I suspect that their information isn't quite correct. Stock engines NEVER made 300 horsepower...... so either the number is wrong, or, the statement that 'everything is stock' is wrong.....

 

My $0.02 - take it for what it's worth...

You need to compare apples to apples, A "Stock Replacement Engine" will be built to the exact manufacturer's specifications and come pretty close to the factory power ratings. A "Crate" engine is tweaked here and there to improve performance over a stock engine on the dyne. Drop it back into a stock application with factory intake, exhaust, emissions, and programming and you'll see improvement over factory, but it likely won't be making the advertised power. That's because most dyno pulls I've seen are done with ideal tuning conditions and no smog control equipment.

As for your question about why people are able to make better power after pulling all the factory stuff off and going back to carburetor, the answer is the elimination of all factory smog controls. Smog controls will be a bucket of cold water on performance on this generation of engines no matter what you do. Modern systems are so much better at controlling things than they were in the 90's and don't hit so performance so hard. The down side of this is when (and eventually most places will) it has to be certified compliant with the appropriate emissions regulations. Technically, removal of factory emissions controls is a violation of Federal law, but since very few people are ever charged, no one really pays attention to it. Don't think I'm a tree-hugger here as I've a truck from another manufacturer that only has the factory EFI left on it and it runs great. Just be aware that there is a potential issue depending on where you live to going back to a carb.

 

Thanks for weighing in. Like I said, I understand that these ratings are done on an engine dyno with no accessories or smog equipment, I just didn't think the hit was that substantial. Essentially, what we are saying, is the the belt drive parasitic loss, combined with the smog stuff, costs 70 crank hp on these motors. (230 factory crank rating for a 5.9, 300 crank rating for crate with same components plus carb). I guess that's just the way it is, it just seems like quite a loss.

I for one wouldn't trade my efi for a carb for 70 horse as it's my all year DD and I love being able to remote start the thing in the winter haha! So I wasn't implying the carb was superior, just baffled by the power difference.

 

Does anyone know exactly what all his modifications were? I dug through all his posts and he annoyingly never once mentions everything. He offhandedly mentions an intake and exhaust once, talks about cams and keg mods and manifolds, but there's no way to know for sure exactly what he had on the truck for that dyno run just by looking through his posts. I for one would be highly interested in knowing the combo!

 

Possibly

 

What is the stock throttle body rated(CFM)? 500 if recall correctly. Most guys are going to put on a larger cfm carb than 500. The stock kegger is better for low rpm power so removing it and replacing it will bring up the power band. Stock tune in the pcm is another issue.

 

Valid points. The advertised numbers are generally peak numbers. I can build a motor and get truly stupid horsepower and torque numbers out of it, but, it will be completely useless in a truck, and not anything even remotely resembling "streetable"...... So, it isn't just how much, WHERE the engine develops power is actually even more important. 1200 horsepower at 6100 RPM won't do you any good at all.

 

how bout his address and phone number?

all i had to do was google his name...

posted it and changed my mind... he's seems like a very nice and most likely private guy.

cool shop though and mopars everywhere, even has his own wrecking yard lol. david was right though... bfe

 

Yeah, that's why I mentioned an email. I don't want to call the guy or send him a letter, haha. That's too invasive, good call.

 

If the stock heads only flow like 180cfm wouldn't upstream improvements not matter very much. As I recall, the keg and heads both flow about 180cfm and the stock tb should easily supply more than double that, so it seems like a waste of time. This might not be the case, I don't have a fully developed understanding of the details of engine physics.

Again, fair point. It might be revving 1000rpm higher (totally plausible) and trading a bunch of area under the curve. This, combined with the different way they are tested (no accessories), the smog stuff, and the stock tune all come together to pretty much explain the difference.

Thanks guys.