Rekeever

So I finally got the truck dyno tuned after the cam swap. It's a different animal. However I something just isnt adding up.

Break down of my rig. 4.8L 220/224 .581 on 114 and yellaterra rockers. 6 lbs of boost from a blow dryer like maggie MP112. 1 3/4 long tubes no cats and dual 3 inch exhaust bullet mufflers. Turning a T56 through a Spec stage 3 and lightened flywheel.
4.56 gears and a truetrac wrap up the driveline.

Anyhow on a dyno jet it made 418 rwhp and 402 rwtq on the 20s if that matters. I was happy with the numbers considering the canned maggie tune after the cam swap only put down 323. 100 rwh gain from a tune seems crazy to me but over 9 pulls that was the finish.

Finally got to the track on some drag radials 305/45 18 ET streets. First time the truck felt like it was doing any kind sticking.
1st pass They waved the left lane off for failing to stage and I missed half the tree barely got on the 2 step I had set to 2600. 2.2 60 ft 13.89 at 100
2nd pass Good stage .067 RT bumped 2 step to 3k and did a 2.15 60 ft 13.88 at 100.
3rd and final Good stage .127 RT 2 step at 3200 2.13 60 ft 13.83 at 100.

It's consistently disappointing. Could be great in bracket racing but I thought she would be pulling a low 13 maybe a 12. What am I missing here. Truck never seemed to spin. Maybe a half a rotation if anything.
Never scaled it but it's a RCSWB with no spare or jack. PW and locks. Is weight the issue? Or is the dyno a liar? It was really hot and humid tonight though

GMCtrk

iTrader: (27)

Trap speed is definitely well low for the stated power.

My guess is IATs were pulling a ton of timing.

George C....

Remove the rockers and install lighter stockers, you may be seeing valve float

Rekeever

No valve float I had fear of that when I put them on. I know what it feels like. And you can see it on a dyno graph.

Rekeever

I know when I popped the hood to cool it and adjust the 2 step it was real hot. Nearly burned my hand on the brake booster.

Rekeever

I'd really like to bring down my 60 ft times. Right now I have worn out Monroe shocks and shackles. Would pulling the overoad and adding some traction bars get me out of the hole faster?

gamble686

iTrader: (3)

Sounds like heat soak is killing you. When iats get high you are gonna loose a lot of power. Are you using the Maggie heat exchanger? Also have you looked at getting a phenolic spacer? A larger heat exchanger from frozen boost and the phenolic spacer will make a dramatic difference.

Rekeever

I am using the maggie heat exchanger still. I will look into the frozen boost version I thought about it once before. What is the phenolic spacer?

During the dyno tune IATs were below 130. But it was only 72 out and humidity was low. Last night at the track it was pushing 90 and had flash floods the night before.

Bluecollar Hotrods

iTrader: (18)

Are you racing at a high altitude track? I wonder what the DA was...

Rekeever

No I'm in Oklahoma it was hot and humid I don't know the D/A but this isn't Colorado