I wanted to get my '93 dyno tuned before I start spraying it... Mainly to check my A/F ratio.
The car ran 12.05 @ 112 MPH at the end of last season. Over the winter, I swapped to 3.73's (from 4.10's), and added an aluminum driveshaft.
On the dyno Friday night, the tune that went 12.0 only pulled 300 RWHP???? The dyno runs were on a DynoJet, and the numbers were uncorrected. It was pretty hot and humid.
Bryan and Alvin from PCMFORLESS both attribute the lower numbers to my 9.5", 3800 stall, non lockup converter. OK, I can see losing some power there, but I should be making somewhere closer to 370 RWHP to run low 12's, shouldn't I?

I've never been real big on dyno numbers anyway. Qarter mile times are what matters...but...Something seems odd about those numbers.

Frank

 

Yep thats the verter causing that.. It's slipping.. If it wsa locked you might have had a higher number...being it would have been a 1:1

 

But, how much HP can a converter cost?

Frank

 

I really don't believe there is a exact science to know how much!... It really depends on the individual converter.. They are all made up to peform diff. One's looser than the other and vice versa.. Most who dyno A4's.. Dyno w/ it locked up.. So your theory of track performance is a better way to see what your car is doing.. Using only the dyno to monitor your Under Load A/F is a good way to get er' tuned.. just don't expect braggin' right's w/ a non-lockup verter..

 

LOL... That's my theory, too. I was just looking for input to see if maybe anyone else pulls such low dyno numbers and runs what I do.

Frank

 

Never raced a Dyno----Converter and gear will cause that.See what it does at the track.

 

How do you "lock up" a convertor???

I have the Vigi 2800.

 

FWIW, I saw an ls1 pull 270 rwhp then run a 12.0 the next day. It bothered me a little bit because I pulled 345 rwhp on the same dyno and only ran 12 teens that same day. He did have some weight reduction and a large stall, but it still didn't add up.

 

I remember awhile back 98TAauto had a 3600 or so on a bolt on LS1. .and he dynoed like 277 to the tire And he was running low 12's i believe back then.. not sure..

 

As you can see from my sig. My race car has run 11.34@118 and it made 347 RWHP and 490 RWTQ on a Dynojet. This is through a 9 in. 4000 stall, non lockup convertor in a Turbo 350. The convertor was set up loose because I am footbraking it not using a trans brake. The car weighs 3180 with me in it. I have run those numbers through several online calculators, and that vehicle weight and that trap speed equates to around 500 HP at the flywheel. My point is with a non lock up, high stall convertor, you can't put too much emphasis on chassis dyno numbers. IMO

 

Frank, 300 rwhp seems really low. I use a very accurate hp calc, and based on the weight of your car, I'd expect to see right around 360 - 370, as you say. Have you run the car on radials before? I'd be interested to see the trap speeds, as I'd expect them to be a good 2 - 4 mph higher, granted with a decent 60'. SSeya, for some reason, your dyno numbers jive with what I'd expect, especially at that weight.

Frank - is your car a stripper? It is EXTREMELY light with you in it. My car is 3385 without me. Unless you weigh 65lbs, you have a lot less weight in your car.

 

Frank, remember the dyno is a tuning tool only!!!

RamAir95TA got crap for dyno numbers, but his car is going to move. He was just simply blowing right through his converter. His HP curve looked like a TQ curve, it was just a flat line across the board.

Simply said, who cares what the numbers were?? You KNOW you have a good tune for the gas now, and your car's still fast!

 

Frank just before my 11 sec passes I dynoed 299.9 unlocked and 318 locked up. I'm pretty sure my TQ#'s were in the 340-350 range, I'll have to look them up.
Steve...

 

Thanks for the input everyone. I guess the bright side is, we did pick up HP and torque with the dyno tune. I'm making 10 more HP at some points on the graph, and 20 more FT LBS of torque down low. Maybe the improvements will get it in the 11's.

Frank

 

Here's my take.

1) The numbers are uncorrected, and you said yourself that it was hot and humid. If you find out the exact weather conditions that day, you can correct the numbers yourself using some of the on-line calculators.

2) You run a 12.0, but that's on a 1.6-1.7 60' time. Most guys on street tires are cutting 2.0 60's. That right there is gaining you about 0.6 seconds compared to other normal times. So you have to compare to a 12.6 for typical people.

3) Your auto and stall are probably sucking up 30-40 rwhp compared to a M6. (as a guess)

I think once you correct your numbers for the weather conditions, and take into account your auto, 9.5", and stall you will be close to the numbers you thought you are at.

Dan