so i went to the track for my first time last night, it was awesome!, but i'm a little disappointed in my times, first a little background, it's a 305 TPI with a procharger, with the original ECM and programming it dyno'd 381hp and 400 ft/lbs to the rear wheels, i made some changes and i think i lost some power some where, the best i did last night was a 1.889 60ft and 13.24 1/4 mile at 105.5 mph how can i figure out if those figures matches my original dyno'd power? i was hoping for mid or low 12's

 

Sounds like you got a nice ride there. Are you running slicks? Your 60ft times are not good. I would think that at 381hp your mph should be better than that though.

 

i'm running 255/50/16 mickey thompson et drag radials, i did some figuring and that et seems to come out to 320 or so rwhp, looks like i need to get back to the dyno, any other insight?

 

Dyno HP is corrected to a sea level standard day. That way someone in Denver or Florida could easily compare results regardless of the location of the dyno.

Because of track elevation and air conditions, you'll probably never seen dyno HP numbers from a 1/4 mile run. Based on my performance, my car makes about 800 dyno hp but my 1/4 mile time says I'm only making about 700 hp. I lose a lot because I race at altitude.

I can't give you a 1/4 mile calculation without knowing the race weight (car, driver, fuel etc sitting on the start line). I can't give a correction to see if you're close to your dyno results without knowing the track elevation, temperature, humidity and barometric pressure (station pressure preferred)

Your MPH is the best indication of HP. ET depends too much on traction. You could spin off the line and have a slower ET but still run the same MPH.

 

i'm not sure of the weight of my car, i need to get that done, but here's my slip

Reaction *** 0.355
60 foot *** 1.893
330 foot *** 5.586
1/8 mile *** 8.570
1/8 MPH *** 83.44
1000 foot *** 11.120
1/4 mile *** 13.243
1/4 mph *** 106.44

bar 29.52, 63.5 Deg, hum 85%, calt 992

 

I'm going to assume you race at New England Dragway which is a sea level track with an official altitude of 60'.

That's not bad. Your timeslip says your corrected altitude was 992'. My calculations from the weather conditions put it at 993. Close enough.

To try and get your dyno HP to match your ET, you car would need to be over 4000 pounds race weight.

Estimating a heavy 3500 pound race weight, you're getting just under 300HP to the wheels. There's very little difference in the correction formula because your altitude is so low. Just a matter of a couple HP. If the race weight is less than 3500 then there's even less HP getting to the wheels. At 3300 pounds, you're only using 280 HP. That's still down a lot from your dyno results and even something like a head wind won't slow you down that much. That's why I don't really care about dyno results. Simple things like chassis setup and traction at the track can't be simulated on a dyno.

Now, to see where the car makes or loses power, break down the runs into sections. How long did it take to go the first 60' is easy because it's on the timeslip. How long did it take to go from the 60' mark to the 330' mark. How long did it take to go from the 330 to the 1/8, 1/8 to 1000 and 1000 to 1/4 mile.

Doing this breakdown can give you an idea what the car is doing while going down the track. You get one quick ET followed by a slow ET. The second ET has a slower 60' time and doing a breakdown you see the incremental time is the same all the way down the track. You lost all the time in the first 60'. You could also see where the car may speed up or slow down at the top end of the track. This could be caused by any number of things such as fuel starvation, headwind etc.

A guy at work had his engine dynoed before installing it into his second gen. Even accounting for a drivetrain power loss, his 1/4 mile performance is nowhere near what the dyno says he should be making.

 

Well, your 1/8th compared to mine, a budget 383, i ran a smidge under 90 MPH in the 1/8th, you are running allot slower, i estimated my 383 to be making a bit over 400 FWHP, but i am at 100 ft above seal level.

 

back in the day, i have ran a 12.7 @ 107 on a 1.8xx 60ft.. not saying you cant drive but i think the problem may be you rowing those gears.. also i had less power and probably less weight but still think about it.. 1 mph difference with the same 60ft doesnt equal half a second in the 1/4.. i was running a 3.89 gear on 26" tire and the t-5..

 

 

keep us posted on new dyno and track times. i have a similar car to yours. and i havent been near a dyno or track yet. with good tuning im aiming for mid 12's but im leaving stock ecm ,24 motorsport injectors and use the fmu with a custom tuned chip. im a little scared of taking my car to a sticky track with a 10 bolt though. i think youre problem lies in the new tuning youve done with the car. seat of the pants, does it feel alot quiker now, than it did back when it was dynoed?

 

Looks like you need to hook up a wideband and do some data logging on the street. With those kind of rear wheel #'s, I'd expect you to be trapping in the mid teens even at a 3500-3600 lb race weight.

I'll have to agree with Stephen and say it traps like a car that makes around 300 RWHP. What kind of chassis dyno did you get your #'s from originally?

 

i do have a wideband, i do my own tuning, but with out a dyno i can only get the afr good, not tune for power.

i do feel the car is slower.

Stephen, i went to lebanon valley dragway in west lebanon, ny

not sure about the dyno, it just says dynojet research on the graph

 

There is no way that dyno was right if you trapped 105, with 380 to the wheels it should be more like 110-113ish. If you lost enough power to drop 7mph you would feel it 7mph is a lot of power.

 

no way your making anywhere near 381rwhp only trapping 106. something must be wrong....?

my stock '99 LS1 with 6 speed went 13.20's @ 105ish on 17" street tires. 8.50's@85 in the 1/8 with a 2.0 60'. it would have had roughly 305-310rwhp or something like that.
later on i did a cam/heads and made 376rwhp. (bad heads!) anyways, it ran 7.44@93 with a 1.55 60' on 16" et streets. also had a 12 bolt for the launches. never ran the 1/4 with that setup.

 

diggler, i think you would have run 11.7-11.8 @ 115-116 in the 1/4.. my 1/8th is the same with .14 slower 60ft.. so you would run slower to the 1/4 than me.. but not by much


1.69
7.44 @ 93
11.65 @ 116

 

I was there with 86SC, along with 4 other guys from our club. My car (see sig) isn't tuned 100% but its still fast as s**t and with a 2.48 60' I only clocked 104.30 in the trap and 13.735 ET. NOT a good performance by any means. I do know mine though, needs some work on the timing table. My car doesn't have power windows...thats about the only weight difference between our 2 cars. If anything I'd be willing to say mine is just a hair heavier. Traction I think was an issue. Me personally, I spun 1st,2nd, and half of 3rd. In the end I only datalogged 4.7PSI of boost at 4400RPM.

 

Lebanon Valley Dragway has an official altitude of 600 feet. Just as before, their corrected altitude on the timeslip is what I come up with.

The 85% humidity could be a cause for the lack of power. That's a lot of moisture in the air at 63F. The dew point would have been 59F. Water doesn't burn. I'm sure if you try again on a lower humidity/dew point day, performance will be better.

 

as soon as i get back to the dyno, i'll post up the difference, heres my original dyno sheet

 

get him to graph it in sae.

 

What is SAE? Besides Society of Automotive Engineers.

 

SAE Correction Method - What is it and why does everyone use it?


"One common use of the dyno correction factor is to standardize the horsepower and torque readings, so that the effects of the ambient temperature and pressure are removed from the readings. By using the dyno correction factor, power and torque readings can be directly compared to the readings taken on some other day, or even taken at some other altitude.

That is, the corrected readings are the same as the result that you would get by taking the car (or engine) to a certain temperature controlled, humidity controlled, pressure controlled dyno shop where they measure "standard" power, based on the carefully controlled temperature, humidity and pressure.

If you take your car to the dyno on a cold day at low altitude, it will make a lot of power. And if you take exactly the same car back to the same dyno on a hot day, it will make less power. But if you take the exact same car to the "standard" dyno (where the temperature, humidity and pressure are all carefully controlled) on those different days, it will always make exactly the same power.

But when you want to see how much more power you have solely due to the new headers, or the new cam, then you will find that the corrected power is more useful, since it removes the effects of the temperature, humidity and atmospheric pressure and just shows you how much more (or less) power you have than in your previous tests."

 

Thanks for the explanation. After reading that, that's something that probably 100% developed by the SAE.

 

update, that was uncorrected, as is the new ones, i knew i lost power, first run which was same tune from the track i made 330rwhp and 390 ft/lbs after tuning and 5 runs i'm at 379hp and 418 ft/lbs of torque, not to shabby, so if i did a 13.2 1/4, what do you think i'll do with the new numbers?

 

12.5-12.7 Im just guessing. Then again ive also seen cars with 350hp in the 11's. i guess it all depends on setup and weight.

 

Let some air outta those DR's your running and then drop the clutch at 4k!

 

it's all in the launch...time to do the driver mod, lol! 105-106mph is good for 12.4x-12.5x...you'll get there! i've been 12.38 @ 108mph in my 305 car...so mid 12's is possible.

 

excellent....

 

mw66nova, driver mod may be in order.. i do believe its in stock as well..

calculator says you are 12.1-12.2 @ 111.. with a horrible launch, maybe at worse a 12.7 @ 107.. i honestly dont see you going much slower than a 12.5 though.. i was doing low 1.8xx short times (DR's and a stick like you) and 12.3-12.4's @ 110.. so not much different from you.. i ran 15x8 with 275/50-15 mt dr's on 11psi.. went consistent 1.81-1.83 60ft's..

btw, i find the calculator to be very accurate for me.. i'm right around 3100lbs and 380rwhp.. calculator says i should be at 11.64 @ 116.2..

 

5678TA, you have that calculator link?? I was there with 86SC that night at the track and we both drove away disappointed. He's got his sh*t together now it seems and is ready for the '09 season, while on the other hand I'm doing a rebuild and new top end (heads and procharger included). Be curious to see where we both fall next season.

 

http://www.tciauto.com/Products/Tech...alculators.asp

 

went to the track again with the new power, they were busy only got 2 runs in, i was playing with tire pressure...

Reaction *** -0.02037
60 Foot *** 1.791
330 foot *** 5.289
1/8 mile *** 8.14182
1/8 mph *** 85.84
1000 foot *** 10.594
1/4 mile *** 12.64
1/4 mph *** 110.20

bar 29.62 52.7 deg f 53% humidity calt 37

2nd

Reaction *** 0.17730
60 foot *** 1.818
330 foot *** 5.269
1/8 mile *** 8.12594
1/8 mph *** 85.68
1000 foot *** 10.589
1/4 mile *** 12.64
1/4 mph *** 109.94

bar 29.59 53.6 deg f 54% humidity calt 140

 

Wow! Nice bracket racer consistancy. Just get those reaction times down and you can enter the gambler!!

 

That's MUCH better! Get it to leave a little harder and you should see low 12's w/o much trouble... possibly 11.90's with all the planets alignred.