Small Block & Big Block Chevy Specific Mouse & Rat Motor Discussion & Conversions

450+whp from a 305/350?

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Old 06-27-2007, 11:32 PM
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Default 450+whp from a 305/350?

Honestly, I'd be happy with 400whp NA, that way I could throw a 125shot at it and hit 500whp, but ultimately I want 500whp.

I'm going to pick up a motor sometime soon, 305/350, what should I start with? What should I take it up too? I've seen 383s mentioned quite a bit.

What can a stock block handle, once built I mean? What can a stock block/internals? I'm a previous 5.0 ford guy, it seems about 450whp is the limit on those...

Anyone have a crate motor in mind that I should look for, or should I just build my own setup with a cheap block. I see them all day for a couple hundred bucks. My budget for the engine build is $5k as of now...

So what'll it take for 400 or 500 RWHP? Any years/gens to avoid or to specifically look for?

Anyone got a recipe for me, haha?

Thanks for any and all help.
Old 06-28-2007, 09:44 AM
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Find a late model(87-up) one piece rear main and buld a 383, with semi-stock internals(i.e. hypereutectic pistons, powdered rods, stock crank) you can expect it to hold 450rwhp with relative ease. If you are going to sqeeze forged pistons are a must. An aluminum headed, nicely cammed, 10:1 383 will pretty easily make 500hp and if you want more, step up to 11.5:1 and a solid roller cam and make 550+hp. BTW check out some Hot Rod, Car Craft, and Super Chevy magazines as every month atleast one of them will do a 450+hp 383 build.
Old 06-28-2007, 09:45 AM
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Or go with 400+ cubes and make all the power you want, but thats a whole other story and budget. Good luck.
-Jeremy
Old 06-28-2007, 11:07 AM
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My previous 355 was a 9.75:1 compression street/strip motor with stock truck rods (with ARP hardware), stock crank and TRW forged pistons. 195 cc / 67 cc heads, crane solid cam (under .540 lift) Victor Jr. intake and 650 Holley double-pumper carb. Street driven and raced for 7 years, then the stock crank broke! But I figure I got my money's worth on time lasted and about 320 rwhp through a TH350 and a 3400 stall 10" converter. Put my 3400 lb (with driver) Nova in the high 11s in good air, and 11.teens on a 125 shot.

To duplicate with new (only used parts being crank, rods and block) stuff would probably cost 4-6 thousand depending on labor and what you want to do yourself.

Built a 383 with the only changes from the 355 being 10.7:1 compression, Eagle cast crank and SIR rods, and a 750 Holley HP carb. This made 371 rwhp, and based on my time with it in the last 3 years, I'll never likely build another 355.

If you plan on spraying a good amount, step up to good internals and short fill a 74-later block (earlier ones have higher nickel content, thus stronger).

The engine I have for sale right now (link in my sig) will give you an idea how much it costs (with labor) to build a 550-575 hp pump gas engine that will take 250-300 of spray on top using a stock block.

Good luck!

Derek
Old 06-28-2007, 11:21 AM
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Forget the 305 it is just a debored 350 that was suppose to better on gas and emissions not really a performance motor (It is GM’s versions of Fords 255 V8 of the late seventies). It may be a 5 liter but it really was no chance against Ford's 302 when it comes to modding because of it design small bore longer stroke. Its smaller bore means that the valves are shrouded and don't breath very well. True a 350 has the same stroke but its extra breathing ability means that it can flow enough air to make hp with that stroke not just torque down low.
Old 06-28-2007, 11:55 AM
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A local guy I know has an 01 LS1 bare block for sale for $250, can these blocks be built using all the regular sbc parts? Or what? I figure they are strong enough, and the weight savings would be nice from the aluminum block,but I want to make sure I can still use the millions of cheap parts available for the sbc.

I read that the 85' and up blocks are roller setups, is that true across the board?

What can the physical BLOCK handle, like a 350/4bolt, in terms of power. Not worrying about internals here, just what the block can handle.

My buddy is telling me 400whp, and is telling me to buy a Dart Little M sbc block for like $1500 new and build that, but I don't think I need that much power.

I'd most likely buy a bare 350/400 4bolt main block, or this ls1 block if I can use it carb'd, and then just buy a stroker kit that has forged internals and get the block work sent out and assemble it myself. Get some nice aluminum heads, healthy cam, and other bolt ons and be done with it. I think $4k or less should be plenty.
Old 06-28-2007, 12:02 PM
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LS1's are from a totally different engine family and have nothing in common with SBC except their bore spacing.
Old 06-28-2007, 12:09 PM
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Guess that idea's out, lol. Thanks man.

So would you chose a 350 and take it to a 383 or just buy a 400?

What's the largest sbc in terms of cubes?
Old 06-28-2007, 12:58 PM
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Originally Posted by BAM6i4
Guess that idea's out, lol. Thanks man.

So would you chose a 350 and take it to a 383 or just buy a 400?

What's the largest sbc in terms of cubes?
With aftermarket blocks I think they are into the 48x CID range now. A 400 would be nice but are you looking to use a production 400 block or an aftermarket one? Race worthy production 400 blocks are few and far between now. With a 4.125" bore they do have lots of potential.
Old 06-28-2007, 01:12 PM
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Alot of that depends on how well your heads and intake flow you have a set of so-so heads and an intake. I wouldn't bother going with any kind of stroker because all your going to do is make similar hp that is going to peak lower in the rpm range. Now if you have decent setup I'd choice the 383 people like to say nothing's better than cubes but it seems to me that a 383 gives that perfect combo of torque and revablility and can be done on a budget. There are 2 ways to go 383 though 4.00 3.8 this was what the 383 orginally was from GM itself. What you see today is an overbored .03 over bore (4.030) and a 3.75 stroke GM never made a 383 like this. The 400 uses a 400 block (Not a 350) and it has a much large bore of 4.125 and a stroke of 3.75 because of the large bore the heads breather better but it will cost ya alot more than a 350 based build because 350 are everywhere.
Old 06-28-2007, 03:13 PM
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Although GM currently offers a 383 over the counter because it's a popular size, it was never offered in a production vehicle.
Old 06-28-2007, 06:30 PM
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do a 350 or a 400, add some dart or afr heads and a roller cam and you goal is realistic. my 355 is around the 400rwhp and adding a 150 shot on top of that.



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