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ss396si 09-02-2009 06:12 PM

383 or 406 small block?
I have a 69 chevelle STREET car w/ a TH400 and 3.73 12 bolt in the back. I want to build a 450-500HP motor,my original plan was a 383 stroker. I spoke to an engine builder he suggested a 406 small block to be more reliable because of a bigger displacement. I would like to know is a 406 a better choice over a 383 for reliablity and performance?

FmrStrtracer 09-02-2009 06:27 PM

The more cubes you have, the easier it is to reach your goal.

If you were to build 2 motors, identical except that one was a 383, and the other was the 406, the 406 will make more power across the entire rpm range.

Choosing the larger motor allows you to attain you HP goal at a lower projected RPM than the smaller 383. (They both use the same stroke crank)

Achieving you power goals at lower rpms means less stress on the internal components, which usually translates into longer engine life.

If you can afford an aftermarket block, you could go larger than 406(427-454 small block)

ss396si 09-02-2009 06:37 PM

Bigger displacement is key to power and realibity. I was looking into the Dart 400 small block or the Motown 400 both can be bored to a 406 and the Dart is a little cheaper. If I'm spending all this money I want realibity and HP. So a right foundation is important.

Blazin72 09-02-2009 06:49 PM

I don't think you need to fork over that kind of cash for a new block if you're going for 450-500 hp? I dunno, maybe you do. But, if you're gonna buy one of those blocks go with a longer stroke than 3.75". I think those blocks are good for at least 3.875" or possibly even 4.00". Keep the block at 4.125" to start with and each subsequent rebuild you can punch it out a little more and your engine will get bigger and bigger. Either the Dart or World Products block can go to 4.200", I forget which it is but that leaves a lot of room and it could quite possibly make it the last engine block you'd ever need.

Chevrolet4x4s 09-02-2009 09:54 PM

No experience with a 303 but I'm very pleased with my 406

TorkMonster400 09-02-2009 10:05 PM

I originally built my 406 because I hadn't seen a lot of them running on the streets around here, but now it seems everyone is doin it :mwink: I like the idea of a small block that kind of impersonates a big block when it comes to putttin numbers to the pavement :thumbup: Take your time which ever you do. Remember do it right or do it twice!

techinspector1 09-03-2009 01:12 AM

If I were gonna start with a Little M block, I think I'd go with a 4" arm in it and make a 427. (4.125" x 4.000") Go big or go home. :thumbup:

my87Z 09-03-2009 07:58 AM

i dont really agree with buying an aftermarket block, if all you plan on making is 450-500hp, they are typically used for high cube (421+) and high power output applications, the 383 is likley going to be cheaper and easier to build, simply cause finding a good 2 bolt main 400 block isn't easy, but the 400 will make more power due to the extra cubes

someone made the claim that the 400 would last longer due to the fact that is would make its power lower in the rpm range, this is false, they both have the same 3.75 stroke, there rpm ranges with be next to identical, but at any given rpm the 400 will make more power. "there is no replacement for cubic inch displacement" i agree with tech insp 1, if i were to buy an aftermarket 400 block it would deffinetly be 427cid or larger and my output goals would be much higher

OLNOLAN 09-03-2009 09:26 AM

Hmm, What Engine ?
Hey Friend, Lots of good feedback here. I like the way blazer72 thinks, if you're gonna spend the bucks, go with the smallest bore first. This leaves room for boring,insuring future rebuilds. If you go biggest bore, it's a one life cycle engine. I checked out your photo's, nice chevelle. Just another opinion, but if it was me and I had the bucks to buy a new block and such, you could probably build a big block for less than the aftermarket small block. The look of your Chevelle is just beggin for a big block with real quiet exhaust. A wolf in sheeps clothing, ultimate sleeper car. Think about it. olnolan :mwink:

ericnova72 09-03-2009 09:38 AM

Also, you don't need the Little M at the power level you intend. Dart's new SHP block will suit you fine. It is rated by Dart at 600 hp but has already been tested well beyond that (800+). About $800 cheaper than the M.

bentwings 09-03-2009 12:25 PM

Even though I like the SBC for this one I'd go with the big block. You can get a crate 454 that will make 450 hp easily. You can even get a crate 502 for a little more. A 427 SBC will be in the same game as far as cost as the big block at this hp level.

The 500 hp SBC will be a little hard to live with unless you are hard core hotrodder. Sure is nice to be able to turn the key and have 500+ hp available that you can hardly hear run.

Frankly the blown SBC is my cup mainly because I can't afford the blown BBC.

ss396si 09-03-2009 12:34 PM

The Dart SHP is realitivly affordable, the block is tested at high HP ratings. I figured its a great foundation than looking for a block (which I did, a 1970 350). I did consider a big block, I need the springs changed new fuel,power steering pump etc etc. It's cheaper for me to stick with the mouse.

Soto SS 09-14-2009 05:13 PM

383 or 406 small block
I currently building a 406 with a 4340 forged scat rotating assembly and a set of 195 AFR heads. It will go in a swb Chevy stepside. I started building the 383 stroker and mid stream changed it for the bigger cubes. I got the DART SHP block 31161211 thru summit racing on special financing. 12 months NO INTEREST plus tax-free. This set up is a bullet proof street ride. It will be transferring the power through TKO600 to set of 4.56 gears. Man I can't wait to cruise it to the local hamburger joint where hot rodders hang out. You can get this same block already to go on Ebay through tim allen motorsports.


SBCfan04 09-14-2009 06:14 PM

i was actually thinking the same thing, i had parts and plans all picked out for a 383 small block and figured why not build a 406(had the block layin around) the 406 on a desktop dyno made more power than the 383 with the same parts. the parts i put together net a 430 horse and 525 ft lbs. i have it in a 78 gmc jimmy (6200lbs dry) the engine moves it like it a smart car....i dream what it could have done in like a GTO or any muscle car...

406 all the way

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