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Discussion Starter · #1 ·
Buddy of mine with an ultra light foxbody (2600lb w/driver) was seeing almost 180mph in the eighth, so he was a little surprised when some of the more reliable online HP calculators (Competitiondiesel for RWHP Wallace for Flywheel) showed about 2000rwhp and 2350hp crank, respectively. He thought he was making more. I was like your car is light man! Anyone have a combo close to this they've actually dynoed, either engine or chassis? I'm curious at how accurate these things are.
 

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Wallace nails my 1/8 mile ET exactly compared to the dyno HP and the car ran exactly what it said it would. 850 hp at 2850lbs and I ran 5.48 last weekend....
I just tried that on our SS/JA car. Makes 641 on dyno.Class weight is 3195 and I was at 10 over minimum. Last time out at SGMP @ 200 feet air density it went 9.54 @ 138. (1.46 under) (1.23 60 foot and 5.99 @ 111.50) And that was with a right down the track steady headwind of 12 MPH.The calculator said 9.95 at 135. That is way way off .. .Our car is full of ceramic bearings, lightweight gear oil, radial tires, the "right gearing and convertor flash" proper pinion angle, and so many other tricks that you can't really use a standard calculator. Plus it depends greatly on how long your powerband stays around that peak HP number. How " flat" it is..
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Most of the time they are fairly close. Radial and power adder cars throw the numbers off some. Even dynos numbers are not 100% accurate. In the end none of it really means anything... All of them will get you in the ball park.
 

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Most of the calcs use equations developed decades ago and the standard hp correction factor was STD at that time. That can throw off some calculations too if you your dyno numbers are the corrected to the newer SAE.
 

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Most of the time they are fairly close. Radial and power adder cars throw the numbers off some. Even dynos numbers are not 100% accurate. In the end none of it really means anything... All of them will get you in the ball park.
Oddly enough, the dyno sheet I posted was on Ray Everhams. It's now Joey Arrentons but still prints Everham on the dyno sheets. He has 4 of them in a row. One of them is electric! After these sessions, I was told by the operator that "That particular dyno is 1% high. So subtract 1%. We don't want to give you any fictitiously high hopes". I knew right then I was in the right engine shop. Talk about honesty ..
 

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Discussion Starter · #7 ·
I just tried that on our SS/JA car. Makes 641 on dyno.Class weight is 3195 and I was at 10 over minimum. Last time out at SGMP @ 200 feet air density it went 9.54 @ 138. (1.46 under) (1.23 60 foot and 5.99 @ 111.50) And that was with a right down the track steady headwind of 12 MPH.The calculator said 9.95 at 135. That is way way off .. .Our car is full of ceramic bearings, lightweight gear oil, radial tires, the "right gearing and convertor flash" proper pinion angle, and so many other tricks that you can't really use a standard calculator. Plus it depends greatly on how long your powerband stays around that peak HP number. How " flat" it is.. View attachment 359734
Yeah the calc's were off on the supercharged Mercedes I had too, it made 391rwhp, but made over 300 from 3500rpm to 6500rpm. Looks like you have the same thing going but from 6500-8500. Engine dyno I am guessing?
 

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Yeah the calc's were off on the supercharged Mercedes I had too, it made 391rwhp, but made over 300 from 3500rpm to 6500rpm. Looks like you have the same thing going but from 6500-8500. Engine dyno I am guessing?
Yea.. Here is the first 3 minutes of that same dyno session. Like for you to listen to a Superstock engine on the dyno. This is just the warm up and initial testing for a pull but listen to when they open the door so you can hear these engines. These Nascar boys said they had never had a Chevrolet small block engine sound like these SS engines, and they had had a shit load of small blocks on these dynos. This was a brand new motor.. I'm on the laptop .

 

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Yea.. Here is the first 3 minutes of that same dyno session. Like for you to listen to a Superstock engine on the dyno. This is just the warm up and initial testing for a pull but listen to when they open the door so you can hear these engines. These Nascar boys said they had never had a Chevrolet small block engine sound like these SS engines, and they had had a shit load of small blocks on these dynos. This was a brand new motor.. I'm on the laptop .


You SS guys are pushing things just a bit harder than us NA bracket guys do I think....

Probably need a special calculator 11500 RPM motors. :LOL:
 

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Discussion Starter · #10 ·
Competitiondiesel puts you at 571rwhp or what would be about a 12% drivetrain loss. I'm betting it's more, your motor is just so flat on the power curve. Be interesting to find a "normal" engine that made the same average hp in a 2000rpm range. I bet peak hp is definitely more. Also, sounds awesome lol.
 
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