vortec 8.1L 496ci VS. vortec 7.4L 454ci

[smithkid1996]

A well built 454 with a good set of ported heads would be a great engine. The 454 engine is a staple of the HD towing world but seems to have a mish-mash of low performing parts in the late model vehicles. A good RV cam would be a plus, too. The 496 is cool in its own way but I'd steer clear considering how easy a 6.2L swap could be.

true....

[88RCLB]

In my experience an 8.1 does the same on fuel, so you can take that out. None of them are going to get better than 12 without a lot of very careful driving in a very light truck so I wouldn't worry myself about that.

The 8.1 has a lot of potential but it's limited by the throttle body. They just can't flow enough air to support the higher RPM. Also, the marine world has tons of horsepower parts but they say marine so they cost more, a lot more. They're a great motor if you leave them stock, with maybe a cam that emphasizes the low-end. But they can put a serious drain in your wallet if you get into them.

If I did a 454 I'd actually go back to a carb. The 96+ vortec doesn't make that great of power, and the tbi's are anemic. I'd build a vortec one and put a good sized carb on it myself.

[FELONIOUS]

How are you saying that the 496 has less aftermarket available than the 454? They are both BBC...

[Paulster2]

Just get this block as a basis and call it a day ... can anyone say 763ci?

[daddy's_playing_again]

Well actually the 8.1 and the 7.4 are essentually the same block. The difference is in the stroke. The 7.4 has a 4" stroke. The 8.1 has a 4.25 stroke. Both have the same 4.25 bore. Dart makes heads for both. If one was to take the 8.1 and bore it .100 he would have a 505ci motor. The biggest question is in the avalibility of cam, intakes, and TB's to support that. In the carbed old school world those are monsters!!! They will acheive 850hp and around 7500 to 7800 rpms with little effort. In the new injected age, I'm not sure if the parts are readly avalible to acheve the same results. With a carb you would need a 1150cfm to 1350cfm (Dominator) to really feed them properly. It stands to reason someone out there could cut a decent cam for one of the newer versions. Now all thats left is intake and TB. Find that and you have a sb eating beast.

[screaminchicken]

My dad has a Marine 8100 in his 78 GMC motorhome and it rips good and gets 11mpg driving VERY nicely