‘70 Eldo Dyno - 480+ HP (Street) 525+HP (Pro/Street)

The base engine for test mule #2, essentially built to ‘70 Eldorado specs, at 10:1 compression, similar assembly to the 8:1 test mule. The short block features Cad Company's direct replacement forged rods with ARP fasteners, and a balanced rotating assembly due to higher RPM testing to be done later, and was built using:

Bone stock it pulled 323 HP and 504 Ft-Lb of torque, about the same as the stock 8:1 with the CTA 120 cam, thoroughly dispelling the myth of the 200+ HP difference between the ‘70 Eldo engine and the later smogger engines.

Keep in mind the factory rating system was changed in ‘72, and all previous engines were severely over rated, as the calculations didn't take into account things like friction, and assumed impossible conditions such as 100% volumetric efficiency, and peak HP at 4400 RPM (200 RPM above stock valve float?)

As the milder combos follow a pattern, we will skip the repetition and get to the meat and potatoes of this test. The step-by-step changes made to Mule 1 were repeated, with predictably similar results, resulting in a pull of 449 HP and 565 Ft-Lb. That shows what compression does for the milder combos, but from here on out the 10:1 engine has a clear advantage. Stepping up to the SS 300 T cam (Pg 12), which can still be tuned to idle relatively smooth , and is not a monster lift spring or piston killer, gave us boosts of 28 HP and 10 Ft-Lbs, for a reading of 477 HP and 575 Ft-Lbs.

At this point, the Holley (Pg 22) finally de-throned the Q-jet, with a gain of 3 HP and 6 Ft-Lbs, for a final power output of 480.1 HP at 5200 RPM and 581 Ft-Lbs at 3900, though it was still pulling strong with 473.4 HP and 452.4 Ft-Lbs when we quit pulling at 5500 RPM.

Other Tidbits -

Before retiring mule#2 from the dyno, we slipped in our new P/C 625 cam (Pg 12), reaching 508 HP at 5500, and then swapped in the PCIV intake (Pg 21) and a 1050 Dominator for a best pull out of 3 weeks at 527 HP at 5600 RPM and 591 Ft-Lbs at 4000 RPM. This would make a great Pro-Street combo, though it is too hairy for many folks taste, to be driving on the street. It would want around a 2200-2400 stall converter or a manual trans, and most likely wouldn't run your vacuum power brakes (9" at 1000 RPM idle at 5000 Ft Altitude) without a vacuum canister.

Windage:
The Caddy has a big arm, and with it comes windage. Installation of our exclusive PC7 oil pan (Pg 17) brought a gain of 12 HP and 20 Ft-Lbs at 3000 RPM and 10HP/ 14 Ft-Lbs at 4000 RPM. The new aluminum pan has similar windage characteristics (Pg 17) as well.

The carb thing:
Throughout the testing, we tried a number of aftermarket carbs in the 650-850 CFM range, as well as several Q-jets. All were tried as shipped and with 2 jet changes (2 really big jet changes in some cases - like 8 sizes worth, just to get it close enough to run). Throughout the testing, the Q-jet (Pg 22) prevailed, though in the larger combos the 850 CFM Holley 4781 stayed close to the Q-jet. Once we were almost at the limit of the tame street motor, with the 300T cam, etc.., the 4781 came into it's own and beat the Q-jet, but in a daily driver you would likely be paying for your 3 HP with decreased part throttle response. All of the new aftermarket carbs tested need leaning out considerable just to get in the ballpark. Keep in mind that carb manufacturers are catering to the masses, and the 500 gives the carb a much stronger vacuum signal than most engines, therefore needing smaller jets.

Though we have yet to dyno test it, we have adapters for mating OE Chevy 454 TBI to your Cad.

We did try large tube headers (2+", using BB Chevy headers with the header flange kit (Pg 28) once we were in the 500 HP range, and lost 3 Ft-Lbs without gaining HP.

On the first runs with the 8:1, we were running regular unleaded. With a switch to premium and retuned, we were within 1 HP for most of the power curve. The 10:1 was only tested with premium