Car was just dyno tuned. Its a fully forged 383 ,home ported heads/intake, gm847 cam, 1.6rr with upgraded comp springs and trick flow 1 piece pushrods, lpe cai , built 4l60e and a pic 3600 stall. Stock auto gears in a stock 9104 bolt.

Last year before the rebuild, the car put down 380 hp..... it now puts down 320 peak. The only thing besides the motor refresh that was changed was 17" wheels from the 18's I had, and going from a stock converter to the ptc. Does a converter have that much effect on dyno hp????

 

were the heads home ported the first time you got it dyno?

 

IDK How much of an effect, but a converter does have a significant effect on dyno numbers. I'm sure someone will chime in with more knowledge.

 

1st, it's a dyno! Don't get too upset. A dyno is nothing more than a tuning tool. They are all different. Even the same ones may vary after a year if the owner doesn't keep up on calibrations. And that can be expensive.

2nd. A stall can be very detrimental to #'s based on lock, STR etc.

3rd. It could also be in the tune to engine and trans after the upgrades. The only truth to mods is in track times.

Ask yourself, Does it feel more powerful?" If it does, then it does.

 

X2!

Wifes car only lays down 365 at the tire....but runns 11s

 

I'd rather be a track king than a dyno queen. Move on and see what it does at the track.

 

Nice...

 

Dyno's can be very deceiving, I've seen one that would consistantly dyno stockish LS1s around 360-370rwhp. Not to mention stalled auto's are whole nother can of worms.

 

You didn't mention whether or not you had your tune changed in the pcm after the new setup. If you didn't retune, maybe that's the problem also what headers and exhaust are you running?

 

Was the second dyno the same as the first time?

If yes, then yes, you've lost power.

 

Come on guys a 383 with a 847 making 320 peak flat out indicates issues and the usual dynos a tool aint gonna fly here. Op has an issue, I would look for misfires, port quality or the tune itself.

 

When was the home porting done? Maybe the heads are fubar.

 

That's twice that question has been asked....
.... so.... OP ??

 

your answer is your "Home Ported Heads" Thats why you have a weak number. I bet if AI did the heads youd have around 440hp.

 

Ok. It was 334 hp and 344tq . Car has a 3600 stall. The dyno was different. I have it back... and the butt dyno says it's much faster.

I know it would benefit from better heads.

We'll see what times it runs.

 

Oh, and th home porting was done way before the rebuild. No flow numbers. I have pacesetter longtubes, a ORY and a cheap *** catback. It also has a cutout. 3".

 

If you have the means, I would suggest you go to the first dyno again for a few pulls.

 

i would suggest going to the track soon

 

^THIS^
Since you've now said it was a differennt dyno, no need to be concerned at all. @ssed-up dyno results are not uncommon. Some of the operators don't have enough understanding to even follow the operating manual
Calculating hp from your trap speed and race weight will be far more accurate than any dyno.

 

Obviously you've seen a dyno operator blow up a motor because they didn't know how to set the load, what gear to do the pull in, etc.