onebad84z28

Car ran 14.68 at sea level, stock 15"radial ta tires ,transmission and 3.23 gears. car with me 3600 lbs. Has a eaton posi, subframe conectors,banks cat back , hedman headers and y pipe coated and modified to 3 inch outlet. edelbrock carb and intake ,s/r torquer heads and 420/440 lift cam with comp roller tip rockers. stock bottom lg4.best time before was 14.96. no posi and some leaner rods . hp converter says 225 to wheels ,270 flywheel. think this is close?

AlkyIROC

Without knowing temperature, humidity and barometric pressure, "at sea level" doesn't mean much.

14.68 and 3600 pounds works out to the 210 - 230 hp range but without knowing weather conditions, it's only a guess.

Flywheel hp doesn't mean much. It's the power that gets to the wheels that has to move the weight. You can increase the power to the wheels without touching the engine by reducing power losses in the driveline.

onebad84z28

thanks for the reply. the temp was 60, ba was 30.34 and the humidity was 45%, the track is listed at 100 feet above sea level.

AlkyIROC

That gives you a corrected HP number from ET of 214.11.

ET depends too much on traction. It can change a lot from run to run all by itself. MPH is a better indicator of HP and should change very little from run to run. If MPH and ET HP numbers are very close then you know you have good traction.

onebad84z28

I did four runs first one was how i drove it in last 3 lower tires down to 24 lbs, and i know that i am spining a little of the line maybe first 10 to 15 ft .i am sure some drag radial would help. but i only go once in awhile maybe if i can find some used ones.
60ft 2.294
1/8 9.583
1/4 14.823
mph 96.258


60ft 2.212
1/8 9.521
1/4 14.782
mph 95.358

60ft 2.172
1/8 9.448
1/4 14.709
mph 95.385

60ft 2.157
1/8 9.431
1/4 14.68
mph 95.275

AlkyIROC

The car probably got a little slower as it got hotter. The MPH is still pretty close. Ranging from 95.275 to 96.258 is only 1 mph difference.

Best ET = 214.11
Best MPH = 238.55
Worst MPH = 231.32

It's close but you're losing a bit of traction. Some sticky tires should bring the ET down into the 14.3 range. According to the mph, you're getting a corrected 230-240 hp to the wheels.

Those weather conditions actually put you 160 feet below sea level so the engine is making more power than normal. To run that MPH at that weight, you were actually creating 250 HP. If the weather conditions got worse or you went to a higher altitude, the car will slow down but the corrected HP will stay the same.

MaxxMitchell

iTrader: (4)

What were you using to find the corrected numbers, ive been looking for some good formulas or programs to make predictions for myself and others. NvM I checked your site Stephen

I second the sticky tire part, get those 60's under control, and it will run a much better time.

AlkyIROC

I have ET calculation formulas in a spreadsheet. I'm sure there are similar formulas on the web since I spent many years tracking down every formula I needed from the web. Some from racing sites, others from aviation sites. It's all based on power over weight but an engine will make different power when at different altitudes. Weather conditions change the density altitude which also changes the amount of power the engine makes.

To really know how much power you put to the rear wheels, the car should be put on a chassis dyno. All chassis dynos are calibrated to sea level performance so dyno results in Florida will be the same in Denver. Problem is, you'll never see a dyno hp number from a 1/4 run because the dyno can't calculate friction and wind resistance and you'll never race at a perfect standard day, sea level condition.

87TPI350KID

TPI cars would be off a little bit on those conversions. It's all in the 60 ft vs trap vs et. Some may get high 13's, ect, but thats only because of a good launch and tq.

onebad84z28

thanks for all the calculations ,what brand drag radials would you reccomend?( M/T or BFG ) I notice on m/t site they reccomend a 8 rim for 235 60 15 i know i could score some 15" z28 rims cheap but there 7" i think.