Fuzzy Dice

I thought y'all might be interested in my experience...this shows how a torque converter may effect HP on the dyno...

1. Stock converter = 278 rwhp...best 1/4 mile time = 13.52
2. TCI 2400 stall converter = 263 rwhp...best 1/4 mile time = 13.41
3. Vigilante 3200 stall converter = 250 rwhp...best 1/4 mile time - 13.18

These numbers were taken on the same dyno over a three year period with no other changes to the car...weather conditions were 100 degrees on the first one, 90 degrees on the second one and 78 degrees on the third one...clearly the looser converters skewed the numbers...

Obviously I was not making less hp on the third dyno pull than on the first or second one...dyno's are great for getting base numbers for mods and tuning...they are also great for going to the track and, when asked, to be able to honestly tell folks I make 250 rwhp...then I proceed to give them a little surprise...

isosceles

but the REAL numbers are in the 60" times... how bout THOSE?

Corvette Kid

Interesting, to say the least.

bobmic93

Fuzzy, all in all, do you like the difference the 3200 makes? Rpms stay way up in the power band. My D36 was happy to see it go. Doesnt sound like much of a retirement home though. My 2400 doesnt even compare to it and funny thing is I can feel how loose my new stall is compared to the quality of the Vig. That 3200 was still very streetable.

sami85L98

That is true according to alvin and i did dynoed locally here in atlanta, i did dynoed twice in atlanta same place with different transmissions and TC, second i got less HP anf more torque numbers immediately this dyno owner asked me did u changed TC or transmission i said both so, its true more TC less HP but more torque and less TC more HP but less torque, when it comes to Drag racing Torque is the king.

Demonic85

Yes torque is the key to fast acceleration which is why I laugh at all the ricer kids who think they have a fast car because of some high HP numbers when they have half the amount of torque.

hippy

What do 5' times have to do with anything?

bobmic93

The ones you have to look out for have the all wheel drive packages that really get them off the line fast.

Fuzzy Dice

OK...OK..

1. Stock converter...1.89
2. 2400 stall...1.88
3. 3200 stall...1.79

Happy now, triangle boy?.... ...the above are the best of each... my overall average short times with the stock converter were around 1.95, the 2400 stall were around 1.91 and the 3200 is right at 1.84...

Fuzzy Dice

I do like it a lot...hits real good and is very streetable...it turns out our deal was a blessing in disguise...my lock up switch was fubared and I didn't know it...got it fixed when I put in the 3200...

One other "funny" thing happened...my first pass at 1/4 mile with the 3200 it locked up at 1000' dropping my rpm by 500, then unlocked before the traps again...that was my 13.18 pass and would have been a bit better..oh well...a scan showed my computer was set to lock the converter at 90 mph while at WOT...why it never did that with the lower stall converters, I don't know...we burned a new chip and raised it up to 115 mph so that will not be an issue anymore...

Good luck with the heads and cam...sounds like you have a runner now...

LT4BUD

[QUOTE=Fuzzy Dice]clearly the looser converters skewed the numbers...
QUOTE]

Please excuse my ignorance....but I thought dyno testing with automatics was always performed with the converter in lockup, and if that is the case wouldn't the stall speed be meaningless?????

Same question regarding your locking up at 90mph......seems lockup should be related to rpm....not mph.....again excuse my ignorance but trying to understand a little better

AORoads

94Controller

Don't you know Hippy? If you're ahead after 5 feet, it's all over...

thanks, I needed a good laugh this morning

mseven

I am not sure I understand, at any time in the dyno runs was the converter locked?

Gold1986Vette420

Did HP actually go down as in MPH at the end of the track????????

Corvette Kid

That's what I find fascinating about this. Had I made a guess, I would've thought that a smaller, lighter converter would have increased HP and possibly reduced peak torque. Very interesting thread.

Alvin

The higher stall convertor is translating more power into more torque just like a higher gear. However I've never seen a car dyno more torque than usual with a higher torque convertor.. I think the biggest HP loss is just the fact that the torque convertor is slipping you are not transferring all of that rotatino.

Ramanstud

[QUOTE=LT4BUD]Well, the lockup could be slipping some adding to HP loss, or they manually have the TC unlocked. Variations in TC diameter also could theoretically change HP numbers due to rotating mass. Generally though, they are supposed to be locked in third during dyno pulls.

As for the Lockup control - depends on the chip programming. The "normal" lockup is controlled by throttle position versus MPH, but there is a cutoff that automatically locks (or unlocks) the converter given a certain MPH. It's all in the programming.

hippy

I think that's right. I'd bet if you'd manually lock the convertor your HP #'s would be very close.
When I let my conv go into lockup around 90mph I saw higher peak tq numbers due to stall flash.
When I made my conv lock thru the whole dyno pull my flash tq #'s weren't as high.

Fuzzy Dice

I can tell you that we discovered the lock up was commanded by the computer at 90 mph...I always was under the impression the computer would NOT lock up the converter at WOT regardless of mph...apparently I was wrong...the chip in the car when I bought it was stock...I had a chip burned about 3 years ago which only changed the fan settings and the A/F ratio...

My trap speeds have dropped some with each converter change...with the stock converter my best trap was 105.92 mph...with the 2400 stall it was 104.28 and my best trap with the 3200 so far is 103.98 and that was on my 13.18 pass a month ago...

When we burned the new chip two weeks ago to raise the lock up from 90 mph to 115 mph we put it on the dyno to check it...sure enough it did not lock up till 115...that run produced 250 rwhp and 290 rwtq...fwiw, the stock converter made 303 rwtq and the 2400 converter made 298 rwtq...