Drag Racing Tech - 1/4 ET and MPH seem off?

So I am testing out my 68 C10 LWB fleetside build. Its a LQ4 6.0 out of a '04 Silverado SS and it has a 224/228 .600 lift cam and comp cams valve springs, upgraded high volume oil pump, and dual roller timing chain. Doug Thorley LT Headers dual 3.5" magnaflow exhaust, STOCK truck intake though.

Dyno tuned made 319RWHP/413RWTQ. The dyno graph shows a very flat peaking HP graph from 4500 - 6600 its just over the 300rwhp mark the whole time and it only has a peak of 19 more rwhp somewhere in the 5800 area, so thats weird right?

Also running a stock TH400 with a cheap summit racing 3k stall which was on sale for like $100 lol. Its RWD with the stock 12bolt posi and 3.73 gears oh and 6lug wheels 275/50/15 street tires on all corners. Not sure on weight but guessing somewhere just shy of 4k lbs from what I have researched about these trucks. Have to shift manually or it will shift waaayy early if left in drive and I'll end up with a 15.1@95MPH or something lame.

Best timeslip was:

60'......2.058
330.....5.721
1/8.....8.780
MPH....80.94
1000...11.459

1/4.....13.681
MPH....98.10

I'm ok with the ET given no drag radials and just street tire but MPH seems really low. Had about 5 other runs all with very similar MPH 96-98mph

I'm thinking the sloppy converter and truck intake is really messing this combo up. Any other suggestions?

I have a trailblazer ss that weights around 4,500 lbs that would run 97-99 mph trap speeds. I think it makes around 310 rwhp. If your expecting to run the same as an f-body, it won't. Your et is quite a bit better than mine.

that seems about right on a truck. like he said. fbodys with that power run about 12-13 @100-110 depending on the normal factors

For your weight and HP the mph doesn't too far off especially if the DA is high. A good quality converter would probably pick you up a lot though.

So would a turbo :D

The numbers/info you posted seem about right for your truck and mods.

hmm guess i just was use to my bolt-on Fbody trapin 110ish.

Not bad at all pushing a brick through the air :)

Not bad at all pushing a brick through the air :)

Lol


what's the weight on that truck anyways op?

Never had it on a scale but from a little bit of research I'm thinking around 4klbs.