Fast355

Here you go guys, messed around with the tuning this afternoon on a Mustang dyno. Dyno has been verified to be 10% lower than a Dynojet. This is 3rd gear with the torque converter locked, commanded 3rd/Lockup at 30 MPH and 1,500 rpm. Engine is the stock long block save for the LT4 cam, 1.6:1 roller rockers, and LT4 valve springs, retainers, etc. Has stock manifolds (tired of cheap, leaking shorty headers) on it again, stock HD truck sized exhaust, highflow cats and magnaflow muffler. The intake manifold is stock, has the GM MFI injector upgrade, a reworked stock throttle body and an 0411 PCM swap with HP Tuners. Also ditched the mechanical fan, added a pair of E-fans and an underdrive pulley I found on Ebay. I think its making decent power for just a little L31 350. An average of 275 RWTQ from 1,500 to 5,950 atests to that. 281 RWHP @ 5,540 and 295 RWTQ @ 4,440 with 240 RWTQ from 1,500 rpm the LT4 cam advanced 4* is anything but gutless in the bottem. Run #2 was made heat soaked, immediately after Run#1, E-fans roaring on high fan speed trying to keep the engine from going above 180*F. The IATs were very elevated on run #2 and it was causing the ECM to retard the timing about 4-5*. On a Dynojet it would read around 310 RWHP/330 RWTQ.



350 Vortec Start - YouTube

CCrowell2

Not bad numbers at all.

Fast355

Someone swapped cams to a mild Comp 4x4 XE based torque cam, added a home depot CAI, and switched over to the marine L31 intake. Since the previous dyno I pulled out the 2nd 4L60E POS and replaced it with a 100K mile stock, junkyard pull 4L80E using a B82 4.3 G-Van converter. Also swapped in a 3.73 geared 9.5" corporate 14 bolt rear end. So its making more power, despite having much more drivetrain loss.









Next up are these babies!



The guy that will be building the exhaust system to match these will also be mandral bending me a 3.5" aluminum intake to match the bends of my Home Depot intake and I will be switching to a composite 5-pin 5.3 MAF.

Vortec350ss

iTrader: (20)

Wow those are awesome numbers for an L31!!

Who makes the headers?

Fast355

Doug Thorley made those but they are currently not being made. I tracked down this set on Amazon.

It runs well but I am in search of more. The original engine had 906 heads on it, the crate motor has 062s. It has never run as well as the original engine. I recently stumbled across an independent flow test of the Hecho en Mexico 062 head and they barely touch 220 cfm on the intake flow. A full 20 cfm lower than the 906s flowed before they were ported.

I am considering adding a set of 1.7:1 rockers to offset my .458" lift cam and swapping to ETec170 heads and going for 370+ rwhp NA.

Fast355

Got to my 370+ RWHP number.... With 374 RWHP @ 5,600 and 368 RWTQ @ 4,900!!!! At only 2,300 RPM where the pull started it was 330 RWTQ and at 6,500 it was still over 350 RWHP. Feeling it will get 4.56s for sure now, rather than 4.10s. I think it would also like a little more stall than 2,200, but with that much grunt everywhere its hard to say.

Box stock Etec 170s, Doug Thorley Tri-Ys, 3" thunderbolt metallic core cats, 2.5" DI/ 3" SO 22" case magnaflow, 90mm LS1 throttle body and a comp cam 271/276 @ .006, 215/220 @ .050 , .534/.544" lift, 114* LSA, 110* ICL

Vortec350ss

iTrader: (20)

its great seeing these old vortec's perform. I wish I had known more when I owned my 2 door tahoe. I could have had fun with that. It was a slug when I owned it though.

Fast355

This level of performance never would have been possible without the addition of the 0411 letting the engine get above 5,800 RPM and the tuning options it opened up compared to the 1997 black box. The marine intake and doug thorley headers really helped bring the heads/cam to life.

outlawz2004

iTrader: (18)

and another dyno sheet that he stole and altered and claimed as his own.
http://www.grandsportregistry.com/dy...liday_dyno.jpg

Quyonmob

Different forums, same sad story.