Starting to Learn on 95 G30 5.7 for Towing

[Fast355]

I messed around with putting the van on the dyno today. Pretty close to the same numbers six months later. If you want dynojet numbers multiply by about 1.10. All runs were with a locked converter and locked in 3rd to eliminate that variable. The ramp rate was slowed down. I wanted to have plenty of time to get a/f readings and the long slow pull is pretty much what happens every time the van hits a hill towing the dyno. The engine is stock, except for the heads, 196 roller cam and a nice ss exhaust.
181 peak was a base line run, I had a few of these runs all within about a hp.
178 Peak was when I multiplied the last three rows of timing numbers in the table by 1.05 and re burned the chip. Yes it lost power! Timing is really close to the stock vortec table listed here somewhere. This mirrors what happened last time when a tried to increase timing for WOT runs. I do think there is a little to be had at part throttle still, but I will save that for another day. No knock retard except for one table cell and that was usually less than 1 degree.
184.5 peak was when I pulled off the air cleaner and ring and let cool to 166. You will see a noticeable jump in the mid range, bigger than the peak numbers. I kept the ring and air filter off for the rest of the tests.
182.8 and 182.6 peaks runs were run hotter to see if the temp was the reason for the hp jump. Just lost a hp or two for the 10 degree jump in engine temp. The run that started late was just that. The sun was on the screen and I was like oh I can go now. Its not a race car. Most of today's work allowed me to pull a little bit of fuel out of the upper transition areas for even better mileage. The hp runs were just a check and then I had to mess with a few things to see if I can improve. I think the jegs power bowl or what ever they are calling it may have some interest next. It already has a 14x3 summit filter.

Good to see you are starting to get somewhere. Torque is finally starting to reach where I feel it should be.

My guess is the stock manifolds just have a strangle hold on your engine. As I said earlier I made 204 rwhp and right at 300 rwtq with a stock 8.75:1 350 TBI long block with nothing more than long tube headers, bored edelbrock 3704 intake, 1.6 full roller rockers and a 454 TBI unit. I had a Caddy TBI bonnet and built myself a custom 3.5" air intake with a large cone filter down by the passenger front wheel well. I was running a GM 85mm maf at that time with the 7427 computer. That stock head/cam L05 engine pulled 200 rwhp from 3,600 rpm to 4,600 rpm with a peak of 204 at a little over 4,300.

My 5.7 vortec with the same cam you are running with 1.6 rockers and thorley tri-ys even floating the valves at 4,500 rpm made 229 hp and 304 tq. Swapped the springs and it made 257 rwhp and 310 rwtq. That was with the stock crappy vortec intake with all the spider junk in the way. Also through a 4L80E and 9.5" 14-bolt.

Both of those engines made peak power at 28-30° of timing at 3,500 rpm and beyond.

Power bowl should help just open up the air cleaner base to match the opening.

I really don't understand your peak torque being at 2,700 rpm. My 5.7 Vortec head 395' roller cam with hood LS6 springs made peak torque at 3,200 rpm and that is about where GM rates the marine L31 for peak toque as well. Maybe your cam is sitting in the engine advanced from its normal 106 ICL spec.