Complete mods list is on my cardomain page linked below, but the quick and dirty run down: It's a fully forged 383 with the LE2 head/cam package. 11.5:1 compression. All bolt-ons. Stock ignition. etc.

Ok... I finally took my TA to the dyno and it did terrible. It put down 360/336. I know that longtubes would help. I know the auto. is knocking off a percentage. The 2800 stall was perfect with the bolt-on LT1, but it's probably not optimal for the 383.

I only did 2 runs. It blew a black cloud on both runs. You can also see on the graph what looks to be detonation up high.

I'm assuming I may have an ignition problem. Wires & plugs are fine. I'm guessing I'm probably having some opti problems. Maybe the coil.

Possible bottlenecks

• Shorty headers instead of longtubes.
• PI 2800 stall
• Automatic
• No Dyno Tune. Mail order tune (Bryan Herter) should be close though.

Here's the sheet (sorry about img quality):


What do you guys think?
Could the miss be a problem with the opti?
How bad would a miss like that hurt my numbers?

I was thinking (hoping) that even on a bad day this thing would put down 400whp. I know that a dyno will hurt a lot of peoples feelings, but I thought for sure this thing would do better than 360/336. Somethings got to be F'd.

Any thoughts or advice is appreciated.

 

Longtubes will definately help. Black smoke indicates that it's running rich. What's the A/F ratio? I can,'t see it. Make sure all the components are adjusted/correctly installed and working properly. Check the lash, look for knock, timing, opti. Once you do that you'll be pleased. Don't get too caught up on dyno #'s. See what it runs at the track.

 

The guy at the shop told me that the A/F ratio seemed to be as close as I could expect. The guy who does the tuning wasn't there though... I've got an appt. with him next weekend.

What can I do about the opti... just replace it? You see how the graph gets choppy up over 6k... what does that indicate? And if it is detonation, would that be because of my opti?

 

Was the converter locked or unlocked?

 

tune

 

mother of god.....You need to call FastChip and get a tune from the Master....Dr. Ed Wright. My 355 put down more than that

 

Are these 1 5/8" shorties? What Y-pipe? Catyletic converter?
It really looks like you are starving the ever living hell out of the motor.

 

That horsepower curve has more waves in it than the ocean Need to get more tuning done. If you don't wanna spend the cash on lt headers right now at least get the tune dialed in and then see if you want to change exhaust to find more power. A/F seems to be bang on 13:1 so the black smoke is kinda wierd. I gained 65rwhp 30 rwtq through tuning over my base tune when I did my LE2 h/c last year. Get the bugs worked out and you'll be happy.

 

PCMforless can put down a great tune. I've got the MPH to prove it

 

Your too lean... these LT1's like 12.5-12.8 A/F...

also, Bryan is known for running too much timing... so you are probably getting knock retard up top.

 

Interesting, I have seen more agressive timing tables from Ion, but Bryans tunes seem to be habitualy rich. But I understand why, who wants to buy an engine for a 75 dollar tune.

 

Brian is usually rich on his tunes (from my experience), but looking at the graph above is why I said that.

 

I had another look at the A/F after seeing your post. Had to really look hard to see the line and yeah its real lean upto 4750rpm not bad till 6000 then leans out again. My car likes 12.8-13.0 but each combination can vary a bit. Def needs more tuning.

 

I can't even see the AFR on that graph

 

OPEN YOU EYES!