it's just straight physics that a it takes X amount of HP to get X lbs to go X speed. The nice part about it is it also tells effiency of the car. My #'s were right on with MPH and dyno #'s.

here's yours
707 FWHP
637 RWHP
107.85% effiency

I have seen only 2 cars ( now 3) achieve above 104 % effiency N/A, nitrous cars have achieved 114% because of the additional TQ from spraying right from the starting line.

I would be happy to send this to anyone that wants this. e-mail hardinm@sjrmc.com

Another thing, peak horsepower(whether it be flywheel or chassis numbers) dont mean a whole lot for many reasons....at least they dont mean everything. Two guys can make 600 horses at the crank and even in an identical setup car, one motor can still be faster than the other. The overall power curve and the average power across that whole curve means a lot more than your peak number. Peak only happens once, so everything before and after means a whole lot more. Thats why the one car is capable of being faster than the other.

And of course, two identically setup engines that both make the same power still wont run the same numbers depending on the car these engines are in. Differences in the drivetrain in general like gearing, converter stall speed, diameter, efficiency and even the brand of the converter, tire type, make, height...... See what Im gettin at. Vehicle weight matters of course. There are too many variables to rely on any formula or anything to tell you for sure. You never know til you get to the track.

In the case of your car, I cant pinpoint exactly what it should be capable of. But, based on your torque and horsepower numbers along with the supercharger(which means a big flat power curve), I expect a motor like that "on average" to have more than 131 miles per hour in it.

:waving:

:waving:

Hey Mike,

What about mine......just for fun.....how does it come out??

433RWHP at 3700 POUNDS and 128 MPH

Thanks
Luc

Hey John.
And usually when it's nice and cool, the humidity is high. you know, dew forming on the car. We race in the evenings.



Ron, that describes the bulk of our winter weather. Mostly when its cool, its also very humid or just plain wet. As the sun goes down and the cool air comes, the dew settles and the track is gone. Every now and then, we get some cool, dry air. The weather from my best pass to date was 53dg, 30.3 pressure, 45dg dew pt. Thats around -700 DA, pretty awesome air.

that's why i like this formula so much. If the combo makes good peak HP, but it's 85% effiency then something is off in the combo. Gearing, tire slippage, converter...etc.

I think 131 is right on with 7 lbs of boost and a crate motor.
My friends 3400 68 camaro with a 468 BBc , 6-71 blower, AFR 315 heads runs 10.40 @128, but it's got a hyd flat tappet cam with 240 253@ .050 575 lift, 11" converter and 373 gears with 29" tall tires and makes 6 lbs of boost. He drives it to the track runs low 10's on pump gas and drives it home. I'm sure when he sprays it with the anticipated 300 shot it'll pick up quite well. Now add a roller cam,run 12-14 lbs of boost and a 4000 stall and the car would be MUCH quicker, but all thatb takes away from driveability.

Luc,

It's not even close to the 433 you put in the post.

I'm getting
672 FWHP
606 RWHP

10.64 100 % effiency

Woooo! that's a tiny bit off!!!

At least I almost got 100% effiency :)

Interesting that I it only looses 66 HP trough the drive train!

Thanks Mike.......

Is it look back through the thread and compare your weight and MPH to the others . Your weight is similar, but your stating quite a bit more power.


I was just reading about a back to back chassis dyno and engine dyno on a 88 vette with a 4+3 speed and the stock IRS D-44....12% drive train loss. Seems low to me.

Wow 0 ft DA, can't imagine!;)

Have you guys ever run your cars at say 5000ft or higher?

When looking at corrected dyno #'s, its real important to know which correction factor the dyno operator is using. Both engine dyno's I've used go by SAE-J607
which corrects to 29.92", 60dg, 0% humidity.

The Mustang chassis dyno I use goes by SAE-J1349 which corrects to 29.235, 77dg, 0% humidity. My most recent chassis dyno showed 485rwhp. If we go by the SAE-j607, that # would be closer to 510hp. You guys that want to correlate dyno #'s (chassis or engine) with on track performance cannot ignore weather/DA data or the correction factors.

Hey John, it there a website link or info somewhere that stipulates what the details are of the SAE standards please?
I am only partly familiar with J1349 but want/need to know more.. Thanks.

Hey John, it there a website link or info somewhere that stipulates what the details are of the SAE standards please?
I am only partly familiar with J1349 but want/need to know more.. Thanks.

http://www.revsearch.com/dynamometer/dyno_testing_defininations.html

http://www.land-and-sea.com/dyno-tech-talk/corrected-horsepower.htm

http://wahiduddin.net/calc/calc_hp_dp.htm

Ron, that describes the bulk of our winter weather. Mostly when its cool, its also very humid or just plain wet. As the sun goes down and the cool air comes, the dew settles and the track is gone. Every now and then, we get some cool, dry air. The weather from my best pass to date was 53dg, 30.3 pressure, 45dg dew pt. Thats around -700 DA, pretty awesome air.

Thanks again John. Our cars are pretty close, with way different combinations.

Tonight was a perfect example of cool, but very humid conditions. It was 64 for a high in Portland, rained in parts of the city, but not at the track. It was our last "heads-up" race of the year, so the diehards were there. While waiting to get into the track at 5pm, of course it began to rain. Not hard, but steady for about 1/2 hour. Took 2 hours to get the track dry enough to race. But we ended up running 1/8 mile. As soon as we began to make runs, the dew settled in and it was a constant clean the windshield affair. But the track wasn't too bad. At least for me! My suspension tuning has finally paid off.
In 5 runs, I was 1.47-1.49 60ft, and between 6.53 and 6.56 ET's. The mph was down about 1mph, but with that much water in the air, no wonder.
I won the race! Cracked me up. I was #2 qualifier, but #1 is basically a low nine second car, and they really suffered in the traction dept when the dew showed up.
The cool thing for me is that I'm the only NA car in the group. And only 2 of us actually drive to the track. And us 2 ended up in the final. He drives a very nice 67 GTO stick car with a pontiac engine and a bunch of NOS.

Anyway, point being, it's just rare here to get that perfect day. But when we do, even the butt dyno knows after just one run.

I could probably hit a 6.3 or a 10.0 under those conditions, but it would be my luck I'd be doing something else on a day like that. Like golfing!

Good stuff!

Ron