I took my chevelle to a mustang dyno to see if I could get rid of a high gear miss I have and to my amazement the car had far better numbers then I thought. I asked the dyno operator if the numbers are correct or are they higher just to make the person happy with the numbers, he claimed they are accurate.

I got 670 torque and 473HP, when the converter flashed it was 730 torque. Is this possible with a 502 with a little larger cam (245/253), dual throttle bodies on a tunel ram with multiport fuel injection?

It seems high but if it is accurate it would explain why I'm having a tough time getting the car to hook well.

Anyone with a 502 have any dyno time to compare?

Lee

these numbers at the wheels? I doubt it. Friend has a 502 with a larger cam and if I remember well it dynoed around 540 HP or so and high 500s or so on engine dyno.

Do not get too hung up on any dyno numbers. The dyno can be "corrected" in a number of ways that result in different readings. The dyno is wonderful tool for evaluating tuning changes and diagnostics like your high speed miss.

I have seen torque converter spikes like yours all the time on dynos, just beware that the great torque multiplication of your converter only lasts for a brief moment - it is what helps to move your somewhat heavy musclecar off the line. Also, often times a converter will flash torque like that down low only to trade it off for high speed efficiency - a lot of cheap high performance converters are that way.

Just take it to the track and run it - the dragstrip is the ultimate dyno.

I would much rather have the problem of how to deal with the torque, rather than how to make the torque.

Thomas

Remember guys this is on a mustang dyno, which I believe produce a little higher number than the normal dynos found at speed shops.

yanniz- This is rwhp not engine. Also, maybe my intake and fuel injection has helped with the numbers over a carb'd version. Also, did you mean that he had high 500's on the engine dyno and 540 at the wheels? Only a loss of 40-50HP?

Bomber67 - This is a yank SS3800 converter, I dont think Yank builds a cheap converter. I wouldnt call it a spike, it held ~650ft-lb from 2400RPM thru 3600RPM, didnt drop to 500 until 4700RPM. My problem has been getting traction, I have terrible spin even going into 2nd gear. There was another topic here that I was trying to address that problem.

JCOOSS - I've heard just the opposite from everyone I've talked to including both dyno shops in town, one with a dynojet and the other a mustang. I local guy took his car to booth dyno's and the mustang was a good deal lower in numbers.

I'm not too interested in dyno numbers, I hear too many people bench race dyno times. My goal was to find a problem but after seeing the numbers I was wondering if the torque was true or not just because I just cant get this car to hook. I'm going to install moroso 47200 springs this week to see if that helps or not.

Lee

A Mustang dyno will show less rwhp and torque than a Dynojet. So that makes your numbers incredible and a little suspect in my opinion. 670 rwtq would be 750-800 at the crank and that crate motor wouldn't even come close. I also feel it's the converter. Any numbers under it's stall will be inflated.

Bottom line, it's a very healthy engine and definitely sounds like a lot of fun.

Jody

Fun numbers no matter how you slice them, but I also have a feeling the converter is at play with your mega-torque numbers. Not to say you won't feel it or have to deal with it one way or another off the line, but they are just numbers that have been inflated by those insidious little fluid couplings we call torque converters.
The 473hp # I do not doubt and would imagine the car is a scream, but your torque numbers are really probably in that same region, either plus or minus a bit.
Either way, putting almost 500rwhp and probably what would equate to 500rwtq to the tires is a good job. Have fun! Numbers are just numbers, the fun numbers in my game are MPH, for others they may be ET, so on and so forth.

Either way, sounds like a rockin lil 502. A long runner manifold with EFI I would suspect could put you a bit above 500ft-lbs at the wheels if it were behind a stick, so just know what you have is serious NA power.

Matt

I should have added some words: it is possible to have a converter be very loose below its stall, and efficient at the top end - it is the cheap converters that have the problem of doing both. Easy enough to check converter efficiency at the track: note the indicated rpms as you cross the finishline. Compare your indicated rpms against the theoretical no-slip rpms for the actual mph. Theoretical no-slip rpms = (mph x gear ratio x 336) all divided by tire diameter in inches. Efficient non-lockup coverters lose ~ 3% to 6%, more common to find them at 8% to 10%, beyond that is too ineffiecient to consider.

I am concerned that your 115 mph trap speed is much lower than I would expect for 473 rwhp. Yank converters have a generally good reputation, so I am not going to suggest anything other than maybe you should verify its efficiency.

The immediate answer to the traction equation would be slicks if none are being used.

Thomas

MadMarv - I'm sure the converter is responsible for the big numbers but I didnt think a converter could make that big a difference. Yanks WEB site lists the STR of 2.7 so obviously it's living up to it!

Bomber'67 - Did I mention that I dont have a roll bar? If not sorry. I let off near the 1000' foot mark to keep out of trouble with the track. I purchased a cage 2 years ago but I just havent wanted to cut up the car. My mind has been set to go ahead and do it, hopefuly before the end of this season. My 1/8 mile is ~7.2@96. My best 60' ever was on drag radials and it only happened once and that was 1.69, usually it's around 1.76-1.78 with hoosier QTP with a best of 1.72.

As for the converter efficiency, I dont know because I let up. I do know that when I let up the RPM is usually around 5200RPM logged with the computer that runs the fuel injection.

The times in my sig was from 2 years ago, since then I have it better dialed in. I 'think' that I could run an 11.6x now.

Lee

Lee, for coasting after the 1,000 ft mark...115 mph is damn good!

Based on your 60' and 1/8 e.t. you should expect 11.3x's once you unleash it for the full 1/4 mile.

I don't know how well you judged the 1,000 ft mark, but the same formula for converter top end efficiency applies: observerved rpms vs theoretical no-slip rpms.

Get that cage in there already - and then you can REALLY play!

Thomas