Originally Posted by TRBenj
I do not believe that is true. The ZR-450 uses a cam made specifically for PCM, per the engineer I spoke with at length. The cam, intake and different A/F curve (which makes use of 93 ocatane) are the things that separate a 409 and a 450.
That could very well be the case. I wouldn't know for 100% sure. If you talked to a PCM engineer, I am sure you are probably right. I just know that GM offers several variations of the 5.7, 6.0, and 6.2 to the marine industry.
Im not disagreeing on the different hp rating conventions. Ilmore does seem to be the only one quoting the CARB numbers, for whatever reason. I dont doubt the different marinizers put out comparable hp levels when comparing similar engines. It is convenient that all of the Indmar and PCM numbers are low, though. Who actually conducted the CARB testing? Do all marinizers go through this (and only Ilmore chooses to publish those numbers) or did Ilmore take the initiative to have the competitors tested to the same standard they chose? The numbers on the 350 based PCM sure look way out of bed with the way those boats perform (277hp vs. 330-343 stated). I saw the same chart posted at the MC booth at the boat show, I took it for marketing spin. Its not like automotive headers on a dyno will give you real world hp numbers anyways. Like I said, the proof is in the pudding (the way the boats perform).
California air resources board (CARB) sends a technician to pick a few examples of each engine variation to test. They then require that all accessories, and emissions components are on the engines when they are dyno'd. (Following SAE guidelines, which is what the automotive industry is held to) They then record emission, and performance data. CARB is particularly interested in HP levels, because it is a relative consideration for hp/emission performance compared to the actual engine size. CARB testing is done by the engine manufacturer, but under the supervision and guidance of an on-site CARB technician. (Probably cheaper than sending 4 engines, for each engine model, out to California.)
CARB is an independent government agency. I wouldn't think that Ilmore has any pull there....