I have a 1994 z28 mods are 355 short block, LT4 hot cam, 36# injectors

Heads were ported and polished, with valve job parts include
(1618-16)1.6 roller rockers, (26918-16)COMP Cams Valve Springs, (7940-16)COMP Cams Hi-Tech Pushrods, (11501-8) Manley Race Series Stainless Steel Valves, (11566-8) Manley Race Series Stainless Steel Valves

MSD optispark, MSD coil, MSD wires, NGK iridium plugs,

K&N CAI, RKsport midtubes, cat back exhaust,

LEVEL 2 Transmission with 3k stall From Xtremetransmissions.com

What could be the cause of the low numbers?
the car is definitely faster than it was stock, but those numbers seem too low to me, I don't know what it could be it runs fine and idles good. The tuner showed me a loop at the end of the dyno sheet and told me that reason the numbers were low is the converter was not locking up and the button wouldn't work.

(Currently adding 3.73 gears to rear end)

 

Additional videos of idle and first dyno pull (before tune)

http://img405.imageshack.us/i/qiw.mp4/
http://img545.imageshack.us/i/c4w.mp4/

 

Kind of hard to read the dyno graph. Appears it peaked at around 268 on both torque and HP?? Results shown as "uncorrected".

 

HP = 267 and TQ 268

the A/F is a tiny tad over 13 at 5.8rpm

This is the print out sheet the tuner gave me when he was done... No idea why it says uncorrected in the corner?????

 

It should be corrected to "SAE" or "Standard" conditions. Otherwise, its affected by the temperature, barometric pressure and humidity. The correction brings it back to a standard set of conditions so you can directly compare future pulls.

But that's not going to account for about 30-50 missing HP.

 

I have no idea? i was hoping someone on here could help me figure it out

 

Did you have the heads flowed?

 

Compression test? All valves sealing properly, rings seated? Is your camshaft timed properly? How many break-in miles?

 

Did you have the heads flowed? - No i did not have them flowed.

Compression test? Never ran a compression test because I bought the 355 with the hot cam in it already built from a friend.

All valves sealing properly, rings seated? The machine shop did the valve job, and i bought all the supporting mods titanium retainers etc. If that answers your question....

timing was done by the tuner so i assume so and it now has around 12000 miles from when it was built till now

 

What kind of Dyno? DynoJets are known for reading low; not to mention a LOT of dyno operators fudge the settings in their dynos or just don't calibrate them properly.

 

Top of the sheet says dynojet so I think it was a dynojet

 

How does the car perform at the track? If it performs as expected at the track don't worry about the number on a dyno.

Here is an interesting article on chassis dyno's. They tested a 2011 GT500 Super Snake on 5 different dyno's. The results were 577, 600, 630, 650 and 662 HP. From highest to lowest that is a difference of 85HP.

Bottom line - They are just a tuning device.

http://www.hotrod.com/techarticles/g...ing/index.html

 

Your pull starts to break up around 5000rpm (surprised no one has mentioned that). Something is certainly wrong. Valve float, incorrectly gapped plugs, misfires, valve adjustment, etc. are possibilities.

 

If the tuner did not say something about what happened to the "curve" at 5000rpms then I have to throw out an accusation of raging incompetence. Joe threw out some good suggestions.

 

I called 2 shops about getting my roller rockers checked, I am going to have to take them the car so they can physically see it. However they both said that if there was something wrong with the rockers i would hear it rattling. what type of valve adjustments should i be looking to do?