My original plan was to put a 454 in her. Stock bottom end. 9-9.5:1 CR. Aluminum heads, intake manifold & carburetor. 500+ HP with smooth idle on 87 octane. Can you get that kind of HP out of a LS with smooth idle on 87 octane with out using nitrous, turbos or blower? And if you can do it with an LS how about doing that with a 350 since I already have the engine. Of course I would need to stroke it and heads and such. Thoughts?

 

Given 500 crank is closer to 400 at the tire, what LS are you looking at using?

A cammed 5.7 ls1 can easily get 400 whp but it likely wont be on 87 oct and will have choppy idle, however good tuning can make it drivable.

add ported heads and intake to the ls1, you can come down in cam size and make that kinda of power much smoother and maybe even on low octane.

a 6.0 lq or ls based deal would better. My fav would be ls3 or l92 heads. Ls3 intake. Easily get there on a mild cam and likey be ok on 87 gas although 89-93 would be better with any performance vehicle

cubes typically help here, low comp needs air volume to make power and that you get from inches. A good late model 454 with some head work and a cam and good intake should be able to get there and do it on 87 gas. David Vizard bbc books cover this i believe and also look at mark jones, i think vortecpro on other forums like chevelles.com, speedtalk, etc. good bbc sources.

 

[QUOTE=Orr89RocZ;6474311]Given 500 crank is closer to 400 at the tire, what LS are you looking at using?

Yep, 500 at the crank is what I meant. The bigger LS for sure depending availability.

A cammed 5.7 ls1 can easily get 400 whp but it likely wont be on 87 oct and will have choppy idle, however good tuning can make it drivable.

add ported heads and intake to the ls1, you can come down in cam size and make that kinda of power much smoother and maybe even on low octane.

a 6.0 lq or ls based deal would better. My fav would be ls3 or l92 heads. Ls3 intake. Easily get there on a mild cam and likey be ok on 87 gas although 89-93 would be better with any performance vehicle

So you think I could get that HP with my 350 with a aftermarket aluminum heads? Stroking it to a 383 I'm sure would help but then the CR might be to high for 87 Octane.

 

why the 87 octane limitation?

 

Because if I have to run premium I won't drive it as much. 87 is high enough price wise. And it can be fairly easily done with a 454. Tring to find out now in stead of later when someone tells me "you should have...."

 

A carb’ed 454 swap would probably be easier to swap in than doing the LS pathway, however I would think overall drive ability of the LS would be better and more reliable. The beauty of the LS is modifications to increase power are almost limitless at this point. You could build a streetable 700+ hp motor probably easier with an LS than with a 454.

 

You're not gonna get 500hp from a smooth-idling, 9.5:1 454...

 

Consider all of the other costs associated with either swap. They may offset the difference in fuel price.

 

Yosemite Sam has a 454 that gets 10 miles per gallon and the fuel costs $4.50 per gallon for Regular.

Porky Pig has an LS3 that gets 15 miles per gallon and the fuel costs $5.10 per gallon for Premium.

How much does each spend on gas to drive 1000 miles?

 

I don't know anything about the electronics on an LS so that would be challenging to say the least. But I understand why it is so popular, well somewhat. 95% of my driving is a 2 lane road out in the country going 60 mph, rpm 1700 so I need a torque converter that locks up before that so that's the reason for the smooth idle. Thanks for all the responses. Keep em coming.

 

https://vortecpro454.com/

check out some of his builds. Hes got 467’s that make 517 hp with a nice simple 228 deg cam, very good manners

 

Do you need either then? If this car is just a cruiser, and MPG's are your biggest requirement, I'd keep it stockish.

 

you should be comparing low rpm torque for that kind of situation instead of hp. a 500hp 454 will make much more torque down low than a 500hp 5.3 ls or whatever.

 

I know. The 454 has massive torque.

 

So does a well built 383 or 406 without the big blocks pork. My 383 makes nearly 450 tq at 2,000 rpm.

 

Stall speed while cruising really does not matter if you have a lockup converter in say a 4L80E. My 2,800 rpm converter in my 85E locks up in 2nd gear and stays locked. Turn 2,100 rpm at 70 mph.