[Navy Horn 16]

Last year, I put a "fresh" 469 in the Trans Am. It's a 1970 455 block, 40 over, forged everything, just a hair over 10:1 compression, with an uncut RMP Performer Intake, 800cfm Q-Jet (from Jet Industries). 1.75 inch headers, into 2.5 inch exhaust, TH350 and 3:42 gears. E-Heads from Kauffman, ported to flow 320. This cam with 1.65 roller rockers:



That made 379.82hp and 384ft/lbs of torque. (all numbers listed here are rear-wheel) Since then, I've made the following changes:

Added a HSD intake that is within .010 of port matching the heads (and a 1 inch spacer). Both intakes require the WFO-1 drop base air cleaner.
Replaced stock HEI with D.U.I. unit, 14 initial, 35 total degrees of timing.
Replaced TH350 with an Art Carr 200 4R
Swapped the Chevy Truck Q-Jet for Pontiac unit from a 1970 GTO, performance built by Quadrijet Performance LLC in Texas.
Installed 3 inch exhaust cutouts (Doug's) behind the headers.

I did three different types of runs at the Dyno (the same chassis dyno as last year, same settings).

I started out on pump gas, 93 octane with the exhaust dumps closed. I've got full dual exhaust with X pipe and flowmasters. That put up 389.91hp and 391.45ft/lbs. That was an increase of 10hp, and about 6ft/lbs increase over the previous year.

I followed that by opening the exhaust dumps and the numbers jumped to 403.15hp and 407.11ft/lbs of torque. I made the exact same torque at 4000rpm which was the previous peak. That continued to climb to about 4400rpm which was the new peak. I made more torque than the previous peak all the way from 4K-5500rpm. So I didn't pick up a spike, it was a broad increase.

Finally, I added 4 gallons of 100LL to the tank. I had filled up before I made the trip to the dyno, and 4 gallons is all that I could get in. That bought me 4hp up to 407.33, and half a foot pound of torque to 406.62. The run with 100LL was consistently about 5hp (and up to 10hp) higher than the 93, though the peak only showed a gain of 4. I don't know if that is a function of octane, or displacing some of the 10% ethanol with 100% gasoline. We all know the "power penalty" of ethanol. I'm pretty sure this proves it.

For a street car that makes a couple trips to the strip a year, I'm pretty darn happy with those numbers. I know that I gave up some power going to the overdrive transmission, but I more than made up for it with the upgrades in intake and exhaust. The D.U.I. has really made the acceleration and power band smooth, and starting a lot easier. I'm probably cam limited at this point, and I'm traction limited on the street as it is. Chasing extra hp in a street car is kinda pointless when you can't hook up with properly inflated drag radials.

I'm looking forward to getting it back to the strip later this summer.